Research On The Drag-free Control And Simulation For A Spacecraft With Two Test Masses

The scientific satellite platform based on the drag-free control is an important tool for exploring the geodesy and basic space physics.The satellite platform can realize the ultralow interference space environment on which the measurement depends.Compared with the general standard attitude and orbit control system,the drag-free control system can provide additional test environment: non-conservative acceleration minimization.Especially for the current space gravitational wave detection program at the forefront of experimental physics,each spacecraft contains two test masses,and the form of drag-free control is more complicated.Therefore,the high-precision drag-free control technology of a spacecraft with two test masses is a key technology that needs to be fully overcome and verified in advance.In response to the needs of the space gravitational wave detection program "Tian Qin",this paper analyzes and models the relative motion and control system between the two test masses and a single spacecraft in detail,and focusing on the motion and control relationship between three objects in the plane.The systematic research on the visual simulation system has been carried out to theoretically achieve the scientific goal of drag-free control of the spacecraft with two test masses.It provides an important reference for the verification,simulation and demonstration of the drag-free control system.The main research contents of this paper are as follows:Firstly,taking a single spacecraft and its two test masses as the research object,the basic vector and the coordinate system and its conversion are defined,in addition,a detailed dynamic modeling of the motion of the spacecraft and the two test masses in the twodimensional plane is carried out.At the end,a planar linearized motion model with 9 degrees of freedom of three rigid bodies as input and 7 degrees of freedom detected by sensors as output is obtained.Then,the control design of the planar dynamics of the spacecraft and the two test masses are analyzed.According to the basic principles of gravitational wave exploration spacecraft,a method of applying the diagonal matrix decoupling method to the drag-free control system with cross-coupling is proposed,and the corresponding simulation and verification are carried out.At the same time,the physical meaning of the drag-free control decoupling is given.Finally,the dynamic coupling between the control loops of attitude control,drag-free control and electrostatic suspension control is analyzed and explained.Finally,a visual simulation of the motion and the control between the planar spacecraft and two test masses is carried out.Based on a 3D modeling software such as Solid Works,the model of the spacecraft and two inertial sensors is built,and a method of visual simulation of the motion and control relationship using 3D model and Simulink co-simulation was proposed.Finally,a visual simulation system for the planar drag-free motion control was established,and the combined simulation of numerical value and the graphics was realized.The realization of this technology provides a visual reference for the drag-free control system of gravitational wave detection satellites,and provides visual engineering technology and simulation applications for gravitational wave detection at home and abroad such as “Tian Qin”.