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  • 51.
    Edrén, Johannes
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Jerrelind, Jenny
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Stensson Trigell, Annika
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Drugge, Lars
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Implementation and evaluation of force allocation control of a down-scaled prototype vehicle with wheel corner modules2013Inngår i: International Journal of Vehicle Systems Modelling and Testing, ISSN 1745-6436, Vol. 8, nr 4, s. 335-363Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The implementation of wheel corner modules on vehicles creates new possibilities of controlling wheel forces through the utilisation of multiple actuators and wheel motors. Thereby new solutions for improved handling and safety can be developed. In this paper, the control architecture and the implementation of wheel slip and chassis controllers on a down-scaled prototype vehicle are presented and analysed. A simple, cost-effective force allocation algorithm is described, implemented and evaluated in simulations and experiments. Straight line braking tests were performed for the three different controller settings individual anti-lock brakes (ABS), yaw-torque-compensated ABS and force allocation using both wheel torque and steering angle control at each wheel. The results show that force allocation is possible to use in a real vehicle, and will enhance the performance and stability even at a very basic level, utilising very few sensors with only the actual braking forces as feedback to the chassis controller.

  • 52.
    Edrén, Johannes
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Jonasson, Mats
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Jerrelind, Jenny
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Stensson Trigell, Annika
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Utilization of Vertical Loads by Optimization for Integrated Vehicle Control2012Inngår i: Proceedings of AVEC12, 11th Symposium on Advanced Vehicle Control, September 9-12, Seoul, Korea, 2012., 2012Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    This paper presents results on how to optimally utilise vertical loading on individual wheels in order to improve vehicle performance during limit handling. Numerical optimisation has been used to find solutions on how the active suspension should be controlled and coordinated together with friction brakes and electric power assisted steering (EPAS). Firstly, it is investigated whether the brake distance can be shortened. Secondly, the performance during an evasive manoeuvre is investigated. The result shows that brake distance can be improved by at least 0.5 m and the speed through the evasive manoeuvre by roughly 1 km/h for the studied vehicle. Quick actuators is shown to give even better performance. These results provide guidance on how active suspension can be used to give significant improvements in vehicle performance.

  • 53.
    Edrén, Johannes
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Jonasson, Mats
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Jerrelind, Jenny
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Stensson Trigell, Annika
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Drugge, Lars
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Energy efficient cornering using over-actuationManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    This work deals with utilisation of active steering and propulsion on individual wheels in order to improve a vehicle’s energy efficiency during a double lane change manoeuvre at moderate speeds. Through numerical optimization, solutions have been found for how wheel steering angles and propulsion torques should be used in order to minimise the energy consumed by the vehicle travelling through the manoeuvre. The results show that, for the studied vehicle, the cornering resistance can be reduced by 10% compared to a standard vehicle configuration. Based on the optimization study, simplified algorithms to control wheel steering angles and propulsion torques that are more energy efficient are proposed. These algorithms are evaluated in a simulation study that includes a path tracking driver model and an energy efficiency improvement of 6-9% based on a combined rear axle steering and torque vectoring control during cornering is found. The results indicate that in order to improve energy efficiency for a vehicle driving in a non-safety-critical situation the force distribution should be shifted towards the front wheels.

  • 54.
    Edrén, Johannes
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Jonasson, Mats
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Jerrelind, Jenny
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Stensson Trigell, Annika
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Drugge, Lars
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Energy efficient cornering using over-actuation2019Inngår i: Mechatronics (Oxford), ISSN 0957-4158, E-ISSN 1873-4006, Vol. 59, s. 69-81Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This work deals with utilisation of active steering and propulsion on individual wheels in order to improve a vehicle's energy efficiency during a double lane change manoeuvre at moderate speeds. Through numerical optimisation, solutions have been found for how wheel steering angles and propulsion torques should be used in order to minimise the energy consumed by the vehicle travelling through the manoeuvre. The results show that, for the studied vehicle, the energy consumption due to cornering resistance can be reduced by approximately 10% compared to a standard vehicle configuration. Based on the optimisation study, simplified algorithms to control wheel steering angles and propulsion torques that results in more energy efficient cornering are proposed. These algorithms are evaluated in a simulation study that includes a path tracking driver model. Based on a combined rear axle steering and torque vectoring control an improvement of 6–8% of the energy consumption due to cornering was found. The results indicate that in order to improve energy efficiency for a vehicle driving in a non-safety-critical cornering situation the force distribution should be shifted towards the front wheels.

  • 55.
    Edrén, Johannes
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Jonasson, Mats
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Jerrelind, Jenny
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Stensson Trigell, Annika
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Drugge, Lars
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Utilization of optimization solutions to control active suspension for decreased braking distanceManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    This work deals with how to utilize active suspension on individual vehicle wheels in order to improve the vehicle performance during straight-line braking. Through numerical optimization, solutions have been found to how active suspension should be controlled and coordinated with friction brakes to shorten the braking distance. The results show that, for the studied vehicle, the braking distance can be shortened by more than 1 m when braking from 100 km/h. The applicability of these results is studied by investigating the approach for different vehicle speeds and actuator stroke limitations. It is shown that substantial improvements in the braking distance can also be found for lower velocities, and that the actuator strokes are an important parameter. To investigate the potential of implementing these findings in a real vehicle, a validated detailed vehicle model equipped with active struts is analysed. Simplified control laws, appropriate for on-board implementation and based on knowledge of the optimized solution, are proposed and evaluated. The results show that substantial improvements of the braking ability, and thus safety, can be made using this simplified approach. Particle model simulations have been made to explain the underlying physics and limitations of the approach. These results provide valuable guidance on how active suspension can be used to achieve significant improvements in vehicle performance with reasonable complexity and energy consumption.

  • 56.
    Edrén, Johannes
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Jonasson, Mats
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Nilsson, Andreas
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Rehnberg, Adam
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Svahn, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Stensson Trigell, Annika
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Modelica and Dymola for education in vehicle dynamics at KTH2009Inngår i: Proceedings from 7th Modelica Conference 2009, 2009, s. 775-783Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Dymola and Modelica has been used at KTH Vehicle Dynamics (KTHVD) for research work since 2000, see e.g. [1]. With the Vehicle Dynamics Library (VDL) [2], Modelica has become far more accessible for both researchers and students in the field of vehicle dynamics. Therefore a project aiming at introducing it as a tool in education was initiated in order to evaluate the current state of Dymola and Modelica as tools for wider use in education at the division. The work presented in this paper was realized as a part of a PhD course, where one of the tasks were to design dedicated exercises to illustrate fundamentals of vehicle dynamics for students.

  • 57.
    Edrén, Johannes
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Jonasson, Mats
    Vehicle Dynamics and Active Safety, Volvo Car Corporation, Göteborg, Sverige.
    Stensson Trigell, Annika
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Drugge, Lars
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Jerrelind, Jenny
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    The developement of a down-scaled over-actuated vehicle equipped with autonomous corner module functionality2010Inngår i: FISITA Proceedings 2010, paper F2010B056, 2010Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper presents the development of a functional down-scaled prototype of a passenger car with capability to control steering, wheel torques, wheel loads and camber individually. The adopted chassis technology is based on a modularised platform, referred to as Autonomous corner modules (ACM), which simplifies the re-use of components at the four corners of the vehicle and between different vehicles.

    This work gives an insight in the design of the vehicle and the selection of electrical actuators and sensors to provide all ACM functions. Since a part of the implemented chassis components do not admit to be scaled down at the same level, necessary design modifications are suggested. The problems of scaling, meaning that a down-scaled prototype cannot fully emulate a full-scaled vehicle’s all functions simultaneously, are a great disadvantage of down scaling. For example is gravity one desired parameter that is hard to physically scale down.

    In order to evaluate the behaviour of the down-scaled prototype, it is of high importance to establish the characteristics of the developed vehicle and its subsystems. In particular, tyre design is considered as complex. For this reason, different ideas of methods to confirm tyre characteristics are proposed.

    Also the paper presents the initial process of developing the prototype vehicle that is later to be used in vehicle dynamics research.

