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  • 1.
    Ait-Ali, Abderrahman
    et al.
    Swedish National Road and Transport Research Institute (VTI), Malvinas väg 6, 114 28, Stockholm, Sweden, Malvinas väg 6; Linköping University, Bredgatan 32, 602 21, Norrköping, Sweden, Bredgatan 32.
    Kurt, Filiz
    Deutsches Zentrum für Luft-und Raumfahrt e.V. (DLR), Lilienthalplatz 7, 38108, Braunschweig, Germany, Lilienthalplatz 7.
    Isberner, Alessa
    Deutsches Zentrum für Luft-und Raumfahrt e.V. (DLR), Lilienthalplatz 7, 38108, Braunschweig, Germany, Lilienthalplatz 7.
    Odolinski, Kristofer
    Swedish National Road and Transport Research Institute (VTI), Malvinas väg 6, 114 28, Stockholm, Sweden, Malvinas väg 6.
    Berg, Mats
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Assessing Innovations in High-Speed Rail Infrastructure2023In: Socioeconomic Impacts of High-Speed Rail Systems - Proceedings of the 2nd International Workshop on High-Speed Rail Socioeconomic Impacts, IW-HSR 2022, Springer Nature , 2023, p. 217-233Conference paper (Refereed)
    Abstract [en]

    Innovations in high-speed rail (HSR) have had substantial effects on different stakeholders within and outside the railway system. As part of the European Shift2Rail research programme, several innovative solutions are developed for, among others, improving the HSR infrastructure. The Joint Undertaking behind this research program has set objectives for these innovations in terms of punctuality, capacity, and life cycle costs. With a focus on infrastructure-related innovations for HSR, this paper aims at assessing their impacts in relation to these targets. We review the relevant research literature about the effects of HSR innovations and their assessment. The paper presents a hybrid assessment methodology combing different approaches to assess capacity, punctuality, and cost effects. This contributes to reducing the existing gap that is found in the research literature. Based on a reference scenario for HSR line and collected data from different stakeholders, the results indicate that infrastructure innovations in HSR, being developed within the European Shift2Rail research programme, can contribute to reaching the target set for punctuality. Further innovations in HSR infrastructure and/or other railway assets may be needed to reach additional targets and for more accurate improvement values giving more insights into their impacts.

  • 2.
    Amb, Joel
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Additive Manufacturing: Comparative Analysis and Application in Suspension Design2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Additive manufacturing (AM), also known as 3D printing, has emerged as a rapidly growing manufacturing technique with numerous advantages over traditional methods. This thesis project investigates the application of AM in suspension design. The aim is to explore the advantages of AM, suitable product selection, and the potential for gaining a competitive edge by leveraging AM effectively.

    Through this research, a printable part specifically designed for AM will be developed. The project's results demonstrate the advantages of AM when the technique is harnessed effectively. Merely switching manufacturing techniques without considering AM's value-added aspects is unlikely to yield the desired benefits. However, designing components with AM in mind from the initial stages can unlock numerous advantages.

    The findings of this thesis project contribute to understanding how AM can be leveraged to optimize mountain bike suspensions. By evaluating the advantages and disadvantages of the designed parts, valuable insights are provided for Öhlins and the wider biking industry. This knowledge enables informed decision-making for strategic integration of AM in future product development and manufacturing processes.

    This research underscores the significance of thoughtful design considerations and effective integration of AM to harness its full potential in enhancing the performance, cost-efficiency, and functionality of mountain bike suspension.

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  • 3.
    Bouchouireb, Hamza
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    O'Reilly, Ciarán J.
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Göransson, Peter
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics.
    Exploring the aero-structural-battery energy storage coupling within the early-stage development of life cycle energy optimal electric vehiclesManuscript (preprint) (Other academic)
    Abstract [en]

    The Life Cycle Energy Optimisation (LCEO) methodology is used to explore the coupling existing between an electric vehicle's aerodynamic shape, structural material composition and design, and the properties of its onboard battery's chemistry in order to enable the development of more sustainable vehicle configurations. To this end, a mixed integer nonlinear programming formulation of the LCEO methodology was developed to include the effects of battery energy storage systems on the Life Cycle Energy (LCE) optimal vehicle designs. In particular, the vehicle's battery size and number of such batteries needed over its life cycle were introduced as variables subject to a range and a battery cycle life constraint. The former is derived from the battery-capacity-to-structural-mass ratio of recent production vehicles, while the latter ensures that the batteries' cycle lives are sufficient for the entirety of the vehicle's use phase. Additionally, three lithium-based battery chemistries with varying properties were included: lithium nickel manganese cobalt oxide (NMC), lithium iron phosphate (LFP) and lithium cobalt oxide (LCO); along with a closed-loop end-of-life recycling scenario for the battery materials. The results of the coupled aero-structural-battery energy storage LCE-driven design optimisations demonstrate that battery chemistry and recycling potential have a significant impact on the system's design in terms of overall LCE footprint, battery size and number, as well as aerodynamic shape. More specifically, a change in battery composition was found to lead to up to 12.5% variation in drag coefficient, while battery recycling can on average reduce a vehicle's associated LCE by 32%. Furthermore, battery material recycling was found to decrease the role played by the specific energy and cycle lives of the batteries, and increase that played by their embodied energy. Consequently, the LFP battery chemistry was found to be the best performer from an LCE perspective in the presence of battery material recycling; while the NMC chemistry was found to perform marginally better in the absence of the latter.

  • 4.
    Bouchouireb, Hamza
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    O'Reilly, Ciarán J.
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics.
    Göransson, Peter
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics.
    Schöggl, Josef-Peter
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics.
    Baumgartner, Rupert J.
    Potting, José
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Vehicle aerodynamic shape significantly impacted by vehicle material composition and material circularity potential in life cycle energy optimal vehicle designManuscript (preprint) (Other academic)
    Abstract [en]

    This paper explores how the systemic-level energy consumption of light-duty vehicles could be reduced through integrative design. To this end, the Life Cycle Energy Optimisation (LCEO) methodology is used to achieve the coupled optimal use of materials (including their circularity potential) and vehicle aerodynamic shape to reduce the overall Life Cycle Energy (LCE) footprint of light-duty vehicles, with the results being compared to the lightweight and aerodynamic alternatives. Initially, the methodology is functionally expanded to handle aerodynamic functional requirements through the definition of a novel allocation strategy for the aerodynamic energy, and a parametrised simple vehicle body model that ensures that the LCE knock-on effects of aerodynamically-motivated design decisions are fully accounted for. Subsequently, the methodology is used to perform the first, to the knowledge of the authors, aero-structural LCE-driven design optimisation of a vehicle subsystem, with the impact of the materials’ circularity potential being taken into account through various end-of-life (EOL) processing scenarios, including recycling. The results show that the environmental footprint of light-duty vehicles could significantly be reduced through integrative early-stage design. Specifically, it shows that a life cycle energy optimal vehicle's aerodynamic shape is significantly impacted by the vehicle's material composition and the latter's EOL characteristics — particularly recycling potential. Furthermore, LCE optimal vehicles have been found to be on average longer, heavier and more aerodynamic than their lightweight counterparts, as well as offering up to 20% energy savings per vehicle; while also being shorter and lighter than optimal aerodynamic configurations.

  • 5.
    Boutry, Oscar
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Development of a shock-absorber pre-sizing tool: from vehicle to shock-absorber physical characteristics2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    During the first phase of development of a new vehicle, shock-absorber pre-sizing is a crucial issue as it will have a direct impact on the vehicle behavior, handling and comfort. The shock-absorbers force versus velocity relation has first to be defined properly, then their physical parameters are to be chosen carefully in order to get maximum performance with respect to the target force versus velocity relation. Indeed, two shock-absorbers with almost the same force versus velocity relation can give very different results in terms of comfort when it comes to subjective evaluation. This is particularly true when comparing high-end versus low-end shock-absorbers. This paper focus on the development of a global numeric shock-absorber pre-sizing tool going from vehicle physical characteristics to shock-absorbers ones. First, the target shock-absorbers force versus velocity relations are determined from the physical properties of the vehicle, from its typing, and from objective comfort criteria computed thanks to a half-vehicle simulation with non-linear shock absorbers, and compression bump stops. Then, the physical characteristics of the shock-absorbers are determined from the previously designed force versus velocity relations, and from a shock-absorber simulation together with a genetic algorithm optimization program. This tool, fully developed with Matlab, makes it possible to pre-size the shock-absorbers in an efficient and objective way, and in very few steps.

  • 6.
    Brodén, Erik
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Wheel Wear and Reprofiling Alternatives for Swedish Rc4 Locomotive – Measurements and Simulations2006Independent thesis Advanced level (degree of Master of Fine Arts (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Railway wheels have to be reprofiled or replaced if they do not fulfil certain demands and the costs for these actions can be considerable for the vehicle owner. The purpose of this work is to study wheel profiles at reprofiling through wheel wear simulations and reprofiling statistics.

    The application at hand is the Rc4 locomotive used by the railway freight company Green Cargo. The locomotives travel the whole electrified Swedish railway network but a large part of the traffic is on the lines Malmö-Hallsberg and Luleå-Ockelbo. For these two lines the distributions of curve radius, track quality and lubrication have been analysed.

