| 1. |
- Huang, Yansong, 1992, et al.
(författare)
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Optimized Rear-Axle Concept for Battery Electric Vehicles: A Show Case Study for New Suspension Development Methods
- 2022
-
Ingår i: Tongji Daxue Xuebao/Journal of Tongji University. - 0253-374X. ; 50, s. 1-9
-
Tidskriftsartikel (refereegranskat)abstract
- One of the main challenges for battery electric vehicles (BEV) is a sufficient range. Therefore, a maximized battery volume is desirable in any recent vehicle concept. Suspension, as one of the largest subsystems, has a significant impact on that. Starting from a conventional car with an internal combustion engine (ICE), a suspension is developed to fulfill new packaging requirements for BEVs, while at the same time maintaining typical requirements concerning driving dynamics. The objective of this study is to use automated methods for suspension development to develop a new steerable suspension concept for an electric propulsion system. The suspension concept was optimized for premium cars with large battery sizes. Moreover, advanced active systems such as air springs and active rear wheel steering with large steering angles were also considered. The concept proposes a packaging solution with a well-tuned kinematic performance which meets typical tuning philosophies. In order to address the resulting high complexity, newly developed methods were used. The kinematic optimization was done with an innovative method, which automatically proposes new hard points, depending on the given requirements. For the design, simplified models were used to represent the shape of sophisticated parts. Therefore, it was possible to automatically judge whether a kinematic concept is feasible from a packaging point of view. The results show, that the new suspension concept can handle the challenge packaging issues and complex kinematic requirements.
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| 2. |
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| 3. |
-
2021 Vehicle Dynamics seminar
- 2021
-
Proceedings (redaktörskap) (övrigt vetenskapligt/konstnärligt)abstract
- The seminar is held annually. The full title of this year's seminar was "2021 Vehicle Dynamics seminar -- for Future Mobility ...and not only Lateral".
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| 4. |
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| 5. |
- Al Mouatamid, Faouzi, 1989, et al.
(författare)
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Towards Evaluation of Post Impact Braking Function in Driving Simulator
- 2013
-
Ingår i: Proceedings of the IEEE International Conference on Systems, Man, and Cybernetics, Manchester, United Kingdom, Oct 13-16, 2013.. - 9780769551548 ; , s. 4549-4554
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Konferensbidrag (refereegranskat)abstract
- This paper presents a method to evaluate the vehicle Post Impact Braking function in driving simulator environment. This function is designed to apply automatic braking after an initial impact on the vehicle body. Four representative impact scenarios and three typical driving styles are investigated, assuming Anti-lock Brake System (ABS) is either functioned or malfunctioned. The performance of PIB is quantified by comparing certain post impact states when the function is enabled and disabled. The results show that PIB helps the drivers to lower the risk and severity of secondary collisions with respect to reduced displacements and road leaving speed; while it leads to higher risk for possible side collisions due to increased yaw angle; these influences seem to be more considerable when no ABS is available. Passive drivers are found to gain more benefits than Alert-Skilled drivers that it indicates full-braking can degrade the vehicle steerability and thus the lateral and yaw responses to some extent. © 2013 IEEE.
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| 6. |
- Albinsson, Anton, 1989, et al.
(författare)
-
Design of tyre force excitation for tyre–road friction estimation
- 2017
-
Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 1744-5159 .- 0042-3114. ; 55:2, s. 208-230
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Tidskriftsartikel (refereegranskat)abstract
- Knowledge of the current tyre–road friction coefficient is essential for future autonomous vehicles. The environmental conditions, and the tyre–road friction in particular, determine both the braking distance and the maximum cornering velocity and thus set the boundaries for the vehicle. Tyre–road friction is difficult to estimate during normal driving due to low levels of tyre force excitation. This problem can be solved by using active tyre force excitation. A torque is added to one or several wheels in the purpose of estimating the tyre–road friction coefficient. Active tyre force excitation provides the opportunity to design the tyre force excitation freely. This study investigates how the tyre force should be applied to minimise the error of the tyre–road friction estimate. The performance of different excitation strategies was found to be dependent on both tyre model choice and noise level. Furthermore, the advantage with using tyre models with more parameters decreased when noise was added to the force and slip ratio.
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| 7. |
- Albinsson, Anton, 1989, et al.
(författare)
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Estimation of the inertial parameters of vehicles with electric propulsion
- 2015
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Ingår i: Proceedings of the Institution of mechanical engineers. Part D, journal of automobile engineering. - : SAGE Publications. - 0954-4070 .- 2041-2991. ; , s. 1-18
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Tidskriftsartikel (refereegranskat)abstract
- More accurate information about the basic vehicle parameters can improve the dynamic control functions of a vehicle. Methods for online estimation of the mass, the rolling resistance, the aerodynamic drag coefficient, the yaw inertia and the longitudinal position of the centre of gravity of an electric hybrid vehicle is therefore proposed. The estimators use the standard vehicle sensor set and the estimate of the electric motor torque. No additional sensors are hence required and no assumptions are made regarding the tyre or the vehicle characteristics. Consequently, all information about the vehicle is available to the estimator.The estimators are evaluated using both simulations and experiments. Estimations of the mass, the rolling resistance and the aerodynamic drag coefficient are based on a recursive least-squares method with multiple forgetting factors. The mass estimate converged to within 3% of the measured vehicle mass for the test cases with sufficient excitation that were evaluated. Two methods to estimate the longitudinal position of the centre of gravity and the yaw inertia are also proposed. The first method is based on the equations of motion and was found to be sensitive to the measurement and parameter errors. The second method is based on the estimated mass and seat-belt indicators.This estimator is more robust and reduces the estimation error in comparison with that obtained by assuming static parameters. The results show that the proposed method improves the estimations of the inertial parameters. Hence, it enables online non-linear tyre force estimators and tyre-model-based tyre–road friction estimators to be used in production vehicles.
