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  • 1.
    Bhat, Sriharsha
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics. KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    An Investigation into the Optimal Control Methods in Over-actuated Vehicles: With focus on energy loss in electric vehicles2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    As vehicles become electrified and more intelligent in terms of sensing, actuation and processing; a number of interesting possibilities arise in controlling vehicle dynamics and driving behavior. Over-actuation with inwheel motors, all wheel steering and active camber is one such possibility, and can facilitate control combinations that push boundaries in energy consumption and safety. Optimal control can be used to investigate the best combinations of control inputs to an over-actuated system. In Part 1, a literature study is performed on the state of art in the field of optimal control, highlighting the strengths and weaknesses of different methods and their applicability to a vehicular system. Out of these methods, Dynamic Programming and Model Predictive Control are of particular interest. Prior work in overactuation, as well as control for reducing tire energy dissipation is studied, and utilized to frame the dynamics, constraints and objective of an optimal control problem. In Part 2, an optimal control problem representing the lateral dynamics of an over-actuated vehicle is formulated, and solved for different objectives using Dynamic Programming. Simulations are performed for standard driving maneuvers, performance parameters are defined, and a system design study is conducted. Objectives include minimizing tire cornering resistance (saving energy) and maintaining the reference vehicle trajectory (ensuring safety), and optimal combinations of input steering and camber angles are derived as a performance benchmark. Following this, Model Predictive Control is used to design an online controller that follows the optimal vehicle state, and studies are performed to assess the suitability of MPC to over-actuation. Simulation models are also expanded to include non-linear tires. Finally, vehicle implementation is considered on the KTH Research Concept Vehicle (RCV) and four vehicle-implementable control cases are presented.

    To conclude, this thesis project uses methods in optimal control to find candidate solutions to improve vehicle performance thanks to over-actuation. Extensive vehicle tests are needed for a clear indication of the energy saving achievable, but simulations show promising performance improvements for vehicles overactuated with all-wheel steering and active camber.

  • 2.
    Bhat, Sriharsha
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics.
    Davari, Mohammad Mehdi
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Nybacka, Mikael
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics. KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Study on energy loss due to cornering resistance in over-actuated electric vehicles using optimal control2017In: SAE International Journal of Vehicle Dynamics, Stability, and NVH - V126-10, 2017Conference paper (Refereed)
    Abstract [en]

    As vehicles become electrified and more intelligent in terms of sensing, actuation and processing; a number of interesting possibilities arise in controlling vehicle dynamics and driving behavior. Over-actuation with in- wheel motors, all wheel steering and active camber is one such possibility, which facilitate the control strategies that push boundaries in energy consumption and safety. Optimal control can be used to investigate the best combinations of control inputs to an over-actuated system. This paper shows how an optimal control problem can be formulated and solved for an over-actuated vehicle case, and highlights the translation of this optimal solution to a real-world scenario, enabling intelligent means to improve vehicle efficiency. This paper gives an insight into the Dynamic Programming (DP) as an offline optimal control method that guarantees the global optimum. Therefore the optimal control allocation to minimize an objective function and simultaneously fulfill the defined constraints can be achieved. As a case study the effect of over-actuation on the cornering resistance were investigated in two different maneuvers i.e. step steer and sine with dwell, where in both cases the vehicle assumes to be in steady state situation. In this work the cornering resistance is the main objective function and maintaining the reference trajectory is the constraint which should be fulfilled. A parameter study is conducted on the benefits of over-actuation, and depending on the type of over-actuation about 15% and 50% reduction in cornering resistance were observed during step steer and sine with dwell maneuver respectively. From a second parameter study that focused on COG position from a safety perspective, it is more beneficial for the vehicle to be designed to under-steer than over-steer. Finally, a method is described to translate the offline optimal results to vehicle implementable controllers in the form of both feed-through lookup-tables and rule-based feed-forward control.

  • 3.
    Bout, Martijn
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    A Head-Mounted Display to Support Remote Operators of Shared Automated Vehicles2017Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    Automated driving systems will be severely challenged under the unpredictable conditions of mixed traffic. Consequently, some form of human support remains essential in the foreseeable future. This challenge is particularly true for Shared Automated Vehicles, as these vehicles will likely not include any human driver onboard. When a Shared Automated Vehicle encounters a situation it cannot handle, a remote human operator will be needed to intervene. The remote operator can help the passengers to continue their journey by resuming vehicle operations. This thesis has investigated whether using a Head-MountedDisplay in comparison to a computer display improves Situation Knowledge for remote operators of Shared Automated Vehicles. This research adopted a user-centered design approach to develop a Head-Mounted Display and computer display prototype. In one of the first studies on a Shared Automated Vehicle remote control interface, this thesis considered implicit measurements of Situation Knowledge and did not focus on performance indicators. In a userstudy, twelve participants were given the task to determine the reason why theShared Automated Vehicle had stopped based on pre-recorded driving scenarios.Strong qualitative evidence indicates that a Head-Mounted Display canprovide remote operators with improved Situation Knowledge in comparisonto computer displays. To deepen the understanding of the performance andSituation Knowledge for remote operators of Shared Automated Vehicles undervarious conditions further research is necessary. Future studies can extendknowledge by assessing different scenarios and tasks in a live remote controlsituation, and develop and evaluate additional interface elements.