    The simulation method is based on a load collective concept where the load collective is a discretization of actual conditions such as track design geometry, rail profiles, track irregularities, lubrication, vehicle speed and traction. The discretization results in a number of dynamic time-domain simulations to be performed in each wear step. The time-domain simulations are done with the MBS (Multi-Body-Simulation) tool Gensys. From these simulations the wear is calculated with a program developed in MATLAB, the wheel profile is updated and the next wear step is entered. In the vehicle-track simulations the wheel-rail contact is modelled with the Hertzian theory for the normal contact and Kalker’s simplified theory for the tangential forces. Archard’s wear equation together with wear coefficients have been used to calculate the material worn off from the wheel. The wear coefficients have been determined from dry conditions and to compensate for both natural and manmade lubrication two scaling factors are used.Reprofiling of wheels on the Rc4 locomotive is done in two workshops and wheel profiles and wheel lathe differs between these two workshops. At assembling of new wheels the wheels have the UIC/ORE S1002 profile with flange thickness 32.5 mm but in order to save wheel diameter at reprofiling two different profiles with smaller flange thickness are used. From a wheelset database used by Green Cargo for maintenance planning statistics such as distribution of reprofiling causes, seasonal variations of wheel wear and damages, running distances, life length of wheels and wear rates for different profiles have been extracted.

    For evaluation purposes wheel profiles of three locomotives were measured before and after the first reprofiling. When comparing measured and simulated wheel profiles it can be concluded that the simulation overestimates flange wear somewhat but the shape of the flange is close to measurements. Wheel tread wear is generally well predicted but the shape differs more. The simulation results are also compared, with good agreement, to simple measurements of wheel wear scalars from the wheelset database. For some wheel profiles problems in the simulations with unrealistic cavities at the wheel tread remain to be solved.Through simulations it has been seen that with a slight change of one of the profiles used at reprofiling running distance before reprofiling due to thin flanges can be increased with 95 kkm.

  • 7.
    Castillo Aguilar, Juan Jesús
    et al.
    Department of Mechanical Engineering, University of Málaga, Spain.
    Postigo Pozo, Sergio
    Department of Mechanical Engineering, University of Málaga, Spain.
    Ruiz Mora, Isabel
    Depatment of Advertising and Audiovisual Communication, University of Málaga, Spain.
    Casanueva, Carlos
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Abramovic, Borna
    University of Zagreb.
    Marin, Marinov
    Aston University.
    Aplicación de la metodología basada en Design Thinking para el aprendizaje de conceptos técnicos ferroviarios2022In: XV Congreso Iberoamericano de Ingeniería Mecánica, UNED - Universidad Nacional de Educacion a Distancia , 2022Conference paper (Other academic)
    Abstract [en]

    Professors and researchers from the areas of Mechanical Engineering and Audiovisual Communication of the University of Malaga participate in a European Erasmus+ project called ASTONRail. Among the activities developed during the execution of this project, an intensive course on different topics within the railway field was designed. Students from different universities attended classes on railway safety, infrastructure, operation, administration and management, rolling stock and technology. The session on rolling stock was given by lecturers from the University of Malaga and KTH Royal Institute of Technology. For this session, the methodologies used were Design Thinking, collaborative learning and flipped classroom. This paper will describe the project within which the activity was planned and its motivation. It will also present the development of the activity and the evaluation of the results achieved

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  • 8.
    Cederqvist, Hugo
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Development of validation tool for antenna positioners on vehicles in motion2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Artificial satellites play a vital role throughout the world today. They providea broad range of services ranging from navigation to communication and reconnaissance. As antenna technology is evolving and ground based antennas are getting smaller and smaller, the demand for on-the-move solutions is growing.These antennas can be used whilst mounted on for example, a moving vehicle,where the mechanical performance of the antenna must be sufficient for thecurrent conditions. During this project, a computer based tool that can helpengineers when iterating and optimizing a two-axis gimbal type antenna designwas created. The tool uses simulated and recorded data from road vehicles andboats to calculate the required torque on the two axes necessary to sustain communication with a geostationary satellite. When completed, the tool was easy to use and configure whilst not requiring much computational power.

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  • 9.
    Chatelais, Léa
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Vehicle dynamics modelling of electromagnetic suspensions for MAGLEV applications2024Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    MAGnetic LEVitation Guidance System (MAGLEV) technology was commercially introduced relatively recently in the guided transport field. It is based on removing the wheels and rails of classic railway systems and supporting and guiding the train with magnets and magnetic forces instead. But, as for conventional railways, those trains need to fulfil dynamic requirements in order to make trains safe and comfortable. The dynamics of a train being mainly influenced by its suspensions characteristics, the magnetic forces generated in MAGLEV systems are of prime importance. Having a model of those systems allows to check the requirements of a certain design, and to consider the influence of different parameters on their fulfilment. This thesis leans on research work on MAGLEV vehicle modelling to model and implement magnetic levitation components in a quarter-car model in order to study the fulfilment of vehicle dynamics requirements. Specifically, the modelled vehicles are based on Electro- Magnetic Suspension (EMS) and Electro-Dynamic Suspension (EDS) (Inductrack) technologies, for which the modelling equations are analysed to study the magnetic force dependencies with physical and operational parameters. Finally, the dynamic requirements are checked in response to a set of track irregularities amplitudes, anda parametric study is carried out to verify the fulfilment of those requirements for other design cases. The results show that it is possible to model and implement simple MAGLEV MBS models for dynamic studies, although it is challenging to model and simulate specific MAGLEV components because of the lack of component specifications or experimental data on track irregularities.

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  • 10.
    Chen, Jiaxi
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Lennstring, Jonathan
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Microscopic traffic simulation of free-riding cyclists in downhills2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A key component of traffic models for simulating bicycle traffic focuses on capturing the interactions between cyclists and the cycling infrastructure. One of the most relevant features of the infrastructure that has a significant impact in bicycle traffic is the gradient of a bicycle path. Bicycle traffic simulations are a rather uninvestigated topic since historically, most focus on simulations has been on cars. However, bicycle simulations are an important tool to further investigate and understand cyclist’s behaviour. Therefore, the main objective of this thesis is to investigate and simulate free-riding behavior of cyclists in connection to the gradient, particularly on downhills. To do so, trajectory data of cyclists traveling on a downhill with a maximum gradient of 5.5\% are analysed to identify the impact of gradient on the speed and acceleration. The data received needed processing in order to be useful. This included filtering of the trajectories and excluding the data from cyclists which could not to be regarded as free-riding. As a result, a linear correlation is found between pedaling power and the gradient that can be used in microscopic bicycle traffic simulation. Based on this knowledge regarding this linearity, the approach used for modeling the gradient’s effect on the pedaling power is linear regression. The model can be developed in various ways, so instead of only choosing one model, several were developed and compared against each other. These models are then used for the simulation. The results indicate that the simulation captures well the impact of downhill gradients in a population of cyclists as it reproduces similar speed profiles to the ones observed. Therefore, it can be concluded that a power-based model is suitable for simulating free-riding behaviour of cyclists traveling in downhills.

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  • 11.
    Cisarella, Luca
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Vehicle ride and handling optimization by development of an automation toolchain2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Vehicle ride and handling (R&H) characteristics are one of the key areas of the virtual development of vehicles. The number of relevant model parameters increases depending on the complexity of the model and the use-case. Due to increasing vehicle complexity and topology, it is challenging to achieve key performance indicators (KPI) via a traditional trial & error approach. Optimization tools are required to gain a better understanding of the key parameters affecting the performance and efficiently achieve targets using a structured process. 

    The master thesis describes the development of a toolchain for selected ride and handling use-cases: an automated simulation environment focused on full vehicle optimization that runs all required simulation models and tools, using remote computational resources for heavy simulation runs. The toolchain has been designed during the master thesis project in collaboration between Hyundai Motor Europe Technical Center (HMETC) chassis department, Politecnico di Torino and KTH Royal Institute of Technology. The toolchain has been implemented in MATLAB/Simulink and integrated with vehicle dynamics CAE software generally used by HMETC (based on both multi-body and functional models) and with HEEDS MDO, which provides the optimization algorithm. Finally, different R&H use-cases show the system's reached level of robustness and flexibility. 

    The resulted automated toolchain has been capable of investigating a large number of vehicle variants in different vehicle dynamics environments, while showing the key performance factors and the most influential parameters for improving the vehicle behavior. Accurate constraints and design space definitions provided feasible optimal parameters values, characterized by groups of solutions with minor differences among parameters and comparable KPIs, which help to find different development directions. Finally, the structured methodology proposed by the toolchain has effectively increased the efficiency of the virtual development process, finding optimal designs in a limited amount of time, working autonomously in the background and modifying a large number of parameters.

  • 12.
    Clop, Julien
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Numerical modelling of the pneumatic ejection of a projectile via Simscape2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Numerical modelling and simulation is a key element in the development and implementation of new equipment. This project focuses on the modelling and simulation of a pneumatic system with Matlab/Simulink and the extension Simscape. The development of such a model aims to prove that the physical system works as intended, to test the behaviour of the system under specific conditions, to have a virtual test bench of the system that is time and resource efficient, and to develop new products based on the same concept. This project concerns the creation of a model of a pneumatic circuit and a pneumatic ejection of a projectile, and of a model that simulate the trajectory of the projectile in the air accounting for various initial conditions and aerodynamic loads. The Simscape models created are then parametrised and calibrated by comparing the simulation results and experimental data of the physical system through statistical methods. The validity of the models is tested and their operating range can be evaluated. Outside of this operating range of initial conditions, the accuracy of the models decreases significantly and the latter become unable to simulate the behaviour of the real system. The obtained models at the end of the project can be used to accurately study the behaviour of the real system around its nominal operating point. Some ways of improving the models, in order to increase their validity and robustness, are discussed.

