Simulation research on rear active steering-based 4WIS electric vehicle steering control

Abstract

An ideal steering characteristic is of great importance to improve the handling stability of four-wheel independent steering (4WIS) electric vehicle. For this reason, we proposed in this paper to use LQR optimal control theory to control variable gear ratio steering control through rear active steering. To realize great steering gain (i.e., quick response to handling) at low speeds and small steering gain (i.e., stable steering) at high speeds, first, the desired yaw rate of vehicle needs to be calculated according to the variation curve of variable gear ratio; second, an LQR optimal control theory based control strategy of rear active steering is designed to track the desired value; third and last, a driver-vehicle-road closed-loop control simulation system is established for the simulation experiment under double lane change conditions. The experimental results demonstrate that the proposed control strategy can achieve the hypothesized ideal steering characteristic.