| 1. |
- Wanner, Daniel, et al.
(författare)
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Survey on fault-tolerant vehicle design
- 2012
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Ingår i: World Electric Vehicle Journal. - : The World Electric Vehicle Association (WEVA). - 2032-6653. ; 5:2, s. 598-609
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Tidskriftsartikel (refereegranskat)abstract
- Fault-tolerant vehicle design is an emerging inter-disciplinary research domain, which is of increased importance due to the electrification of automotive systems. The goal of fault-tolerant systems is to handle occuring faults under operational condition and enable the driver to get to a safe stop. This paper presents results from an extended survey on fault-tolerant vehicle design. It aims to provide a holistic view on the fault-tolerant aspects of a vehicular system. An overview of fault-tolerant systems in general and their design premises is given as well as the specific aspects related to automotive applications. The paper highlights recent and prospective development of vehicle motion control with integrated chassis control and passive and active fault-tolerant control. Also, fault detection and diagnosis methods are briefly described. The shift on control level of vehicles will be accompanied by basic structural changes within the network architecture. Control architecture as well as communication protocols and topologies are adapted to comply with the electrified automotive systems. Finally, the role of regulations and international standardization to enable fault-tolerant vehicle design is taken into consideration.
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| 2. |
- Agebro, Markus, 1975-
(författare)
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Driver Preferences of Steering Characteristics
- 2007
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The future of vehicle steering systems lies within by-wire technology. With by-wire technology mechanical or hydraulic systems are replaced by electronic systems. Removal of the steering column and possibly other linkage and gears yields vast potential of further improvement of performance, comfort and safety. Steer-by-wire technology also enables the manufacturer to tailor the steering feel to better suit the individual drivers’ need and preference. Since a driver gains critical information about the vehicle from feedback through the steering wheel, steering feel will play a very important part in consumer acceptance of steer-by-wire systems. It will also be possible to customize steering characteristics to the individual driver. This thesis presents a methodology for investigating steering characteristics through analysis of simulator experiments and to find the impact of specific steering characteristics on drivers of varying skill. There are many key aspects to consider when designing simulator experiments. A validated vehicle model is required. Evaluation criteria need to be well defined as well as concise and simple. The utilized scenario has to be able to capture the selected evaluation criteria. Recruitment of test subjects should represent the target population. How to utilize the available time in the simulator most effectively and how to analyze the results are also important. In this work three studies are performed. Paper A investigates how steering gear ratio and steering wheel effort of a passenger car affect preferences of high and low mileage drivers. Paper B is an extended study of Paper A, where the resolution is higher, speed dependence is investigated and performance of the drivers is also evaluated. In Paper C the impact of four important steering system characteristics on driver performance and preference is evaluated. The major conclusions drawn from this work are that variation of steering gear ratio has considerable impact on perceived steering feel and manoeuvrability as well as on driver performance. Variation in steering wheel effort affect perceived steering feel and stability, but no significant influence is detected in perceived manoeuvrability or driver performance. There are distinguishable differences in preferences of the investigated evaluation criteria between driver categories of varying skill. However, general trends of the preferences for the categories are fairly similar. Low skilled drivers prefer lower effort and higher ratio than high skilled drivers, especially at the highest investigated speed, 100 km/h. The developed methodology for performing simulator experiments to evaluate steering characteristics has proven satisfactory through findings of three different studies. This work also shows that there are several important steering characteristics that need to be considered when designing steering systems, particularly steering systems with by-wire applications and especially considering drivers of varying skill.
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| 3. |
- Agebro, Markus, et al.
(författare)
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Driver preferences of steering gear ratio and steering wheel effort : A driving simulator study
- 2006
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Ingår i: Proceedings of the FISITA World Automotive Congress, Yokohama, Japan 2006..
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Konferensbidrag (refereegranskat)abstract
- When driving an automobile, the driver has to correct the course as a result of road curvature and external disturbances. In order to make the vehicle both controllable and comfortable to drive, it is important that the steering system is designed with different drivers in mind. In this work, driver preferences of steering system characteristics is investigated by comparing standard steering wheel settings with unconventional steering gear ratio and steering wheel effort. The investigation is made using 18 test subjects in a moving base driving simulator. The evaluation includes two scenarios. In the first scenario the driver is overtaking a bus at 110 km/h when meeting traffic in the opposite lane. In the second scenario the driver is doing a manoeuvre by following a cone track at 55 km/h. To investigate if there are differences in preference of drivers with varying experience of driving, the drivers are chosen to either be low or high mileage drivers. People that drive less than 5,000 km/year are considered to be low mileage drivers, and people that drive more than 25,000 km/year are considered to be high mileage drivers. The results show that original settings of a typical passenger car, which served as reference, prove to display favourable characteristics compared to the unconventional settings investigated. However, there might be settings within the investigated intervals that can be considered superior. A distinct trend in the results is that increasing effort will lead to increased perceived stability, independent of ratio. High mileage drivers find the setting with low ratio and reference effort to possess better qualities than the reference when evaluating the attributes steering wheel force and response and only slightly less favourable properties than the reference when evaluating the attribute stability. High mileage drivers display a more distinct opinion and a higher sensitivity when evaluating the attributes. Despite the differing setup of the scenarios, many similarities can be observed when studying the results. Even though there are similarities in the results both between the scenarios and the categories of drivers, a study of the individual test subjects´ preferences reveal that several drivers prefer other settings than the reference for the investigated scenarios. Therefore, it is clear that the driver-vehicle system would benefit from tailoring the steering characteristics to the situation and driver.