  • 13.
    Collin, Felix
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Predictive Deceleration Control2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    For vehicles equipped with electric motors there exist a possibility to recuperate energy during deceleration. This master’s thesis presents a driver support function, a Predictive Deceleration Control (PDC), that warns the driver when to release the accelerator pedal. If the driver follows the instructions from the function the vehicle will decelerate to an appropriate speed at the upcoming road feature, such as a roundabout. The function should both improve energy consumption and enhance driver comfort. This master’s thesis focused on how such a function can be implemented and a proof of concept was designed in a Matlab/Simulink environment.

    Within the scope of the proof of concept the function should warn the driver to release the accelerator pedal ahead of roundabouts, intersections, speed limit signs and stop signs. With the help of map information and the vehicle most probable path, the distance to the road features could be determined and the predicted braking distance to these road features could be calculated by the function. A feedforward controller was used to control the deceleration phase and was based on a longitudinal vehicle model.

    The PDC was tested both in a Lynk & Co 01 and CEVT’s dynamic simulator and the results proved that the function can be implemented in for example a Lynk & Co 01 without any additional hardware needed. However, it requires software that can provide the function with map information. During the tests performed during the master’s thesis, map information was acquired with a frequency of 1 Hz, but for the function to become more robust a higher update frequency is required.

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  • 14.
    Dirks, Babette
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Vehicle Dynamics Simulation of Wheel Wear for Swedish High-Speed Train X20002003Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A wheel profile wear simulation tool has been used to predict the wheel profile development due to wear of the Swedish high-speed train X2000 running on the railway line Stockholm-Göteborg. The methodology used in this study is based on a load collective concept, where the load collective determines a set of dynamic time-domain simulations depending on what the wheels are likely to encounter when travelling on this specific railway line. Different curves, track irregularities, rail profiles and coefficient of friction define the operational conditions of the vehicles.

    In the load collective the railway line is primarily discretisized based on the curve radius distribution. The largest part of the track is straight track (65%). Parametric studies have been performed for optimisation of the load collective, regarding the simulation time.

    The vehicle-track simulations are performed with the MBS (Multi-Body-System) tool GENSYS and the wheel-rail contact mechanics is modelled according to the Hertzian theory in combination with the simplified theory by Kalker (FASTSIM).

    Since the shape of the wheel profiles affect the wheel-rail contact mechanics and the vehicle’s behaviour, the wheel profiles get updated after each wear step. A wear step is defined as one loop in the main programme and corresponds to a maximum wear depth on the wheel profiles or to a maximum simulated running distance. The maximum wear depth in each wear step has been set to 0.1 mm and the maximum running distance has been set to 1500 km.

    Archard’s wear model has been used for modelling the wear. The wear coefficients used in this model have been determined by laboratory measurements by others. However, all measurements have been performed under dry conditions, which means that for some track parts the wear coefficients have to be compensated in some way in order to represent lubricated conditions. It is determined that on this line narrow curves with a curve radius under 700 m are man-made lubricated which will lower the wear coefficients. Also natural lubrication (weather etc.) will lower the wear coefficients. These compensating factors used in this study were obtained by others.

    Wear due to disc braking has been estimated by using a factor that increases wear for straight track running. Only trailer wheels have been included, so traction has not been a part of this study. 

    The tool has been verified by comparing scalar measures and equivalent conicity of the simulated profiles with measured wheel profiles on several intermediate cars of the X2000 trains running on the railway line Stockholm-Göteborg. Wheel profile measurements were performed from 1991 till 1995.

    Several simulations have been performed with good results, compared to measured wheel profiles.

  • 15.
    Eriksson, Robin
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Rosvall, Gustav
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Auxiliary Heaters for LNG Buses2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In the bus transportation industry, a customer of a new bus has the choice to have an auxiliary heater installed in their new bus to improve its ability to heat up the passenger compartment and other components during cold and/or freezing weather. This is often a non-issue, as an appropriate auxiliary heater could make use of any fuel that is already carried by bus. However, in the case of LNG(liquefied natural gas) buses, this is not trivial as there are no suitable heaters available today that can draw fuel from the LNG tank without risk. This is due to that LNG will need to be vaporized by the cooling system before use, thus taking heat away from the cooling system and risks freezing it. Today, customers must instead rely on less optimal auxiliary heater solutions such as diesel heaters. This master thesis project investigates the possibility to install an auxiliary heater on an LNG bus using products that are already available today and identifies which system modifications are needed to make this possible. To do this, the problems that normally prevent the use of an auxiliary heater running on LNG were identified. Then, concepts were generated that could solve said problems which then could be combined into full solutions. These solutions are verified using thermodynamic theory to show that they would indeed prevent the issues at hand. MATLAB models of the cooling system were also created to demonstrate how the entire system would be influenced by such a change. In the end, one solution is presented as the most viable one to proceed to further development and potentially also production.

  • 16.
    Frimodig, Susanne
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Modelling of Track Flexibility for Rail Vehicle Dynamics Simulation2005Independent thesis Advanced level (degree of Master of Fine Arts (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The railway track is a complicated construction with many components that affect the trains in various ways. The track flexibility is an especially important issue when it comes to train-track interaction, but in simulations many models today do not pay special attention to it. There is therefore a need for a better understanding of this field and what effects the track flexibility has on the vehicle dynamics behavior.

    After investigating some existing track models, this thesis proposes new track flexibility models. For the proposed track models the number of degrees of freedom is a central factor. Some track receptance data from measurements done by Banverket are reported and various parameters' effects on the track's flexibility are assessed. The track data from the measurements are then compared to receptances of the proposed track models.

    A Regina train model is used to simulate runs over a track and the wheel-rail forces are analysed. The program used for the simulations is the multibody dynamics program GENSYS. It is shown that the flexibility of the track effects the wheel-rail forces significantly. The main conclusion drawn is that the flexibility is important and can not be overlooked in models of train-track interaction.

  • 17.
    Fritzell Westlund, Mårten
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Song, Xujing
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Steer-by-wire system safety aspects2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis research the system safety aspects of a Steer-by-Wire system by studying how a driver handles faults in the system. To start with, identification of risks in the SbW system was performed, followed by identification of potential faults with the help of a HAZOP study. Furthermore, an assessment of risk severity and controllability was performed by the use of the ISO26262 standard and its ASIL classification scheme, as well as the safety analysis FMEA.

    A steering feel model, with the possibility to simulate the faults from the risk assessment research, were implemented in Simulink and CarMaker. A vehicle model as well as a test scenario were built for both country road driving and highway driving. An experimental study was done using a Logitech G29 steering wheel where six test subjects were involved. To analyse the experiment results and evaluate the severity of the system faults, both subjective evaluation criteria and objective evaluation criteria were introduced in this study. A trend of severity was seen in the majority of the evaluation criteria, showing the signal delay and reduction in steering gear ratio as the two most severe faults. Finally, some examples of mitigation strategies, such as the use of redundancy, was discussed.

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  • 18.
    Ge, Zhaohui
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Investigation of the comfort improvements by an integrated chassis control strategy2021Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Autonomous driving is one of the megatrends in today’s automotive industry. Passengers are expected to do more non-driving tasks in an autonomous driving vehicle. Therefore, the comfort of the vehicle has become a more important factor for the passengers. This thesis investigates the possibility of increasing comfort through an integrated active chassis control strategy.

    First, this thesis has defined comfort in objective ways. Then, the objective comfort evaluation variables are used for comfort evaluation of the vehicle in different scenarios. The improvement in comfort is evaluated for four active chassis systems, including active suspension, active anti-roll bar, active rear-wheel steering and torque vectoring systems. Since more than one active chassis system can affect vehicle body motion in one direction, those four active chassis systems should be controlled in an integrated way. The model predictive control (MPC) is used because it can control a multi-input multi-output system in an optimized way. Two MPC controllers have been developed in this thesis to control multiple active chassis systems for comfort improvement. The original MPC controller is a linear MPC controller that uses a time-invariant state-space vehicle model. The adaptive MPC controller is a linear MPC controller that uses a time-variant state-space vehicle model. These two controllers are tested in the simulation software CarMaker with various scenarios, such as slalom, double lane-change, and bumps that are both symmetrical and shifted unsymmetrical. Finally, the simulation results are evaluated with objective comfort evaluation methods to assess the controller performances in comfort improvement.

    In conclusion, the model predictive control can be a feasible way to improve comfort with multiple active chassis systems. The simulation results show that the two MPC controllers can reduce the objective comfort evaluation variables. The discussions of the design process and simulation results point out future works that need to be done before this project becomes a product of real vehicles.

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  • 19.
    Giossi, Rocco Libero
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Mechatronic aspects of an innovative two-axle railway vehicle2023Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Within the Shift2Rail research program the goals for a sustainable growth of the railway sector are set. Among these are substantial reduction of Life Cycle Costs, improved reliability and energy efficiency, the reductionof noise emissions, and the achievement of full interoperability of the rolling stock. Therefore, a new generation of running gear is envisioned.

