Development Of The 2-dof Spacial Parallel Platform With Actuation Redundancy

This thesis recounts the course of development and research status on the heavy swaying platform at home and abroad. A novel 2-DOF parallel platform with actuation redundancy is put forward. On base of that, this thesis investigates into some issues on conceptual design, inverse kinematics analysis, dimensional synthesis, forward position, trajectory planning, dynamic analysis and some other key issues. The following works have been accomplished.A novel 2-DOF parallel platform with actuation redundancy is put forward. It has the virtues, which include higher stiffness, stronger carrying capacity, better operability and dynamic characteristics. It is very suitable for heavy and large workspace requirements.With the vector method, the inverse models of position and velocity of a 2-DOF parallel platform with actuation redundancy are established. After the Jacobin matrix is found and the singular values of the Jacobin matrix are analyzed completely, the conclusion is drawn that the minimal singular values of the Jacobin matrix is well suitable as the evaluation index of kinematic characteristics. When the influence law of optimal scale parameters to the global operational performances is disclosed accurately, the optimal solution in global which are the optimal scale parameters can be determined. Introducing the constrain involving the ratio of the effective stroke versus the minimum length of the UPU branched-chains which would work firstly, the determination of the other optimal scale parameters can be resolved into a series of solving nonlinear programming problem with constrained condition. Finally, all of the scale paremeters can be determined.This thesis has applied Newton-Raphson iterative approach to solve the position forward issues of 2-DOF parallel platform with actuation redundancy and through simulation of the examples Newton-Raphson iterative approach is proved to be an efficient numeric algorithm. Therefore, the method could meet the requirements of real-time monitoring. Adopting the sine method and according to the requirements of working conditions, the variable curves of the rotational trajectory, angle velocity and angle acceleration of 2-DOF parallel platform with actuation redundancy can be gained. By simulation with Matlab, the rationality and validity of the method adopted to plan the trajectory is tested.With application of principle of virtual work, the inverse dynamic model of 2-DOF parallel platform with actuation redundancy is set up. The optimal driving forces can be carried out, with the method of driving optimization. In the dynamic analysis, there are three schemes which can achieve 2 rotational DOF. And compared the driving forces among the three schemes when given the same trajectory, it is seen that the third scheme is the best. Meanwhile, two complementary dynamic performance indices which involves the effects of acceleration term, velocity term and gravity term in the inverse dynamic formulation is put forward, and the method is suitable for heavy and redundant parallel platform. Through analyzing the examples, rationality and consistency of the conclusion compared with the simulation is proved.