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| 4. |
- Andreasson, Johan, 1976-
(författare)
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On Generic Road Vehicle Motion Modelling and Control
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- With the increased amount of on-board electric power driven by the ongoing hybridization, new ways to realize vehicles are likely to occur. This thesis outlines a future direction of vehicle motion control based on the assumptions that: 1) future vehicle development will face an increased amount of available actuators for vehicle propulsion and control that will open up for an increased variety of possible configurations, 2) the onboard computational power will continue to increase and allow higher demands on active safety and drivability that will require a tighter interaction between sensors and actuators, 3) the trend towards more individualized vehicles on common platforms with shorter time-to-market require design approaches that allow engineering knowledge to be transferred conveniently from one generation to the next. A methodology to facilitate the selection of vehicle configurations and the design of the corresponding vehicle motion controllers is presented. This includes a method to classify and map configurations and control strategies onto their possible influence on the vehicle's motion. Further, a structured way of implementing and managing vehicle and subsystem models that are easy to reconfigure and reuse is suggested and realised in the developed VehicleDynamics Library. In addition, generic ways to evaluate vehicle configurations, especially the use of the adhesion potential to identify safety margin and expected limit behaviour are presented. Special attention is given to how the characteristics of a vehicle configuration can be expressed so that it can be used in vehicle motion control design. A controller structure that enables a generic approach to this is introduced and within this structure, two methods for control allocation are proposed, via tyre forces and directly. The first method uses a developed mapping of available actuators as constraints onto the achievable tyre forces and inverse tyre models to calculate the actuator inputs. The second method allocates the actuator inputs directly for an adapted problem that is linearized around the current operating point. It is shown that the methods are applicable to a variety of different vehicle configurations without redesign. Therefore, the same controller can manage a variety of vehicle configurations and there is no need to recognize and treat each different situation separately. Finally, a road map on how to continue this research towards a possible industry implementation is given. Also suggestions on more detailed improvements for modelling and vehicle motion control are provided.
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| 5. |
- Berghuvud, Ansel, et al.
(författare)
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Consequences of nonlinear characteristics of a secondary suspension in a three-piece freight car bogie
- 2001
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Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 0042-3114 .- 1744-5159. ; 36:1, s. 37-55
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Tidskriftsartikel (refereegranskat)abstract
- Mechanical systems with nonlinear characteristics can show a complex dynamic behavior that should be taken into account when analysing dynamic performance and reliability. The dynamic behavior of the main suspension in a three-piece freight car bogie with constant friction damping is considered in this work. The aim is to investigate the vertical behavior of a specific suspension design due to different driving conditions, weather and wear of the friction wedges. A variation in weather and wear is represented by different friction configurations in the model of the suspension. Models of different levels of detail that are based on experimental data on existing designs are developed. It is found that the suspension performance is very sensitive to variations of the friction configuration and this indicates a possible presence of nonlinear dynamic phenomena at in service like conditions
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| 6. |
- Berghuvud, Ansel, et al.
(författare)
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Dynamic behaviour of ore wagons in curves at Malmbanan
- 1998
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Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 0042-3114 .- 1744-5159. ; 30:3-4, s. 271-284
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Tidskriftsartikel (refereegranskat)abstract
- The transportation of ore can be made more cost efficient by use of bigger and heavier trains. An increase in axle load is thereby wanted. The fleet of ore wagons of today at Malmbanan/Ofotbanan in northern Sweden and Norway has to be updated. It is of interest to find out if it is possible to allow a higher axle load on the track with new wagons. To be able to understand and predict the effects on track wear depending on what type of vehicle that is in use, the contact forces between wheels and rails have to be determined. A computer aided analysis has been made of the dynamic behaviour of three test vehicles equipped with different types of three-piece bogies running at Malmbanan. The vehicles are modelled and their interaction with the track is analyzed using the multibody simulation package GENSYS. The simulations show that, even if the axle load is increased from 25 tons to 30 tons and the velocity is increased from 50 km/h to 60 km/h, it is possible to reduce lateral track forces and wear in curves by using a different bogie than the standard three-piece bogie used today
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| 7. |
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| 8. |
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| 9. |
- Berghuvud, Ansel, et al.
(författare)
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Prediction of lateral wheel-rail contact forces for ore wagons with three-piece bogies
- 1998
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Ingår i: Proceedings of the 6th Mini Conference on Vehicle System Dynamics, Identification and Anomalies. - Budapest : Techn. Univ.. - 9634206352 ; , s. 161-170
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Konferensbidrag (refereegranskat)abstract
- The transportation of ore can be made more cost efficient by use of bigger and heavier trains. An increased load on the track gives higher demands on both vehicle and infrastructure performance in order to limit the maintenance cost. At Malmbanan/Ofotbanen in Sweden and Norway there are many tight curves along the track experiencing high wear. One criterion for allowing a higher axle load is therefore to reduce the lateral track forces compared to the level of today. To evaluate the effect of an increased axle load, instrumented wheelset measurements were performed on different test vehicles of three-piece type. The measurements show essential variations in lateral force levels depending not only on curve radius and coefficient of friction in the wheel-rail contact, but greatly on the actual individual curve. This effect is studied in this work. The curving performance of one of the vehicles when running through curves with different rail profiles have been simulated. Both simulations and experimental results show large lateral forces for the typical situation on the studied track. The importance of matching wheel and rail profiles in order to get low contact forces and, as a consequence, less wear is shown.