    An innovative two-axle vehicle that can reduce weight, initial investmentand maintenance cost, and emissions is proposed for a metro line system. The vehicle proposed will have only one suspension step. To further reducethe weight and incorporate the otherwise missing anti-roll bar, a compositematerial connection frame is introduced. The two-axle configuration suffers from poor ride comfort, due to the lack of a second suspension step acting as filter, and from poor steering capability, due to the long distance between wheelsets. Active suspensions are therefore introduced to improve both ride comfort and steering capability.

    This Ph.D. thesis showcases the key activities undertaken during the developmentof the innovative vehicle, building a simulation framework where the vehicle can be virtually tested. Several modelling environments are used such as: SIMPACK for vehicle dynamics, Abaqus for finite elements modelling, Simscape for hydraulic physics simulations, and Simulink for control logic development. During the Ph.D. time two elements of the mechatronic vehicle have been designed and manufactured, i.e. the carbon fiber connection frame and the steering active suspension. The two components models have been experimentally validated and introduced into the simulation environment. A ride comfort and a wheelset steering control strategy have been designed to overcome the limitations introduced by the two-axle configuration. The proposed solutions aim at being applicable in the whole operational scenario of the innovative vehicle.

    The present work emphasises the possibility of introducing innovative mechatronic solutions as an alternative to standard bogie solutions aiming at reducing costs and emissions, blurring the boundaries between academic view and possible industrial applications.

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  • 20.
    Giossi, Rocco Libero
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics.
    Persson, Rickard
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Wheel wear reduction of a mechatronic two-axle vehicle controlled with feedforward wheelset steering approachesManuscript (preprint) (Other academic)
    Abstract [en]

    The mechatronic vehicle developed within the Shift2Rail projects Run2Rail, Pivot, NEXTGEAR, and Pivot2 is evaluated with respect to wheel wear. The KTH wear model is used to determine the coefficients of Archard’s wear map to reproduce measured worn wheel profiles of the present vehicle running on Metro Madrid line 10. The same wear model is then used to evaluate the performance of the mechatronic vehicle controlled with two variants of a feedforward controller. The first one uses on-board measurements, while the second one is optimized using firefly optimisation algorithms assuming knowledge of the travelled track. The control strategy based on on-board measurements shows improvements above 60% in terms of lost wheel volume due to wear, compared to the standard bogie vehicle. The optimized controller reaches improvements above 70%. Good coherence is found between improvements predicted with the wear number and the ones achieved in terms of lost wheel volume.

  • 21.
    Giossi, Rocco Libero
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Shipsha, Anton
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics.
    Persson, Rickard
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics.
    Wennhage, Per
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Active Modal Control of an Innovative Two-Axle Vehicle with Composite Frame Running Gear2021In: IAVSD 2021: Advances in Dynamics of Vehicles on Roads and Tracks II, Springer Science and Business Media Deutschland GmbH , 2021, p. 8-17Conference paper (Refereed)
    Abstract [en]

    Within the Shift2Rail projects Pivot2 and NEXTGEAR, an innovative Metro vehicle with single axle running gear and only one suspension step is proposed. A composite material running gear frame is developed to be used both as structural and as suspension element. The design with only one suspension step can significantly degrade the passengers ride comfort. Thus, active modal control is implemented both in lateral and vertical direction to increase the performance of the system. The running gear frame is modelled in Abaqus® as well as the carbody. Structural modes of both elements are implemented in SIMPACK®. A hydraulic actuator model is developed in Simscape®, where two pressure-controlled valves are used to control the pressure inside the chambers of a double acting hydraulic cylinder. A co-simulation environment is then established between SIMPACK® and Simulink®. The vehicle is running with speeds between 10 and 120 km/h. Active modal control makes it possible to maintain ride comfort levels of conventional bogie vehicles with this innovative single axle and single suspension step running gear, promising substantial weight savings of about 400 kg/m. The single axle running gear solution with active comfort control developed here can be an attractive alternative to bogies, providing reduced Life Cycle Costs.

  • 22.
    Gustavsson, Daniel
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Movell, Daniel
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Simulation of Movements of Trains for the Purpose of Exterior Sizing (Gauging)2004Independent thesis Advanced level (degree of Master of Fine Arts (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This report is a Master Thesis, which has been made in order to test and verify a new proposed standard on how to design railway vehicles in aspect to its exterior size. The newly proposed standard is called alternative gauging. The project has been done for Bombardier Transportation and The Swedish National Rail Administration (Banverket).

    Rail vehicles exterior size has to be adapted so that the vehicles never interfere with obstacles of the infrastructure and other vehicles on adjacent tracks. This could be done by allowing large clearances by designing slim vehicles but this does not make efficient use of the available space. The clearances between vehicles and obstacles must allow for movements of the vehicle in particular due to vertical and lateral movements in the suspension. The process of exterior sizing in Sweden has up to now (2004) mainly been based on conservative geometric considerations assuming that movements are the largest possible to suspension stops etc. By tackling the process differently it should be possible for the vehicles to use the available space given by the infrastructure more efficiently. The newly proposed standard uses more realistic assumptions and it is based on two methods for calculating movements. The first one is based on dynamic simulations and the second one on geometrical formulas. These two methods need to be verified in order to prove their suitability and validity. Verification and further development of the new gauging procedure is the purpose of this thesis.

    This study has been done with two types of vehicles of very different types: Regina, a regional high-speed train and Laaips962, a two-axle freight wagon. The resulting movements given by formulas and simulations have been compared with a reference contour, in this case a so-called dynamic envelope, which shall include the vehicle and all its movements.

    A comparison between the results from formulas and simulations has been made. It was desired that vehicle movements from formulas should be a bit more conservative in the sense that they would give slightly larger movements. Using the original formulas and procedures in this investigation, this requirement is not always fulfilled. Therefore a few slight modifications to the original formulas have been proposed. Furthermore, in order to receive smaller and more realistic simulated movements the cant irregularities should be scaled to what maximum allowed is according to BVF 587.02 instead of being scaled with the same factor as for the vertical irregularities. Also, in order to avoid exaggerated simulated movements, it is recommended to calculate the movements of an evaluation point in relation to an average dynamic envelope determined from the track position from -5 m to +5 m from the evaluation point to avoid that very local irregularities shift the reference contour. Finally, calculation of vertical movements, including suspension, and wheel wear, should be further developed and clarified.

    Most important of all is that the proposed standard is useful and reliable in all cases tested in this study.

  • 23.
    Gürsac, Isabelle
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Klimantovich, Tsimafei
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Research and Analysis of Suspension Dynamics of an Autonomous Bidirectional Road Vehicle2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The bidirectionality of road vehicles is a novel research area, which is directly connected with autonomy, efficiency, flexibility and sustainability of transportation. The research in this area is mostly performed with stringent restrictions in corporate secrecy. This fact makes the area publicly unexplored, moreover highly future oriented.

    Since so little information is publicly available about bidirectionality in road vehicles, the Master thesis project was proposed by Scania CV AB to the students of The Royal Institute of Technology (KTH). This thesis topic will focus on the suspension systems investigation as well as touch upon drivetrain systems. The main objective for this project was to find the relative importance of the different suspension angles for a bidirectional vehicle, additionally to study the settings of the suspension angles for such vehicle. The study of suitable suspension systems and drivetrains was performed with tailored requirements from the corporate side of the project. 

    The investigation was performed as a complementary study of the possible technical solutions for a bidirectional vehicle. This included a study of suitable suspension and drivetrain systems, analytical 2-Dimensional analysis of the selected suspensions with a further investigation of one of the systems in multi-body simulations software Adams Car from MSC software. With a later, more detailed, analysis of bidirectionality implications based on the built simulation model. Ending the project was the study of relative importance of suspension angles in bidirectional vehicle with subsequent discovery of the best performing angle setups. 

    This thesis project provides a comprehensive introduction to the topic of bidirectionality of road going vehicles with an outlook for further investigation of the discovered suspension setups and their optimisation in urban delivery vehicle environment.

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  • 24.
    Hesse, Carl
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Performance of Simplified Carbody Tilt – Simulations of the Regina 2502008Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis work is performed at Bombardier Transportation in order to evaluate previous work in the field of simplifying the tilt system on a high speed train. The system is modelled in the multi-body simulation program Simpack. 

     Current tilting systems are rather expensive, approximately three to six per cent of the total investment; therefore the aim is to investigate the performance of a simplified carbody tilting system. The simulations are connected to the Bombardier Transportation electric multiple unit Regina 250 intercity train, R250T; however the results are meant to be adaptable also to other rail vehicles. The main priority is to investigate whether the subsystems are appropriate for carbody tilt. The subsystems of special interest are the force controlled actuator and rubber-steel laminate springs.  

     The system is designed for 245 mm cant deficiency, the maximum allowed in Sweden. 0.8 m/s2 of lateral acceleration is allowed on the passengers in the middle of the carbody and the actuator should work at a maximum quasi-static force of 25 kN. All of the above criteria are fulfilled during normal operation in all types of curves tested. 

     The model has been tested with three different heights of bolster centre of rotation to suit different vehicles. With the lowest value of the centre of rotation the system response is not acceptable. This can be cured with stiffer tilting elements; however this will need an actuator with a higher force output. The R250T is regarded as safe in all tested cases, e.g. normal service, failure scenario and snow packing, as concerns risk of derailment.  