  • 58.
    Edrén, Johannes
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Sundström, Peter
    Modelon AB, Göteborg, Sweden.
    Jonasson, Mats
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Jacobson, Bengt
    Chalmers Univerity of Technology, Gothenburg, Sweden.
    Andreasson, Johan
    Modelon AB, Lund, Sweden.
    Stensson Trigell, Annika
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Road friction effect on the optimal vehicle control strategy in two critical manoeuvres2014Inngår i: International Journal of Vehicle Safety, ISSN 1479-3105, Vol. 7, nr 2, s. 107-130Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper presents results on how to optimally negotiate two safety-critical vehicle manoeuvres depending on available actuators and road friction level. The motive for this research has been to provide viable knowledge of limitations of vehicle capability under the presence of environmental preview sensors, such as radar, camera and navigation. An optimal path is in this paper found by optimising the sequence of actuator requests during the two manoeuvres. Particular interest is paid on how the vehicle control strategy depends on friction. This work shows that actuation of forces and torques on and around the vehicle centre of gravity are all approximately scaled with the friction coefficient. However, this pattern is not valid at a wheel individual level, i.e. the optimal force allocation among the wheels differs under different friction conditions. One key is that lower friction level yields lower load transfer which substantially influences the wheel individual tyre force constraints.

  • 59.
    Engman, Marcus
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Szilassy, Andreas
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    Powertrain dynamic torque reduction using clutch slip control2014Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The torque dynamic caused by the firing pulse from diesel engines set high robustness demands for gearboxes and final drives in today’s heavy duty trucks. If these dynamic loads could be eliminated or dampened, the driveline can be built lighter because of the lower demands which in turn would save fuel for the driver and material cost for the manufacturer. There exist solutions to this problem that include expensive and complicated hardware; for example the double mass flywheel, but there is one opportunity that is potentially for free to the manufacturer, namely clutch slip control.

    The hypothesis of this thesis is that the torque oscillations from the engine can be reduced by controlling the clutch slip velocity. It is also evaluated if it is possible to control a slip using existing hardware in a Scania powertrain and if the control performance can be improved by changing one of the powertrain parameters. For the scope of this thesis, the wear rate and temperature of the clutch when slipping is not considered.

    The first step of the thesis is to construct a MBS model of the powertrain in question. Further on, two control designs, namely fuzzy control and two degrees of freedom control are implemented using model based control design. Both control algorithms are implemented in a heavy duty truck and the performance is evaluated. To find the parameter that constrains the performance, a parameter variation is performed using the developed model to save both time and cost.

    It is proved that the torque dynamics from the diesel engine can be dampened by forty to eighty percent in amplitude by slipping the clutch and that the implemented control design gives acceptable results for gears seven to twelve using existing hardware. The parameter variation shows that the actuation delay is the main limiting factor, enabling stable control at the first gear if removed completely.

    The slip control concept shows potential but sets high demands for hardware specification, especially for actuation delays if all gears are to be used with slip control. Using existing hardware, the control is fully implementable for gears seven to twelve with good results.

  • 60.
    Eqbal, Qudus
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Test Method Optimization ofSemi-Automatic ParkingFunction2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This is a Master of Science project performed at Volvo Cars in Gothenburg and at The RoyalInstitute of Technology KTH in Stockholm. The project is about optimization of the testmethod for semi-automatic parking. The current test method to verify the parking functions aredescribed in a document called design verification method, DVM. The test method in DVMconsiders each function’s parameter separately which takes a lot of test time and all of thefunctions cannot be tested because of time shortage. The aim of this project is to develop anoptimized test method which can solves this issue and can replace the current test method.There are also some other issues that the project need to deal with, such as the sensor’smeasuring error and the optimization of the distance from vehicle to the curb.The current test methods are based on principle of one factor at a time method, which is verytime consuming. Several other test method such as Factorial Design, Taguchi Design andPlacket Burman Design which are based on the principle of factorial design are thereforestudied. Amongst these the factorial design is chosen since it is an adequate design in term ofreduction of test time and other properties which are beneficial for the aim of this project.The proposed test method is evaluated by first performing a test version with a number ofrelevant inputs parameters for which the process is described in Chapter 3 and the evaluationof the method is described in Chapter 4. In Chapter 5 the process on how the proposed methodcan replace the current method is described.The result of this thesis work is a proposed and verified system verification test method forparking assistance which can also be used for other systems as well on some levels.

  • 61.
    Eriksson, Johan
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Nordmark, Arne B.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Drugge, Lars
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    An Experimental and Numerical Study of Pantograph Dynamics, with the Application of Dimension Estimation.Manuskript (preprint) (Annet vitenskapelig)
  • 62.
    Erséus, Andreas
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Driver-Vehicle Interaction: Identification, Characterization and Modelling of Path Tracking Skill2010Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Since the dawn of the automobile, driver behaviour has been an issue. Driving can result in accidents that may harm not only the driver but also passengers and the surroundings. This calls for measures that restrict the usage of vehicles and to assist the individual driver to conduct the driving in a safe, yet practically efficient manner. The vehicles should therefore be both safe and intuitive, and preferably answer to thedifferent needs of all kinds of drivers.

    Driving skill can be defined in many ways, depending on the objective of the driving task, but answer in some way to the question of how well the driver can conduct the driving task. To assist low skill drivers without compromising the driving demand for high skill drivers, it is of highest importance that vehicles are tested and designed to meet those needs. This includes both the testing activities in the vehicle design phase in general but also the configuration for active systems and preventive safety, preferable with settings that adapts to the skill of the individual driver.

    The work here comprises the definition of skill and of driver recruitment procedures, scenario design, the development of an analysis method for objective measures, and the gathering of metrics to characterize the driver skill. Moreover, a driver model has been developed that makes use of driver skill characteristics. To gather the information needed, extensive multidisciplinary literature studies were conducted, as well as using field tests and test using an advanced moving base driving simulator. Here the focus is on path tracking skill, which is the main control aspect of driving, although the developed driving scenarios allow a varying degree of path planning, which is more related to regulation. The first simulator test was done with a very simple criterion fordriver selection, but the results gave a good insight into the variation between drivers ingeneral. For the following tests the recruitment procedure was refined to find drivers with high or low vehicle control and regulation skill, a recruitment that also was verified to really represent two different populations.

    A method was defined that successfully identified sets of skill-related measures, with some variation in composition depending on the path tracking demand on the driver. Int he curving road scenario, for example, the highest number of skill-related measures is identified in the curves, which is reasonable since the straight segments do not require the same amount of active control from the drivers.

    The driver model developed uses a quasi-static analytical description of the driver knowledge of the vehicle dynamics, but possesses the capability of nonlinear descriptions. The parameters in this model are mainly physical properties that easily can be related to the driving process. Metrics gathered are used for identification of the driver model setup for a double lane change scenario using an optimization routine, with adjusted parameter settings for different velocities.

    With a subjective comparison of the recorded driving simulator data, the method is verified to enable driver skill settings for driver models. In addition, the method allows metrics to be gathered for driver skill identification routines, meeting the defined objectives of the project.

  • 63.
    Erséus, Andreas
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Drugge, Lars
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Stensson Trigell, Annika
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    A path tracking driver model with representation of driving skill2011Inngår i: International Journal of Vehicle Systems Modelling and Testing, ISSN 1745-6436, Vol. 6, nr 2, s. 145-186Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A flexible and intuitive non-linear driver model is proposed, which allows setting of physically relevant parameters for representation of both typical high and typical low skill drivers in a path tracking scenario with constant speed. The model is equipped with a relatively simple internal vehicle model and is divided into three levels of driving skill: perceptual, anticipatory and interpretational skill; decisional skill; and execution skill. Validation of the model is performed using the results from moving base driving simulator tests with the double lane change scenario described in ISO 3888-1:1999. The parameter sets used for the model configuration are selected based on physical relevance to the model and optimisation is carried out with a Nelder-Mead implementation, showing that the model is able to resemble the characteristics of the driver types in the scenario for 70 km/h, and with adjustments being able to represent drivers at other speeds.

