Indirect Fault Estimation and Active Fault-Tolerant Control for Spacecraft

As spacecraft on-orbit environments become increasingly complex, actuator efficiency degradation and faults occur more frequently, severely compromising operational safety. For reaction wheel-configured spacecraft subject to additive and multiplicative actuator faults, a fault detection mechanism and active fault-tolerant control system are designed. First, an actuator fault detection scheme based on an angular velocity observer is proposed, along with sufficient conditions for fault detection. Second, by introducing an auxiliary variable, an indirect fault estimator with angular velocity integral compensation is designed, ensuring the estimation error converges exponentially to an origin-containing invariant set. Upon fault detection, the indirect estimator compensates the fault, and linear quadratic regulator-based fault-tolerant control is applied to compensate for torque deviations induced by faults without identifying individual actuator failures. Numerical simulations validate that the proposed fault-tolerant control approach effectively detects and reconstructs actuator faults, achieving robust fault-tolerant performance.