     The rubber laminate springs give the vehicle good ride characteristics regarding tilt angle. It is highly plausible that a rubber spring with the required characteristics can be built; there are existing elements which closely match the needed characteristics used on rail vehicles today.   

     The force controlled actuator is able to create the required tilt angle and provide a safe ride; however the roll angle velocity is not as constant as what a position controlled actuator can perform. It might be possible to solve this with a more advanced control loop, or perhaps use stored track data when possible. The conclusion is that the simplicity of this actuator cannot yet be fully utilized, without further study.  

  • 25.
    Hintzy, Léo
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Development of a hydroformed anti-intrusion bar concept2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Reducing the fuel consumption of vehicles is one of the main automotive industry's objectives. The obvious solution is to reduce the mass of the vehicle, so less mass has to be put into motion, which requires less energy. With this in mind, it was decided to look at anti-intrusion bars. This passive safety component installed in the doors plays a key role in side impacts, as it reduces the penetration of the bodywork into the passenger compartment. Thus, the lightening of vehicles should not be accompanied by a reduction in safety.The aim of this thesis is to explore the advantages of the hydroforming process, which has not yet been used to shape these parts. The work carried out focused on the design of hydroformed bars by considering the numerous constraints due to the implementation of such a part and the study of different usable materials. Finally, numerical simulations comparing a deep-drawn bar with the designed parts showed that hydroforming appears to produce anti-intrusion bars that are 10% lighter than and as effective as deep drawing. Simple simulations of the hydroforming process also showed that it appeared possible to shape the designed parts using this process.This work needs to be continued with more accurate calculations of the hydroforming process, simulations of crash tests with a full vehicle model and physical realisation of the part for real-world testing.

  • 26.
    Hissler, Clément
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    How to determine the fuel consumption for a hydrogen light commercial vehicle project to be competitive?2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The automotive industry and the whole transport sector are currently facing the need to act against climate change. In fact, over the globe the passenger road vehicles emitted 3.6 Gt of CO2 in 2018 and the road freight vehicles emitted 2.4 Gt of CO2 [1]. These road and freight emissions represents 11% and 7% of the total CO2 emissions that year respectively [2]. One solution that has been chosen to limit and reduce the greenhouse gas (GHG) emissions from road transportation is to shift from internal combustion engine (ICE)-based vehicles to electric vehicles which will emit no GHG during operation. There are mainly two types of electric vehicles suitable for this purpose. The first one is the battery electric vehicles (BEVs) which is already commercially and industrially mature and already on the road (11.3 million in 2020 [3]). It uses large Li-ion batteries to store the energy on-board to then power the electric motors. The second one is the fuel cell electric vehicles (FCEVs) which is still being researched and whose number on the road is quite limited (34.8 thousand in 2020 [4]). Yet, this technology is suitable for many applications and especially the light commercial vehicles (LCVs). The stakes of this technology have been studied regarding the current market of LCVs in France and by comparing it to BEVs in terms of cost and mass. To better frame the development of new hydrogen LCVs, a tool has also been developed to calculate the range of such vehicles throughout the life of the project and the evolution of its specifications. The analysis of the market and the comparison between FCEVs and BEVs is not exhaustive and only some specific points have been dealt with, enough to give an overview of the main stakes of hydrogen LCVs. The tool developed is limited to simple input data as it aims to be used with little information at an early stage of the project.

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  • 27.
    Holmström, Gaston
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Pantograph-catenary wear modelling using dynamic simulation2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Wear condition modelling is a research topic which lately has increased in popularitydue to its significance to the railway industry. Large sums are spent on maintenanceof the network every year, which has generated a demand for understanding and predictingwear mechanisms in a multitude of components within both railway vehiclesand infrastructure. To acquire this knowledge, using a simulation software to predictwear and maintenance needs, is a cheap and dependable option. This thesis sets outto create a wear modelling software for the catenary-pantograph interaction, which intheory could enlighten railway operators of the condition of their infrastructure.

    This research contains an extensive literature review on the subject of wear modelling,analysing different strategies and theories of the wear mechanism and desired modelproperties. Thereafter, an attempt to recreate a model for a representative Swedishcase was conducted; implementing parameters of a typical Swedish rail vehicle to awear rate formula, recreating a passage of a pantograph sliding along the catenary.The output was a wear rate as a function of time, a determination of life expectancyfor the infrastructure and a worn profile of the catenary wire after one year of operation.

    The model, named AWEAR, was deemed functional for determining wear mechanismtendencies and behaviour for a few cases of alternating parameters. However, sinceno validation could be performed due to a lack of resources, the validity of the outputvalues could not be confirmed - thus leaving calibration of the model to future work.In conclusion, AWEAR needs to be calibrated for future research but does contain amultitude of enhancement opportunities proposed in this thesis. While not completelyfunctional, the software was deemed a useful foundation for future projects and mightresult in a product that aids operators maintaining their infrastructure.Keywords: Wear modelling, catenary pantograph interaction, mechanism,

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  • 28.
    Hvitfeldt, Henrik
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Drugge, Lars
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Jerrelind, Jenny
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Driver gaze model for motion cueing yaw feedback optimisation2023In: 28th Symposium on Dynamics of Vehicles on Roads and Tracks, 2023Conference paper (Refereed)
    Abstract [en]

    Driving simulators are increasingly important in vehicle development, benefiting from hardware and motion cueing algorithm (MCA) advancements. However, current state-of-the-art MCAs are optimising with regards to a vehicle fixed vestibular system, ignoring active and passive head movements during manoeuvres. Research shows that drivers actively move their heads to focus their gaze and passively stabilising it during involuntary trunk movements, resulting in significant differences between vehicle and head yaw angles. Humans isolate trunk and head movement in the range of 0.1-1.0 Hz, suggesting neck-driven gaze stabilisation. This behaviour is not accounted for in current MCAs, warranting an investigation. This study develops a driver gaze model to enhance motion cueing strategies and compares it to existing methods. Findings indicate significant discrepancies between vehicle and estimated head yaw rate in winter testing with high slip angles, and that omitting vestibular models and separating the slip angle in the yaw feedback improves the motion cueing with regards to induced head movements. Further, the results shows that there is a clear relationship between motion cueing, visual feedback, and induced driver head movement. In conclusion, driver gaze models can improve motion cueing strategies in driving simulators, and thus the study highlights the need for considering driver gaze behaviour and provides insights for tuning and optimising MCAs.

  • 29.
    Hvitfeldt, Henrik
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Jerrelind, Jenny
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Drugge, Lars
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Enhancing perception of vehicle motion by objective positioning of the longitudinal axis of rotation in driving simulatorsManuscript (preprint) (Other academic)
    Abstract [en]

    The automotive industry is heading towards a more objective approach to vehicle testing, but subjective evaluation is still an important part of the development process. Subjective evaluation in physical testing has environmental implications and is dependent on ambient conditions. A more repeatable, faster, safer, and more cost-effective tool for subjective evaluation is to use moving base driving simulators. The motion cueing algorithms (MCA) maps the movement of the vehicle into the limited space of the simulator. The choice of reference point, i.e., where on the vehicle to sample the motion to feed to the MCA and the alignment of the axis of rotation of the simulator cabin is still an open topic. This paper investigates the choice of reference point and corresponding simulator longitudinal axis of rotation in roll using two methods. The first method uses a linearised model of the combined system of vehicle, simulator, and vestibular models. The second method, to position the cabin longitudinal axis of rotation, is based on offline optimisation. The linear model can capture important characteristics of the specific forces and rotations that are fed to the driver through the motion cueing algorithms and offers a method to objectively analyse and potentially tune the motion cueing. The analysis is further complemented with a subjective evaluation of corresponding settings. The results from the linear model, the offline optimisation and the subjective evaluation shows that a reference point at the driver’s head has a clear advantage over the full frequency range compared to a reference point in the chassis roll axis and that the positioning of the cabin longitudinal axis of rotation has a significant effect on the perceived vehicle characteristics. 

  • 30.
    Hyttinen, Jukka
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Engineering Mechanics. Scan CV AB, Granparksvagen 10, S-15148 Södertälje.
    Ussner, Matthias
    Scan CV AB, Granparksvagen 10, S-15148 Södertälje, Sweden..
    Osterlof, Rickard
    Scan CV AB, Granparksvagen 10, S-15148 Södertälje, Sweden..
    Jerrelind, Jenny
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Engineering Mechanics.
    Drugge, Lars
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Effect of Ambient and Tyre Temperature on Truck Tyre Rolling Resistance2022In: International Journal of Automotive Technology, ISSN 1229-9138, E-ISSN 1976-3832, Vol. 23, no 6, p. 1651-1661Article in journal (Refereed)
    Abstract [en]

    Rolling resistance is consuming a large portion of the generated powertrain torque and thus have a substantial effect on truck energy consumption and greenhouse gas emissions. EU labelling of tyres mandates the manufacturers to measure rolling resistance at +25 degrees C ambient temperature after stabilised rolling resistance has been established. This is a convenient way of comparing rolling resistance but disregards aspects such as transient rolling resistance and influence of the ambient temperature. For many purposes, such as dimensioning batteries for electric vehicles, this value is not representative enough to give a good understanding of the rolling resistance. In this article, the rolling resistance of a truck tyre was measured at different ambient temperatures (-30 to +25 degrees C) in a climate wind tunnel and a considerable tyre and ambient temperature dependency on rolling resistance was found. The investigation shows that the temperature inside the tyre shoulder has a good correlation with rolling resistance. Measurements with spraying water on tyres were conducted showing a considerable increase in rolling resistance due to higher cooling effect. Driving range simulations of a long haulage battery-electric truck have been conducted with temperature-dependent rolling and aerodynamic resistance, showing a significant decrease in driving range at decreasing temperature.

