Backstepping Integral Nonsingular Terminal Sliding Mode Based Fault-tolerant Control of Dual-motor Synchronous Anti-backlash Servo System with Extended State Observer

Considering the actuator failures of the dual-motor synchronous anti-backlash servo system, this paper proposes a robust fault-tolerant control strategy to ensure the system stable operation when the above faults occur. Firstly, the position controller is designed by the backstepping integral nonsingular terminal sliding mode control method with a double power reaching law. To avoid the excessive control value caused by the derivation process, the reference position signal is smoothed by a command-filter. Meanwhile, the linear extended state observer is introduced to compensate the whole disturbance of the system which improves the robustness ability of the system. Secondly, an adaptive torque distribution controller is designed to solve the motor actuator failures. When one side motor failure is detected, the controller can adaptively change the proportional gain of the motor torque/current command to guarantee the system can still work normally in the single motor driving condition. The co-simulation experiment results demonstrate the effectiveness of the proposed method.