A new design of drag-free and attitude control based on non-contact satellite

A 2-DOF drag-free control ground simulation system based on Stewart platform

Space-based gravitational wave detection missions use multiple satellites to form a very large scale Michelson laser interferometer in space. This requires extremely high precision displacement measurements at the picometer level between test masses even millions of kilometers apart. Drag-free control is a key technology to ensure the ultra-static and ultra-stable space experiment platform for space-based gravitational wave detection. This paper proposes an innovative ground simulation scheme for drag-free control principle based on the Stewart platform. The kinematics and dynamics modeling of the Stewart platform used in the experiment is presented. A drag-free ground simulation experimental equipment is designed and built. A two-degree-of-freedom (2-DOF) drag-free controller is designed based on the H∞ loop shaping algorithm which outperforms a PID controller in Simulink simulation. A semi-physical simulation experiment is conducted to verify the controller designed using rapid control prototyping technology. The experimental results show that the control performance reaches the limit accuracy of the hardware device, thus verifying the effectiveness of the drag-free control algorithm.

Event-Triggered Attitude-Tracking Control for a Cableless Non-Contact Close-Proximity Formation Satellite

The cablelessness of non-contact close-proximity formation satellites can fundamentally avoid the influence of non-contact interface coupling effects and can further enhance the attitude pointing accuracy and stability of the payload module (PM). However, it also brings the problem of limited on-board resources and system latency. In this paper, an event-triggered attitude tracking controller of the support module (SM) that avoids the Zeno phenomenon was proposed. The update time of the control signal was determined by the event-triggering mechanism based on intermediate variables, thus, reducing the communication burden and actuator asynchrony between the two modules. The feasibility and effectiveness of the proposed approach was demonstrated by numerical simulations.