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| 8. |
- Albinsson, Anton, 1989, et al.
(författare)
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Evaluation of vehicle-based tyre testing methods
- 2019
-
Ingår i: Proceedings of the Institution of Mechanical Engineers. Part D, Transport engineering. - : SAGE Publications. - 2041-2991 .- 0954-4070. ; 233:1, s. 4-17
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Tidskriftsartikel (refereegranskat)abstract
- The demand for reduced development time and cost for passenger cars increases the strive to replace physical testing with simulations. This leads to requirements on the accuracy of the simulation models used in the development process. The tyres, the only components transferring forces from the road to the vehicle, are a challenge from a modelling and parameterization perspective. Tests are typically performed on flat belt tyre testing machines. Flat belt machines offers repeatable and reliable measurements. However, differences between the real world road surface and the flat belt can be expected. Hence, when using a tyre model based on flat belt measurements in full vehicle simulations, differences between the simulations and real prototype testing can be expected as well. Vehicle-based tyre testing can complement flat belt measurements by allowing reparameterization of tyre models to a new road surface. This paper describes an experimental vehicle-based tyre testing approach that aims to parameterize force and moment tyre models compatible with the standard tyre interface. Full-vehicle tests are performed, and the results are compared to measurements from a mobile tyre testing rig on the same surface and to measurements on a flat belt machine. The results show that it is feasible to measure the inputs and outputs to the standard tyre interface on a flat road surface with the used experimental setup. The flat belt surface and the surface on the test track show similar characteristics. The maximum lateral force is sensitive to the chosen manoeuvres, likely due to temperature differences and to vibrations at large slip angles. For tyre models that do not model these effects, it is vital to test the tyres in a manoeuvre that creates comparable conditions for the tyres as the manoeuvre in which the tyre model will be used.
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| 9. |
- Albinsson, Anton, 1989, et al.
(författare)
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Friction utilization for tyre-road friction estimation on snow: an experimental study
- 2017
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Ingår i: 13th International Symposium on Advanced Vehicle Control, AVEC'16. - 9781315265285 ; , s. 541-546
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Konferensbidrag (refereegranskat)abstract
- Friction estimation using effect-based approaches are challenging during normal driving due to the large tyre excitation needed for an accurate estimate. The required excitation level varies for different tyres, road surfaces, road conditions and tyre models used in the estimator. Previous research has investigated the required friction utilization on different surfaces but due to the small sample sizes it is hard to draw any general conclusions. This paper investigates the tyre excitation required to estimate the tyre-road friction coefficient with a generic estimator for 76 different tyres on snow for five different tyre models and for different levels of measurement noise.
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| 10. |
- Albinsson, Anton, 1989, et al.
(författare)
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Identification of tyre characteristics using active force excitation
- 2016
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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. 501-510
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Konferensbidrag (refereegranskat)abstract
- Knowledge of the maximum tyre-road friction coefficient can improve active safety systems by defining actuator boundaries and adaptable intervention thresholds. Estimation of the coefficient of friction based on tyre response measurements requires large level of force excitation. Under normal driving conditions, manoeuvres with large tyre utilizations are rare. This study investigates a method where wheel torques with opposite signs are applied to the front and rear axle simultaneously. This procedure allows for an intervention with large tyre excitations without disturbing the motion of the vehicle. The intervention is evaluated in simulations and experiments. Further, a method is proposed which does not require measurement of the vehicle longitudinal velocity. The results show that it is possible to estimate the current friction coefficient with the proposed method, although the assumption made in the proposed method makes the friction estimate sensitive to measurement noise on the wheel speed signal.
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| 11. |
- Albinsson, Anton, 1989, et al.
(författare)
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Tire Force Estimation Utilizing Wheel Torque Measurements and Validation in Simulations and Experiments
- 2014
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Ingår i: 12th International Symposium on Advanced Vehicle Control (AVEC '14), Tokyo Japan. ; , s. 294-299
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Konferensbidrag (refereegranskat)abstract
- This study investigates a new tire force estimator based on the recursive least square (RLS) method. Tire force estimation with known driving wheel torque is studied and compared to the case with torque estimation from the internal combustion engine. This is motivated by a future scenario with electric propulsion, which reasonably gives improved wheel torque estimations. Sensitivity to vehicle parameters and challenges with individual lateral tire force estimation are also investigated. The results, experimental and simulation data, show good performance and potential for tire force estimation using the RLS method.
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| 12. |
- Albinsson, Anton, 1989, et al.
(författare)
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Tire Lateral Vibration Considerations in Vehicle-Based Tire Testing
- 2019
-
Ingår i: Tire Science and Technology. - : The Tire Society. - 0090-8657 .- 1945-5852. ; 47:3, s. 211-231
-
Tidskriftsartikel (refereegranskat)abstract
- Vehicle-based tire testing can potentially make it easier to reparametrize tire models for different road surfaces. A passenger car equipped with external sensors was used to measure all input and output signals of the standard tire interface during a ramp steer maneuver at constant velocity. In these measurements, large lateral force vibrations are observed for slip angles above the lateral peak force with clear peaks in the frequency spectrum of the signal at 50 Hz and at multiples of this frequency. These vibrations can lower the average lateral force generated by the tires, and it is therefore important to understand which external factors influence these vibrations. Hence, when using tire models that do not capture these effects, the operating conditions during the testing are important for the accuracy of the tire model in a given maneuver. An Ftire model parameterization of tires used in vehicle-based tire testing is used to investigate these vibrations. A simple suspension model is used together with the tire model to conceptually model the effects of the suspension on the vibrations. The sensitivity of these vibrations to different operating conditions is also investigated together with the influence of the testing procedure and testing equipment (i.e., vehicle and sensors) on the lateral tire force vibrations. Note that the study does not attempt to explain the root cause of these vibrations. The simulation results show that these vibrations can lower the average lateral force generated by the tire for the same operating conditions. The results imply that it is important to consider the lateral tire force vibrations when parameterizing tire models, which does not model these vibrations. Furthermore, the vehicle suspension and operating conditions will change the amplitude of these vibrations and must therefore also be considered in maneuvers in which these vibrations occur.