  • 31.
    Hyttinen, Jukka
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Ussner, Matthias
    Scania.
    Österlöf, Rickard
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. Scania.
    Jerrelind, Jenny
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics.
    Drugge, Lars
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Do heat-insulated wheelhouses affect truck tyre temperature and rolling resistance?Manuscript (preprint) (Other academic)
    Abstract [en]

    Due to legislations introduced to prevent global warming, vehicle manufacturers must find new ways to reduce CO2 emissions. This paper explores a way to reduce rolling resistance by heat insulating and covering a truck's wheelhouse. The rolling resistance of a truck tyre was measured at +5 °C ambient temperature for consecutive speed steps in a climate wind tunnel with and without heat insulation. The study showed that by encapsulating and insulating the wheelhouse, already generated strain-induced heat could be kept in the tyre, consequently producing a lower rolling resistance. During the tests, the tyre shoulder temperature was monitored along with the tyre pressure. When the wheelhouses were encapsulated, a significant reduction in rolling resistance and an increase in tyre pressure and temperature were measured at all evaluated speed levels.

  • 32.
    Hyttinen, Jukka
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Wentzel, Henrik
    KTH, School of Engineering Sciences (SCI).
    Österlöf, Rickard
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. Scania.
    Jerrelind, Jenny
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics.
    Drugge, Lars
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Development and analysis of an on-road torque measurement device for trucksManuscript (preprint) (Other academic)
    Abstract [en]

    Background: Rolling resistance and aerodynamic losses cause a significant part of a truck's energy consumption. Therefore there is an interest from both vehicle manufacturers and regulators to measure these losses to understand, quantify and reduce the energy consumption of vehicles. On-road measurements are particularly interesting because it enables testing in various ambient conditions and road surfaces with vehicles in service.

    Objective: Common driving loss measurement devices require unique instrumented measurement wheels, which hinders effective measurements of multiple tyre sets or measurements of vehicles in service. For this purpose, the objective is to develop a novel load-sensing device for measuring braking or driving torque.

    Methods: The strength of the measurement device is calculated using finite element methods, and the output signal is simulated using virtual strain gauge simulations. In addition to the signal simulation, the device is calibrated using a torsional test rig.

    Results: The simulation results confirm that the device fulfils the strength requirements and is able to resolve low torque levels. The output signal is simulated for the novel cascaded multi-Wheatstone bridge using the strains extracted from the finite element analysis. The simulations and measurements show that the measurement signal is linear and not sensitive to other load directions. The device is tested on a truck, and the effort of mounting the device is comparable to a regular tyre change.

    Conclusions: A novel driving loss measurement device design is presented with an innovative positioning of strain gauges decoupling the parasitic loads from the driving loss measurements. The design allows on-road testing using conventional wheels without requiring special measurement wheels or instrumentation of drive shafts, enabling more affordable and accurate measurements.

  • 33.
    Hyttinen, Jukka
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Österlöf, Rickard
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. Scania.
    Jerrelind, Jenny
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics.
    Drugge, Lars
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    A semi-physical thermodynamic non-stationary rolling resistance model with nonlinear viscoelasticityManuscript (preprint) (Other academic)
    Abstract [en]

    Rolling resistance dictates a large part of the energy consumption of trucks. Therefore, it is necessary to have a sound understanding of the parameters affecting rolling resistance. This article proposes a semi-physical thermodynamic tyre rolling resistance model, which captures the essential properties of rolling resistance, such as non-stationary changes due to temperature effects and the strain amplitude dependency of the viscous properties. In addition, the model includes cooling effects from the surroundings. Both tyre temperature and rolling resistance are obtained simultaneously in the simulation model for each time step. The nonlinear viscoelasticity in rubber is modelled using a Bergström-Boyce model, where the viscous creep function is scaled with temperature changes. The cooling of the tyre is considered with both convective and radiative cooling. Finally, the article explains different material parameters and their physical meaning. Additionally, examples of how the model could be used in parameter studies are presented.

  • 34.
    Höglund, Rickard
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Modelling of a high-performance vehicle in MATLAB/Simulink and Canopy Simulations2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The car industry is constantly evolving. High demands from customers and governing bodies force the manufacturers to speed up development of new vehicle models. This process used to be a very costly, time consuming and not very ecologically sustainable because new and expensive parts had to be made that are difficult to manufacture. Today, there are many different computer softwares that can help the development process by allowing the manufacturers to move this process into a digital environment which can save money, time and at the same time help to become ecologically sustainable.

    This Master's thesis is a collaboration with Koenigsegg Automotive AB and aims to evaluate computer softwares and their vehicle models. Three different softwares are tested by looking at the correlation between them and measurement data from a real vehicle test. This to build a better understanding of how the softwares work and how they can be used in the development process of vehicle dynamics and control. The tested softwares are MATLAB/Simulink, CarMaker and Canopy Simulations. A longitudinal model and a lateral model, also known as the dual track model is created in MATLAB/Simulink and it is compared to the vehicle created in the table based software CarMaker and the vehicle created in the optimization oriented software Canopy Simulations.

    To test the different models against each other some standard maneuvers are used, such as slalom and constant radius cornering. The models are compared by measuring the lateral acceleration and yawrate. Track driving is also tested since Canopy Simulations is specifically developed for track driving.

    The tests show a good correlation between the vehicle models, especially at lower velocities. The developed dual track model during this Master's thesis is a good vehicle model and can predict the lateral acceleration and yawrate and shows most accurate results at lower velocities and during non transient maneuvers where the load transfer is minimal. The model is heavily dependent on the tire model which has to be taken into consideration. CarMaker shows similar results to the dual track model but this software is more suited for testing different driver aids. The way Canopy Simulations works makes it more complex to perform standard maneuvers and test the correlation, but initial simulations show a good correlation and its capabilities when it comes to vehicle development. It is a great tool for optimizing a vehicle for performance on track.

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  • 35.
    Jawahar, Aravind
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Palla, Lokesh
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Lateral Control of Heavy Vehicles2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The automotive industry has been involved in making vehicles autonomous to different levels in the past decade rapidly. Particularly in the commercial vehicle market, there is a significant necessity to make trucks have a certain level of automation to help reduce dependence on human efforts to drive. This could help in reducing several accidents caused by human error. Interestingly there are several challenges and solutions in achieving and implementing autonomous driving for trucks. First, a benchmark of different control architectures that can make a truck drive autonomously are explored. The chosen controllers (Pure Pursuit, Stanley, Linear Quadratic Regulator, Sliding Mode Control and Model Predictive Control) vary in their simplicity in implementation and versatility in handling different vehicle parameters and constraints. A thorough comparison of these path tracking controllers are performed using several metrics. Second, a collision avoidance system based on cubic polynomials, inspired by rapidly exploring random tree (RRT) is presented. Some of the path tracking controllers are limited by their ability and hence a standalone collision avoidance system is needed to provide safe maneuvering. Simulations are performed for different test cases with and without obstacles. These simulations help compare safety margin and driving comfort of each path tracking controller that are integrated with the collision avoidance system. Third, different performance metrics like change in acceleration input, change in steering input, error in path tracking, deviation from base frame of track file and lateral and longitudinal margin between ego and target vehicle are presented. To conclude, a set of suitable controllers for heavy articulated vehicles are developed and benchmarked.

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  • 36.
    Joel, Hansson
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Reduction of Flexural Vibrations in Rail Vehicle Carbodies Using Piezoelectric Elements and Passive Shunt Circuit2003Independent thesis Advanced level (degree of Master of Fine Arts (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The demand on light weight in modern rail vehicles often contradicts the goal of high structural stiffness. Because of this, there is a need for development of new methods for reducing flexural vibrations without adding significant weight, in order to improve ride comfort. One method could involve attaching piezoelectric elements on the car body.

    The attached piezoelectric elements convert mechanical energy from the structural vibrations into electrical energy, which is then dissipated in a shunt circuit. The piezoelectric elements are in this study shunted with two types of passive shunt circuits, one designed to damp a single structural vibration mode and another designed to damp two modes simultaneously.

    Simulations, where the car body is modelled as an elastically supported simple beam, indicate that the method yields significant vibration suppression at the targeted modes with only a small amount of added weight. The simulations are supplemented by experiments on a 1:5 scale model of a Shinkansen 100 series vehicle.

  • 37.
    Kleinsteuber, Friedemann
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Domain Adaptation Of Front View Synthetic Point Clouds Using GANs For Autonomous Driving2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The perception of the environment is one of the main enablers of Autonomous Driving and is driven by Cameras, RADAR, and LiDAR sensors. Deep Learning algorithms used in perception need a vast amount of labeled, high-quality data which is costly to obtain for LiDAR sensors. Simulated data is easier to generate but does not reflect the complexity of real data. To overcome this Domain Adaptation can be used to translate data from the simulated to the real domain.

    In this thesis CycleGAN, a Generative Adversarial Network, is used to learn the domain adaptation between real LiDAR data collected with a race vehicle of the Technical University Munich as part of the \textit{Autonomous Challenge @ CES} and the corresponding race simulated with an Unreal engine. The Front View representation of the LiDAR point clouds is chosen to use all information available in the dataset.