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| 10. |
- Dahlberg, E., et al.
(författare)
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The dynamic rollover threshold - a heavy truck sensitivity study
- 2006
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Ingår i: International Journal of Vehicle Design. - 0143-3369 .- 1741-5314. ; 40:03-jan, s. 228-250
-
Tidskriftsartikel (refereegranskat)abstract
- Knowledge of rollover mechanics, which is required in heavy truck development, commonly relies on a static analysis, providing the steady-state rollover threshold, SSRT. In a rolling vehicle, kinetic energy is always present and that deteriorates the analysis of roll stability from SSRT and implies the need for a dynamic rollover threshold, DRT as a complement. A method to determine DRT is presented and a parameter sensitivity study The influences on SSRT and DRT, including interaction effects, from roll stiffnesses and roll centre heights, are calculated. Results show that a rigid truck and a tractor semitrailer combination are unequally sensitive to parameter changes. Design changes can hence affect SSRT and DRT differently, which indicates that two vehicles can be equally stable statically but differently dynamically. Therefore, if DRT is not analysed, a redesign of a vehicle can deteriorate roll stability even though it appears to improve it.
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| 11. |
- Daniel, Wanner, et al.
(författare)
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Experimental implementation of a fault handling strategy for electric vehicles with individual-wheel drives
- 2016
-
Ingår i: The Dynamics of Vehicles on Roads and Tracks - Proceedings of the 24th Symposium of the International Association for Vehicle System Dynamics, IAVSD 2015. - : CRC Press. - 9781138028852 ; , s. 147-152
-
Konferensbidrag (refereegranskat)abstract
- This paper presents a fault handling strategy for electric vehicles with four individual-wheel drives, which are based on wheel hub motors. The control strategy to handle the faults is based on the principle of control allocation and is implemented in an experimental vehicle. Experimental tests has been performed with the experimental vehicle and with simulation. The results show that the directional stability of such a vehicle can be improved for the analysed manoeuvre and failure mode, and the tendencies of the experimental results correspond with the simulation results. It has been found that the lateral and yaw motion could be strongly improved.
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| 12. |
- Davari, Mohammad Mehdi, et al.
(författare)
-
A Multi-Line Brush Based Tyre Model to Study the Rolling Resistance and Energy Loss
- 2015
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Ingår i: Proceedings of 4th International Tyre Colloquium. - 9781844690329
-
Konferensbidrag (refereegranskat)abstract
- This study aim to develop a three dimensional multi-line brush based tyre model for investigating the rolling resistance and energy loss in tyres. The losses in the model are characterised by the external losses originated from the sliding phenomenon in the tyre contact patch, and the internal losses due to the tyre viscoelastic nature which is employed by a rubber model. The Extended Brush tyre Model (EBM) proposed in this work can be used to estimate the dissipated energy and the rolling resistance under different driving manoeuvres and wheel conditions. This paper focuses on the estimation of energy loss and in-plane rolling resistance.
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| 13. |
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| 14. |
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| 15. |
- Davari, Mohammad Mehdi, et al.
(författare)
-
Energy Efficiency Analyses of a Vehicle in Modal and Transient Driving Cycles including Longitudinal and Vertical Dynamics
- 2017
-
Ingår i: Transportation Research Part D. - : Elsevier. - 1361-9209 .- 1879-2340. ; 53, s. 263-275
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Tidskriftsartikel (refereegranskat)abstract
- The growing concerns about the environmental issues caused by vehicles and a strive forbetter fuel economy, urge the legislators to introduce conservative regulations on vehicletesting and homologation procedures. To have accurate evaluations, driving cycles thatcan sufficiently describe the vehicles’ conditions experienced during driving is a prerequisite.In current driving cycles there are still some issues which are disregarded. The aim ofthe presented work is to study the contribution of chassis and vehicle dynamics settings ontyre rolling loss in comparison with the original assumptions made in the NEDC, FTP andHWFET driving cycles. A half-car model including a semi-physical explicit tyre model tosimulate the rolling loss is proposed. For the chosen vehicle and tyre characteristics,depending on the specific chassis settings and considered driving cycle, considerable differenceup to 7% was observed between the energy consumption of the proposed- and conventionalapproach. The current work aims to provide the legislators with a betterinsight into the real effects of chassis and vehicle dynamics during the certification processto further improve the test related procedures required for homologation such as generationof road load curves. I.e., the aim is not to provide a new homologation process, sincethere are also other effects such as road roughness and tyre temperature that need to beconsidered. The results are also of interest for the vehicle manufacturers for further considerationsduring test preparation as well as in the development phase in order to reduce theenvironmental impacts.