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| 13. |
- Albinsson, Anton, 1989, et al.
(författare)
-
Validation of vehicle-based tyre testing methods
- 2019
-
Ingår i: Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. - : SAGE Publications. - 2041-2991 .- 0954-4070. ; 233:1, s. 18-27
-
Tidskriftsartikel (refereegranskat)abstract
- The development process for passenger cars is both time- and resource-consuming. Full vehicle testing is an extensive part of the development process that consumes large amount of resources, especially within the field of vehicle dynamics and active safety. By replacing physical testing with complete vehicle simulations, both the development time and cost can potentially be reduced. This requires accurate simulation models that represent the real vehicle. One major chal- lenge with full vehicle simulation models is the representation of tyres in terms of force and moment generation. The force and moment generation of the tyres is affected by both operating conditions and road surface. Vehicle-based tyre testing offers a fast and efficient way to rescale force and moment tyre models to different road surfaces, in this study the Pacejka 2002 model. The resulting tyre model is sensitive to both the operating conditions during testing and the road surface used. This study investigates the influence of the slip angle sweep rate and road surface on the lateral tyre force characteristics of the fitted tyre model. Tyre models fitted to different manoeuvres are compared and the influence on the full vehicle behaviour is investigated in IPG Carmaker. The results show that by using the wrong road surface, the resulting tyre model can end up outside the tolerances specified by the ISO standard for vehicle simulation model verifi- cation in steady-state cornering. The use of Pacejka 2002 models parameterized in a steady-state manoeuvre to simulate the vehicle behaviour in sine-with-dwell manoeuvres is also discussed.
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| 14. |
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| 15. |
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| 16. |
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| 17. |
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| 18. |
- Andersson, Jan, 1968, et al.
(författare)
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Route Adaptation of control strategies for a hybrid city bus
- 1999
-
Ingår i: JSAE Review. - 0389-4304. ; 20:4, s. 531-536
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Tidskriftsartikel (refereegranskat)abstract
- A series hybrid city bus with diesel engine and electric batteries is studied on a specified route. The study uses two different basic control strategies, “On/off” and “Continuous” strategy. These basic strategies are complemented in two ways. First, an “Adviser” strategy which filters the driver commands and gives driver support feedback based on the route data. Second, an “Adapter” strategy, which adapts and the control to the route, using different control depending on the vehicle present position. Simulation results are presented. They show that the adviser and adapter strategies improves both emissions and fuel consumption.
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| 19. |
-
Automated Comfortable Docking at Bus Stops
- 2021
-
Proceedings (redaktörskap) (övrigt vetenskapligt/konstnärligt)abstract
- This proceedings presentation illustrates the optimization problem of autonomous bus parallel parking subjected to ride discomfort while navigating in a path with rectangular geometry constraints. During bus parking, passengers - especially standing- can experience discomfort due to acceleration and jerk components. In our project, a novel discomfort model was derived, utilizing acceleration and jerk data. This model was then implemented in an optimization problem to minimize discomfort. Simulation results and experiment results have been shown. The experiment was conducted using Volvo Autonomous Bus.
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| 20. |
- Bernhard, Westerhof, et al.
(författare)
-
HEAVY VEHICLE BRAKING USING FRICTION ESTIMATION FOR CONTROLLER OPTIMZATION
- 2018
-
Konferensbidrag (refereegranskat)abstract
- A novel electronic brake system (EBS) has demonstrated a 17 percent reduction in stopping distance on a tractor semi-trailer combination during vehicle tests in low friction conditions relative to a modern EBS. Even though these results were promising, it was observed that the novel EBS required more information about the road surface to achieve optimal braking performance. In this paper, the development of an on-line friction estimation method for heavy vehicles, as well as an optimization method that can be used to adjust the slip controller settings, according to the road friction, is described. Results from both simulation and real testing of a Volvo 8x4 FMX truck showed that real-time friction estimation is feasible and increased braking performance can be achieved. Simulation results have shown a reduction in braking distance of up to 20 percent on most road surfaces, as well as a reduction in air usage in most cases.
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| 21. |
- Boran, Colm, et al.
(författare)
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Saving Lives with V2X versus On-Board Sensing Systems -Which will be More Effective?
- 2012
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Ingår i: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191 .- 2688-3627.
-
Tidskriftsartikel (refereegranskat)abstract
- Infrastructure systems such as vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2X) communication can theoretically prevent nearly all accidents by gathering the speed, locations, and travel directions of traffic participants, and intervening to control vehicle motion as required to help prevent collisions. However, during the phase-in of the communication systems, there will be many vehicles and many roads that do not have the communication systems in place, and therefore the system will not be effective in those cases. This lack of availability is likely the main disadvantage.On-board sensing (autonomous) systems such as cameras and radar sensors may not detect all potential hazards (e.g. due to weather, or hidden hazards), but they are effective in many situations and can help prevent crashes without depending on communication with infrastructure or other vehicles.This paper evaluates and compares the effectiveness of communication and on-board sensing technology in saving lives. Various implementation scenarios and system capabilities are investigated.
