Research On Configuration Optimization And Control Scheme Of 6-DOF Microgravity Simulation Platform

With the continuous development of space technology, the requirements of various types of space equipment are becoming more and more complex and sophisticated. The dynamic characteristics of space equipment in the space of and the earth's surface are completely different. Therefore, the more realistic the simulation of the microgravity, the more reliable the space equipment design can be guaranteed.In this paper, a variety of different microgravity simulation methods were analyzed and compared. Based on this, a semi-physical simulation based on the Stewart platform with six degree of freedom was proposed, which could simulates the microgravity on six dimensions.In order to provide a theoretical basis for the mechanism design, size optimization and control strategy, the inverse kinematics of the platform was calculated and the inverse dynamics of the platform was modeled by the Kane method. The corresponding dynamic calculation program was compiled and the relevant simulation results were verified.According to the minimum working range, high precision and high load requirements of the micro gravity experimental platform, the three objective functions, such as spherical working space radius, global dexterity and global load index, were presented. Aiming at the three performance indexes, the configuration parameters of the platform were optimized by using the NSGA-2 algorithm.The principle of microgravity simulation is that, According to the force exerted on the object, the movement of the object is calculated and the platform is driven to replicate this movement. In order to realize the high load and high precision micro gravity simulation, the supporting legs of the cylinder and the motor ball screw were proposed in parallel.The control strategy of single leg system was analyzed. The nonlinear mathematical model of the pneumatic constant pressure system was established in MATLAB/Simulink. The PID and fuzzy PID control simulation were carried out respectively, and the effectiveness of fuzzy PID control is verified by comparing and analyzing. Finally, a preliminary simulation of the motor ball screw was carried out, and the feasibility of the simulation of the supporting leg system of the cylinder and the ball screw in parallel with the micro gravity simulation was verified.