Research On Fuzzy Control Strategy Of 6 DOF Motion Platform

With the requirement of space optical remote sensor on the ground resolution, the size of the optical path is increasing. But the size of the structure and the adaptability of the environment are limited. The relative position relationship between the secondary mirror and the primary mirror is needed to meet the relative position between the camera and the main mirror through the six degree of freedom. For nearly half a century, the six DOF motion platform has the characteristics of high rigidity, strong bearing capacity, small cumulative error and high precision, because of its relative to the traditional series motion platform. So the six degree of freedom motion platform has been widely used in aerospace, precision manufacturing, flight simulation and so on. But there are still some problems, such as the establishment of exact dynamic model, the positive solution of kinematics, workspace and singularity. In this paper, the characteristics of the six degree of freedom motion platform structure stability and high precision are used in the space camera secondary mirror adjustment device, the specific work of this paper is as follows:First, the kinematics of the six degree of freedom motion platform is studied in detail. The positive solution and the inverse solution of the platform position are analyzed. The analytical solution of the inverse position solution is calculated based on the dynamic and static coordinate system. The geometric iteration method is applied to the positive position of the platform and the convergence of the solution is analyzed.Compared with the classical Newton Taylor numerical iteration algorithm for positive solution, it effectively improved the calculation speed, simplify code.Secondly, in the control strategy, the simulation model of the stepping motor is combined to study the closed-loop control strategy. The design of the classical control strategy(PID, fuzzy PID control algorithm) is completed. And the effect of closed-loop control of the fuzzy PID control for stepping motor is analyzed. The superiority of the fuzzy PID controller over the traditional PID controller in terms of the parameters are illustrated by simulations.Finally, the research on the variable structure control algorithm of the six degree of freedom motion platform is built. And the sliding mode variable structure control system is used to build the platform model. Fuzzy variable structure controller is proposed by combining fuzzy control and sliding mode control. It can effectively restrain the chattering phenomenon and improve the control accuracy, and realize the high speed and high precision control of the six degree of freedom motion platform.