  • 4.
    Bout, Martijn
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Pernestål-Brenden, Anna
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Klingegård, Maria
    RISE Viktoria.
    Habibovic, Azra
    RISE Viktoria.
    Böckle, Marc-Philipp
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    A Head-Mounted Display to Support Teleoperations of Shared Automated Vehicles2017In: AutomotiveUI 2017 - 9th International ACM Conference on Automotive User Interfaces and Interactive Vehicular Applications, Adjunct Proceedings, New York: ACM Digital Library, 2017, , p. 4p. 62-66Conference paper (Refereed)
    Abstract [en]

    Automated driving systems will be severely challenged in the unpredictable conditions of mixed traffic. Consequently, some form of human support remains essential in the foreseeable future. This challenge is especially true for Shared Automated Vehicles (SAVs), as these vehicles will likely not include any human driver on-board. When an SAV will encounter a scenario it cannot handle, a remote human operator will need to intervene and help the vehicle and its passengers. In this study a user-centred design approach is used to study whether a Head-Mounted Display (HMD) interface can support such operators and provide them with additional spatial awareness. Two prototypes (an HMD and a computer display) are developed and evaluated using pre-recorded real-world scenarios. Twelve participants assessed three possible scenarios a remote operator may encounter. Among participants, the study found evidence of strong implicit spatial awareness when using an HMD interface.

  • 5.
    Böckle, Marc-Philipp
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Pernestål Brenden, Anna
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Klingegård, Maria
    RISE Viktoria.
    Habibovic, Azra
    RISE Viktoria.
    Bout, Martijn
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    SAV2P – Exploring the Impact of an Interface for Shared Automated Vehicles on Pedestrians’ Experience2017In: AutomotiveUI 2017 - 9th International ACM Conference on Automotive User Interfaces and Interactive Vehicular Applications, Adjunct Proceedings, New York, USA: ACM Digital Library, 2017, p. 136-140Conference paper (Refereed)
    Abstract [en]

    To study future communication needs between pedestrians and shared automated vehicles (SAVs), an interface that communicates the intentions of SAVs to pedestrians was designed and implemented in a virtual reality (VR) environment. This enabled the exploration of behaviors and experiences of 34 pedestrians when encountering SAVs, both with and without the interface, in several street crossing situations. All pedestrians assessed the level of perceived safety and comfort directly after each encounter with the SAV. The results show that the pedestrians’ level of perceived safety and comfort is higher in encounters with the interface than in encounters without the interface. This may have a positive influence on the acceptance of SAVs, and implies that future SAVs may gain from this, or similar interface.

  • 6.
    Engholm, Albin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Pernestål, Anna
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Kristoffersson, Ida
    VTI Statens väg- och transportforskningsinstitut.
    System-level impacts of self-driving vehicles: terminology, impact frameworks and existing literature syntheses2018Report (Other academic)
    Abstract [en]

    The intention with this report is to contribute toward the development of systemic and holistic studies of impacts of self-driving vehicles. The report is targeting system-level impacts of self-driving vehicles on the transportation system but also wider societal impacts on factors such as: land-use, public health, energy and emissions, etc. This report is complimentary to two papers that are focused on in-depth literature review of simulation studies  (Pernestål Brenden and Kristoffersson 2018) and future scenario studies of impacts of self-driving vehicles (Engholm, Kristoffersson, and Pernestål Brenden 2018).

    The first aim of the report is to summarize knowledge to enable future design of a high-level conceptual framework for impacts from self-driving vehicles from a systems perspective. The second aim is to summarize knowledge on impacts from self-driving vehicles in a selection of the available literature. The main contributions of the report are the following:

    • A terminology for different types of automated vehicles, connected vehicles and mobility concepts for automated vehicles is presented
    • Frameworks for classifying system-level impacts from SDVs in the existing literature are summarized and analyzed
    • Existing literature studies on system-level impacts from SDVs are synthesized and common themes and gaps in current research are analyzed

    The terminology proposed in this report distinguishes between different types of automated and connected vehicles and is primarily intended as a tool to enable stringent analysis in this report when analyzing literature that apply different terminologies. Two frameworks for classifying system-level impacts are identified and compared. The analysis of the frameworks covers their scope, specification of mechanisms generating system impacts and briefly reviews their applicability as a starting point for developing a systems model of impacts from self-driving vehicles. The review of existing literature syntheses shows that there is a large variation in availability on literature for different system impacts. Impacts on road safety, road capacity and vehicle ownership forms are well studied. Examples of less studied impacts are costs of ownership, public health, infrastructure, air pollution and accessibility. The review identifies several contractionary mechanisms and effects that can affect various system-level impacts. The results of the review highlight the need to approach impact assessments of self-driving vehicles from a systemic and holistic point of view.

  • 7.
    Gao, Fan
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics. KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    State-Estimator Design for the KTH Research Concept Vehicle2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The Research Concept Vehicle (RCV) is a pure electric vehicle with four in-wheel motors and individual steering as well as camber actuators. It serves as an experimental research vehicle which is built by the Integrated Transport Research Lab (ITRL). The development of the RCV’s functionality never stops after the platform started running. In order to involve the advanced driver assistance systems and realize autonomous driving in the RCV, accurate information of vehicle dynamic states and the environment is required. In this case, based on the sensors we have on the RCV, sensor fusion and state estimation are critical to be adopted for solving this problem.

    The purpose of this thesis is to find appropriate estimators, define the specifications and design the corresponding logics to estimate vehicle dynamic parameters and the navigation information. The classic Kalman Filter (KF) and its extension for nonlinear systems Unscented Kalman Filter (UKF) are explained and used for solving the problem. A double-track vehicle model is implemented in the estimator for current use and further development. The results of all estimations are shown, and the mathematical evaluation of position estimates indicate that they outperform the original signals which are inputs to the sensor fusion algorithm. At last, some suggestions for further improvement are presented.