    The resulting algorithms have an unsatisfying performance. The domain adaptation in both directions learned the general differences between the two datasets but fails to create a point cloud that can be recognized as a sample of the goal domain. Further work needs to be done in this field as the problem of sparse and costly real LiDAR data remains.

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  • 38.
    Kumarasamy, Gobi
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Optimal Force Distribution for Active and Semi-active Suspension Systems2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The development needs of handling and ride vehicle dynamic characteristics are constantly evolving, crucial for safety and comfortable commute since many active safety and driver assistance systems depend on these characteristics. Ride improvements enhance passenger comfort, which plays a significant role in quality and brand value. Chassis and suspension systems greatly influence these vehicle dynamic characteristics. These systems should provide stability, high precision and a high degree of adaptive performance with quick response time. One of the ways to achieve these demands is by incorporating mechatronics suspension systems. Semi-active and fully active mechatronics suspension systems offer passengers a more comprehensive range of vehicle characteristics in terms of driving experience than vehicles with purely mechanical suspension systems. The efficient implementation of mechatronics suspension systems depends on the controller type and how its commands are realised. A typical control strategy is to decide a desired behaviour on the vehicle body and realise that behaviour with the help of the semi-active or active actuators. This work focuses on the realisation of the modal coordinate controller commands that counteracts the undesired body motions. The commands are in vehicle body coordinates with respect to the COG of the vehicle. The biggest challenge is to translate these counteracting forces and torques into semi-active damper vertical forces. This challenge is addressed with different algorithms with different levels of complexity and capability. The complexity ranges from the linear system of equations to real-time optimisation. Essentially, the algorithms will fragmentise and distribute the centralised command among different actuators and finally realise them back as close as commanded by taking the actuator and other physical limitations into account. This work also focuses on developing relative weights tuning methods, which play a significant role in the cost function formation and optimisation solution. The algorithms are evaluated in three different road conditions to incorporate typical driving environments related to primary and secondary rides. The enhancements in the ride performance are visualised by comparing against the existing methodology. The conclusions strongly support the optimisation-based force allocation algorithm over the existing method. It enables significant improvements in the ride performance and a high degree of flexibility by efficiently distributing commands among four actuators, which results in utilising the full potential of the semi-active dampers.

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  • 39.
    Labbé, Anton
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Ahsan, Mahim
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Improving Water Droplet Prediction for Vehicle Exterior Water Management: Insights from Experimental and Simulation Studies2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis focuses on the study of water transportation on vehicle surfaces, which is crucial for ensuring the unobstructed operation of sensors and cameras in autonomous vehicles. The research aims to develop and validate experimental and simulation methods to enhance the understanding of water droplet behaviour and to create accurate models for computational fluid dynamics (CFD) simulations. The primary objective is to investigate the feasibility of simulating water droplets using CFD. The study examines the behaviour of water droplets on a lacquered metal sheet and a glass surface. Physical experiments and CFD simulations are conducted to analyse droplet movement under the influence of gravity and airflow. The findings provide insights into the factors influencing droplet behaviour and validate the accuracy of the simulation models through physical tests. The research also discusses the limitations of the study and the implications for Volvo Cars, aiming to improve their ability to predict water droplet movement on their vehicles.

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  • 40.
    Li, Yiquan
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Model-Based Coordinated Steering and Braking Control for a Collision Avoidance Driver Assist Function2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    ADAS (Advanced Driver Assistance System) functions can help the driver avoid accidents or mitigate their effect when they occur, and are pre-cursors to full autonomous driving (SAE defined as Level 4+). The main goal of this work is to develop a model-based system to actuate Evasive Maneuver Assist (EMA) function.

    A typical scenario is the situation where Autonomous Emergency Braking (AEB) is too late and the driver has to adopt evasive maneuver to avoid an object suddenly appearing on the road. At this time, EMA can help improve the driver’s steering and braking operation in a co-ordinated way. The vehicle maneuverability and response performance will be enhanced when the driver is facing the collision. The function will additionally let the vehicle steer in a predetermined optimized trajectory based on a yaw rate set point and stabilize the vehicle.

    The first part of the thesis deals with the introduction of EMA function and the analysis of the benchmarking data. Benchmarking has shown different strategies from several OEMs (Original Equipment Manufacturers) and suppliers, in which the discipline of how they want the vehicle performance to be and where improvement could be found.

    The second part deals with the functional requirement and performance metrics of EMA function. Most of the functional requirements come from the interior function definition systemweaver of CEVT and the rest come from the benchmarking and premise research. The performance metrics are based on objective and subjective evaluation.

    Then frequency analysis is used to develop transfer functions to understand actuator effects, and Model-Based Design (MBD) is employed to subsequently develop the controller function using co-simulation between Matlab/Simulink and VI-CarRealtime. Results and analysis are presented at key vehicle speeds.

    The final part introduces the driving simulator test after the development of the function. The signal results could be compared with simulation results and driver's performance without EMA. Eventually, a questionnaire survey was made to understand the needs for future improvement.

  • 41.
    Li, Yiquan
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Petrovich, Simon
    CEVT AB.
    Nybacka, Mikael
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Model-Based Coordinated Steering and Braking Control for a Collision Avoidance Driver Assist Function2023In: WCX SAE World Congress Experience: ADAS and Autonomous Vehicle System: AD/ADAS Path Planning and Control - Part 1 (AE103) / [ed] SAE International, SAE International , 2023Conference paper (Refereed)
    Abstract [en]

     ADAS (Advanced Driver Assistance System) functions can help the driver avoid accidents or mitigate their effect when they occur, and are pre-cursors to full autonomous driving (SAE defined as Level 4+). The main goal of this work is to develop a Model-Based system to actuate the Evasive Maneuver Assist (EMA) function. 

    A typical scenario is the situation in which longitudinal Autonomous Emergency Braking (AEB) is too late and the driver has to adopt an evasive maneuver to avoid an object suddenly appearing on the road ahead. At this time, EMA can help improve the driver’s steering and braking operation in a coordinated way. The vehicle maneuverability and response performance will be enhanced when the driver is facing the collision. The function will additionally let the vehicle steer in a predetermined optimized trajectory based on a yaw rate set point and stabilize the vehicle. 

    The EMA function is introduced with some analysis of benchmarking data. Benchmarking has shown different strategies from several OEMs (Original Equipment Manufacturers) and suppliers, in which the discipline of how they want the vehicle performance to behave and where improvements could be found. 

    Functional requirement and performance metrics of EMA function are created. The performance metrics are based on objective and subjective evaluation. 

    Frequency analysis is used to develop transfer functions to understand actuator effects, and Model-Based Design (MBD) is employed to subsequently develop the controller function using co-simulation between Matlab/Simulink and VI-CarRealtime. Results and analysis are presented at key vehicle speeds where intervention could be necessary. 

    The final part introduces driving simulator tests after the development of the function. The measured signal results could be compared with simulation results and driver’s performance without EMA. Eventually, a questionnaire survey was made to define a direction for further improvement. Additional ideas are presented for more advanced work. 

  • 42.
    Linzbichler, Philipp
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Holistic embedding of equivalent conicity in wheelset maintenance2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With continuing digitization of railways an increasing number of data is recorded but particularly in operation advanced analysis tends to be partially rudimentary. Yet, it is essential to implement sophisticated processing for all records in order to develop more purposeful and predictive vehicle maintenance strategies that adhere to the increasing requirements imposed by the homologation. Typically developing requisites are permissible track forces and lateral accelerations which are directly affected by the vehicle's condition. The present work addresses this issue by executing a case study focused on a Swiss high-speed electric multiple unit with equivalent conicity being the main parameter of interest. This geometry quantity holds high relevance in determining the running stability of track guided vehicles, respectively in assessment of comfortable and safe operation. Currently, it experiences an increasing significance in the homologation as well. Thus, wheelset maintenance is challenged to elaborately embed equivalent conicity to the other influencing factors in the re-profiling strategy.

    A framework is established on how operational data can be analyzed and findings systematically be evaluated. The required records are provided by a Swiss railway operator and majorly processed by visualization as well as statistic tools while considering vehicle design and operational aspects. The subsequent proposition of strategies is accompanied by holistic balancing of vehicle needs, maintenance resources, and vehicle scheduling needs.

    As a result, correlations concerning the vehicle's configuration, design, and operational properties are observed. Incorporating these observations, for example by applying advanced warning limits, enables deduction of more predictive and holistic strategies. The potentially emerging benefits are manifold and range from lower demand on engineering staff, increased mileages, to fewer unplanned servicing tasks and subsequently increased operational stability. Further, the findings emphasize the need of in depth understanding about relevant data to derive more advanced and holistic maintenance strategies.

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  • 43.
    Liu, Yunqi
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Comfort of children in cycle carriers2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Carriers attached as bicycle trailers that can transport small children are becoming increasingly popular in recent years. They replace cars as a convenient and sustainable way to travel for families in commuting and other everyday activities. However, research into the level of whole-body vibration experienced by children in this type of vehicle is very limited, with none conducted in laboratory conditions. Prolonged exposure to high levels of vibration can cause discomfort and even lead to health concerns. In this thesis project a test-bed is designed to perform controllable and repeatable measurements. Various load and tyre pressure conditions are used to study their impact on the vibration level. Sinusoidal inputs are used to excite the carrier, and output responses are measured with accelerometers placed on the surface of the carrier seat. In addition, a basic ADAMS model is built to simulate the same setups as the laboratory measurements. In both methods, the average frequency-weighted acceleration values are found to be much higher than that in passenger cars, reaching an "extremely uncomfortable" level according to ISO 2631-1 standards. It is also observed that tyre pressure has a significant impact on vibration, and its relation with vertical acceleration is non-monotonic. Suggestions for further improvement on the test-bed design and wider use of computer models are made.

