Analysis Of The Similar-Scara Parallel Manipulator With Mobile Platform Rotating Continuously

In this article, a three-DOF parallel manipulator with mobile platform rotating continuously is proposed, which is based on the trends of wafer handling robots. After the institutional constructed, it deals with its degrees of freedom, kinematic analysis, dimensional synthesis, dynamic analysis and some other key technologies. It provides a theoretical basis for the design and platform construction of wafer handling robots prototype, the main contents are as follows.Firstly, through the analysis of the demands for wafer handling robot in IC industry and combining with the advantages and disadvantages of series-parallel robot, it studies a new wafer handling robot which structure is parallel (it named for the similar-SCARA parallel manipulator with mobile platform rotating continuously). Compared with the traditional parallel manipulators, the peculiarities are that the three limbs are embedding together and the mobile platform can achieve 360 degree rotation continuously. Besides, it can translate along a leader-rail in radial direction. Based on screw theory, it writes the screw system of each limb and then obtains the corresponding anti-screw. Finally, it calculates the degrees of freedom by using G-K formula which has been modified and completes the configuration of institutions.Secondly, we established the position, velocity, acceleration model of the parallel loop body in the cylindrical coordinate, then analyses its singularity position and simulates the position, velocity and acceleration of the manipulator'end, the result of simulation showed the variation of it. Considering both the mean value and fluctuation of the condition number of Jacobian matrix, a global conditioning index is proposed. Meanwhile, a set of constraints has been built and given the initial value. We get rod length witch satisfies the constraints by MATLAB and verify the correctness of the optimization.Thirdly, based on the analysis of the kinetic and potential energy of each component, the dynamic model of mechanism is established and some necessary simulations are carried out by using the Lagrange equation , finally we can get the variation of the torque which is driven by servo motors.