Vehicle Dynamics Control for Active Safety Functions using Electrified Drivelines
Doctoral thesis, 2018
Studies have shown that even considering pledges and commitments made by various governments and organisations, the growth in electrified vehicle sales is likely to be insufficient to reduce CO2 emissions for mitigating global warming. Some form of added incentive is needed that can help drive electrified vehicle sales in the open market. On the other hand, there is an increased need for traffic safety due to customer demand and the adoption of ambitious goals such as the Vision Zero. This thesis attempts to identify vehicle dynamic opportunities to improve vehicle safety that are enhanced or enabled by electrified drivetrains, thereby offering an opportunity to add value to electrified vehicles and make them more attractive to consumers.
As an example of low hanging fruit, the possibility of accelerating an electrified lead vehicle to mitigate the consequences of, or prevent being struck from behind was investigated. A hypothetical Autonomous Emergency Acceleration (AEA) system (analogous to the Automatic Emergency Braking (AEB) system) was envisioned and the safety benefit due to the same was estimated. It was found that the AEA system offers significant opportunities for preventing or reducing injuries in rear-end collisions.
The possibility of using propulsion to improve safety in an obstacle avoidance scenario in the presence of oncoming traffic was also investigated. In order to better understand the manoeuvre kinematics, a point mass based optimal control analysis is done, in which a characteristic parameter is identified that correlates well with the need to increase or decrease speed in the manoeuvre for mitigating the risk of collision with the oncoming vehicle. After verification through experiments, an integrated motion controller is formulated, implemented and tested in a high-fidelity simulation environment. Results showed that consistent reductions in collision risk to the oncoming vehicle could be achieved using the integrated controller. Specifically, the results showed that the availability of electric drives consistently reduced collision risk by enabling greater torque vectoring magnitudes and mitigating the deceleration side effect of differential braking. The integrated controller was then evaluated for robustness to steering effort in simulations followed by real-time implementation of the controller and testing using a Volvo XC90 test vehicle.
Intersection accidents are then investigated with regards to the possibility of crossing the intersection ahead of a bullet vehicle for collision avoidance. Optimal manoeuvres for the same were derived using analytical optimal control theory and it was seen that optimal manoeuvres could be represented as a maximisation of the tyre forces in a fixed global direction. Based on this finding an integrated motion controller is implemented and tested. Simulation results showed that collision risk can be reduced significantly over a passive vehicle even in limit scenarios where the tyre forces are saturated.
In summary, several vehicle dynamic opportunities for improving safety using electrified drivetrains were identified. Detailed investigations of select cases showed that significant safety benefit potentially stands to be gained by appropriate control of electrified drivetrains in the accident scenarios. Consequently, a strong opportunity is seen for adding safety related value to electrified vehicles at little to no extra cost.
As an example of low hanging fruit, the possibility of accelerating an electrified lead vehicle to mitigate the consequences of, or prevent being struck from behind was investigated. A hypothetical Autonomous Emergency Acceleration (AEA) system (analogous to the Automatic Emergency Braking (AEB) system) was envisioned and the safety benefit due to the same was estimated. It was found that the AEA system offers significant opportunities for preventing or reducing injuries in rear-end collisions.
The possibility of using propulsion to improve safety in an obstacle avoidance scenario in the presence of oncoming traffic was also investigated. In order to better understand the manoeuvre kinematics, a point mass based optimal control analysis is done, in which a characteristic parameter is identified that correlates well with the need to increase or decrease speed in the manoeuvre for mitigating the risk of collision with the oncoming vehicle. After verification through experiments, an integrated motion controller is formulated, implemented and tested in a high-fidelity simulation environment. Results showed that consistent reductions in collision risk to the oncoming vehicle could be achieved using the integrated controller. Specifically, the results showed that the availability of electric drives consistently reduced collision risk by enabling greater torque vectoring magnitudes and mitigating the deceleration side effect of differential braking. The integrated controller was then evaluated for robustness to steering effort in simulations followed by real-time implementation of the controller and testing using a Volvo XC90 test vehicle.
Intersection accidents are then investigated with regards to the possibility of crossing the intersection ahead of a bullet vehicle for collision avoidance. Optimal manoeuvres for the same were derived using analytical optimal control theory and it was seen that optimal manoeuvres could be represented as a maximisation of the tyre forces in a fixed global direction. Based on this finding an integrated motion controller is implemented and tested. Simulation results showed that collision risk can be reduced significantly over a passive vehicle even in limit scenarios where the tyre forces are saturated.
