Abstract
To improve the trackability of in-wheel motor drive (IWMD) and wheel-individual steer electric vehicles (EVs) when steering actuators fail, the fail-operation control strategy was proposed to correct vehicles in a steering failure situation and avoid losing control of vehicle steering. A linear quadratic regulator (LQR) decides the additional yaw moment of the vehicle according to vehicle state errors. The tire force estimation module estimates the compensating resistance moment generated by the failed wheel according to the tire slip angle and the vertical tire force. By isolating the failed wheel, the optimal torque distribution (OTD) controller allocates the additional yaw moment and the compensating resistance moment to normal wheels to realize the fail-operation control of the IWMD vehicle. The control effect was verified through co-simulation of MATLAB/Simulink and Trucksim. Compared with the uncontrolled and direct torque allocation methods, the proposed OTD method reduces the lateral trajectory error of the vehicle by 86% and 60.5%, respectively, when failure occurs, and achieves better velocity maintaining ability, which proves the effectiveness of the proposed fail-operation control strategy.
Highlights
An in-wheel motor drive (IWMD) and wheel-individual steer vehicle removes the transmission system from traditional vehicles, and the drive torque and steering angle of each wheel can be controlled independently
optimal torque distribution (OTD) method reduces the lateral trajectory error of the vehicle by 86% and 60.5%, respectively, when failure occurs, and achieves better velocity maintaining ability, which proves the effectiveness of the proposed fail-operation control strategy
Kim et al [6,7] and Nah et al [8] presented the drive control algorithm of a multi-axle IWMD vehicle, and computer simulations proved the feasibility of the in-wheel motor used in multi-axle vehicles
Summary
An in-wheel motor drive (IWMD) and wheel-individual steer vehicle removes the transmission system from traditional vehicles, and the drive torque and steering angle of each wheel can be controlled independently. It is a feasible way to forces to other hub motors, we canthrough form an additional moment to steer and correct the vehicle, improve the IWMD vehicle’s fail-operation ability by adjusting the wheel torques when a drive motor realizing the fail-operation control of the vehicle. Nah et al [12] used high slip ratio-based optimal control (the failed wheel rotates at a high slip driving forces to other hub motors, we can form an additional yaw moment to steer and correct the rate by means of wheel torque control) to reduce lateral resistance force By evaluating the trackability of an IWMD and wheel-individual steer compensating resistance moment to normal wheels, reducing the lateral displacement error of vehicle in the steering failure case, the By proposed optimal torque distribution control methodsteer is the failed vehicle effectively.
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