Designing Active Fault- tolerant Controller for Spacecraft under Actuator Fault

Fault-tolerant control is one of the important issues in automatic control. The reason for this importance is the probability of fault/failure occurrence in control subsystems (sensor-actuator-system). Direct access to spacecraft is not always possible, therefore fault-tolerant control has become even more important in space systems. On the other hand, due to the necessity for weight reduction in these systems, employing hardware redundancy has limitations. Therefore, analytical redundancy has gained much attention in such systems. In this paper, reference inputs are corrected based an open-loop control command adjustment. Using simulation, it is shown that without reference input adjustment, the controller will not be able to satisfy mission requirements when actuator faults occur. Then, the proposed method is used and the desired requirements are satisfied. The advantage of the proposed method is that, there is no need for taking the first and second derivatives of the reference inputs and it is possible to obtain these inputs using integration. This will prevent computational problems associated with differentiation.