  • 8.
    Held, Manne
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Optimal Speed and Powertrain Control of a Heavy-Duty Vehicle in Urban Driving2017Licentiate thesis, monograph (Other academic)
    Abstract [sv]

    A major challenge in the transportation industry is how to reduce the emissions of greenhouse gases. One way of achieving this in vehicles is to drive more fuel-efficiently. One recently developed technique that has been successful in reducing the fuel consumption is the look-ahead cruise controller, which utilizes future conditions such as road topography. In this this thesis, similar methods are used in order to reduce the fuel consumption of heavy-duty vehicles driving in environments where the required and desired velocity vary. The main focus is on vehicles in urban driving, which must alter their velocity due to, for instance, changing legal speed restrictions and the presence of intersections. The driving missions of such vehicles are here formulated as optimal control problems. In order to restrict the vehicle to drive in a way that does not deviate too much from a normal way of driving, constraints on the velocity are imposed based on statistics from real truck operation.

    In a first approach, the vehicle model is based on forces and the cost function involves the consumed energy. This problem is solved both offline using Pontryagin's maximum principle and online using a model predictive controller with a quadratic program formulation. Simulations show that 7 % energy can be saved without increasing the trip time nor deviating from a normal way of driving.

    In a second approach, the vehicle model is extended to include an engine and a gearbox with the objective of minimizing the fuel consumption. A fuel map for the engine and a polynomial function for the gearbox losses are extracted from experimental data and used in the model. This problem is solved using dynamic programming taking into consideration gear changes, coasting with gear and coasting in neutral. Simulations show that by allowing the use of coasting in neutral gear, 13 % fuel can be saved without increasing the trip time or deviating from a normal way of driving.

    Finally, an implementation of a rule-based controller into an advanced vehicle model in highway driving is performed. The controller identifies sections of downhills where fuel can be saved by coasting in neutral gear.

  • 9.
    Henriksson, Manne
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control. Scania CV AB, Sweden.
    Flärdh, Oscar
    Scania CV AB.
    Mårtensson, Jonas
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Optimal Powertrain Control of a Heavy-Duty Vehicle Under Varying Speed Requirements2017Conference paper (Refereed)
    Abstract [en]

    Reducing the fuel consumption is a major issue in the vehicle industry. In this paper, it is done by formulatinga driving mission of a heavy-duty truck as an optimal control problem and solving it using dynamic programming.The vehicle model includes an engine and a gearbox with parameters based on measurements in test cells. The dynamic programming algorithm is solved by considering four specifictypes of transitions: transitions between the same gear, coastingin neutral gear, coasting with a gear engaged with no fuel injection and transitions involving gear changes. Simulations are performed on a driving cycle commonly used for testing distribution type of driving. In order to make sure that the truck does not deviate too much from a normal way of driving, restrictions on maximum and minimum allowed velocities are imposed based on statistics from real traffic data. The simulations show that 12.7% fuel can be saved without increasing the trip time by allowing the truck to engage neutral gear and make small deviations from the reference trajectory.

  • 10.
    Henriksson, Manne
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL. Scania CV AB, Sweden.
    Flärdh, Oscar
    Mårtensson, Jonas
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Optimal Speed Trajectories Under Variations in the Driving Corridor2017In: IFAC-PapersOnLine, Elsevier, 2017, Vol. 50, p. 12551-12556Conference paper (Refereed)
    Abstract [en]

    The optimal speed trajectory for a heavy-duty truck is calculated using the Pontryagin's maximum principle. The truck motion depends on controllable tractive and braking forces and external forces such as air and rolling resistance and road slope. The velocity of the vehicle is restricted to be within a driving corridor which consists of an upper and a lower boundary. Simulations are performed on data from a test cycle commonly used for testing distribution driving. The data include road slope and a speed reference, from which the driving corridor is created automatically. The simulations include a sensitivity analysis on how changes in the parameters for the driving corridor influence the energy consumption and trip time. For the widest driving corridor tested, 15.8% energy was saved compared to the most narrow corridor without increasing the trip time. Most energy was saved by reducing the losses due to braking and small amounts of energy were saved by reducing the losses due to air resistance. Finally, optimal trajectories with the same trip time derived from different settings on the driving corridor are compared in order to analyse energy efficient driving patterns.

  • 11.
    Henriksson, Manne
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL. Scania CV AB, Sweden.
    Flärdh, Oscar
    Mårtensson, Jonas
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Optimal Speed Trajectory for a Heavy Duty Truck Under Varying Requirements2016In: IEEE Conference on Intelligent Transportation Systems, Proceedings, ITSC, IEEE, 2016, p. 820-825, article id 7795650Conference paper (Refereed)
    Abstract [en]

    The optimal speed trajectory for a heavy duty truck is calculated by using the Pontryagin’s maximum principle. The truck motion depends on controllable tractive and braking forces and external forces such as air and rolling resistance and road slope. The solution is subject to restrictions such as maximum power and position dependent speed restrictions. The intended application is driving in environments with varying requirements on the velocity due to e.g. legal limits and traffic. In order to limit the vehicle to a speed trajectory that follows the normal traffic flow, data from real truck operation have been analysed and used for setting upper and lower boundaries for the decelerations. To evaluate the solution, simulations have been performed on a segment of a road normally used as a distribution test cycle. Three different policies were compared where the solution adopts to free optimization, optimization following traffic flow and finally cruise control using look-ahead control. Results from the simulations show that fuel consumption and trip time can be reduced simultaneously while following the traffic flow.

