Proposing a BSPID Control Strategy Considering External Disturbances for Electric Power Steering (EPS) Systems

Abstract

EPS systems provide superior efficiency compared to mechanical steering systems. Steering feel and comfort are supported by an electric motor, which is controlled by an appropriate controller. This article introduces an integrated control algorithm for the EPS system with two novel contributions. Firstly, this algorithm is synthesized based on a backstepping (BS) controller and a proportional integral derivative (PID) controller, called the BSPID controller. The control signals are amplified based on optimal coefficients determined by the loop algorithm. Secondly, a complex steering dynamics model is established based on five state variables that consider the influence of road reaction torque and other external disturbances. According to numerical simulation results, the value of the steering motor and steering column angles increases when using the EPS system instead of the conventional steering system. Under the same driver torque conditions, the variation of output parameters will decrease as the speed increases. On the contrary, the change in output parameters will increase sharply when driver torque increases (under the same speed conditions). The results obtained from the BSPID signal always closely track the reference signal in all investigated conditions with negligible errors, even though the steering system is still subject to external random disturbances.