  • 64.
    Erséus, Andreas
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Stensson Trigell, Annika
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Drugge, Lars
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Characteristics of path tracking skill on a curving road2015Inngår i: International Journal of Vehicle Design, ISSN 0143-3369, E-ISSN 1741-5314, Vol. 67, nr 1, s. 26-44Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The objective of this research work is to evaluate the relation of driver skill to measurements done when driving on a regular curving road, i.e., performing a primary driving task. A curving road scenario is designed using both clear sight and fog-limited sight distance. Measures are compared under equal conditions to identify the best separation of recruited driver types. A moving base simulator, VTI Simulator III, is used for the acquisition of driver metrics. Curves are found to be more reliable for identifying driver skill than straight road segments, and a number of measures show good performance in characterising driving skill under the tested conditions, both for clear sight and with the preview limited down to 30 m. The standard deviation proves to be very useful and qualifies for successful driver skill categorisation for commonly sampled data such as the lateral acceleration, yaw rate and steering wheel angle.

  • 65.
    Erséus, Andreas
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Stensson Trigell, Annika
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Drugge, Lars
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Methodology for finding parameters related to path tracking skill applied on a DLC-test in a moving base driving simulator2013Inngår i: International Journal of Vehicle Autonomous Systems, ISSN 1471-0226, E-ISSN 1741-5306, Vol. 11, nr 1, s. 1-21Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The objective of this research is to develop and assess a method that can evaluate the relation of the driver's path tracking skill to a large number of vehicle parameters. The proposed methodology for comparison of measures under equal conditions is applied on test data from a double lane change test in a moving base simulator. Several measures are found to separate the recruited high and low skill driver groups, with the best results for the second part of the manoeuvre. Standard deviation qualifies for successful driver skill categorisation using commonly sampled data, e.g., steering wheel rate and angular acceleration.

  • 66.
    Falk, Per
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Test Fixtures for Vibration Testing of Components2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The aim of this thesis has been to try to improve vibration testing of electrical and electromechanical components that are used within Scania’s segment of the vehicle industry. To do this, guidelines regarding the design of vibration test fixtures has been developed. Since every fixture is mounted on a bottom plate during vibration testing these bottom plates have also been under study and a proposal for a standardized bottom plate is presented. In order to be able to easily test components with basic designs a modular fixture has also been designed, manufactured and evaluated within the scope of this thesis.

    Implementation of the proposed guidelines for fixture design is most importantly argued to enable power transfer between the component and fixture during testing that as far as possible resembles the power transfer that takes place when the component is mounted on/in an actual vehicle. Using the standardized bottom plate and producing new fixtures to fit the same hole pattern is argued to decrease the work load for each vibration test considerably. Finally good results are shown regarding the performance of the modular fixture.

  • 67.
    Favre, Tristan
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Aerodynamik.
    Jarlmark Näfver, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Stensson Trigell, Annika
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Efraimsson, Gunilla
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Aeroakustik.
    Static coupling between detached-eddy simulations and vehicle dynamic simulation of a generic road vehicle model in unsteady crosswind with different rear configurationsArtikkel i tidsskrift (Annet vitenskapelig)
  • 68.
    Gao, Fan
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik. KTH, Skolan för industriell teknik och management (ITM), Centra, Integrated Transport Research Lab, ITRL.
    State-Estimator Design for the KTH Research Concept Vehicle2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    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.

  • 69.
    Gil Gómez, Gaspar
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik. Volvo Cars.
    Towards efficient vehicle dynamics development: From subjective assessments to objective metrics, from physical to virtual testing2017Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Vehicle dynamics development is strongly based on subjective assessments (SA) of vehicle prototypes, which is expensive and time consuming. Consequently, in the age of computer- aided engineering (CAE), there is a drive towards reducing this dependency on physical test- ing. However, computers are known for their remarkable processing capacity, not for their feelings. Therefore, before SA can be computed, it is required to properly understand the cor- relation between SA and objective metrics (OM), which can be calculated by simulations, and to understand how this knowledge can enable a more efficient and effective development process.

    The approach to this research was firstly to identify key OM and SA in vehicle dynamics, based on the multicollinearity of OM and of SA, and on interviews with expert drivers. Sec- ondly, linear regressions and artificial neural network (ANN) were used to identify the ranges of preferred OM that lead to good SA-ratings. This result is the base for objective require- ments, a must in effective vehicle dynamics development and verification.

    The main result of this doctoral thesis is the development of a method capable of predicting SA from combinations of key OM. Firstly, this method generates a classification map of ve- hicles solely based on their OM, which allows for a qualitative prediction of the steering feel of a new vehicle based on its position, and that of its neighbours, in the map. This prediction is enhanced with descriptive word-clouds, which summarizes in a few words the comments of expert test drivers to each vehicle in the map. Then, a second superimposed ANN displays the evolution of SA-ratings in the map, and therefore, allows one to forecast the SA-rating for the new vehicle. Moreover, this method has been used to analyse the effect of the tolerances of OM requirements, as well as to verify the previously identified preferred range of OM.

    This thesis focused on OM-SA correlations in summer conditions, but it also aimed to in- crease the effectiveness of vehicle dynamics development in general. For winter conditions, where objective testing is not yet mature, this research initiates the definition and identifica- tion of robust objective manoeuvres and OM. Experimental data were used together with CAE optimisations and ANOVA-analysis to optimise the manoeuvres, which were verified in a second experiment. To improve the quality and efficiency of SA, Volvo’s Moving Base Driving Simulator (MBDS) was validated for vehicle dynamics SA-ratings. Furthermore, a tablet-app to aid vehicle dynamics SA was developed and validated.

    Combined this research encompasses a comprehensive method for a more effective and ob- jective development process for vehicle dynamics. This has been done by increasing the un- derstanding of OM, SA and their relations, which enables more effective SA (key SA, MBDS, SA-app), facilitates objective requirements and therefore CAE development, identi- fies key OM and their preferred ranges, and which allow to predict SA solely based on OM. 

  • 70.
    Gil Gómez, Gaspar
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Towards Efficient Vehicle Dynamics Evaluation using Correlations of Objective Metrics and Subjective Assessments2015Licentiatavhandling, med artikler (Annet vitenskapelig)
  • 71.
    Gil Gómez, Gaspar
    et al.
    Volvo Cars.
    Alexander, Lönnergård
    SEGULA Technologies.
    Mohit, Asher
    Volvo Cars.
    Nybacka, Mikael
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Bakker, Egbert
    Volvo Cars.
    Drugge, Lars
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Analysis and optimisation of objective vehicle dynamics testing in winter conditions2017Inngår i: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 55, nr 7, s. 945-969Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Objective testing of vehicle handling in winter conditions has not been implemented yet because of its low repeatability and its low signal-to-noise ratio. Enabling this testing, by identifying robust manoeuvres and metrics, was the aim of this study. This has been achieved by using both experimental data, gathered with steering-robot tests on ice, and simulation models of different complexities. Simple bicycle models with brush and MF-tyre models were built, both optimally parameterised against the experimental data. The brush model presented a better balance in complexity performance. This model was also implemented in a Kalman filter to reduce measurement noise; however, a simpler low-pass filter showed almost similar results at lower cost. A more advanced full vehicle model was built in VI-CarRealTime, based on kinematics and compliance data, damper measurements, and real tyre measurements in winter conditions. This model offered better results and was therefore chosen to optimise the initial manoeuvres through test design and simulations. A sensitivity analysis (ANOVA) of the experimental data allowed one to classify the robustness of the metrics. Finally, to validate the results, the proposed and the initial manoeuvres were tested back to back in a new winter campaign.

