Research On Optimization And Control Of The Six-Degree-of-Freedom Vibrati On-Isolation Platform

Control moment gyroscopes are utilized to adjust the attitude of the satellite, and micro-vibration caused by the CMGs such as uneven quality distribution leads to the slowdowns in pointing accuracy and resolution of the satellite, as well as the life and performance of the equipment on the satellite. High-resolution remote sensing image plays an increasingly prominent role in human social life, satellite vibration suppression aiming at CMGs is of great significance.This subject proposed a scheme of vibration isolation based on Stewart mechanism. Performance optimization and control system are deeply studied through theoretical modeling and simulation analysis. The main content of this thesis is as follows:1. Studied the passive & active vibration isolation, and built the dynamic model of single leg. Discussed how the mass ratio, damp ratio and natural frequency ratio influenced on the isolation characteristics respectively, and then optimized the stiffness and damp factor of the passive isolation by GA. Finally, analyzed the condition number and stiffness of Stewart, and optimized these two conflicting target by NSGA-?.2. Established the dynamic model of active & passive isolation platform using Newton-Euler method. The equation concerning the output, displacement and voltage of actuator was built through the analysis of piezoelectric material. The relation of constraint force caused by spherical hinge and output of actuator was found according to the kinematics and dynamics of single leg. Finally, the forward dynamic model was established, and then did the numerical simulation based on the dynamic model.3. Simulated the vibration isolation of single leg with the mathematical dynamic model, and then built the controller system of platform. It showed that robust control had strong anti-interference and better stability. During the robust control, discussed how the weight matrix of Q and R influenced on the performance, and designed the reduced dimension observer according to practical situation. Also, H-Infinity controller was designed based on performance requirements. Finally, ADAMS-MATLAB Co-simulation was utilized to design the PID controller based on platform. The simulation result of Z axis verified the effectiveness of vibration-isolation platform.