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| 16. |
- Davari, Mohammad Mehdi
(författare)
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Exploiting over-actuation to reduce tyre energy losses in vehicle manoeuvres
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Due to environmental and economic challenges road vehicles need bettersolutions to reduce energy consumption. Improvement in tyre rolling e-ciency is one of the key enablers for lower energy consumption. The shifttowards electrication and intelligent driving creates new opportunities todevelop energy-ecient vehicles. For instant over-actuated vehicles whichenables dierent objectives such as safety, performance and energy e-ciency to be fullled during a manoeuvre. The objective of this thesis is todevelop a simulation environment to simulate the energy dissipated fromthe tyre in order to investigate the potential to controlling dierent chassisparameters to reduce rolling losses during driving.The rst part of the thesis is dedicated to develop a high-delity semi-physical non-linear tyre model called the Extended Brush Tyre Model(EBM) to be used for energy studies in vehicle dynamics simulations andlater answer whether it is reasonable to believe that there is any potentialto reduce the rolling loss, and thereby energy consumption, using over-actuation.In the second part of the thesis the benets of over-actuation are invest-igated to enable rolling loss reduction. A control strategy using camber-sideslip control (CSC) is proposed. The allocation problem is solved in the formof an optimisation problem using Dynamics Programming (DP) and ModelPredictive Control (MPC). Exploiting the function for a chosen vehicle ina simulation environment shows a signicant improvement of about 60% inrolling loss reduction while maintaining path tracking. Also by using thisfunction the tyre forces can be distributed more evenly while maintainingthe global force, which results in an increase in the available tyre forcesthat is especially benecial when driving at the limit. It is revealed thatoptimising the vehicle manoeuvre from an energy perspective is sometimesin con ict with the safety demand, thus the energy and safety criteria needto be considered simultaneously during optimisation.Finally, experimental studies using an over-actuated concept vehicleconrmed that the CSC function can reduce overall energy consumptionduring low velocity manoeuvres up to about 13%. By increasing the speed,the saving potential decreases but the contribution is nonetheless of signi-cance. The developed simulation environment, including the EBM, willenable future studies of dierent solutions using over-actuation to reducerolling losses in dierent types of vehicles and driving tasks.
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| 17. |
- Davari, Mohammad Mehdi, et al.
(författare)
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Extended Brush Tyre Model to Study Rolling Loss in Vehicle Dynamics Simulations
- 2017
-
Ingår i: International Journal of Vehicle Design. - : InderScience Publishers. - 0143-3369 .- 1741-5314. ; 73:4, s. 255-280
-
Tidskriftsartikel (refereegranskat)abstract
- This paper describes a semi-physical tyre model that enables studies of rolling loss in combination with vehicle dynamic simulations. The proposed model, named extended brush tyre model (EBM), takes the effects of driving conditions, wheel alignment, and tyre materials into account. Compared to the basic brush tyre model, EBM includes multiple numbers of lines and bristles as well as integrated rubber elements into the bristles. The force and moment characteristics of the model are shown to have a good correlation with the Magic Formula tyre model and experimental data. The numerically estimated rolling resistance coefficients under different conditions are compared to findings in the literature, FE-simulations and experiments. The model can capture some aspects that are not covered by the available literature and experimental observations such as camber effect on rolling loss. EBM can be used as a platform for future studies of rolling loss optimisation using active chassis control.
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| 18. |
- Davari, Mohammad Mehdi, et al.
(författare)
-
Investigating the potential of wheel corner modules in reducing rolling resistance of tires
- 2014
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Ingår i: FISITA 2014 World Automotive Congress - Proceedings. - : FISITA.
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Konferensbidrag (refereegranskat)abstract
- The improvement in tire rolling efficiency is one of the key elements to optimize the fuel economy and thereby reduce the vehicle emissions. Earlier efforts to reduce the rolling resistance have mainly been focusing on new materials in the tire compounds. The overall research aim of this study is to present the potentials of implementing innovative chassis concepts with the focus on Wheel Corner Modules (WCM) by describing the possibilities in affecting rolling resistance and relating them to previous research findings. The core idea of the concept is to actively control and actuate all degrees of freedom in the wheel i.e. implementing steering, suspension and propulsion functions into a unique module which can be implemented in each corner of the vehicle. Using this concept the limitations of traditional wheel kinematics can be resolved extensively. This article presents the first step towards creating a vehicle simulation model that can show how the WCM functionality can influence the rolling resistance. A model of loss is chosen after analysing the behaviour of a three different rubber models and then implemented into a brush tire model. An effective way, but less complicated compared to current methods, to introduce the loss into tire model is presented. In conventional suspensions, the design is compromising between for example safety, comfort and rolling resistance, etc. at all driving conditions. However, using the WCM, the possibility of achieving a better compromise between those objectives is possible.Finally, based on WCM functionalities a plausible control architecture is proposed.
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| 19. |
- Davari, Mohammad Mehdi, et al.
(författare)
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Investigating the Potential of Wheel Corner Modules in Reducing Rolling Resistance of Tyres
- 2014
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Ingår i: Proceedings of FISITA "14 World Automotive Congress, Maastricht, Netherlands (2014).
-
Konferensbidrag (refereegranskat)abstract
- The improvement in tire rolling efficiency is one of the key elements to optimize the fuel economy and thereby reduce the vehicle emissions. Earlier efforts to reduce the rolling resistance have mainly been focusing on new materials in the tire compounds. The overall research aim of this study is to present the potentials ofimplementing innovative chassis concepts with the focus on Wheel Corner Modules (WCM) by describing thepossibilities in affecting rolling resistance and relating them to previous research findings. The core idea of theconcept is to actively control and actuate all degrees of freedom in the wheel i.e. implementing steering,suspension and propulsion functions into a unique module which can be implemented in each corner of the vehicle. Using this concept the limitations of traditional wheel kinematics can be resolved extensively. This article presents the first step towards creating a vehicle simulation model that can show how the WCM functionality can influence the rolling resistance. A model of loss is chosen after analysing the behaviour of three different rubber models and then implemented into a brush tire model. An effective way, but less complicatedcompared to current methods, to introduce the loss into tire model is presented. In conventional suspensions, thedesign is compromising between for example safety, comfort and rolling resistance, etc. at all drivingconditions. However, using the WCM, the possibility of achieving a better compromise between those objectivesis possible. Finally, based on WCM functionalities a plausible control architecture is proposed.