  • 72.
    Gil Gómez, Gaspar
    et al.
    Volvo Cars.
    Andersson Eurenius, C.
    Volvo Cars.
    Donnay Cortiñas, J.
    Volvo Cars.
    Bakker, Egbert
    Volvo Cars.
    Nybacka, Mikael
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Drugge, Lars
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Jacobson, Bengt
    Chalmers University of Technology.
    Validation of a Moving Base Driving Simulator for Subjective Assessments of Steering Feel and Handling2017Inngår i: 13th International Symposium on Advanced Vehicle Control, CRC Press/Balkema , 2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Moving Base Driving Simulators (MBDS) have a large potential to increase effectiveness in vehicle dynamics development. MBDS can reduce dependency on vehicle-prototypes by allowing subjective assessments (SA) of models. Little is, however, known about the relation of SA in MBDS and in physical ve- hicles. This paper aims to increase this knowledge, and proposes and implements a methodology to validate MBDS for SA of steering feel and handling. Firstly, vehicle models were generated from Kinematics & Com- pliance measurements of real vehicles. These models were validated versus objective tests, with steering ro- bots, of the physical vehicles. These vehicles and their MBDS-models were assessed by expert drivers, using a scanned-test track in the MBDS. Comparison of the SA in both environments enabled the MBDS validation. Promising results, with higher SA accuracy for handling than for steering feel, indicates that the major im- provement effort should focus on the steering model and its simulation in the MBDS.

  • 73.
    Gil Gómez, Gaspar
    et al.
    Volvo Cars.
    Nybacka, Mikael
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Bakker, Egbert
    Volvo Cars.
    Drugge, Lars
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Analysing vehicle dynamics objective and subjective testing in winter conditions2016Inngår i: The Dynamics of Vehicles on Roads and Tracks: Proceedings of the 24th Symposium of the International Association for Vehicle System Dynamics, IAVSD 2015, Taylor & Francis Group, 2016, s. 759-768Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper presents a test procedure developed to gather good quality data from objective and subjective testing on winter conditions. As the final goal of this test is to analyse the correlation between objective metrics and subjective assessments on winter for steering and handling, this procedure has to ensure a minimum change of the surface properties, which has a major influence on vehicle performance, during the whole test campaign. Therefore, the method presented keeps the total test time very low and allows similar vehicle configurations to be test- ed, objectively and subjectively, very close in time. Moreover, continuous maintenance work on the ice is performed. Reference vehicles are also used to monitor the changes on vehicle per- formance caused by weather conditions, which are inevitable. The method showed to be very effective. Initial results on objective metrics and subjective assessments are also presented. 

  • 74.
    Gil Gómez, Gaspar
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik. Volvo Cars.
    Nybacka, Mikael
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Bakker, Egbert
    Volvo Cars.
    Drugge, Lars
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Correlations of subjective assessments and objective metrics for vehicle handling and steering: A walk through history2016Inngår i: International Journal of Vehicle Design, ISSN 0143-3369, E-ISSN 1741-5314, Vol. 72, nr 1, s. 17-67Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Achieving customer satisfaction concerning steering feel and vehicle handling requires subjective assessments and tuning of vehicle components by expert test drivers and engineers. Extensive subjective testing is expensive, time consuming and requires physical vehicles, which is in conflict with reduction of development time and cost. Objective testing and model-based development are constantly increasing but translating subjective requirements into objective ones is non-trivial. This paper summarises, discusses and classifies the methods, strategies and findings in previously published research regarding correlations of subjective assessments and objective metrics for vehicle handling and steering. The aim is twofold: (i) to identify key parameters of steering, handling and their preferred values and (ii) to compile and discuss the fundamental issues to deal with in the continued search for correlations between objective metrics and subjective assessments. The paper gives a comprehensive overview and insight of different aspects to take into account when conducting research in this field.

  • 75.
    Gil Gómez, Gaspar
    et al.
    Volvo Cars.
    Nybacka, Mikael
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Bakker, Egbert
    Volvo Cars.
    Drugge, Lars
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Findings from subjective evaluations and driver ratings of vehicle dynamics: steering and handling2015Inngår i: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 53, nr 10, s. 1416-1438Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper investigates subjective assessments (SA) of vehicle handling and steering feel tests, both numerical and verbal, to understand drivers’ use of judgement scales, rating tendencies and spread. Two different test methods are compared: a short multi-vehicle first-impression test with predefined-driving vs the standard extensive single-vehicle free-driving tests, both offering very similar results but with the former saving substantial testing time. Rating repeatability is evaluated by means of a blind test. Key SA questions are identified by numerical subjective assessment autocorrelations and by generating word clouds from the most used terms in verbal assessments, with both methods leading to similar key parameters. The results exposed in this paper enable better understanding of SA, allowing improving the overall subjective testing and evaluation process, and improving the data collection and analysis process needed before identifying correlations between SA and objective metrics.

  • 76.
    Gil Gómez, Gaspar
    et al.
    Volvo Cars.
    Nybacka, Mikael
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Bakker, Egbert
    Volvo Cars.
    Drugge, Lars
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Objective metrics for vehicle handling and steering and their correlations with subjective assessments2016Inngår i: International Journal of Automotive Technology, ISSN 1229-9138, E-ISSN 1976-3832, Vol. 17, nr 5, s. 777-794Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper focuses on increasing the available knowledge about correlations between objective metrics and subjective assessments in steering feel and vehicle handling. Linear and non-linear correlations have been searched for by means of linear regression and neural network training, complemented by different statistical tools. For example, descriptive statistics, the t-distribution and the normal distribution have been used to define the 95% confidence interval for expected subjective assessments and their mean, which makes it possible to predict the subjective rating related to a given objective metric and its area of confidence. Single- and multi-driver correlations have been investigated, as well as how the use of different databases and different vehicle classes affects the results. A method for automatizing the search for correlations when using the driver-by-driver strategy is also explained and evaluated. Ranges of preferred objective metrics for vehicle dynamics have been defined. Vehicles with characteristics within these ranges of values are expected to receive a higher subjective rating when evaluated. Finally, linear correlations between objective metrics have been studied, linear dependency between objective metrics has been identified and its consequences have been presented.

  • 77.
    Gil Gómez, Gaspar
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik. Volvo Cars.
    Nybacka, Mikael
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Drugge, Lars
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Bakker, Egbert
    Volvo Cars.
    Machine learning to classify and predict objective and subjective assessments of vehicle dynamics: the case of steering feel.2018Inngår i: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 56, nr 1, s. 150-171Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Objective measurements and computer-aided engineering simu- lations cannot be exploited to their full potential because of the high importance of driver feel in vehicle development. Further- more, despite many studies, it is not easy to identify the relation- ship between objective metrics (OM) and subjective assessments (SA), a task further complicated by the fact that SA change between drivers and geographical locations or with time. This paper presents a method which uses two artificial neural networks built on top of each other that helps to close this gap. The first network, based solely on OM, generates a map that groups together similar vehicles, thus allowing a classification of measured vehicles to be visualised. This map objectively demonstrates that there exist brand and vehi- cle class identities. It also foresees the subjective characteristics of a new vehicle, based on its requirements, simulations and measure- ments. These characteristics are described by the neighbourhood of the new vehicle in the map, which is made up of known vehicles that are accompanied by word-clouds that enhance this description. This forecast is also extended to perform a sensitivity analysis of the tolerances in the requirements, as well as to validate previously pub- lished preferred range of steering feel metrics. The results suggest a few new modifications. Finally, the qualitative information given by this measurement-based classification is complemented with a second superimposed network. This network describes a regression surface that enables quantitative predictions, for example the SA of the steering feel of a new vehicle from its OM. 

  • 78.
    Gil Gómez, Gaspar
    et al.
    Volvo Cars.
    Vestlund, Johannes
    Volvo Cars.
    Bakker, Egbert
    Volvo Cars.
    Berger, Christian
    Chalmer University of Technology.
    Nybacka, Mikael
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Drugge, Lars
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Improving subjective assessments of vehicle dynamics evaluations by means of computer tablets as digital aid2016Inngår i: Computer software and hardware: Vehicle dynamics, SAE International , 2016Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Vehicle dynamics development relies on subjective assessments (SA), which is a resource-intensive procedure requiring both expert drivers and vehicles. Furthermore, development projects becoming shorter and more complex, and increasing demands on quality require higher efficiency.