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| 22. |
- Botha, Theunis, et al.
(författare)
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Vehicle Motion Measurements Using Front Facing Camera and Digital Image Correlation
- 2016
-
Ingår i: ASME 2016 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, IDETC2016. - 9780791850138 ; 3
-
Konferensbidrag (refereegranskat)abstract
- Modern active vehicle safety systems rely on certain vehicle motion states to function. ABS requires the vehicle longitudinal speed to calculate the tire slip. The vehicle speed is typically estimated using the speed of all the wheels and is therefore dependent on the slip states of all the wheels. Electronic stability programs can also make more informed decisions if the vehicle side-slip angle is known. Currently the side-slip angle is not measured on commercial vehicles due to the cost of the sensors. The side-slip angle can however be estimated using multiple onboard vehicle measurements. However, these estimation techniques require accurate sensors and large excitations to estimate accurately. The measurement of the vehicle motion is therefore crucial for modern vehicle safety systems. This paper proposes a method whereby all 6 vehicle velocities can be measured using inexpensive forward facing mono and stereo cameras utilizing Digital Image Correlation (DIC) algorithms.
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| 23. |
- Brandt, Adam, 1993, et al.
(författare)
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Base wake dynamics and its influence on driving stability of passenger vehicles in crosswind
- 2022
-
Ingår i: Journal of Wind Engineering and Industrial Aerodynamics. - : Elsevier BV. - 0167-6105. ; 230
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Tidskriftsartikel (refereegranskat)abstract
- The unsteady flow around a travelling vehicle induces fluctuating aerodynamic loads. Automotive manufacturers usually set targets on the time-averaged lift forces to ensure good straight-line stability performance at high speeds. These targets are generally sufficient in preventing unstable vehicle designs. Yet, small changes in averaged values occasionally yield unexpectedly large differences in the stability performance, indicating that the changes in averaged normal loads cannot solely explain these differences. The unsteady aerodynamic effects on driving stability are, therefore, an interesting topic to study. The objective of the present work is to investigate the differences in wake dynamics and fluctuating aerodynamic loads for two variants of a roof spoiler on a sports utility vehicle: a baseline that was known to cause stability issues and an improved design which resolved them. The vehicle designs were investigated using accurate time-resolved CFD simulations for a set of crosswind conditions. The unsteady aerodynamic response was coupled to a vehicle dynamics model to analyse the resulting impact on driving stability. It was shown that in crosswinds the baseline spoiler, contrary to the improved spoiler, has bi-stable wake dynamics that induce lift force fluctuations at frequencies close to the 1st natural frequency of the rear suspension.
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| 24. |
- Brandt, Adam, 1993, et al.
(författare)
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Drivers' Perceived Sensitivity to Crosswinds and to Low-Frequency Aerodynamic Lift Fluctuations
- 2023
-
Ingår i: SAE Technical Papers. - 0148-7191 .- 2688-3627.
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Konferensbidrag (refereegranskat)abstract
- The automotive industry continues to increase the utilization of computer-aided engineering. This put demands on finding reliable objective measures that correlate to subjective driver assessments on driving stability performance. However, the drivers' subjective perception of driving stability can be difficult to quantify objectively, especially on test tracks where the wind conditions cannot be controlled. The advancement in driving simulator technology may enable evaluation of driving stability with high repeatability. The purpose of this study is to correlate the subjective assessment of driving stability to reliable objective measures and to evaluate the usefulness of a driving simulator for the subjective assessment. Two different driver clinic studies were performed in a state-of-the-art driving simulator. The first study included 38 drivers (professional, experienced and common drivers) and focused on crosswind gust sensitivity. The second study focused on straight-line driving stability at constant crosswinds, where the influence of unsteady aerodynamic wake fluctuations was assessed. This study involved three of these professional drivers. It was found that the subjective assessment of crosswind sensitivity can be correlated with the sensory motion response of the vehicle (lateral acceleration and yaw velocity), and also with vehicle path curvature (visual feedback). The assessment of fluctuating CFD loads showed that blind-tested professional drivers could differentiate vehicle configurations in agreement with their on-road subjective ratings. Based on the results of this study, a new aerodynamic lift target for high speed straight-line stability, which also accounts for the fluctuating loads of the wake, is proposed.
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| 25. |
- Brandt, Adam, 1993, et al.
(författare)
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High speed driving stability of road vehicles under crosswinds: an aerodynamic and vehicle dynamic parametric sensitivity analysis
- 2022
-
Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 1744-5159 .- 0042-3114. ; 60:7, s. 2334 -2357
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Tidskriftsartikel (refereegranskat)abstract
- Crosswinds affect vehicle driving stability and their influence increase with driving speed. To improve high speed driving stability, interdisciplinary research using unsteady aerodynamics and vehicle dynamics is necessary. The current demands of faster development times require robust virtual methods for assessing stability performance in early design phases. This paper employs a numerical one-way coupling between the two disciplines and uses a variety of realistic crosswind gust profiles for the aerodynamic simulations to output representative forces and moments on three vehicle dynamic models of different fidelity levels, ranging from a one-track model to a full multi-body dynamic model of a sports utility vehicle. An investigation on required model fidelity was conducted along with a sensitivity study to find key aerodynamic and vehicle dynamic characteristics to minimise the yaw velocity and lateral acceleration response during crosswinds. Transient aerodynamic simulations were used to model crosswind gusts at high speeds. Analysis of the forces and moments showed that rapid changing gusts generate overshoots in the yaw moment, due to the phase delay of the flow between the front and rear of the vehicle. A methodology for modelling this phase delay is proposed. The response of the vehicle was captured equally well by the enhanced model (mid-level fidelity) and the full multi-body dynamic model, while the simplest one-track model failed to emulate the correct vehicle response. The sensitivity study showed the importance of the positioning of the centre of gravity, the aerodynamic coefficient of yaw moment, wheel base, vehicle mass and yaw inertia. In addition, the axles' side force steer gradients and other suspension parameters revealed potential in improving crosswind stability.