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| 20. |
- Davari, Mohammad Mehdi, et al.
(författare)
-
Rolling loss analysis of combined camber and slip angle control
- 2016
-
Konferensbidrag (refereegranskat)abstract
- The objective of this work is to present a new functionality of over-actuated systems, such as Wheel Corner Modules, to reduce the rolling loss in vehicles. The findings are based on numerical simulations using a bicycle model coupled with a newly proposed tyre model which is capable of simulating the tyre losses during vehicle motions. The results show that for the considered vehicle in the considered manoeuvre the rolling loss can be reduced about 25–40% by proper control of camber and slip angle combinations, while still maintaining the vehicle performance.
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| 21. |
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| 22. |
- Drugge, Lars, et al.
(författare)
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A laboratory model study of a railway current collection system
- 2008
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Ingår i: Proceedings of the ASME Design Engineering Technical Conferences and Computers and Information in Engineering Conference, Vol 5, PTS A-C. - NEW YORK : AMER SOC MECHANICAL ENGINEERS. ; , s. 1805-1810
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Konferensbidrag (refereegranskat)abstract
- A vital system on modem high-speed electric trains is the overhead catenary system and the pantograph current collector. As speed limits are increased, train operators and railway engineers need measures of system performance in a number of situations. In this work a laboratory model is built to study the pantograph behaviour on curved track running on a catenary system with large stiffness variation. The model is designed to be simple, yet exhibit the most characteristic dynamic properties of the real system. Another objective is the possibility to run the pantograph at speeds near the wave propagation velocity of the contact wire. The situation of several trailing pantographs, with even spacing, which excites the system to steady state, is considered. Effects of changes in design features such as tension in the contact wire and torsion and translation stiffness of components in the pantograph are studied for different speeds. The interaction is complex and the performance depends on the dynamic properties of both the catenary system and the pantograph. The results show that the pantograph configuration mainly affects the size of amplitudes in the system while the contact wire tension influences at which velocities large amplitudes and contact losses occur.
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| 23. |
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| 24. |
- Drugge, Lars, et al.
(författare)
-
Modelling and simulation of catenary-pantograph interaction
- 2000
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Ingår i: Vehicle System Dynamics. - : Taylor & Francis Ltd.. - 0042-3114 .- 1744-5159. ; 33:suppl, s. 490-501
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Tidskriftsartikel (refereegranskat)abstract
- Modelling and simulation of the dynamic behaviour of catenary-pantograph interaction is an important part when assessing the capability of a current collection system for railway traffic. The large variation in infrastructure characteristics in different countries and railway companies, different types of traffic, designs of pantographs etc. makes it almost impossible to develop a final simulation model of such a system. Instead, it would be favourable to have a tool that has the ability to set up models of such systems, choose relevant detail of the models, run simulations and finally visualize the results. To make the tool useful for engineers, design experts as well as simulation experts, the functionality of the tool must be worked out. Aspects on computer simulation such as developed models, simulation methods and computer tools are presented. The aim is to develop a scenario that considers different designs, models, solution methods and user levels. The scenario focuses on how to structure the use of simulation of dynamics in catenary-pantograph development. A scenario is sketched built on different user levels, a modular structure and a structure for information management
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| 25. |
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| 26. |
- Drugge, Lars, et al.
(författare)
-
Modelling and simulation of catenary-pantograph interaction
- 1999
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Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 0042-3114 .- 1744-5159. ; 33:suppl 1, s. 490-501
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Tidskriftsartikel (refereegranskat)abstract
- Modelling and simulation of the dynamic behaviour of catenary-pantograph interaction is an important part when assessing the capability of a current collection system for railway traffic. The large variation in infrastructure characteristics in different countries and railway companies, different types of traffic, designs of pantographs etc. makes it almost impossible to develop a final simulation model of such a system. Instead, it would be favourable to have a tool that has the ability to set up models of such systems, choose relevant detail of the models, run simulations and finally visualize the results. To make the tool useful for engineers, design experts as well as simulation experts, the functionality of the tool must be worked out. Aspects on computer simulation such as developed models, simulation methods and computer tools are presented. The aim is to develop a scenario that considers different designs, models, solution methods and user levels. The scenario focuses on how to structure the use of simulation of dynamics in catenary-pantograph development. A scenario is sketched built on different user levels, a modular structure and a structure for information management
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| 27. |
- Drugge, Lars, et al.
(författare)
-
The nonlinear behaviour of a pantograph current collector suspension
- 1999
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Ingår i: Proceedings of the 1999 ASME Design Engineering Technical Conferences.
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Konferensbidrag (refereegranskat)abstract
- The pantograph-catenary system is a critical component for trains required to run at higher speeds. The pantograph often includes nonlinear characteristics and the scope of this work is to investigate if nonlinear dynamic phenomena can occur in an existing design. A model of a pantograph suspension subsystem has been developed according to physical parameter values of the head suspension of the Schunk WBL88/X2 pantograph, providing electric power to the Swedish high-speed train X2. Studies of the system response for different force excitation show both harmonic, subharmonic and chaotic behaviour for the investigated parameter regions.
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| 28. |
- Edrén, Johannes, 1983-, et al.
(författare)
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Energy efficient cornering using over-actuation
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- 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.
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| 29. |
- Edrén, Johannes, et al.