    Most research in this area has focused on moving from physical to virtual testing. However, SA remains the central method. Less attention has been given to provide better tools for the SA process itself. One promising approach is to introduce computer-tablets to aid data collection, which has proven to be useful in medical studies. Simple software solutions can eliminate the need to transcribe data and generate more flexible and better maintainable questionnaires. Tablets’ technical features envision promising enhancements of SA, which also enable better correlations to objective metrics, a requirement to improve CAE evaluations.

    However, it cannot be assumed that a tablet-based solution is feasible in vehicle dynamics SA context. Any distraction might result in low SA quality and safety issues when test-drivers are subjected to high mental workload pushing the vehicles to their performance-limits.

    In this study, a SA tablet-software for steering feel, handling, and ride was developed and systematically evaluated versus the traditional pen-and-paper method. The results indicate that the new approach is technically feasible in this context, meets more use-cases, and the drivers’ attitude towards it is positive. It increased questionnaire completion and rating resolution while reducing the error rate and transcription time.

    Although attendees reported that the paper-based approach has advantages from a usability point of view, the benefits of the tablet-based approach enable further process-related advantages.

  • 79.
    Gindroz, Bastian
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Optimization of a Predictive Drive Strategy for a Plug-In Hybrid Vehicle: Optimierung der vorausschauenden Antriebssteuerung bei einem Plug-In Hybrid2014Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    As the world’s natural resources are depleting while the environment constraints on society become om- nipresent, new technological alternatives for transports are sought.

    Over the past years, the regulations in terms of pollutants stimulated the industries’ innovation in almost all regions of the world, using directives such as the European emission standards have managed to limit the carbon dioxide emissions up to 82% between Euro 1 and Euro 4.

    Between research towards new fuels and the improvement of internal combustion engines (ICE), one solution stands out: combining an electrical machine with a traditional ICE to reduce the environmental impact and the fuel consumption. The most advanced level of hybridization is the Plug-In Hybrid Vehicle (PHEV), which usually has a battery capacity allowing it to drive all electric on short ranges and can be recharged at a power socket. This technological solution opens to a wide range of possibilities and improvements in terms of fuel consumption, as well as commercial opportunities.

    This master thesis, conducted at Audi AG in Ingolstadt (Germany) will focus on one development feature of Plug-In Hybrid Vehicles: the predictive drive strategy. Driving all electric everywhere would be the best solution in terms of fuel economy. However, a PHEV does not always allow it, especially on long rides. Mainly three drive modes are available: an electric mode that will use the ICE as seldom as possible, a hybrid mode that allows electrical experience at low speed and uses the ICE for higher needs in power, and a charge mode aiming at recharging the battery through the ICE. Some enhanced algorithms are also able to detect the different environments the vehicle is expected to drive through, and compute fuel and electrical consumption estimates for each modes available. Based on this information, an optimizer will determine the best drive strategy - i.e the best temporal combination of modes - in terms of fuel consumption, but also taking into account some external requirements, such as Zero Emission Zones that might come up along the route.

    The method used to compute the best drive strategy relies on four main stages. A first step is to identify the different driving environments constituting the route, based on long-range power predictions. This can be done using statistical comparison methods based on the assumption that one driving environment can be characterised by a range of values for a single parameter. The interval the parameter belongs to will determine the driving environment. The Kolmogorov-Smirnov test function is the second method used, which compares the cumulative distributions of two series of values and assesses their similarity. Once the itinerary is properly split into segments, it is possible to compute the expected fuel and electrical consumptions by taking the drivetrain efficiency chain, the regenerative braking and E-boost characteristics into account. For each section, a high- priority drive mode can also be given in order to allow a more flexible optimization in terms of coding and algorithmic. Mainly two prioritization options have been studied in this thesis. One pertains to the use a finite number of identified driving environments, to which a prioritization of the driving mode has been performed offline beforehand. The second option, the online priority, uses realtime computed values for a given segment and compares them in order to find the mode to be prioritized. Finally, two optimizers have been developed to compute an efficient drive strategy. The tree-based global optimizer considers the drive mode combinations for the whole route and selects the most efficient one, while a simplified optimizer would only improve a given basic strategy to reduce the fuel consumption.

    The results of the comparison methods show interesting perspectives for the Kolmogorov-Smirnov test func- tion, as it only tells two segments apart without trying to identify the environment they belong to, hence a faster implementation. The parametric method proved its efficiency when working with a dual-environment condition, although an extension to more than two environments would make the whole interval computation process much more complex. Then, the consumption computation processes have been precisely defined. Fi- nally, both optimizers gave interesting results. The global optimizer is very complex algorithm which requires considerable CPU resources. However, it provides absolute optima to the optimization problem that will be used to observe the trend, behaviour and accuracy of some drive strategies. The simplified optimizer is a suggestion of a faster algorithm that does not computes the best solution but rather a good one. If the quality of the resulting solution is very route-dependant, it can provide drive strategies very close to the best ones computesby the global optimizer.

  • 80.
    Gowthaman, Rahul
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Jagwani, Suhail
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Advanced bushing script program in MSC ADAMS2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The thesis focuses on investigating and optimizing a bushing script implemented as a tool in MSC ADAMS/Car. The study provides an insight on the representation of a rubber bushing and identify parameters which can be used to define the properties of a bushing in a simulation environment such as ADAMS/Car. The tool being studied here can be used to implement different kind of bushings such as a hydro bushing and a general rubber bushing, but optimization was implemented for the rubber bushing only. With an increasing reliance on Computer Aided Engineering (CAE) tools in the designing process, it is necessary that the vehicle behaviour can be predicted without relying on physical testing. CAE tools reduces the need of prototypes and provides a faster approach to designing vehicles. MSC ADAMS/Car is one such tool, which has been used here to predict the vehicle dynamic behaviour, which will influence the ride, handling and comfort characteristics of the vehicle. Rubber bushings, which have been studied here, have a significant contribution to the overall stiffness of the vehicle and as such, it is imperative that the tool being used here, is accurate and makes the designing process easy. The rubber bushing can be imagined to be a combination of a non-linear elastic spring, a frequency dependent Maxwell component and an amplitude dependent frictional element. In order to ease the design of the bushing properties, a reduced number of input properties are used to calculate the bushing properties internally. While trying to validate the force hysteresis loop obtained through the model with the measured data, it was seen that the accuracy was quite poor for the model when loading it with dynamic loads corresponding to amplitudes of0.2 mm and lower. The quasi-static loading and dynamic loading above 0.2 mm is shown to have a satisfactory accuracy when compared to the measured data.

  • 81.
    Grönvik, Gabriél-André
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Chassis layout of an autonomous truck: A transportation concept for the mining industry2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Autonomous driving might increase safety and profitability of trucks in many applications. The mining industry, with its enclosed and controlled areas, is ideal for early implementation of autonomous solutions. The possibility of increased productivity, profitability and safety for the mining industry and the mining area as a ground for development could, through collaboration, result in many benefits for both mining companies and truck manufactures. Scania must investigate how these autonomous vehicles should be constructed. The project goal is thereby to develop a chassis layout concept for an autonomous truck. The concept should improve profitability and safety for transportation of materials within the mining industry while minimizing the introduction of new components to Scania.

    The chosen approach is based on the Ulrich & Eppinger method for product development including generation and selection of concepts. Product requirements were specified from identified customer needs. The generated concepts were evaluated against these requirements and comparisons were performed with weighted matrices. Some benefits of the final chassis layout concept are a higher load carrying capacity, more robust component placement and higher ground clearance. The vehicle concept would also be able to operate in underground mines with low roof clearance which could open new market segments for Scania. However, the concept requires development to gain higher performance on load carrying components in the chassis front.

    The suggested concept shows that Scania could build and deliver autonomous mining vehicles with optimized chassis layouts based on Scania’s existing components within a near future.

