Improved Sliding Mode Control for the Proof Mass Capture of Gravitational Wave Detection Spacecraft

Abstract

To ensure that the gravitational wave detection spacecraft can successfully enter science mode, it is particularly important to control the proof mass to gradually be captured in the center of the cavity in a very short time. This paper presents an improved controller that combines an adaptive finite-time observer for proof mass capture with a nonsingular terminal sliding mode control based on a sigmoid function. Firstly, based on the segmental interval design of the derivation term, an adaptive finite-time observer is designed to increase the observation accuracy of the state quantity in the gradual convergence process, and effectively reduce the chattering of the observer. Secondly, a sigmoid function is used to construct a smoother sliding surface switch, which weakens the chattering of the control system and effectively improves the dynamic performance of the proof mass capture control. Finally, the effectiveness and the feasibility of the proposed approach are verified by a mathematical simulation. The simulation results show that compared with the traditional sliding mode controller, the proposed approach can greatly improve the control precision and capture time for proof mass.