(författare)
-
Energy efficient cornering using over-actuation
- 2019
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Ingår i: Mechatronics (Oxford). - : Elsevier Ltd. - 0957-4158 .- 1873-4006. ; 59, s. 69-81
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 30. |
- Edrén, Johannes, 1983-
(författare)
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Exploring force allocation control of over actuated vehicles
- 2011
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- As the concern for environmental changes and diminishing oil resources grows more and more, the trend of new vehicle concepts now includes full electric or partly electric propulsion systems. The introduction of electric power sources enables more advanced motion control systems due to electrification of the vehicle's actuators, such as individual wheel steering and in wheel hub motors. This can enable a control methodology that uses different chassis control strategies into a system that will be able to fully utilise the vehicle. Due to this, future vehicles can be more optimised with respect to energy consumption, performance and active safety. Force allocation control is a method that distributes the wheel forces to produce the desired response of the vehicle. In order to evaluate if this methodology can be implemented in future series production vehicles, the aim of this work is to explore how force allocation control can be utilised in a real vehicle to improve vehicle dynamics and safety. In order to evaluate different approaches for generic vehicle motion control by optimization, modelling and simulation in combination with real vehicle experiments will be needed to fully understand the more complex system, especially when actuator dynamics and limitations are considered. The use of a scale prototype vehicle represents a compromise between development cost, efficiency and accuracy, as it allows realistic experiments without the cost and complexity of full vehicle test. Moreover since the vehicle is unmanned it allows studies of at-the-limit situations, without the safety risks in full vehicle experiments. A small scale prototype vehicle (Hjulia) has been built and equipped with autonomous corner module functionality that enables individual control of all wheels. A cost effective force allocation control approach has been implemented and evaluated on the prototype vehicle, as well as in vehicle simulation. Results show improvement of stopping distance and vehicle stability of a vehicle during split-m braking. The aspects of vehicle dynamic scaling are also discussed and evaluated, as it is important to know how the control implementation of small scale prototype vehicles compares with full size vehicles. It is shown that there is good comparison between vehicles of different scales, if the vertical gravitational acceleration is adjusted for. In Hjulia, gravity compensation is solved by adding a specific lifting rig. Studies of vehicles considering optimal path tracking and available actuators are also made to evaluate control solutions of evasive manoeuvres at low and high friction surfaces. Results show differences in how the forces are distributed among the wheels, even though the resulting global forces on the vehicle are approximated to be scaled by friction. Also it is shown that actuator limitations are critical in at-the-limit situations, such as an obstacle avoidance manoeuvre. As a consequence these results will provide good insights to what type of control approach to choose to handle a safety critical situation, depending on available actuators. The built prototype vehicle with implemented force allocation control has shown to be a useful tool to investigate the potential of control approaches, and it will be used for future research in exploring the benefits of force allocation control.
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| 31. |
- Edrén, Johannes, 1983-, et al.
(författare)
-
Implementation and evaluation of force allocation control of a down-scaled prototype vehicle with wheel corner modules
- 2013
-
Ingår i: International Journal of Vehicle Systems Modelling and Testing. - 1745-6436. ; 8:4, s. 335-363
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 32. |
- Edrén, Johannes, et al.
(författare)
-
Modelica and Dymola for education in vehicle dynamics at KTH
- 2009
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Ingår i: Proceedings from 7th Modelica Conference 2009. - : Linköping University Electronic Press. ; , s. 775-783
-
Konferensbidrag (refereegranskat)abstract
- 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.
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| 33. |
- Edrén, Johannes, 1983-
(författare)
-
Motion modelling and control strategies of over-actuated vehicles
- 2014
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- With the growing concern for environmental change and uncertain oil resources, the development of new vehicle concepts will in many cases include full or partial electric propulsion. The introduction of more advanced powertrains enables vehicles that can be controlled with a variety of electric actuators, such as wheel hub motors and individual steering. With these actuators, the chassis can be enabled to adjust its properties depending on the driving situation.Manoeuvring of the vehicle, using for example electric propulsion, braking, suspension, steering and camber control may also allow a variety of combinations which, if properly utilised, can increase the outer limits of vehicle performance and safety. The fact that the vehicle has a greater number of actuators than required to control a certain number of degrees of freedom is called over-actuation. Since there is a great need for energy optimised vehicles, energy efficient control is also required. For this reason, this work is about the allocation of wheel forces can improve safety, performance and energy efficiency in future electrified vehicles in different driving situations.Studies of optimally controlled vehicles show that performance, safety and efficiency can be improved by utilising available actuators in over-actuated vehicles. Path tracking and optimal actuator control signals are evaluated in evasive manoeuvres at low and high friction surfaces. The results show how the forces are distributed differently among the wheels, even though the resulting global forces on the vehicle are similar. Optimal control of camber angles and active suspension show that vehicle performance and safety can be greatly improved. The limits of tyre forces can be increased and better utilised in a way that a passive system is unable to achieve. Actuator performance is also shown to be important, however even low actuator performance is shown to be sufficient to improve vehicle performance considerably. Energy efficiency is also improved as unnecessary vehicle motions are minimised during normal driving and wheel forces are used in a better way.Simplified algorithms to control available actuators, such as wheel angles, vertical actuation and propulsion torques, have been developed, based on the analysis of the results of the optimisation studies. Analyses of the impact of these simplifications have been made. For the cases studied, it has been shown that it is possible to get significantly better performance at reasonable levels of actuator performance and control complexity. This helps to simplify the introduction of this technology in electrified vehicles.Control allocation is a method that distributes the wheel forces to produce the desired response of the vehicle. Simplified control allocation algorithms are proposed that allocate wheel forces in a way that resembles the behaviour of the optimisation solutions. To be able to evaluate the applicability of this methodology for implementation in vehicles, a small-scale prototype vehicle with force allocation control possibilities has been designed and built. The vehicle is equipped with autonomous corner module functionality that enables individual control of all wheels regarding steering, camber, propulsion/braking and vertical loads. Straight-line braking tests show that force allocation can be used in a real vehicle and will enhance performance and stability even at a very basic level, using few sensors with only the actual braking forces as feedback.In summary, this work has contributed to a better understanding of how the allocation of wheel forces can improve vehicle safety, performance and energy efficiency. Moreover, it has contributed to increased understanding of how vehicle motions should be modelled and simulated, and how control strategies for over-actuated vehicles can be made more suitable for implementation in future electrified vehicles.