  • 82.
    Gurov, Alexey
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Sengupta, Abhinav
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Jonasson, Mats
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Drugge, Lars
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Collision avoidance driver assistance system using combined active braking and steering2014Inngår i: Proceedings of AVEC’14, 12th symposium on Advanced Vehicle Control, Sept 22-26, Tokyo, Japan., 2014Konferansepaper (Fagfellevurdert)
  • 83.
    Guyon, Olivier
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Methodology for the Life Cycle Assessment of a Car-sharing Service2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Nowadays, circular economy is becoming more relevant in society. In the context of the automotive industry, we no longer simply work on emissions emitted during the vehicle use phase but rather on the environmental impacts induced during all phases of the vehicle's life cycle (manufacturing, logistics, use, maintenance and end of life). For this purpose, many automakers, including the Group PSA, use life cycle assessment (LCA) to determine these environmental impacts. Also, the economy of sharing is gradually established and follows innovative uses of the car. New mobility systems emerge and compete with the classical system of sales of vehicles. These new uses of the automobile mainly take the form of car-sharing. In the future, it will become essential to evaluate these services from an environmental point of view.Some studies of the use of car-sharing already demonstrate important consequences such as reductions in the number of vehicles and in the number of kilometers traveled but also an increase in the use of other means of transport. However, to my knowledge, there is no LCA-based method to quantify the environmental benefit of the use of a car-sharing service in relation to the use of vehicles for exclusive use by the owner but also which would eco-design these services and the vehicles intended for these services.As part of this six-month project, a LCA approach was implemented to a PSA B2C (business-to-consumers) car-sharing service called “Emov” with a fleet of 500 Citroën C-Zero electric vehicles. The goal was to compare the use of Emov in Madrid, Spain with the urban use of a private Internal Combustion Engine (ICE) vehicle and a battery electric vehicle for one user characterized by its frequency, its average time and its average distance of use over a defined period. Thanks to a modeling of the service on the LCA software Gabi and by controlling over the input parameters related to the Emov service and the parameters related to the user's use of the service (variable parameters), it was therefore possible to show the influence of these parameters on the final results. Furthermore, it was possible to show also in which scenario it was more environmentally beneficial to use the service rather than a private vehicle. For the study, six impact indicators were chosen: the potentials for global warming, photochemical oxidation, air acidification, water eutrophication, resource depletion and primary energy demand.Using Emov’s big data to inform the service parameters and then varying the service user's usage parameters, it was possible to conclude that whatever the user's urban mobility needs, it is more beneficial to use the service than a private ICE vehicle for five of the six impact indicators. Only the acidification potential indicator (SO2 equivalent) is worse when using the service, which can be explained by the manufacture of the batteries of the Emov vehicles.

  • 84.
    Hanna, Ivil
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Mechanical Properties of Niobium Alloyed Gray Iron2011Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The influence of adding an amount of 0.1% and 0.3% niobium to the gray iron alloy used for brake discs, these disc materials are called disc 16 respective 17, have been investigated at RT (room temperature). That is together with two other alloys, the reference disc which contains 0.32% molybdenum but lacks niobium and another one with neither niobium nor molybdenum in it, this is called disc material 15.

    Focus in this thesis work is on the mechanical properties of the studied materials and for this purpose the low cycle fatigue (LCF) properties of the mentioned alloys are investigated. The strain controlled LCF were done at strain amplitudes varying from 0.05 to 0.43%.

    According to the results, all the materials become survivors when the applied strain was 0.05%. For the other applied strain ranges the reference disc material shows the shortest life-span, while it is difficult to distinguish the other three materials. However, on average material 16 and 17 show a slightly better performance compared to material 15. This means that niobium can be used to replace molybdenum in this application. However, an obvious difference between disc material 16 and 17 cannot be observed when material disc 16 showed to be the superior at some applied strains and material disc 17 at the others. For this reason, it is more profitable to replace the 0.32% molybdenum with 0.1% niobium.

    The results also show that if the loading is mainly in the elastic region the life increases dramatically. It is also obvious that the static properties of gray iron increases with increasing niobium content and the fracture stress increases with about 30 MPa when the niobium contents go from 0.1% to 0.3%.

  • 85. Harell, P.
    et al.
    Drugge, Lars
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Reijm, M.
    Study of critical sections in catenary systems during multiple pantograph operation2005Inngår i: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit, ISSN 0954-4097, E-ISSN 2041-3017, Vol. 219, nr 4, s. 203-211Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    To improve the dynamic behaviour of a catenary system, the sections that limit the speed have to be found. A survey was made to gather information about critical sections of the catenary-pantograph system. Interviews with personnel at the Swedish National Rail Administration were performed and problem areas that need consideration were found and are presented. The purpose of this study was to find out how much of these critical sections affect the system and to suggest improvements to the design. Section overlaps and section insulators, both in combination with the usage of multiple pantographs, were modelled, and simulations have been performed at different speeds and for different catenary systems. As a result of this research, a better base could be built on how to ease the operation with multiple pantographs.

  • 86.
    Harell, Pia
    et al.
    KTH, Tidigare Institutioner, Farkostteknik.
    Drugge, Lars
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Reijm, Marten
    Multiple pantograph operation: effects of section overlaps2004Inngår i: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 41, s. 687-696Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The traffic situation of the future goes towards flexibility of train configurations and increasing speed. There is a need for the ability to adjust the number of passenger cars as well as the energy consumption for trains to run efficiently, leading to multiple pantographs and short pantograph distances. Limitations due to this were studied on an existing catenary system. A model of the pantograph catenary system was developed in a finite element program. To verify the correctness of the model, comparison with full scale experiments was done. Results from the simulations indicates that trailing pantographs suffers from high dynamic effects within the section overlap. Effects of changes in design of the section overlap was studied. The results show that it is possible to get lower dynamic effects in the section overlap, even lower than within an ordinary span.

  • 87.
    Harell Poznic, Pia
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Jerrelind, Jenny
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Drugge, Lars
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Experimental evaluation of nonlinear dynamics and coupled motions in a pantograph2010Inngår i: Proceedings of the ASME Design Engineering Technical Conferences and Computers and Information in Engineering Conference, Vol 1, Pts A and B, NEW YORK: AMER SOC MECHANICAL ENGINEERS , 2010, Vol. 1, s. 619-626Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Continuous electric power supply, which is transferred from the contact wire to the train through a pantograph mechanism, is a necessity for a train to function satisfactory. Since various sources of nonlinearities are present, such as friction in the pantograph suspensions and impacts in the subsystems and at the excitation, there is a possibility of nonlinear dynamic behaviour. The aim of this work is to experimentally investigate the dynamic behaviour of a commercial pantograph to verify if nonlinear behaviour and coupling effects can occur. A test rig has been built that has the ability to simulate both the horizontal and vertical excitation generated by the contact wire. Measurements have been performed for sinusoidal input signals both in horizontal and vertical directions. Harmonic and subharmonic motions as well as irregular behaviour are shown to exist in the system. The results show that the pantograph's rotational degree of freedom, friction in the suspension systems and the nonlinear stiffness play an important role for the dynamic behaviour of the system and are therefore crucial to include when creating mathematical models of the system.

  • 88.
    Hauksson, Hédinn
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Energy consumption of an off-road modified pick-up and the possibility of hybridisation or electrification2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Arctic Trucks have been modifying vehicles such as the Toyota Hilux, Toyota Land Cruiser, Isuzu D-Max, Nissan Patrol and Nissan Navara for over 25 years for special projects as well as for recreational purposes both in Iceland and other countries. Arctic Trucks started up as a sub-division for Toyota Iceland but became an independent company in 2005. Their capability to make off-road vehicles is well known, the Toyota Hilux AT38 being their flagship. It has been driven to both the magnetic north pole, the South Pole and various other remote places and is widely used for logistics in Icelandic highlands as well as other places both during summer and winter time. This M.Sc. project in vehicle engineering covers measurements of energy consumption of a modified Toyota Hilux AT38 2017 in order to determine if some improvements are possible when it comes to fuel consumption and the vehicles environmental impact by hybridisation or full electrification of the vehicle. Fuel consumption is measured in various on-road and off-road conditions (gravel, snow and asphalt). Calculations are made to estimate the effect on fuel consumption of the climate control in the vehicle cabin. Air drag coefficient and friction coefficient are estimated based on coast-down tests in real-life conditions. These factors are necessary to evaluate the total running resistance of the vehicle. These fuel consumption measurements show that the fuel consumption for off-road driving is quite high and since this type of vehicle also needs to be light, the advantages of hybridisation or full electrification need to be examined further. For highway and city driving, hybridisation might be feasible but many factors need to be looked at for that case as well. As of now, battery technology and lack of infrastructure are standing in the way of this type of electric or plugin hybrid vehicles, since these vehicles are used in environments where electricity or even fossil fuel is hard and expensive to reach.

