Fault-Tolerant Decoupling Control for Spacecraft with SGCMGs Based on an Active-Disturbance Rejection-Control Technique

This paper describes a fault-tolerant decoupling-control algorithm for spacecraft incorporating single-gimbal control moment gyroscopes (SGCMGs), simultaneously considering the SGCMG rotor and gimbal faults. Double-loop control theory is utilized to design the attitude system. An outer-loop controller is designed to obtain a control torque with proportional-derivative-type (PD-type) technology, and a singular direction-avoidance (SDA) steering law is adopted to calculate a virtual gimbal-rate vector, which will be the reference signal for the inner-loop controller. The actuator fault is not considered in the outer-loop system. In the inner-loop system, an active-disturbance rejection controller (ADRC) is designed. The ADRC incorporates an extended-state observer (ESO) to estimate the total disturbance for each SGCMG gimbal or rotor in order to track the virtual gimbal rate or nominal angular momentum by considering the gimbal- and rotor-rate faults. In this way, a decoupling controller with fault-tolerance capability is achieved. The simulation results demonstrate that the proposed method is strongly robust against actuator faults.