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| 34. |
- Edrén, Johannes, 1983-, et al.
(författare)
-
Road friction effect on the optimal vehicle control strategy in two critical manoeuvres
- 2014
-
Ingår i: International Journal of Vehicle Safety. - 1479-3105 .- 1479-3113. ; Vol. 7:No. 2, s. pp 107-130
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a research study on the optimal way to negotiate safety-critical vehicle manoeuvres depending on the available actuators and road friction level. The motive is to provide viable knowledge of the limitations of vehicle capability under the presence of environmental preview sensors. In this paper, an optimal path is found by optimising the sequence of actuator requests during the manoeuvres. Particular attention is paid to how the vehicle control strategy depends on friction. This study shows that the actuation of all the forces and torques on and around the vehicle centre of gravity is approximately scaled with friction, whereas at individual wheel level, the optimal force allocation will differ under different friction conditions. A lower friction level leads to lower velocities and load transfer, which influences the individual wheels’ tyre force constraints. However, the actuator response compared to the whole system is increased at a lower friction level.
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| 35. |
- Edrén, Johannes, 1983-, et al.
(författare)
-
The developement of a down-scaled over-actuated vehicle equipped with autonomous corner module functionality
- 2010
-
Ingår i: FISITA Proceedings 2010, paper F2010B056.
-
Konferensbidrag (refereegranskat)abstract
- 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.
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| 36. |
- Edrén, Johannes, et al.
(författare)
-
Utilisation of optimisation solutions to control active suspension for decreased braking distance
- 2015
-
Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 0042-3114 .- 1744-5159. ; 53:2, s. 256-273
-
Tidskriftsartikel (refereegranskat)abstract
- This work deals with how to utilise active suspension on individual vehicle wheels in order to improve the vehicle performance during straight-line braking. Through numerical optimisation, solutions have been found as regards 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 optimised 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 physical mechanisms 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.
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| 37. |
- Edrén, Johannes, 1983-, et al.
(författare)
-
Utilization of optimization solutions to control active suspension for decreased braking distance
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- 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.
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| 38. |
- Edrén, Johannes, 1983-, et al.
(författare)
-
Utilization of Vertical Loads by Optimization for Integrated Vehicle Control
- 2012
-
Ingår i: Proceedings of AVEC12, 11th Symposium on Advanced Vehicle Control, September 9-12, Seoul, Korea, 2012..
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- 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.
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| 39. |
- Erséus, Andreas, et al.
(författare)
-
A path tracking driver model with representation of driving skill
- 2011
-
Ingår i: International Journal of Vehicle Systems Modelling and Testing. - 1745-6436. ; 6:2, s. 145-186
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 40. |
- Erséus, Andreas, et al.
(författare)
-
Characteristics of path tracking skill on a curving road
- 2015
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Ingår i: International Journal of Vehicle Design. - : InderScience Publishers. - 0143-3369 .- 1741-5314. ; 67:1, s. 26-44
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 41. |
- Erséus, Andreas, 1975-
(författare)
-
Driver-Vehicle Interaction : Identification, Characterization and Modelling of Path Tracking Skill
- 2010
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- 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.
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| 42. |
- Erséus, Andreas, et al.
(författare)
-
Methodology for finding parameters related to path tracking skill applied on a DLC-test in a moving base driving simulator
- 2013
-
Ingår i: International Journal of Vehicle Autonomous Systems. - 1471-0226 .- 1741-5306. ; 11:1, s. 1-21
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 43. |
- Estepa, Rafael, et al.
(författare)
-
More Effective Use of Urban Space by Autonomous Double Parking
- 2017
-
Ingår i: Journal of Advanced Transportation. - : Hindawi Publishing Corporation. - 0197-6729 .- 2042-3195.
-
Tidskriftsartikel (refereegranskat)abstract
- The new capabilities of autonomous cars can be used to mitigate to a large extent safety concerns and nuisance traditionally associated with double parking. In this paper double parking for autonomous cars is proposed as a new approach to temporarily increase parking capacity in locations in clear need for extra provision when best alternatives cannot be found. The basic requirements, operation, and procedures of the proposed solution are outlined. A curbside parking has been simulated implementing the suggested double parking operation and important advantages have been identified for drivers, the environment, and the city. Double parking can increase over 50% the parking capacity of a given area. Autonomous car owners would (at least) double their probabilities of finding parking compared to traditional drivers, saving cruising time and emissions. However, significant work and technological advances are still needed in order to make this feasible in the near future.
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| 44. |
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| 45. |
- Favre, Tristan, et al.