  • 89.
    He, Jincan
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Bhatt, Sundhanva
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Mission Optimized Speed Control2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Transportation underlines the vehicle industry's critical role in a country's economic future.The amount of goods moved, specically by trucks, is only expected to increase inthe near future. This work attempts to tackle the problem of optimizing fuel consumptionin Volvo trucks, when there are hard constraints on the delivery time and speed limits.Knowledge of the truck such as position, state, conguration etc., along with the completeroute information of the transport mission is used for fuel optimization.Advancements in computation, storage, and communication on cloud based systems, hasmade it possible to easily incorporate such systems in assisting modern eet. In this work,an algorithm is developed in a cloud based system to compute a speed plan for the completemission for achieving fuel minimization. This computation is decoupled from thelocal control operations on the truck such as prediction control, safety, cruise control, etc.;and serves as a guide to the truck driver to reach the destination on time by consumingminimum fuel.To achieve fuel minimization under hard constraints on delivery (or arrival) time andspeed limits, a non-linear optimization problem is formulated for the high delity modelestimated from real-time drive cycles. This optimization problem is solved using a Nonlinearprogramming solver in Matlab.The optimal policy was tested on two drive cycles provided by Volvo. The policy wascompared with two dierent scenarios, where the mission demands hard constraints ontravel time and the speed limits in addition to no trac uncertainties (deterministic). with a cruise controller running at a constant set speed throughout the mission. Itis observed that there is no signicant fuel savings. with maximum possible fuel consumption; achieved without the help of optimalspeed plan (worst case). It is seen that there is a notable improvement in fuelsaving.In a real world scenario, a transport mission is interrupted by uncertainties such as trac ow, road blocks, re-routing, etc. To this end, a stochastic optimization algorithm is proposedto deal with the uncertainties modeled using historical trac ow data. Possiblesolution methodologies are suggested to tackle this stochastic optimization problem.

  • 90.
    Henriksson, Tomas
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Driver Assistance Systemswith focus onAutomatic Emergency Brake2011Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This thesis work aims at performing a survey of those technologies generally called DriverAssistance Systems (DAS). This thesis work focuses on gathering information in terms ofaccident statistics, sensors and functions and analyzing this information and shall thruaccessible information match functions with accidents, functions with sensors etc.This analysis, based on accidents in United States and Sweden during the period 1998 – 2002and two truck accident studies, shows that of all accidents with fatalities or sever injuriesinvolving a heavy truck almost half are the result of a frontal impact. About one fourth of theaccidents are caused by side impact, whereas single vehicle and rear impact collisions causesaround 14 % each. Of these, about one fourth is collision with unprotected (motorcycles,mopeds, bicycles, and pedestrians) whereas around 60 % are collision with other vehicles.More than 90 % of all accidents are partly the result of driver error and about 75 % aredirectly the result of driver error. Hence there exist a great opportunity to reduce the numberof accidents by introducing DAS.In this work, an analysis of DAS shows that six of the systems discussed today have thepotential to prevent 40 – 50 % of these accidents, whereas 20 – 40 % are estimated to actuallyhaving the chance to be prevented.One of these DAS, automatic emergency brake (AEB), has been analyzed in more detail.Decision models for an emergency brake capable to mitigate rear-end accidents has beendesigned and evaluated. The results show that this model has high capabilities to mitigatecollisions.

  • 91.
    Huo, Jin
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Build and evaluate state estimation Models using EKF and UKF2013Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    In vehicle control practice, there are some variables, such as lateral tire force, body slip angle and yaw rate, that cannot or is hard to be measured directly and accurately. Vehicle model, like the bicycle model, offers an alternative way to get them indirectly, however due to the widely existent simplification and inaccuracy of vehicle models, there are always biases and errors in prediction from them. When developing advanced vehicle control functions, it is necessary and significant to know these variables in relatively high precision. Kalman filter offers a choice to estimate these variables accurately with measurable variables and with vehicle model together. In this thesis, estimation models based on Extended Kalman Filter (EKF) and Uncented Kalman Filter (UKF) are built separately to evaluate the lateral tire force, body slip angel and yaw rate of two typical passenger vehicles. Matlab toolbox EKF/UKF developed by Simo Särkkä, et al. is used to implement the estimation models. By comparing their principle, algorithm and results, the better one for vehicle state estimation will be chosen and justified.

    The thesis is organized in the following 4 parts:

    First, EKF and UKF are studied from their theory and features.

    Second, vehicle model used for prediction in Kalman filter is build and justified.

    Third, algorithms of EKF and UKF for this specific case are analysed. EKF and UKF are

    then implemented based on the algorithms with the help of Matlab toolbox EKF/UKF.

    Finally, comparisons between EKF and UKF are presented and discussed.

  • 92.
    Jacquement, Malo
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Acoustic Steering Servo Installation Rig Concept2014Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
  • 93.
    Jain, Nikhil
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Robust post impact vehicle motion control using torque vectoring2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Several statistical studies have suggested that the risk of injury is significantly higher in multiple event accidents (MEAs) than in single event crashes. Improper driving in such scenarios leads to hazardous vehicle heading angles and excessive lateral deviations from thevehicle path, resulting in severe secondary crashes. In these situations, the vehicle becomes highly prone to side impacts and such impacts are more harmful to the occupants since the sides of the vehicle have less crash energy absorbing structures than the front and rear ends.Significant advancements have been made in the area of automotive safety to ensure passenger safety. Active safety systems, in particular, are becoming more advanced by the day with vehicles becoming over actuated with electric propulsion and x-by-wire systems. Keepingthat in mind, in this master thesis a post impact vehicle motion control strategy for an electric vehicle is suggested based on a hierarchical control structure which regulates the lateral deviation of the affected vehicle while maintaining safe heading angles after an impact.Sliding Mode Control (SMC) has been utilized in the higher controller which generates a virtual output used as an input for a lower controller performing torque allocation. The allocation methods were based on optimization, aimed to minimize tire utilization, and anormal force based approach. The performance of the controller was first evaluated with single track and two track model of the vehicle because of their simplicity making them easy to debug and also since they allowed for quick simulations. This was followed with evaluationwith a high fidelity vehicle model in IPG CarMaker for fine tuning the controller. It was observed that the use of SMC strategy to generate virtual yaw moment to be used in torque vectoring for controlling vehicle trajectory post impact proved to be a robust strategymanaging to control the vehicle even in cases of actuator failure. So it can be concluded that the hierarchical control structure with the higher Sliding mode controller, generating a virtual yaw moment, and a lower controller doing torque allocation using a normal force basedstrategy and an optimization approach worked as intended.

  • 94.
    Jaipal, Prithviraj
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Hydraulic hybrids2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Conventional IC Engine powertrain layouts in vehicles tend to consume considerable amounts of fuel and generate emissions that are harmful to the environment. Newer technologies have enabled the development of sustainable vehicle layout designs that favor a reduction in the exhaust emissions and energy consumption without compromising the vehicle’s performance. Hybrid vehicles and electric vehicles are the torch bearers for this development. Although electric vehicles feature high performance at lower emissions, they are generally limited by their range and high battery costs. Development of countries to equip for this electrification is another important factor here as with the development of more electric vehicles comes the problems associated with charging, like charging stations, charge scheduling (from power grid because of the high toll), etc. Hybrid electric vehicles are energy efficient and reduce the emissions considerably but their costs are substantially higher. Along with the higher efficiency generated by the electric machines, the possibility of regenerating braking energy reduces the energy consumption and increases the energy efficiency of the conventional layouts. Hydraulic hybrids in the recent years have gained recognition for their advantages and are known for being the cheaper alternative for hybridizing heavy vehicles. The ability of storing regenerative braking energy in this fluid form allows for higher cyclic efficiency when compared to that of the electrical means of storing energy. This thesis focuses on the design and modeling of the hydraulic hybrids using MATLAB/SIMULINK® to construct models depicting the use of the vehicles under the selected drive cycles. Regenerative braking has been one of prime focus for improving the range and minimising the energy consumption of the vehicle along with high operational efficiencies of the operating components. The thesis takes into account two cases, one with the case of a medium duty vehicle with a conventional  IC Engine layout and the other with the case of electric forklifts. The two cases are compared with their hydraulic hybrid layouts along the lines of energy consumption, operational efficiencies and range. Through the design of these simulations, a comparative analysis of the hydraulic hybrid to the electric hybrid is provided for the case of the medium duty vehicle and the benefits of having an electric hydraulic hybrid layout designed for the electric forklift applications are studied.

