Study About The Multi-degree Of Freedom Parallel Tracking Platform

As increasing telescope caliber and special application requirements, tracking frame appears many problems. We take correlation analysis research of a new tracking structure of telescope——six-degree of freedom parallel platform based on theoretical analysis and simulation of virtual prototyping technology. It can track and observe in a certain range according to requirements of a telescope. And it has good structural rigidity, strong bearing capacity, high position accuracy, fast response, etc.In this paper, first we introduce the traditional large telescope frame structure and related topics background, and clarify the purpose and significance of this thesis. Then from several perspectives we analyse the feasibility of this new parallel platform used for telescope tracking, and introduce in detail the research status of domestic and foreign about six-degree of freedom parallel platform、 key technical problems and the development trend in the future.In order to verify the feasibility of this new telescope tracking frame from the structure principle, we determine its structure model and take the theoretical analysis of kinematics and dynamics model. This lays foundation for further structural stiffness analysis and control.After that, we establish 3-D simplified parameter virtual prototype model based on Adams software, do the related forward and inverse kinematics simulation and dynamic simulation, analyse its kinematic and dynamic characteristics. Then we establish the optimal mathematic model and optimize the design of this new parallel tracking platform based on the optimization tool of Adams software. So its roughly size of scale can be preliminary determined. What’s more, we summarize the determination principle of its main size parameters, and compare it with traditional altazimuth tracking frame to highlight its advantages and disadvantages.Based on the kinematics analysis, we establish its static rigidity model. Then we can obtain the pose deviation under the same external load and different pose caused by the static stiffness through, and analyse the poseture change rule. Further we establish dynamic and static stiffness model of the electric cylinder, analyse the effects of time-varying load to dynamic stiffness of electric cylinder in the process of the moving platform’s fast tracking movement. Accordingly we can study the whole parallel structure’s dynamic stiffness through jacobian matrix. The research results can be an important reference for structure design, servo control and vibration control systems.Finally, based on hinge point control strategy of the kinematic model, we establish co-simulation control model of the whole system making use of Adams and Simulink software(Matlab). Through simulation, we can get the control results of fast and slow targets and centrifugal error of moving platform’s rotation center. According to the simulation results, we propose further requirements and suggestions to control scheme and control algorithm, and from the angle of the control effectively verifie the feasibility of the new track structure.