(författare)
-
Static coupling between detached-eddy simulations and vehicle dynamic simulations of a generic road vehicle model with different rear configurations in unsteady crosswind
- 2016
-
Ingår i: International Journal of Vehicle Design. - : INDERSCIENCE ENTERPRISES LTD. - 0143-3369 .- 1741-5314. ; 72:4, s. 332-353
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, aerodynamic loads of a generic car model obtained from advanced computational fluid dynamics (CFD) simulations are coupled to a vehicle dynamics model to enable the assessment of the on-road response. The influence of four rear configurations is studied. The different configurations yield large differences in yaw moments and side forces, which in turn result in considerable discrepancies in lateral displacements as well as yaw rates. From the simulations, it is seen that through balancing the location of the centre of pressure, the stiffness of the suspension bushings and the cornering stiffness of the tyres, it is possible to obtain stable vehicles in strong crosswind conditions for all four rear designs. The results show that monitoring the location of the aerodynamic centre of pressure with respect to the centre of gravity and the neutral steer point is essential for the possibility of designing stable vehicles in transient crosswind.
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| 46. |
- Hardell, Christian, et al.
(författare)
-
A relational database for general mechanical systems
- 1995
-
Ingår i: Computational Dynamics in Multibody Systems. - Dordrecht : Encyclopedia of Global Archaeology/Springer Verlag. - 792333047 ; , s. 49-59
-
Konferensbidrag (refereegranskat)abstract
- This paper provides a specification of a relational data base structure for mechanical systems. Through the example provided, a robot gripping device, it is demonstrated how the initial development of the data-base structure has successfully led to an implementation in a practical software environment. The data base is accessible to multiple engineering application programs and supports a flexible environment for the continuing development of new applications
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| 47. |
- Holen, Peter, 1975-
(författare)
-
On modally distributed damping in heavy vehicles
- 2006
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis investigates passive damping system performance in heavy vehicles through analytical expressions, simulations with different vehicle models as well as through experimental evaluation in a tractor semi trailer combination. The objective is to study what levels of chassis suspension damping that are desirable for different vehicle modes and how this may be achieved with passive damping systems. To investigate the influence on performance from damper positioning, analytical expressions for a 2D - suspension model are derived. Geometric key parameters controlling roll and bounce damping are found to be damper vertical aligning and perpendicular distance between damper and suspension roll centre respectively. These parameters are often not easily altered within an already existing vehicle. To investigate performance possibilities from damping not restricted by packaging requirements, the concept with distributed damping is furthermore studied. Theoretical expressions for modally distributed damping are first derived from an analytical tractor model with 7 DOF. Considered motions for which damping is prescribed are bounce, pitch and roll of sprung mass, and axle crossing. These equations are evaluated through various simulations with a 4x2-tractor semi trailer model. Results from simulations show that the conflict in damping demands with passive independent dampers for a single lane change and a one-sided pot hole may be significantly reduced with amplitude dependent modal damping. Vehicle damping performance is not only affected by the dampers positioning and their individual setting, but also by the damper attachment structure. The influence from compliance in e.g. brackets and mounting bushings at damper attachment points is therefore studied. Linear analysis with a simple spring mass damper model shows that damper attachment compliance reduces the damper efficiency. Finite element analyses of both the chassis frame and the tractor are furthermore performed to obtain numerical values of front-axle damper-attachment stiffness. The effect from damper-attachment stiffness is quantified though simulations with a tractor semi trailer model. Simulation results show that it is important to consider the attachment stiffness during vehicle manoeuvres containing high frequency inputs such as the passage over a plank. A methodology and equations for prescribing chassis suspension damping as function of general vehicle modes by using electronically controlled variable dampers is presented. A critical input for such implemented modal damping systems are the real time estimation of modal motions necessary for force calculation. From performed simulations it is shown that geometric calculations of modal velocities based solely on relative damper displacements contain significant discrepancies to actual motion for transient road inputs. To overcome this, a time-domain system identification approach is presented, where models that estimate modal coordinate velocities with considerably higher accuracy are identified. The proposed modal damping approach is implemented on a 4x2 tractor and experimentally evaluated through various road tests. It is shown that the system has the desired ability to control sprung mass bounce and pitch modes separately and that it improves vehicle performance on all tested load cases.
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| 48. |
- Jerrelind, Jenny, et al.
(författare)
-
Braille printer Dynamics
- 1999
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Ingår i: Proceedings of the ASME Design Engineering Technical Conferences.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 49. |
- Jerrelind, Jenny, et al.
(författare)
-
Exploring active camber to enhance vehicle performance and safety
- 2013
-
Konferensbidrag (refereegranskat)abstract
- 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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| 50. |
- Jerrelind, Jenny, et al.
(författare)
-
Nonlinear dynamic behaviour of coupled suspension systems
- 2003
-
Ingår i: Meccanica (Milano. Print). - : Springer. - 0025-6455 .- 1572-9648. ; 38:1, s. 43-59
-
Tidskriftsartikel (refereegranskat)abstract
- A two degrees of freedom model of two coupled suspension systems characterised by piecewise linear stiffness has been studied. The system, representing a pantograph current collector head, is shown to be sensitive to changes in excitation and system parameters, possessing chaotic, periodic and quasiperiodic behaviour. The coupled system has a more irregular behaviour with larger motions than the uncoupled suspension system, indicating that the response from the uncoupled suspension system cannot be used as a worst case measure. Since small changes in system parameters and excitation affect the results drastically then wear and mounting as well as actual operating conditions are crucial factors for the system behaviour.
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