  • 95.
    Jarlmark, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Modelling and validation of steering system response to road and driver induced forces2004Inngår i: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 41, nr SUPPL., s. 371-380Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The driver serves both as a controller for the vehicle direction as well as a sensor for the road induced forces. A vehicle model is developed with both computer simulations as well as driving simulator use in mind. Therefore, the included steering system model was divided into one part below and one part above the steering gear. The presented steering system model focuses on force transmission from the wheels to the steering rack and the rack movements including a friction model. Above the steering gear, the model focuses on servo control through the twist of a torsion bar and includes steering wheel inertia and steering column stiffness and friction. The vehicle model has ten degrees of freedom, includes a Magic Formula 5.1 tyre model and is validated together with the steering system model as well as a geometric road model as a complete vehicle-environment model. The validation is made using data from the KTH experimental vehicle in a number of isolated driving cases performed at the Volvo Hällered test track. The simulations performed with the model are mainly focused on the steering wheel moment, sensed by the driver.

  • 96.
    Jarlmark, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Steering system forces due to local camber in ruts2006Inngår i: International Journal of Vehicle Design, ISSN 0143-3369, E-ISSN 1741-5314, Vol. 40, nr 1-3, s. 93-105Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A driver related area that is difficult to simulate and to reproduce in a driving simulator is the steering feel, especially the sense of longitudinal ruts and the self-steering of the vehicle. The hypothesis that the major contribution to the steering feel is due to the lateral movement of the vertical force due to local camber changes is stated. A tyre measurement rig is original hypothesis is proven to be false by computer simulations using the measurements from the rig. Instead the aligning moment created by the tare belt stiffness for a cambered tyre is shown to have the largest significance on a steering system of modern layout.

  • 97.
    Jayakumar, Gautham
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Modeling And Analysis Of Fault Conditions In Avehicle With Four In-Wheel Motors2013Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    A vast expansion is found in the field of automotive electronic systems. The expansion iscoupled with a related increase in the demands of power and design. Now, this is goodarena of engineering opportunities and challenges. One of the challenges faced, isdeveloping fault tolerant systems, which increases the overall automotive and passengersafety. The development in the field of automotive electronics has led to the innovationof some very sophisticated technology. However, with increasing sophistication intechnology also rises the requirement to develop fault tolerant solutions.As one of many steps towards developing a fault tolerant system, this thesis presents anexhaustive fault analysis. The modeling and fault analysis is carried out for a vehicle withfour in-wheel motors. The primary goal is to collect as many of the possible failuremodes that could occur in a vehicle. A database of possible failure modes is retrievedfrom the Vehicle Dynamics research group at KTH. Now with further inputs to thisdatabase the individual faults are factored with respect to change in parameters of vehicleperformance. The factored faults are grouped with respect to similar outputcharacterization.The fault groups are modeled and integrated into a vehicle model developed earlier inMatlab/Simulink. All the fault groups are simulated under specific conditions and theresults are obtained. The dynamic behavior of the vehicle under such fault conditions isanalyzed. Further, in particular the behavior of the vehicle with electronic stabilitycontrol (ESC) under the fault conditions is tested. The deviation in the vital vehicleperformance parameters from nominal is computed.Finally based on the results obtained, a ranking system termed Severity Ranking System(SeRS) is presented. The severity ranking is presented based on three essential vehicleperformance parameters, such as longitudinal acceleration ( ), lateral acceleration ( )and yaw rate ( ̇ ). The ranking of the faults are classified as low severity S1, mediumseverity S2, high severity S3 and very high severity S4. A fault tolerant system must beable to successfully detect the fault condition, isolate the fault and provide correctiveaction. Hence, this database would serve as an effective input in developing fault tolerantsystems.

  • 98.
    Jerrelind, Jenny
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Dankowicz, Harry
    Virginia Polytechnic Institute and State University, Engineering Science and Mechanics, Virginia, USA.
    A global control strategy for efficient control of a Braille impact hammer2006Inngår i: Journal of Vibration and Acoustics-Transactions of the ASME, ISSN 1048-9002, E-ISSN 1528-8927, Vol. 128, nr 2, s. 184-189Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A combined control scheme relying on feedback-based local control in the vicinity of periodic system responses and global control based on a coarse-grained approximation to the nonlinear dynamics is developed to achieve a desirable dynamical behavior of a Braille printer impact hammer The proposed control methodology introduces discrete changes in the position of a system discontinuity at opportune moments during the hammer motion while the hammer is away from the discontinuity, thereby exploiting the recurrent contacts with the discontinuity to achieve the desired changes in the transient dynamics. It is argued that, as the changes in the position of the discontinuity affect the motion only indirectly through changes in the timing and state at the subsequent contact, the control actuation can be applied over an interval of time during the free-flight motion as long as it is completed prior to contact. A forced, piecewise smooth, single-degree-of freedom model of a Braille impact hammer is used to illustrate the methodology and to yield representative numerical results.

  • 99.
    Jerrelind, Jenny
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Drugge, Lars
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Stensson Trigell, Annika
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Nybacka, Mikael
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Simulation of Vehicle-Overhead Power System Interaction on Electric Roads2012Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Due to the upcoming lack of oil and the environmental problems that conventional internal combustion engines are causing, electric vehicles have gained a growing interest during recent years. One solution to improve the efficiency of the existing road network is to make use of electric roads equipped with an overhead power system, thereby allowing also long-distance truck and bus transports to be powered by electricity without the need of heavy, bulky and expansive batteries.

    Providing electric power using an overhead power system has primarily been used in railway applications and only to some extent in road applications, for example in the case of trolley buses in urban areas. In this study, an overhead catenary system providing electric power to a long-distance truck by means of a pantograph mechanism that collects power through sliding contact with the overhead wire is analysed through simulation.

    A model of a truck equipped with a pantograph is developed and its interaction with an overhead catenary system model is simulated using the finite element method. The current collection quality is evaluated by analysing the pantograph-catenary contact force variation during the influence of different disturbances such as road irregularities and contact wire vibrations due to multiple pantographs.

    The study is an assessment of the possibility of using a conventional overhead power system developed for trains in a new context by providing power to long-distance road transports. The results show that the investigated disturbances influence the dynamics of the studied truck-pantograph-catenary system, nevertheless the contact force variation is within the allowed range according to the technical specifications for interoperability (TSI) for trains. It can be concluded that an overhead power system is a promising solution for a more environmentally friendly energy supply for trucks and buses at specific road sections.

  • 100.
    Jerrelind, Jenny
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Edrén, Johannes
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Li, Shiruo
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Davari, Mohammad Mehdi
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Drugge, Lars
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Stensson Trigell, Annika
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
    Exploring active camber to enhance vehicle performance and safety2013Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The aim of this study is to evaluate optimal active camber strategies for improvement of vehicle performance and safety during limit handling. Numerical optimisation is used to find solutions on how the active camber should be controlled and coordinated in cooperation with individual braking and front axle steering. Based on the characteristics of a multi-line brush tyre model, a Simple Magic Formula description is developed where camber dependency, load sensitivity and first order speed dependent relaxation dynamics are included. The vehicle is analysed during an evasive manoeuvre when the vehicle is running at the limit. It is evident from the results that active camber control can improve safety and performance during an avoidance manoeuvre.

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