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| 26. |
- Brandt, Adam, 1993, et al.
(författare)
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Quantitative High Speed Stability Assessment of a Sports Utility Vehicle and Classification of Wind Gust Profiles
- 2020
-
Ingår i: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191 .- 2688-3627. ; 2020-April:April
-
Tidskriftsartikel (refereegranskat)abstract
- The automotive trends of vehicles with lower aerodynamic drag and more powerful drivetrains have caused increasing concern regarding stability issues at high speeds, since more streamlined bodies show greater sensitivity to crosswinds. This is especially pronounced for high vehicles, such as sports utility vehicles. Besides, the competitiveness in the automotive industry requires faster development times and, thus, a need to evaluate the high speed stability performance in an early design phase, preferable using simulation tools. The usefulness of these simulation tools partly relies on realistic boundary conditions for the wind and quantitative measures for assessing stability without the subjective evaluation of experienced drivers. This study employs an on-road experimental measurements setup to define relevant wind conditions and to find an objective methodology to evaluate high speed stability. The paper focuses on the events in proximity to the drivers’ subjective triggers of instability. Wind direction and magnitude, vehicle motion response, along with the subjective event triggering were measured at different conditions of the natural wind. A statistical approach was utilized to analyze the correlation between the vehicle response and subjective triggers together with the wind conditions. A correlation was established between the subjective triggers and a rapid change in lateral acceleration and yaw velocity response. The paper also proposes a set of four crosswind gust profiles of interest for driving stability, combining results from previous research and the experimental data of the natural wind obtained in this study. These findings can be used as objective measures for virtually assessing stability performance and as realistic boundary conditions for simulating wind gusts.
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| 27. |
- Bruzelius, Fredrik, 1974-, et al.
(författare)
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A simple real-time aerodynamic model for vehicles in overtaking situations
- 2013
-
Ingår i: International Journal of Vehicle Systems Modelling and Testing. - 1745-6436 .- 1745-6444. ; 8:3, s. 241-259
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Tidskriftsartikel (refereegranskat)abstract
- Aerodynamic forces and moments play an important role inovertaking situations and affect the trajectory of the involved vehicles. One method of studying these effects and how the driver responds to these is via driving simulator studies. However, models that describe aerodynamic forces and moments are typically computationally complex and not suited for real time execution in driving simulators. The present work presents a simplified real time model of the moments and forces acting in an overtaking situation due to aerodynamic pressure imbalances. The model is compared with experimentally validated Navier-Stokes solutions. Despite the model’s simplicity, implemented as finite impulse response filters, it manages to capture the main features of the forces and moments. The approach used to derive the model is fairly general and might be used in similar applications where computational burden is a key issue.
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| 28. |
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| 29. |
- Chen, Weitao, 1989, et al.
(författare)
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A Method to Improve Stability and Transparency for Mechanical Hardware-in-the-Loop Simulation
- 2021
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- In mechanical hardware-in-the-loop (MHIL) simulation the test hardware and the simulated environment are coupled by an interface, which typically is a dynamometer rig. This interface determines the simulation accuracy and robustness. In this work, MHIL simulation is analysed in a linear robust control framework. The system consists of an inner loop formed by the load motor controller and the rig, and an outer loop formed by the test hardware and the simulated environment. While the inner loop tracking set the overall performance, instability and poor performance may be introduced by the outer loop. We demonstrate how delay tolerance of MHIL simulation varies with the outer loop dynamics. A new method is introduced to improve the robustness and accuracy. The method utilizes flexibility of the simulation model, and only software changes are needed. The proposed method is applied to an MHIL simulation for vehicle and electric power assisted steering (EPAS) system test. The effectiveness of the method is shown analytically and experimentally.
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| 30. |
- Chen, Weitao, 1989, et al.
(författare)
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An Architecture of Hardware and Driver in the Loop Simulation for Electric Power Assisted Steering System
- 2020
-
Ingår i: Lecture Notes in Mechanical Engineering. - Cham : Springer International Publishing. - 2195-4356 .- 2195-4364. - 9783030380762
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Konferensbidrag (refereegranskat)abstract
- This paper introduces an architecture for virtual development of electric power assisted steering (EPAS) system, which is implemented at Volvo Cars. The architecture involves an EPAS power pack rig and driver in the loop, so engineers can test both the ECU software and electric motor on a virtual prototype vehicle. Eective results are shown for tests in low-mid frequency and at mid-high vehicle speed. Currently, the high frequency and low speed test is still challenging due to vibration and instability, which should be addressed by the control improvement.
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| 31. |
- Chen, Weitao, 1989, et al.
(författare)
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Design of Interface in Co-simulation for Electric Power Assisted Steering System Development
- 2018
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Ingår i: Proceedings of the 14th International Symposium on Advanced Vehicle Control.
