Partial loss-of-effectiveness tolerant control of four-motor synchronous driving servo system based on current observer

In this paper, fault-tolerant control (FTC) of a four-motor servo system in the presence of an actuator partial loss of effectiveness (PLOE) is studied. First, a current observer is designed to observe the effectiveness factor and current of each motor to determine the motor’s working status. Second, to reduce the computational burden in the process of backstepping design, the command filter is used for handling the computational complexity. In the design process, the speed synchronisation and torque balance signals are designed to ensure that each motor can still maintain high synchronisation performance after the fault occurs. Finally, the effectiveness of the proposed FTC method is proved and verified through simulations, and the system can accurately track the desired angular position on the premise of ensuring synchronisation performance even in the presence of the fault.