Design of Robust Fault-Tolerant Control for Target Tracking System With Input Delay and Sensor Fault

This paper presents a robust fault-tolerant control scheme that provides reliable tracking and effective disturbance rejection for a low-cost tracking system. As the controlled apparatus, a 2-axis gimbaled mechanism is involved in a networked control system, and an unreliable sensor brings sensor drift into the system. Besides, external disturbances heavily affect the system in practical applications. Representation of the faulty gimbal system with its constraints and disturbances is firstly introduced. Then, the design of the fault-tolerant controller is detailed, which consists of two components: (1) an unknown input observer that estimates the fault and effect of disturbances and network delay simultaneously, and (2) a robust control law, using the observer estimations, designed based on the combination of the super-twisting algorithm, backstepping procedure, and integral sliding mode control technique. Subsequently, simulations and experiments are conducted, in which the performance of the proposed control system is compared to those from the previous studies. The results show the superiority and reliability of the proposed control system.