Nonlinear dual-motor steer-by-wire system cooperative control via fixed-time command-filtered

This paper investigates a novel dual-motor steer-by-wire (DMSBW) system to enhance the reliability of steer-by-wire (SBW) systems. However, various nonlinearities in the DMSBW system complicate the torque variation in each subsystem, resulting in different dynamic responses of the two motors, which leads to serious coordination problems in the system. Therefore, a fixed-time command-filtered cooperative control strategy is proposed. First, the nonlinearity of the system's aligning torque, friction torque, and load torque caused by backlash are considered, and the nonlinear model of the DMSBW system is established. Then, a high-gain observer (HGO) is employed to rapidly estimate the nonlinear alignment torque and friction torque of the system. Next, a fixed-time robust backstepping controller based on the HGO is designed, embedding a robust control term to compensate for the backlash nonlinearity. Fixed-time control enhances the system's convergence performance, and a command filter along with a compensation signal is designed to improve the controller's control accuracy. Finally, hardware-in-the-loop experiments show that the proposed control strategy enables the DMSBW system to achieve high-precision cooperative operation under nonlinear conditions.