  • 12.
    Kokogias, Stefanos
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Svensson, Lars
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Pereira, Goncalo Collares
    KTH, School of Electrical Engineering and Computer Science (EECS), Automatic Control.
    Oliveira, Rui
    KTH, School of Electrical Engineering and Computer Science (EECS), Automatic Control. KTH Royal Inst Technol, Sch Elect Engn, Dept Automat Control, S-10044 Stockholm, Sweden..
    Zhang, Xinhai
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Song, Xinwu
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Mårtensson, Jonas
    KTH, School of Electrical Engineering and Computer Science (EECS), Automatic Control.
    Development of Platform-Independent System for Cooperative Automated Driving Evaluated in GCDC 20162018In: IEEE transactions on intelligent transportation systems (Print), ISSN 1524-9050, E-ISSN 1558-0016, Vol. 19, no 4, p. 1277-1289Article in journal (Refereed)
    Abstract [en]

    Cooperative automated driving is a promising development in reducing energy consumption and emissions, increasing road safety, and improving traffic flow. The Grand Cooperative Driving Challenge (GCDC) 2016 was an implementation oriented project with the aim to accelerate research and development in the field. This paper describes the development of the two vehicle systems with which KTH participated in GCDC 2016. It presents a reference system architecture for collaborative automated driving as well as its instantiation on two conceptually different vehicles: a Scania truck and the research concept vehicle, built at KTH. We describe the common system architecture, as well as the implementation of a selection of shared and individual system functionalities, such as V2X communication, localization, state estimation, and longitudinal and lateral control. We also present a novel approach to trajectory tracking control for a four-wheel steering vehicle using model predictive control and a novel method for achieving fair data age distribution in vehicular communications.

  • 13.
    Kramers, Anna
    et al.
    KTH, School of Architecture and the Built Environment (ABE). KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Ringenson, Tina
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Strategic Sustainability Studies.
    Sopjani, Liridona
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Arnfalk, Peter
    AaaS and MaaS for reduced environmental and climate impact of transport: Creating indicators to identify promising digital service innovations for reduced demand and optimized use of transport resources2018In: ICT4S2018. 5th International Conference on Information and Communication Technology for Sustainability, 2018, Vol. 52, p. 137-152Conference paper (Refereed)
    Abstract [en]

    In this paper, a set of indicators is presented that aim to identify promising service innovations for Accessibility as a Service (AaaS) and Mobility as a Service (MaaS); services that potentially can reduce the demand for transport and optimize use of transport infrastructure and vehicles in urban regions. The proposed indicators characterize service innovations from three different perspectives: 1) Is the service innovation environmentally sustainable? Does it reduce negative impacts on the environment (reduce carbon emissions, use of space), 2) Is it rewardable? Is value created for an organization? Does it make use of new sustainable business models, and 3) How widely is the service spread? How many users are there, what is the geographic distribution and what level of societal transition has occurred? The developed indicators are meant to guide policy makers, decision makers, business developers and academia in the prioritizations that need to be made when allocating land and resources to the most promising and powerful innovations, moving towards more environmentally friendly mobility and accessibility. The next step will be to test the indicators to identify and categorize existing and emerging new services, ideas, pilots and prototypes. The results of this second step will be presented in our next article.

  • 14.
    Kristoffersson, Ida
    et al.
    VTI Swedish National Institute for Road and Transport Research, SE - 102 15 Stockholm, Sweden.
    Pernestål Brenden, Anna
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Scenarios for the development of self-driving vehicles in freight transport2018In: Proceedings of 7th Transport Research Arena TRA2018, 2018Conference paper (Refereed)
    Abstract [en]

    This paper extends previous research by developing future scenarios for self-driving vehicles and their societal impacts in freight transport using Sweden as a case study. Freight experts from vehicle manufacturers, agencies, universities and hauliers were recruited for a workshop where they assessed the benefits, costs, possibilities and barriers for self-driving vehicles in freight transport. The paper shows that reduction in driver and vehicle costs, reduced number of incidents and more fuel-efficient driving are seen as the main benefits of self-driving vehicles in freight transport, and increased vehicle costs, lost jobs, reduced degree of filling and more transport as the main costs. Furthermore, reduced drivers’ costs, more hours-of-service and new business models are identified as the main drivers of the development and traffic management, small hauliers, loading and unloading and cross-border transport as the main barriers. The paper also integrates the description of possible developments of self-driving vehicles in freight transport into the four future scenarios developed for passenger transport in Sweden.

  • 15.
    Kurzer, Karl
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics. KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Path Planning in Unstructured Environments: A Real-time Hybrid A* Implementation for Fast and Deterministic Path Generation for the KTH Research Concept Vehicle2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    On the way to fully autonomously driving vehicles a multitude of challenges have to be overcome. One common problem is the navigation of the vehicle from a start pose to a goal pose in an environment that does not provide any specic structure (no preferred ways of movement). Typical examples of such environments are parking lots or construction sites; in these scenarios the vehicle needs to navigate safely around obstacles ideally using the optimal (with regard to a specied parameter) path between the start and the goal pose. The work conducted throughout this master's thesis focuses on the development of a suitable path planning algorithm for the Research Concept Vehicle (RCV) of the Integrated Transport Research Lab (ITRL) at KTH Royal Institute of Technology, in Stockholm, Sweden. The development of the path planner requires more than just the pure algorithm, as the code needs to be tested and respective results evaluated. In addition, the resulting algorithm needs to be wrapped in a way that it can be deployed easily and interfaced with di erent other systems on the research vehicle. Thus the thesis also tries to gives insights into ways of achieving realtime capabilities necessary for experimental testing as well as on how to setup a visualization environment for simulation and debugging.