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Konferensbidrag (refereegranskat)abstract
- Interface and causality have important effects on the co-simulation used in vehicle system development. In this paper we analyzed these effects by modeling a co-simulated dual mass-spring-damper system as a sampled-data system. By stability and frequency domain analysis we find that the co-simulation interface needs be designed where the coupling interface is less stiff and the force variable should be applied in the direction of larger mass, natural frequency and damping ratio. The analytical results have been verified through two test cases of co-simulation in electric power assisted steering (EPAS) system development: a multi-rate offline co-simulation and a hardware-in-loop (HIL) simulation. Both test cases showed more consistent and stable results using the suggested interface design.
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| 32. |
- Chen, Weitao, 1989, et al.
(författare)
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Explicit parallel co-simulation approach: analysis and improved coupling method based on H-infinity synthesis
- 2021
-
Ingår i: Multibody System Dynamics. - : Springer Science and Business Media LLC. - 1573-272X .- 1384-5640. ; 52:3, s. 255-279
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Tidskriftsartikel (refereegranskat)abstract
- Co-simulation is widely used in the industry for the simulation of multidomain systems. Because the coupling variables cannot be communicated continuously, the co-simulation results can be unstable and inaccurate, especially when an explicit parallel approach is applied. To address this issue, new coupling methods to improve the stability and accuracy have been developed in recent years. However, the assessment of their performance is sometimes not straightforward or is even impossible owing to the case-dependent effect. The selection of the coupling method and its tuning cannot be performed before running the co-simulation, especially with a time-varying system. In this work, the co-simulation system is analyzed in the frequency domain as a sampled-data interconnection. Then a new coupling method based on the H-infinity synthesis is developed. The method intends to reconstruct the coupling variable by adding a compensator and smoother at the interface and to minimize the error from the sample-hold process. A convergence analysis in the frequency domain shows that the coupling error can be reduced in a wide frequency range, which implies good robustness. The new method is verified using two co-simulation cases. The first case is a dual mass–spring–damper system with random parameters and the second case is a co-simulation of a multibody dynamic (MBD) vehicle model and an electric power-assisted steering (EPAS) system model. Experimental results show that the method can improve the stability and accuracy, which enables a larger communication step to speed up the explicit parallel co-simulation.
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| 33. |
- Chen, Weitao, 1989, et al.
(författare)
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Integration and Analysis of EPAS and Chassis System in FMI-based co-simulation
- 2019
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Ingår i: Proceedings of the 13th International Modelica Conference. - : Linköing University Electronic Press. - 9789176851227 ; :157, s. 717-724
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Konferensbidrag (refereegranskat)abstract
- The vehicle steering characteristics and active functions can be virtually developed with a high-fidelity electric power assisted steering (EPAS) model and a multibody chassis model. The simulation of the EPAS model requires small integration step due to high stiffness and interfacing with the controller. The multibody chassis model is computationally heavy for each integration step due to calculation of large matrices. A mono-simulation based on a single solver is not efficient for this case. Instead a co-simulation (solver coupling) approach has been used to overcome the drawbacks.In this paper the EPAS system and chassis system are modeled in Dymola and further exported as separate functional mockup units (FMUs) and integrated with the control algorithms in Matlab. A co-simulation based on the explicit parallel calculation scheme (Jacobi scheme) has been used. A huge simulation speed-up has shown the potential and effectiveness of the approach. To understand its accuracy and tolerance, analysis on the numerical error and dynamics of the coupled-system are given.
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| 34. |
- Chugh, Tushar, 1989, et al.
(författare)
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Steering Feedback Transparency Using Rack Force Observer
- 2022
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Ingår i: IEEE/ASME Transactions on Mechatronics. - 1083-4435 .- 1941-014X. ; , s. 1-12
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Tidskriftsartikel (refereegranskat)abstract
- The closed-loop electric power-assisted steering and steer-by-wire systems are non-transparent toward the environment, i.e., the tire-road interaction dynamics. To achieve driver–environment transparency, a rack force estimate is required. With the introduction of dynamic rack force observer feedback, a closed-loop interconnection is formed. Therefore, the driver coupled stability must be ensured with this interconnection. Consequently, an upper bound condition on transparency is derived using passivity for different control architectures. For selecting an observer with reasonable performance, two rack-force estimation schemes are investigated and compared, i.e., using vehicle motion signals from the inertial measurement unit sensor and the steering system sensors. Experiments indicate that the former approach has inferior performance due to vehicle inertia and signal latency, whereas in the latter approach, nonlinear estimation using second-order dynamics provides the best result; hence, it is selected to realize transparency. Finally, real-world experiments on an electric power-assisted steering vehicle illustrate the differences between non-transparent and transparent steering feedback when driving at the limits of handling on an icy road surface.
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| 35. |
- Edrén, Johannes, 1983-, et al.
(författare)
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Road friction effect on the optimal vehicle control strategy in two critical manoeuvres
- 2014
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Ingår i: International Journal of Vehicle Safety. - 1479-3105 .- 1479-3113. ; Vol. 7:No. 2, s. pp 107-130
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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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| 36. |
- Emvin, Carl, 1998, et al.
(författare)
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Estimation of Accurate Path Length with Geospatial Data Analysis
- 2024
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The core objectives of this study included creating a backend system to process and sort road data, deploying multiple path length estimation methods, and quantifying their accuracy using standard measures. The performance of each method was showcased through a case study, highlighting their effectiveness in different scenarios. Additionally, the study developed a deterministic Operating Cycle (dOC) model to encapsulate road data and facilitate residual range prediction in simulations. For the complete code, click the button in the top right corner "view online".
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| 37. |
- Erdinc, Umur, 1992, et al.
(författare)
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Modelling of Articulated Heavy Vehicles for Computation of Accurate Safe Operating Envelope for Yaw Stability
- 2023
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Ingår i: Proceedings of the 17th International Symposium on Heavy Vehicle Transport & Technology (HVTT17).
