An adaptive fault tolerant control method for electromagnetic formation spacecraft with external disturbances.

• A modified far-field model (FFM) to simplify the calculation of the electromagnetic force is proposed and common interference forces of the dynamic model of Electromagnetic Formation Spacecraft (EMFS) are analyzed. • A novel proportional passive controller is designed as a nominal controller. For comparison, a saturation proportional-derivative (PD) controller is proposed. The proportional passive controller includes a damping term, which has the potential to avoid energy accumulation. The proposed proportional passive control method demonstrates good robustness and enables faster system stabilization. • Based on the observer determination of AFED, a fixed-time FTC method was developed. Although it can effectively handle unexpected failures of actuators, the design process is relatively complex [26]. The nature of actuator failures and efficiency factor information are determined before controller design, so unexpected actuator faults cannot be effectively handled [27]. Different from the FTC mentioned earlier, this paper proposes an ismc-based FTC scheme that can effectively suppress AFED without requiring a fault observer and the reconstruction of the nominal controller. This scheme combines an adaptive estimation method to estimate AFED in real-time, without requiring any information about the disturbance or actuator faults. Fault-tolerant control (FTC) is an essential consideration for the reason that the proper functioning of electromagnetic formation spacecraft (EMFS) actuators are challenged by the harsh space environment. An Integral-Type Sliding Mode Control (ISMC) scheme is proposed for actuator faults and external disturbances (AFED) caused by coil failure and external complex environment of EMFS system. Before the system state reaches the sliding mode surface, we use super-twisting algorithm to accelerate the reaching of the sliding mode surface and reduce the chattering. After reaching the sliding surface, a novel nominal proportional passive controller is proposed that integrates a damping term, thereby enhance system robustness and expediting system stabilization. Moreover, the FTC method proposed incorporates adaptive techniques to handle unknown AFED in real-time while ensuring system stability. This paper proposes a new adaptive FTC method that enhances the actuator's capability without requiring controller reconfiguration. Simulation results illustrate the effectiveness of this method for suppressing AFED in harsh space environment. [ABSTRACT FROM AUTHOR]