Control key technologies for high-performance permanent magnet direct drive servo system in spatial flexible cable

To meet the high-performance control requirements of the aerospace servo system, this paper proposes a current loop delay compensation strategy based on no-difference control to address the current loop delay issue in the permanent magnet direct drive servo system for space flexible tether. The design of the delay compensation loop suppresses the delay in the current loop, while the error corrector is designed to improve the current sampling accuracy, ensuring the accuracy of current prediction. To tackle the challenge of external complex disturbances, a disturbance suppression strategy combining disturbance observation with rotor position tracking is proposed, a novel outer loop controller based on internal model control theory is designed, and a differential structure is introduced into the observer to achieve lag-free disturbance observation. To address the issue of tension impact in flexible tether systems, a shock-resistant tension control strategy based on parameter adaptive regulator is proposed, achieving rapid and accurate tension adjustment through dynamic adjustment of tension regulator parameters. Finally, an experimental platform of the permanent magnet direct drive servo system for space flexible tether is successfully developed, and relevant experiments are conducted. Experimental results show that the proposed control strategy effectively eliminates the delay in the current loop, improves the dynamic and steady-state performance of the current loop; meanwhile, it can accurately estimate and compensate for external disturbances in real time, enhancing the disturbance rejection capability of the entire servo system.Results also show that this control strategy achieves the precise control of tether tension, preventing tension impact phenomena, thereby achieving high-performance control of the space flexible tether system using permanent magnet direct drive servo system.