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Konferensbidrag (refereegranskat)abstract
- As articulated heavy vehicles switch to electric power, new ways of allocating wheel forces have emerged. To improve energy efficiency, it is increasingly common to use propulsion or regenerative braking on only one unit of the vehicle combination. This leads to yaw stability problems, mainly jackknifing if the towing unit has excessive wheel forces, or trailer swing if the trailing unit has excessive wheel forces. Hence, it becomes important to allocate the total force request into different units and actuators in a safe way. This paper formulates a nonlinear two-track model with a nonlinear tire model, combined slip, and roll degree of freedom. Thus, the presented model can accurately simulate brake-in-turn and propel-in-turn maneuvers at high lateral accelerations. And it can be used to study when the yaw instability occurs and understand if the maneuver is safe or not. One way to ensure safe control allocation is by implementing a safe operating envelope that restricts the allocation within predefined limits. This helps maintain control of the system and prevent any potential safety hazards. In this paper, a nonlinear two-track model is utilized to simulate a range of lateral accelerations and various combinations of braking forces between the tractor and semitrailer. Through this process, an envelope is obtained which is then compared to an envelope generated from a single-track model and validated against high-fidelity model-based envelopes. This rigorous process helps to ensure the accuracy and reliability of the two-track model.
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| 38. |
- Erdinc, Umur, 1992, et al.
(författare)
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Safe operating envelope based on a single-track model for yaw instability avoidance of articulated heavy vehicles
- 2023
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Ingår i: Vehicle System Dynamics. - 1744-5159 .- 0042-3114. ; In Press
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Tidskriftsartikel (refereegranskat)abstract
- The electrification of commercial vehicles has led to new wheel torque allocation options for propulsion and braking of articulated heavy vehicles. Each unit or axle can be individually braked or propelled whilst the other units or axles are excluded from such action. This may achieve the best energy efficiency. However, this can also lead to potential yaw stability problems such as jackknifing and trailer swing, especially under bad loading and weather conditions. This paper describes the above instabilities and introduces a nonlinear single-track model to study the vehicle dynamics of the tractor-semitrailer combination. The effects of different vehicle and environment parameters are analysed with this vehicle model. A safe operating envelope for limiting the wheel forces is obtained using this vehicle model. Since the vehicle model introduced in this paper is computationally effective, it can be run online in real vehicles, with an instantaneous safe operating envelope obtained for the momentary conditions. Thus, yaw instabilities such as jackknifing and trailer swing may be avoided.
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| 39. |
- Erdinc, Umur, 1992, et al.
(författare)
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Validation of high-fidelity simulation-based safe operating envelopes for articulated heavy vehicles using real test data
- 2024
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Ingår i: Vehicle System Dynamics. - 1744-5159 .- 0042-3114. ; In Press
-
Tidskriftsartikel (refereegranskat)abstract
- The electrification of towing and trailing units creates new torque allocation alternatives among different units of articulated heavy vehicles. To increase the power and energy efficiency, control algorithms can request propulsion or regenerative braking from a single unit while keeping the other units unbraked or unpropelled. However, this may lead to safety problems, such as jackknifing or trailer swing. This paper uses a high-fidelity simulation tool to formulate safe operating envelopes for a tractor and semitrailer combination for braking-in-turn cases. The effects of different vehicle and environment parameters on the safe operating envelope are studied. The safe operating envelope obtained is then validated using real vehicle tests and can be used with any control algorithm to avoid requesting unsafe unit force combinations.
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| 40. |
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| 41. |
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| 42. |
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| 43. |
- Ghandriz, Toheed, 1982, et al.
(författare)
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A Vehicle Longitudinal Dynamical Model for Propulsion System Tailoring
- 2020
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Integrated vehicle-transportation design, based on specific transportation assignments, has resulted in cost- and energy-efficient transport solutions especially in case of battery electric heavy vehicles. This report presents a longitudinal dynamical vehicle model for fast evaluation of the cost function and constraints within a vehicle-transportation optimization. The model includes conventional, fully electric and hybrid vehicles. The presented model evaluates energy consumption and battery degradation on driving cycles with varying speed limit and topography. The energy consumption accuracy of the presented model compared to a high fidelity vehicle model has been seen to be about 3% for the tested driving cycles, which can be further improved by tuning parameters.
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| 44. |
- Ghandriz, Toheed, 1982, et al.
(författare)
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BENEFIT ANALYSIS OF INTRODUCING ELECTRIC PROPULSION ON CONVERTER DOLLIES
- 2023
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Ingår i: Heavy Vehicle Transport & Technology (HVTT17).
-
Konferensbidrag (refereegranskat)abstract
- Long combination vehicles (LCVs) demonstrated substantially lower cost and energy consumption compared to tractor-semitrailers. However, they suffer from reduced longitudinal performance. Distributed propulsion over axles, i.e., electrically propelling trailers or the converter dolly (e-dolly), can resolve the reduced longitudinal performance and improve energy efficiency of these vehicles. This paper implements an advanced predictive controller for distribution of propulsion, regenerative and service brakes between axles, which ensures both optimal energy efficiency and safety. To generate the results, 4000 different roads with different topography profiles were generated statistically and used for testing the controller performance. The simulation results indicate that the fuel saving of the hybrid A-double, i.e., the one with e-dolly compared to the conventional A-double is, on average, 12%, 14.5%, 16.5%, and 17.5% on flat, predominantly flat, hilly, and very hilly roads, respectively. Both vehicles were equipped with the advanced controller. In addition, with that fuel saving, the hybrid A-double showed lower total cost of ownership in all roads if the distance traveled per year is higher than 45000 km. Moreover, the longitudinal performance, i.e., startability, gradeability, and acceleration capability were improved by 27%, 25%, and 8%, respectively.