  • 16.
    Langbroek, Joram Hendrik Maarten
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Franklin, Joel P.
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Transport Studies, CTS. KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, System Analysis and Economics.
    Susilo, Yusak
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Transport Studies, CTS. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR. KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, System Analysis and Economics.
    A stated adaptation instrument for studying travel patterns after electric vehicle adoption2018In: Transportation Research Procedia, ISSN 2324-9935, E-ISSN 2352-1465, Vol. 32, p. 464-473Article in journal (Refereed)
    Abstract [en]

    This paper describes and evaluates a stated adaptation instrument to investigate the effects of a transition towards electric vehicles on travel behaviour. The respondents were equipped with an “imaginary” electric vehicle with a specific range and were asked whether they wanted to make changes in an activity-travel schedule they had previously registered. It has been found that electric vehicle use may increase car use, and that activities are likely to be cancelled in case of problems with range limitations. In this paper, the validity, reliability and practical implementation of this stated adaptation experiment are discussed.

  • 17.
    Langbroek, Joram H.M.
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, System Analysis and Economics.
    Cebecauer, Matej
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Transport Planning, Economics and Engineering.
    Malmsten, Jon
    Solkompaniet.
    Franklin, Joel P.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, System Analysis and Economics.
    Susilo, Yusak O.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, System Analysis and Economics.
    Georén, Peter
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Electric vehicle rental and electric vehicle adoptionManuscript (preprint) (Other academic)
  • 18.
    Oakes, Benjamin Donald
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Transport Studies, CTS. KTH Royal Inst Technol, Dept Transport Sci, Ctr Safety Res, Stockholm, Sweden..
    Mattsson, Lars-Göran
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Transport Studies, CTS. KTH Royal Inst Technol, Dept Transport Sci, SE-10044 Stockholm, Sweden.;KTH Royal Inst Technol, ITRL, Stockholm, Sweden..
    Näsman, Per
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Transport Studies, CTS. KTH Royal Inst Technol, Dept Transport Sci, Ctr Safety Res, Stockholm, Sweden..
    Glazunov, Andres Alayon
    CTH Chalmers Univ Technol, Commun & Antenna Syst Div, Dept Elect Engn, Gothenburg, Sweden..
    A Systems-Based Risk Assessment Framework for Intentional Electromagnetic Interference (IEMI) on Critical Infrastructures2018In: Risk Analysis, ISSN 0272-4332, E-ISSN 1539-6924, Vol. 38, no 6, p. 1279-1305Article in journal (Refereed)
    Abstract [en]

    Modern infrastructures are becoming increasingly dependent on electronic systems, leaving them more vulnerable to electrical surges or electromagnetic interference. Electromagnetic disturbances appear in nature, e.g., lightning and solar wind; however, they may also be generated by man-made technology to maliciously damage or disturb electronic equipment. This article presents a systematic risk assessment framework for identifying possible, consequential, and plausible intentional electromagnetic interference (IEMI) attacks on an arbitrary distribution network infrastructure. In the absence of available data on IEMI occurrences, we find that a systems-based risk assessment is more useful than a probabilistic approach. We therefore modify the often applied definition of risk, i.e., a set of triplets containing scenario, probability, and consequence, to a set of quadruplets: scenario, resource requirements, plausibility, and consequence. Probability is replaced by resource requirements and plausibility, where the former is the minimum amount and type of equipment necessary to successfully carry out an attack scenario and the latter is a subjective assessment of the extent of the existence of attackers who possess the motivation, knowledge, and resources necessary to carry out the scenario. We apply the concept of intrusion areas and classify electromagnetic source technology according to key attributes. Worst-case scenarios are identified for different quantities of attacker resources. The most plausible and consequential of these are deemed the most important scenarios and should provide useful decision support in a countermeasures effort. Finally, an example of the proposed risk assessment framework, based on notional data, is provided on a hypothetical water distribution network.

  • 19.
    Pereira, Gonçalo Collares
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL. KTH, School of Electrical Engineering (EES), Automatic Control.
    Svensson, Lars
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL. KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Lima, Pedro
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Mårtensson, Jonas
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering (EES), Automatic Control.
    Lateral Model Predictive Control for Over-Actuated Autonomous Vehicle2017In: 2017 IEEE Intelligent Vehicles Symposium (IV), Institute of Electrical and Electronics Engineers (IEEE), 2017, p. 310-316, article id 7995737Conference paper (Refereed)
    Abstract [en]

    In this paper, a lateral controller is proposed for an over-Actuated vehicle. The controller is formulated as a linear time-varying model predictive controller. The aim of the controller is to track a desired path smoothly, by making use of the vehicle crabbing capability (sideways movement) and minimizing the magnitude of curvature used. To do this, not only the error to the path is minimized, but also the error to the desired orientation and the control signals requests. The controller uses an extended kinematic model that takes into consideration the vehicle crabbing capability and is able to track not only kinematically feasible paths, but also plan and track over non-feasible discontinuous paths. Ackermann steering geometry is used to transform the control requests, curvature, and crabbing angle, to wheel angles. Finally, the controller performance is evaluated first by simulation and, after, by means of experimental tests on an over-Actuated autonomous research vehicle.