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  • 44.
    Liu, Zhendong
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Berg, Mats
    KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Bustad, Tohmmy
    Trafikverket.
    Shift2Rail FINE-1 project: Review of Energy Labelling Systems2018Report (Other academic)
    Abstract [en]

    The present report is a review of energy labelling systems of products in different sectors, including other modes of transport than rail, to support a proposal of an energy labelling system for rail vehicles. This report collects the existing energy labelling systems and energy efficiency indicators and briefly analyses their features. Compared with other modes of transport and based on the ongoing studies related to energy in the railway sector, the features of rail vehicles are also analyzed regarding energy efficiency.

    The report is linked to the Energy Labelling Proposal in FINE-1 Task 2.1 External market, normative and internal requirements analysis for eco-labelling proposal.

  • 45.
    Liu, Zhendong
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    Berg, Mats
    KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Weissensteiner, Patrick
    Schmeja, Michael
    Shift2Rail FR8HUB Project - D6.5 Study of Power PeakShaving Concepts2021Report (Other academic)
  • 46.
    Liu, Zhendong
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Jerresand, Alexandra
    KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group. KTH, School of Industrial Engineering and Management (ITM).
    Zarov, Filipp
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Transport planning. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    Diamant, Micaela
    KTH, School of Industrial Engineering and Management (ITM). KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    Berg, Mats
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    Bonnevier, Fredric
    Alstom Transport.
    Malas, Josef
    Trafikverket.
    Saving Energy and Cost with application of Railway Smart Wayside Object Controllers2022Conference paper (Refereed)
    Abstract [en]

    Trackside equipment and signalling devices are controlled by wayside object controllers (OC). Radio communication systems enable the wireless transmission of command control and signalling (CCS) data, which can help to reduce the cost of cabling and installation. However, for regional lines with low traffic volumes in rural areas, most of them are non-electrified, so a special cable for powering the wayside object controller system is still needed to be installed along the track, which would significantly increase the construction cost and maintenance work. A smart wayside object controller (SWOC) is suggested, which would be autonomous, self-sufficient, remotely-monitorized and locally-powered to ensure its proper operation, so the cabling and installation work can be totally removed. In order to demonstrate its viability and benefits over the existing systems, this work studies the possibility to use different renewable energy sources to power the system and then estimates the life cycle cost (LCC) of the SWOC in long-term operation. This study shows that in most places, it is sufficient to use 100% renewable energy sources to power the SWOC, trackside equipment and signalling devices. Compared with the existing system, the SWOC shows a significant cost saving in long-term operation by removing cabling and installation, reducing trackside maintenance and replacing the power supply with renewable energy power sources. Therefore, the SWOC shows its benefits over the existing system in both economical and environmental aspects. In the end, some suggestions on future development and implementation of SWOC are given.

  • 47.
    Matz, Christian
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Development and implementation of a tram line performance model2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Wiener Linien’s tram network is one of the largest and busiest of its kind worldwide. Maintaining and improving the Level of Service (LoS) is one of the major tasks of the operations division. To direct these improvements efficiently to lines and sections of lines in need, tram line performance needs to be assessed. In this master thesis a Python-based model is developed to assess tram line performance using ideal operational constraints. Furthermore, the model is capable of computing the energy consumption for this optimal case. The tool computes Undisturbed Optimal Travel Times (UOTTs) which serve as a benchmark for tram line performance. Therefor it builds on track alignment data (curves and radii, gradients and switches), speed restriction data and a set of optimal parameters (no traffic, constant acceleration, etc.). Furthermore, train resistance, curve speeds and vehicle type are taken into consideration. These parameters are investigated and selected based on literature studies, interviews with employees of Wiener Linien, as well as field tests. Finally, the model results are compared to real world data for evaluation. A discussion of the results regarding further applications and improvements is performed.

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  • 48.
    Nappi, Guglielmo
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Banerjee, Sanjay
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign.
    Reconfigurable force distribution algorithm and model2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This master thesis presents a comprehensive vehicle model that incorporates both longitudinal and lateral dynamics for trucks of different configuration, employing a flexible and adaptable approach. Initially, the vehicle model is automatically generated from the truck variant code to establish the model’s architecture. Subsequently, utilising input data from the trucks, the tyre forces are estimated by means of traction force calculations and a linear tyre model that accounts for both longitudinal and lateral forces. The vehicle’s body dynamics are then computed, encompassing four degrees of freedom: longitudinal motion, lateral motion, yaw motion, and roll motion. Furthermore, the report includes a prediction of future vehicle states, which is compared against measured data to assess the accuracy of the predictions. Finally, the reconfigurable vehicle model is validated against a reference point mass model specifically designed for longitudinal dynamics. This validation serves to demonstrate the accuracy of the proposed model. A key advantage of this resulting model is its ability to be employed in the design of model-based controllers, facilitating the estimation of optimal force distribution to enhance vehicle efficiency across different trucks, without necessitating the reformulation of the problem.

  • 49.
    Nygren, Johan
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics, Technical Acoustics. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics, Marcus Wallenberg Laboratory MWL.
    Boij, Susann
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics, Technical Acoustics. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics, Marcus Wallenberg Laboratory MWL.
    Rumpler, Romain
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics, Technical Acoustics. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics, Marcus Wallenberg Laboratory MWL.
    O'Reilly, Ciarán J.
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics, Marcus Wallenberg Laboratory MWL.
    Vehicle-specific noise exposure cost: Noise impact allocation methodology for microscopic traffic simulations2023In: Transportation Research Part D: Transport and Environment, ISSN 1361-9209, E-ISSN 1879-2340, Vol. 118, p. 103712-103712, article id 103712Article in journal (Refereed)
    Abstract [en]

    This paper proposes a methodology in traffic noise assessment, whose objective is to combine microscopic traffic simulations and noise calculation methods with macro-level, systemic noise impact assessment models. This combination, referred to as the vehicle-specific noise exposure cost (NEC), provides a per-vehicle contribution to the overall noise impact. Three case studies are introduced illustrating the potential of the methodology: a reference case with a dynamic traffic flow, the correlation between vehicle-specific NECs and average speeds, and vehicle-specific NECs in a mixed traffic fleet. The results highlight the interest and importance of using a microscopic approach, as the impact of interactions, vehicle-specific characteristics and behaviors are reflected into the associated NECs. Additionally, the correlation between vehicle-specific NECs and average speeds strongly depends on traffic conditions, further highlighting the importance of methodological features such as the interactions captured in microscopic traffic simulations or the acceleration-dependency of the implemented vehicle noise source model.

  • 50.
    Nygren, Johan
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics, Technical Acoustics.
    Le Bescond, Valentin
    Université Gustave Eiffel, AME-SPLOTT, F-44344, Bouguenais, France; Université Gustave Eiffel, CEREMA, UMRAE, F-44344, Bouguenais, France.
    Can, Arnaud
    Université Gustave Eiffel, CEREMA, UMRAE, F-44344, Bouguenais, France; Institut de Recherche des Sciences et Techniques de la Ville (IRSTV), CNRS, 44321, Nantes Cedex 3, France.
    Aumond, Pierre
    Université Gustave Eiffel, CEREMA, UMRAE, F-44344, Bouguenais, France; Institut de Recherche des Sciences et Techniques de la Ville (IRSTV), CNRS, 44321, Nantes Cedex 3, France.
    Gastineau, Pascal
    Université Gustave Eiffel, AME-SPLOTT, F-44344, Bouguenais, France; Université Gustave Eiffel, CEREMA, UMRAE, F-44344, Bouguenais, France.
    Boij, Susann
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics, Technical Acoustics. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Rumpler, Romain
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics, Technical Acoustics.
    O'Reilly, Ciarán
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Väg- och spårfordon samt konceptuell fordonsdesign. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Agent-specific, activity-based noise impact assessment using noise exposure cost2024In: Sustainable cities and society, ISSN 2210-6707, Vol. 103, article id 105278Article in journal (Refereed)
    Abstract [en]

    This study introduces an agent-specific assessment method of traffic noise exposure in agent mobility simulations. The assessment is achieved through a combination of an energy-based noise exposure impact assessment using noise exposure cost, and the state-of-the-art traffic noise prediction tool NoiseModelling coupled with the activity-based agent mobility simulation software MATSim. The agent-specific noise exposure cost is a measure to evaluate how the noise emissions from the transport of agents relate to the noise-related impact on other agents performing stationary activities. By introducing an agent-specific level, each agent’s individual responsibility for the noise exposure may be estimated. The potential of the agent-specific noise exposure cost concept, combined with the MATSim-NoiseModelling framework, is illustrated through a case study, applying activity-based agent mobility simulations across Nantes, France. The results of the case study highlight, among other considerations, the insights that an agent-specific, activity-based noise exposure cost approach provides by visualizing the noise exposure ”footprint” resulting from an agent’s transportation activities.

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