Study On Some Key Technologies Of Sem Objective Table Positioning System

Spatial imperfect-DOF parallel robots have received much scholars' attention of all the world and have a broad perspective in various fields for the advantages of their simple mechanism, high rigidity mass ratio, easy control and high precision. In this dissertation, we design the SEM objective table positioning system based on the special parallel mechanisms less than 6-DOF by analyzing its disadvantage of the complicated structure and inconvenient operation. This system has two sides: one is manual positioning mechanism made up of 4-PUU and following leg RUPUR, and the other one is automatic positioning mechanism made up of 4-UPU and a motor. Theory analysis about the two mechanisms including kinematics and dynamics are studied. Also, we introduce the application of these two parallel mechanisms in the micro operation system. Firstly, based on the analysis of mechanism model characteristics and the DOF of the parallel mechanisms less than 6-DOF, the kinematics of 4-PUU and 4-UPU is analyzed. During the course, we gave the forward and reverse formula about position, velocity and acceleration, and the numerical values are tested too. At the same time, the workspace and the singularity position of these two mechanisms are studyed . Through the program, we get the chart of the workspace of the mechanism with the fixed pose. Secondly, we found the dynamic model of 4-UPU and analyze the mechanism dynamics. By programming, we also get the relationship of the branch driving force with the change of position, velocity and acceleration of the platform, and analyze the dynamic performance. Finally, In this dissertation, we set up a micro visual servo micro operation system, and the performance of the system's component and the mechanism's other application as a manipulator in the system are mentioned detailed too. The kinematics of the mechanism is simulated using software. The work of this thesis established the theoretical basis for the further research and application of these two parallel mechanisms. Otherwise, the application of the parallel mechanism in micro operation system mentioned in the article proved the future application will be more and more widely.