  • 20.
    Pernestål Brenden, Anna
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Product and Service Design. KTH, School of Computer Science and Communication (CSC), Centres, School of Architecture and the Built Environment (ABE), Centres, Centre for Sustainable Communications, CESC, Green Leap. KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Hesselgren, Mia
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Product and Service Design. KTH, School of Computer Science and Communication (CSC), Centres, School of Architecture and the Built Environment (ABE), Centres, Centre for Sustainable Communications, CESC, Green Leap.
    Possibilities and barriers in ride-sharing in work commuting – a case study in Sweden2018Conference paper (Refereed)
    Abstract [en]

    To understand possibilities and barriers for ride-sharing in work commuting, 451 persons living in the same suburban area and working at the same site were invited to join a ride-sharing program and use a mobile application. Two quantitative web surveys and 16 in-depth interviews have been performed. The results have been analysed using social practice theories as an analytical lens. The participants understood the benefits with the ride-sharing practice, but out of the 451 invited participants, only 8 downloaded the required mobile application for the ride-sharing program. Different to previous results in the literature, trust and security were not seen as issues in this case. Instead the expected loss of flexibility was seen as the main barrier. The participants found a meaning in “being a green commuter” and understood that ride-sharing could contribute to decrease challenges of congestion, environmental impact, and overfull parking places. However, they rated their own current flexibility and convenience in commuting higher than the expected benefits from ride-sharing.

  • 21.
    Pernestål Brenden, Anna
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Kottenhoff, Karl
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    Self-driving shuttles as a complement to public transport – a characterization and classification2018In: Proceedings of 7th Transport Research Arena TRA2018, 2018Conference paper (Refereed)
    Abstract [en]

    Sustainable transportation is a top priority challenge for many cities and urban regions. To reach that, an attractive public transport plays a key role. In this paper an analysis of how the technology of self-driving vehicles, and in particular shuttles for about 6-20 passengers, can complement and improve attractively in public transport. Self-driving shuttles provide a new component to public transport, as smaller vehicles can operate on a higher frequency to a cost of the same order of magnitude as conventional larger buses. Six types of applications of self-driving shuttles in public transport are identified: Feeder line, Truncation of high capacity line, Cross connections, Center line, On-demand feeder line, and Within-area service (line or on demand). The application types are exemplified by two potential cases in Stockholm, and implementation barriers and strategies are discussed. The classification, together with examples from on-going applications, suggests that SD shuttles can contribute to public transport already without being fully self-driving everywhere.

  • 22.
    Pernestål Brenden, Anna
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Koutoulas, Anastasios
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, System Analysis and Economics.
    Fu, Jiali
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Rumpler, Romain
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Sanchez-Diaz, Ivan
    Chalmers University of Technology.
    Behrends, Sönke
    Chalmers University of Technology.
    Glav, Ragnar
    Scania CV AB.
    Cederstav, Fredrik
    Volvo AB.
    Brolinsson, Märta
    Stockholms Stad.
    Off-peak City Logistics – A Case Study in Stockholm2017Report (Other academic)
    Abstract [en]

    Two heavy trucks have been operated in Stockholm city center during night time for e period of one and a half years. New technology has been tested: one the trucks was an electric hybrid with zone management and one was a PIEK certified biogas truck. The two trucks have been operated in different delivery schemes: on dedicated and one consolidated. The off-peak trial has been assessed in from four different perspectives: noise, transport efficiency, users and policy, and socioeconomic aspects. In addition, a literature survey has been performed.  

    Noise produced while travelling with the two trucks tested is not disturbing. The main challenge is noise produced during unloading, and in particular in areas where the background noise is low.

    Transportation efficiency is improved from several perspectives compared with daytime deliveries: transport speed increased, fuel consumption decreased and service times decreased. However, one conclusion from the project is that it is challenging to compare daytime deliveries with off-peak deliveries for an individual truck, since the routing will be different depending on the time of the day even if the delivery points are the same. The reason is that the routing during daytime will be optimized to take congestion into account. Therefore, if general conclusions are to be drawn, data from more different trucks in different delivery schemes need to be collected and analyzed.

    Stakeholder interviews showed that the most important benefits are increased efficiency, shorter travel and deliver times, higher productivity both for carriers and receivers, less environmental impacts and fuel cost savings, as well as better working conditions when trucks are moved from rush hours to off-peak hours. The most important social costs are increased noise levels and noise disturbances, additional staff, equipment and wage costs as well as higher risks in handling goods deliveries at night times, especially in the case of unassisted deliveries. In general, the benefits exceed the costs.

    From the socio-economic analysis it is clear that the dominating type of external cost for daytime deliveries is contribution to congestion. This cost is reduced is nearly eliminated during off-peak deliveries. In addition, off-peak deliveries reduces CO2 emissions, but even more the emissions of air pollutants and can therefore contribute significantly to improving local air quality. The cost of noise is more than twice as big as for daytime deliveries.

    From the city’s perspective the most important remaining challenges are related to 1) Noise measurements and surveillance, 2) general requirements and surveillance, for example concerning vehicles, fuels, and emission levels that are to be allowed, 3) The responsibility for potential additional costs related to infrastructural changes needed. 

    The overall conclusion from the project is that the benefits from off-peak deliveries exceed the costs. The results from the project suggest that the concept of off-peak deliveries is beneficiary in the Stockholm region, and the off-peak delivery program is suggested to continue and be scaled up to involve more vehicles and other types of goods. During the upscaling it is relevant to continue to study effects on transport efficiency, noise levels, and potential business barriers that may arise.

  • 23.
    Pernestål Brenden, Anna
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Kristoffersson, Ida
    VTI.
    Mattsson, Lars-Göran
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Future scenarios for self-driving vehicles in Sweden2017Report (Other academic)
    Abstract [en]

    The development of Self-Driving Vehicles (SDVs) is fast, and new pilots and tests are released every week. SDVs are predicted to have the potential to change mobility, human life and society.

