Design and verification of the state recovery controller for a drag-free satellite with two test masses

This paper proposes a model predictive controller aimed at facilitating the recovery of drag-free satellite states after being impacted by micrometeorites, and designs a ground simulator for verification of the controller on the ground. The drag-free satellite will be in an undesirable working state after being seriously disturbed, and the state recovery is the process of resetting states to the desired states through the control system. The dynamic of the state recovery controller are simplified for the different control bandwidths of microthrusters and suspension controllers. In addition, consideration is given to relative distance constraints to prevent collisions between the test masses and the spacecraft platform. Drag-free satellites usually perform high-precision measurement missions, and existing ground equipment lacks a suitable microgravity environment. Therefore, in order to verify the proposed state recovery controller on the ground, this paper designs a novel ground simulator. We conduct dynamic modeling and numerical simulation analysis on the ground simulator to verify the feasibility of its design. The proposed ground simulator employs a physically constructed five-degree-of-freedom motion platform to simulate the spacecraft platform, while the test masses are simulated using a virtual simulator. To achieve dynamic equivalence between the space and ground environments, the design parameters of the system are determined using the Buckingham's π theorem, which is also extended to the controller design. Monte Carlo simulation results validate the controller's robustness. The overall performance of the ground simulation platform is demonstrated by numerical simulations, emphasizing the dynamic equivalence between the space and ground environments. The results demonstrate the effectiveness of the proposed approach. In the subsequent work, we will construct the ground simulation platform according to the design scheme proposed in this paper.