Cheng Yuehua

Fault tolerant control with on-line control allocation for flexible satellite attitude control system

In this paper, a new method to handle faults for flexible satellite attitude control system during orbit maneuver is investigated. Fault tolerant control based on on-line control allocation is proposed to keep the stability and reliability of the system. First, a robust adaptive controller which considers constrained input and external disturbance is discussed. If faults occur, an on-line control allocation scheme for satellite attitude control system with actuator redundancy is adopted. In this way, fault tolerant control can be realized without reconfiguring the baseline controller. Numerical simulation is given to demonstrate the effectiveness of the methods suggested in this paper.

Sliding mode observer based variable-structure control in attitude control system of small satellite

In view of the small satellite attitude system where no gyro is available or gyro fails, the quaternion estimating angle rate of satellite is proposed by means of sliding mode observer. Based on the attitude rate estimator, the decoupling variable structure controller is designed for attitude control system. The simulation results show that the accuracy of estimating is rather high, and the variable structure control method has advantages of being easily designed and realized.

Data-based incipient fault detection and prediction for satellite's attitude control system

Incipient fault detection (FD) and prediction are crucial for the safe operation of in-orbit satellites attitude control system (ACS). In this paper, a locally linear embedding (LLE) model combined with exponentially weighted moving average (EWMA) technique is proposed in FD for ACS, which is more suitable when the magnitude of the fault is small. After that, fault trend prediction with multi variables is conducted. Firstly, a preprocessing for high-dimensional telemetry data from the satellite ACS is conducted. Considering that there exists non-linear correlation relationship among telemetry parameters in ACS, LLE is used for online FD, while EWMA is used to accumulate the fault value. Based on the results of fault detection, vector autoregressive integrated moving average model (VARMA) is used for tracking the trend of fault. The case study on a simulated satellite ACS demonstrates the effectiveness of the proposed method.