    In literature, both negative and positive effects of SDVs are listed (Litman 2015; Fagnant and Kockelman 2015). Among the positive effects are increased traffic throughput leading to less congestion, improved mobility for people without a driver’s license, decreased need for parking spaces, and SDV as an enabler for shared mobility. On the other hand, SDVs are expected to increase the consumption of transport which leads to an increase in total vehicle kilometers travelled. This effect is further reinforced by empty vehicles driving around. This will increase the number of vehicles on the streets and lead to more congestion and increased energy usage. Since the SDV technology is expensive, segregation may be a consequence of the development. In addition there are several challenges related to for example legislation, standardization, infrastructure investments, privacy and security. The question is not if, but rather when SDVs will be common on our streets and roads, and if they will change our way of living, and if so, how?

    As we are in a potential mobility shift, and decisions made today will affect the future development, understanding possibilities and challenges for the future is important for many stakeholders. To this end a scenario-based future study was performed to derive a common platform for initiation of future research and innovation projects concerning SDVs in Sweden. This study will also be used in the ongoing governmental investigation about future regulations for SDVs on Swedish roads (Bjelfvenstam 2016). A third motivation for the study is to shed light on how demography, geography and political landscape can affect the development of new mobility services.

    Since there are many different forces that drive the development, often uncertain and sometimes in conflict with each other, a scenario planning approach was chosen. In previous studies, different types of predictions have been derived. Most of them are made by US scholars and are therefore naturally focused on the development in the US. The culture, both with respect to urban planning and public transport is different in Europe compared to the US.

    The work has been performed by an expert group and a smaller analysis team. The expert group has involved nearly 40 persons from 20 transport organizations, including public authorities, lawyers, city planners, researchers, transport service suppliers, and vehicle manufacturers. The expert group met three times, each time focusing on a specific theme: 1) trend analysis, 2) defining scenario axes of uncertainty, and 3) consequence analysis. The analysis team, consisting of the present three authors and two future strategists, has analyzed, refined and condensed the material from the expert group.

    During the project certain trends and strategic uncertainties were identified by the expert group. The uncertainties that were identified as most important for the development of SDVs in Sweden are: 1) whether the sharing economy becomes a new norm or not, and 2) whether city planners, authorities and politicians will be proactive in the development of cities and societies or not, especially regarding the transportation system. This led to four scenarios: A) “Same, same but all the difference” – a green, individualistic society, B) “Sharing is the new black” – a governmentally driven innovation society based on sharing, C) “Follow the path” – an individualistic society based on development in the same direction as today, and D) “What you need is what you get” – a commercially driven innovation society where sharing is a key.

    In the paper, we describe the scenarios and the process to derive them in more detail. We also present an analysis of the consequences for the development of SDVs in the four scenarios, including predictions concerning pace of development, level of self-driving, fleet size, travel demand and vehicle kilometers travelled. The paper also includes a discussion and comparison with other studies on the development of SDVs in the US, Europe and Asia.

  • 24.
    Plessen, Mogens Graf
    et al.
    IMT Sch Adv Studies Lucca, Piazza S Francesco 19, I-55100 Lucca, Italy..
    Lima, Pedro F.
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Mårtensson, Jonas
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Bemporad, Alberto
    IMT Sch Adv Studies Lucca, Piazza S Francesco 19, I-55100 Lucca, Italy..
    Wahlberg, Bo
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Trajectory Planning Under Vehicle Dimension Constraints Using Sequential Linear Programming2017In: 2017 IEEE 20TH INTERNATIONAL CONFERENCE ON INTELLIGENT TRANSPORTATION SYSTEMS (ITSC), IEEE , 2017Conference paper (Refereed)
    Abstract [en]

    This paper presents a spatial-based trajectory planning method for automated vehicles under actuator, obstacle avoidance, and vehicle dimension constraints. Starting from a nonlinear kinematic bicycle model, vehicle dynamics are transformed to a road-aligned coordinate frame with path along the road centerline replacing time as the dependent variable. Space-varying vehicle dimension constraints are linearized around a reference path to pose convex optimization problems. Such constraints do not require to inflate obstacles by safety-margins and therefore maximize performance in very constrained environments. A sequential linear programming (SLP) algorithm is motivated. A linear program (LP) is solved at each SLP-iteration. The relation between LP formulation and maximum admissible traveling speeds within vehicle tire friction limits is discussed. The proposed method is evaluated in a roomy and in a tight maneuvering driving scenario, whereby a comparison to a semi-analytical clothoid-based path planner is given. Effectiveness is demonstrated particularly for very constrained environments, requiring to account for constraints and planning over the entire obstacle constellation space.

  • 25. Sanchez-Diaz, Ivan
    et al.
    Georén, Peter
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Brolinson, Marta
    Shifting urban freight deliveries to the off-peak hours: a review of theory and practice2017In: Transport reviews, ISSN 0144-1647, E-ISSN 1464-5327, Vol. 37, no 4, p. 521-543Article, review/survey (Refereed)
    Abstract [en]

    This paper presents a comprehensive review of the literature on off-peak hour deliveries (OPHD). The review identifies different approaches and policy levers used in the past, such as the laissez-faire approach, a road pricing approach, an incentives approach, and a regulatory approach. The paper also identifies different delivery reception schemes discussed in the literature. The authors complement the theory with a synthesis of pilot tests and the analysis of a set of interviews with practitioners (from the public sector and other organisations) in charge of OPHD programmes. The results from this review show the potential benefits that these programmes could bring about, the challenges faced in the early stages - along with potential solutions - and the significant progress that has been made in this domain in the last decade. According to the review, the results from the pilot tests tend to be positive, suggesting the importance of these programmes to reach more efficient and sustainable transportation systems.