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| 45. |
- Ghandriz, Toheed, 1982, et al.
(författare)
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Computationally Efficient Nonlinear One-and Two-Track Models for Multitrailer Road Vehicles
- 2020
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Ingår i: IEEE Access. - 2169-3536 .- 2169-3536. ; 8, s. 203854-203875
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents nonlinear mathematical models of one-and two-track multitrailer vehicles. We derive nonlinear equations of motion in the form of a system of implicit ordinary differential equations (ODEs) by using Lagrangian mechanics. The system of ODEs has the minimum number of states and equations that enables efficient computations yet maintains the most important nonlinear vehicle dynamic behavior and allows actuator coordination and energy consumption evaluation. As examples, we build different models of a 4-unit long combination vehicle, i.e., two-track 11-axle and single-track 6-axle nonlinear models as well as a linear single-track 6-axle model. We compare the performance of these models to experimental data of different driving maneuvers. The nonlinear single-track model demonstrates close dynamic behavior to the experiment, which makes it an efficient alternative to the two-track model. The vehicle equations can be generated automatically by using the code provided in this paper and subsequently used for conducting frequency analysis, evaluating energy consumption, deriving performance measures from simulations, and facilitating optimal control applications that involve combined steering, braking and propulsion control.
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| 46. |
- Ghandriz, Toheed, 1982, et al.
(författare)
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Impact of automated driving systems on road freight transport and electrified propulsion of heavy vehicles
- 2020
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Ingår i: Transportation Research, Part C: Emerging Technologies. - : Elsevier BV. - 0968-090X. ; 115
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Tidskriftsartikel (refereegranskat)abstract
- The technological barriers to automated driving systems (ADS) are being quickly overcome to deploy on–road vehicles that do not require a human driver on–board. ADS have opened up possibilities to improve mobility, productivity, logistics planning, and energy consumption. However, further enhancements in productivity and energy consumption are required to reach CO2–reduction goals, owing to increased demands on transportation. In particular, in the freight sector, incorporation of automation with electrification can meet necessities of sustainable transport. However, the profitability of battery electric heavy vehicles (BEHVs) remains a concern. This study found that ADS led to profitability of BEHVs, which remained profitable for increased travel ranges by a factor of four compared to that of BEHVs driven by humans. Up to 20% reduction in the total cost of ownership of BEHVs equipped with ADS could be achieved by optimizing the electric propulsion system along with the infrastructure for a given transportation task. In that case, the optimized propulsion system might not be similar to that of a BEHV with a human driver. To obtain the results, the total cost of ownership was minimized numerically for 3072 different transportation scenarios that showed the effects of travel distance, road hilliness, average reference speed, and vehicle size on the incorporated electrification and automation, and compared to that of conventional combustion–powered heavy vehicles.
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| 47. |
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| 48. |
- Ghandriz, Toheed, 1982, et al.
(författare)
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Optimization Based Design of Heterogeneous Truck Fleet and Electric Propulsion
- 2016
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Ingår i: Proceedings, ITSC. IEEE 19th International Conference on Intelligent Transportation Systems (ITSC), November 1-4, 2016, Rio de Janeiro, Brazil. - 9781509018895 ; , s. Art no 7795575, Pages 328-335
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Konferensbidrag (refereegranskat)abstract
- Many researches have been focused on vehicle routing problem during past decades where subject vehicles are previously fully designed and ready to start operation. Further, extensive studies have been done on powertrain design irrespective of the routes where the vehicle is going to be employed. In the present paper, we try to define a new branch of problems where the vehicle design, in particular its propulsion system and loading capacity, is treated simultaneously with the routing problem. The focus is on optimization based design of heterogeneous electric truck fleet to perform a prescribed task with a lowest cost on an available set of routes. The approach is illustrated in a simple case study problem. It is shown that long heavy combination vehicles are energy-efficient but not cost-optimal on short routes.
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| 49. |
- Ghandriz, Toheed, 1982, et al.
(författare)
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Optimization data on total cost of ownership for conventional and battery electric heavy vehicles driven by humans and by Automated Driving Systems
- 2020
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Ingår i: Data in Brief. - : Elsevier BV. - 2352-3409. ; 30
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Tidskriftsartikel (refereegranskat)abstract
- In road freight transport, the emerging technologies such as automated driving systems improve the mobility, productivity and fuel efficiency. However, the improved efficiency is not enough to meet environmental goals due to growing demands of transportation. Combining automated driving systems and electrified propulsion can substantially improve the road freight transport efficiency. However, the high cost of the battery electric heavy vehicles is a barrier hindering their adoption by the transportation companies. Automated driving systems, requiring no human driver on–board, make the battery electric heavy vehicles competitive to their conventional counterparts in a wider range of transportation tasks and use cases compared to the vehicles with human drivers. The presented data identify transportation tasks where the battery electric heavy vehicles driven by humans or by automated driving systems have lower cost of ownership than their conventional counterparts. The data were produced by optimizing the vehicle propulsion system together with the loading/unloading schemes and charging powers, with the objective of minimizing the total cost of ownership on 3072 different transportation scenarios, according to research article “Impact of automated driving systems on road freight transport and electrified propulsion of heavy vehicles” (Ghandriz et al., 2020). The data help understanding the effects of traveled distance, road hilliness and vehicle size on the total cost of ownership of the vehicles with different propulsion and driving systems. Data also include sensitivity tests on the uncertain parameters.
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| 50. |
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