In summary, several vehicle dynamic opportunities for improving safety using electrified drivetrains were identified. Detailed investigations of select cases showed that significant safety benefit potentially stands to be gained by appropriate control of electrified drivetrains in the accident scenarios. Consequently, a strong opportunity is seen for adding safety related value to electrified vehicles at little to no extra cost.
driver assistance systems
intersection accidents
torque vectoring
optimal control
rear- end collisions
speed control
active safety
vehicle dynamics
electrified drivetrain
obstacle avoidance with oncoming traffic
KB-salen, Kemigården 4, Chalmers
Opponent: Dr. Patrick Gruber, Department of Mechanical Engineering Sciences, University of Surrey, UK
Author
Adithya Arikere
Chalmers, Mechanics and Maritime Sciences (M2), Vehicle Engineering and Autonomous Systems
Added Value for Electrified Vehicles through Enhanced Active Safety
World Electric Vehicle Journal,;Vol. 8(2016)p. WEVJ8-0623 - 0634-
Paper in proceeding
On the Potential of Accelerating an Electrified Lead Vehicle to Mitigate Rear-End Collisions
Proceedings of the 3rd International Symposium on Future Active Safety Technology Towards zero traffic accidents, 2015,;(2015)p. 377-384
Paper in proceeding
Optimal motion control for collision avoidance at Left Turn Across Path/Opposite Direction intersection scenarios using electric propulsion
Vehicle System Dynamics,;Vol. 57(2019)p. 637-664
Journal article
Integrated evasive manoeuvre assist for collision mitigation with oncoming vehicles
Vehicle System Dynamics,;Vol. 56(2018)p. 1577-1603
Journal article
A. Arikere, D. Yang, M. Klomp, and B. J. H. Jacobson. Evaluating the Robust- ness of Integrated Control for Collision Mitigation with Oncoming Vehicles with respect to Steering Effort. International Journal of Driving Science Submitted (Dec. 5, 2017)
Experimental Verification of Evasive Manoeuvre Assist Controller for Collision Mitigation with Oncoming Vehicles
Proceedings of the 14th International Symposium on Advanced Vehicle Control (AVEC’ 18), Beijing, China,;(2018)
Paper in proceeding
Climate change and air pollution causing poor air quality are among the most pressing issues facing the world today and the transport sector is a major contributor to both. One way to mitigate both these issues is to switch from purely fossil fuel driven vehicles to fully electric or at least electrified vehicles. However, studies have shown that both the growth in electrified vehicle sales and the pledges and promises that have been made by various governments in terms of combating climate change are far short of what is required to successfully mitigate climate change.
Clearly then, a solution to drive electrified vehicle sales on the open market is needed. One way to achieve this can be to add value to electrified vehicles by implementing functions that exploit the advantages of electric drives over traditional internal combustion engines. And since vehicle safety is another important "gap area" in the transport sector, adding safety-related value to electrified vehicles could be an effective way to make them more attractive to consumers.
In this thesis, the possibility of implementing active safety functionality that is enabled or enhanced by electric drives is investigated. It was seen that electric drives can be used to perform several enhanced interventions which can in turn be used to perform active safety interventions in a large number of scenarios to improve safety. Three accident scenarios were investigated in detail, in each of which significant safety benefit could potentially be gained with the help of electric drives: i) rear-end collisions, ii) obstacle avoidance with oncoming traffic and iii) intersection accidents.
In summary, this work shows that a strong opportunity exists for adding safety related value to electrified vehicles at little to no extra cost. This in turn could make them more attractive to consumers, help drive electrified vehicle sales and therefore contribute toward mitigating climate change and air pollution.
Clearly then, a solution to drive electrified vehicle sales on the open market is needed. One way to achieve this can be to add value to electrified vehicles by implementing functions that exploit the advantages of electric drives over traditional internal combustion engines. And since vehicle safety is another important "gap area" in the transport sector, adding safety-related value to electrified vehicles could be an effective way to make them more attractive to consumers.
In this thesis, the possibility of implementing active safety functionality that is enabled or enhanced by electric drives is investigated. It was seen that electric drives can be used to perform several enhanced interventions which can in turn be used to perform active safety interventions in a large number of scenarios to improve safety. Three accident scenarios were investigated in detail, in each of which significant safety benefit could potentially be gained with the help of electric drives: i) rear-end collisions, ii) obstacle avoidance with oncoming traffic and iii) intersection accidents.
In summary, this work shows that a strong opportunity exists for adding safety related value to electrified vehicles at little to no extra cost. This in turn could make them more attractive to consumers, help drive electrified vehicle sales and therefore contribute toward mitigating climate change and air pollution.
Areas of Advance
Transport
Subject Categories
Vehicle Engineering
ISBN
978-91-7597-708-9
Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 4389
Publisher
Chalmers
KB-salen, Kemigården 4, Chalmers
Opponent: Dr. Patrick Gruber, Department of Mechanical Engineering Sciences, University of Surrey, UK