  • 26.
    Tomner, Petter
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics. KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Design and implementation of control and actuation for an over-actuated research vehicle2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    AbstractThe RCV is a four wheel drive and steer electrical vehicle developed and built by the Transport Lab at KTH Royal Institute of Technology. It is fully steer-by-wire and each wheel can be individually controlled, both with regard to steering angle, as well as camber and driving torque.The RCV is planned to be used as a common platform for different fields of research, as a rolling laboratory to implement and evaluate research with.In this report the specification and functionalities of the RCV are reviewed and its data collection capabilities are validated and evaluated through classic vehicle dynamic analyses such as circle tests, step steer and roll out tests. Also, some more experimental functionalities such as simple torque vectoring, toe sweep and steering by joystick, as proof of concept of the RCV as a research and prototyping platform.Finally, some suggestions for further developments for the RCV platform are presented.

  • 27.
    Turner, Rodney
    et al.
    Politecnico di Milano & SKEMA Business School.
    Miterev, Maksim
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Industrial Management. KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Exploring the organizational designs of the project-based organization2018Conference paper (Refereed)
  • 28.
    Valerio, Turri
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Automatic Control. KTH, School of Electrical Engineering and Computer Science (EECS), Centres, ACCESS Linnaeus Centre.
    Flärdh, O.
    Mårtensson, Jonas
    KTH, School of Electrical Engineering and Computer Science (EECS), Automatic Control. KTH, School of Electrical Engineering and Computer Science (EECS), Centres, ACCESS Linnaeus Centre. KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Johansson, Karl H.
    KTH, School of Electrical Engineering and Computer Science (EECS), Automatic Control.
    Fuel-optimal look-ahead adaptive cruise control for heavy-duty vehicles2018In: 2018 Annual American Control Conference (ACC), Institute of Electrical and Electronics Engineers (IEEE), 2018, p. 1841-1848, article id 8431494Conference paper (Refereed)
    Abstract [en]

    In this paper, we investigate the problem of how to optimally control a heavy-duty vehicle following another one, commonly referred as ad-hoc or non-cooperative platooning. The problem is formulated as an optimal control problem that exploits road topography information and the knowledge of the preceding vehicle speed trajectory to compute the optimal engine torque and gear request for the vehicle under control. The optimal control problem is implemented by dynamic programming and is tested in a simulation study that compares the performance of multiple longitudinal control strategies. The proposed look-ahead adaptive cruise controller is able to achieve fuel saving up to 7% with respect to the use of a reference vehicle-following controller, by combining the benefits of adjusting the inter-vehicular distance according to the future slope with those of alternating phases of throttling and freewheeling (driving in neutral gear).

  • 29.
    Xylia, Maria
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy and Climate Studies, ECS. KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Leduc, S.
    Patrizio, P.
    Silveira, Semida
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy and Climate Studies, ECS.
    Kraxner, F.
    Developing a dynamic optimization model for electric bus charging infrastructure2017In: Transportation Research Procedia, Elsevier, 2017, Vol. 27, p. 776-783Conference paper (Refereed)
    Abstract [en]

    Urban regions account for 64% of global primary energy use and 70% of carbon emissions. For that reason, options to decarbonize urban environments are receiving increasing attention. In this context, public transport shall play a key role in decarbonizing urban road transport. One efficient way to achieve that is shifting towards clean fuels and modern electric buses, an option that is already under implementation in several cities around the world. In this paper, the basis for developing a dynamic optimization model for establishing charging infrastructure for electric buses is presented, using Stockholm, Sweden, as a case study. The model places constraints depending on the bus stop type (end or middle stop) which affects the time available for charging at each particular location. It also identifies the optimal technology type for the buses: conductive or inductive. In addition, the electric buses compete with buses run on biogas or biodiesel. In this paper, we present the results of a cost minimization scenario with constraints placed on the available charging time and power, differentiated between end stops and major public transport hubs. The mean charging time is 7.33 minutes, with a standard deviation of 4.78 minutes for all bus stops. The inner city bus routes require less charging time, which ranges on average at around 3 minutes. The installation of chargers at the locations proposed in the model would require scheduling adjustments and careful planning for the density of charging occasions.

  • 30.
    Xylia, Maria
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy and Climate Studies, ECS. KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Silveira, Semida
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy and Climate Studies, ECS.
    The role of charging technologies in upscaling the use of electric buses in public transport: Experiences from demonstration projects2018In: Transportation Research Part A: Policy and Practice, ISSN 0965-8564, E-ISSN 1879-2375, Vol. 118, p. 399-415Article in journal (Refereed)
    Abstract [en]

    Electrification of public bus transport services is currently being explored in various demonstration projects around the world. The objective of this paper is to (i) gather insights from electric bus demonstration projects with a focus on charging technologies (conductive, inductive) and strategies (slow, fast); and explore the role these factors may play as upscaling of electric bus deployment is considered. The focus is on the Nordic region. A survey with stakeholders involved with electric bus demonstration projects is performed for understanding the benefits and drawbacks of each solution, and identifying the main themes emerging from project implementation and upscaling. Advantages of the conductive charging include the maturity of the technology and its higher maximum charging power compared to currently available inductive alternatives. On the other hand, inductive technology entails other benefits, such as the lack of moving parts which could reduce the maintenance costs for infrastructure, as well as minimal visibility of the equipment. The main issues likely to impact the upscaling of electric bus use are related to the maturity, cost-effectiveness, compatibility, and charging efficiency of the available technologies.

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