Abstract
This paper describes a new algorithm that independently manages braking and driving forces to improve the lateral stability of a vehicle equipped with independent drive motors on all wheels. In a similar way to previous research, the proposed algorithm controls yaw rate to improve lateral stability. However, unlike in previous research that only used differential braking, our algorithm controls both driving and braking forces on all four wheels independently to achieve the target yaw rate. The core contribution of this paper is the distribution logic that determines the braking and driving forces to apply at each wheel. To develop this distribution logic, we introduce the concept of yaw moment contour line. Using this concept, the optimal distribution strategy can be derived by considering yaw moment control performance, lateral movement performance, and deceleration minimization performance in eight different driving situations. Based on this strategy, we design a lateral stability control algorithm that is made up of a target yaw rate, a yaw moment controller, and a distributor. Simulations were performed to investigate the performance of the proposed algorithm using MATLAB/Simulink and the CarSim vehicle dynamics software. The simulation results show that the proposed control algorithm improves vehicle motion in terms of yaw rate tracking, lateral movement, and minimization of deceleration.
Highlights
The electric vehicle market has expanded due to the EU's strict CO2 regulations and the emergence of an innovative leading company, Tesla
Using the optimal distribution strategies, we develop the control algorithm consisting of a target yaw rate, Mz controller, and distributor
Driving situations are classified into eight categories according to the signs of the target yaw moment, front-wheel lateral forces, and rear-wheel lateral forces, we introduce a new concept called the yaw moment contour line to derive an optimal distribution strategy for every situation
Summary
The electric vehicle market has expanded due to the EU's strict CO2 regulations and the emergence of an innovative leading company, Tesla. The most important issue in a situation where electric vehicles are in the limelight and the number of mass-produced vehicles is increasing is how far they can travel on a single charge. To solve this issue, electric vehicles are currently equipped with many batteries. One of the ways to solve this problem is the development of a high-performance electric vehicles equipped with independent drive motors at each wheel. This system has the advantage of giving a lot of freedom in terms of motion control because it becomes possible to independently control braking and driving forces at each wheel. Kang et al proposed a driving control algorithm for maneuverability, lateral stability, and rollover prevention in 4WD electric vehicles using an VOLUME XX, 2017
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