An optimal control allocation strategy for an eight in-wheel-motor drive electric vehicle

Abstract

In this paper, an optimal control allocation strategy is presented for an eight in-wheel-motor independent drive electric vehicle/four double front wheel steering(8WD/4WS). The upper level controller consists of a speed following controller and two sliding mode controllers. The speed tracking controller obtains the desired longitudinal force by tracking the longitudinal speed. Two sliding mode controllers obtain the desired lateral force and the desired yaw moment by controlling the sideslip angle error and the yaw rate error, respectively. The lower level controller optimizes the torque distribution using the optimal objective function calculated by Weighted Least Squares(WLS) in eight wheel motors and brakes with comprehensive considering constraint conditions. Closed-loop simulations are carried out in different working conditions such as single lane change and double lane change. The optimal control allocation strategy established by this paper can greatly improve the vehicle handling stability with contrast to the average torque distribution strategy and the tire-dynamic-load-based torque distribution strategy.