Optimization Of A High-speed Parallel Robot With Flexible Links

This dissertation presents a theoretical package for dynamic modeling, modal test, model refining, optimization technique and dynamics index of a translational 2-DOF parallel robot with flexible links named the Diamond 600 robot. The outcome has been employed in the elasto-dynamics optimization of the robot aimed at improvement of the dynamic accuracy of the end-effector for high-speed pick-and-place operation. The following contributions have been made.By taking the Diamond robot as an example, the dynamic model is formulated based on the Kineto-elasto-dynamics (KED) theory. The unsymmetrical variation of modes is explored by modal analysis which corrected the conclusion of the natural frequency distribution symmetrically in workspace. Moreover, the relation between the acceleration maximum and the natural frequency variation is excogitated.A new dynamic test technique is presented in order to obtain the time-varying modal parameter of a mechanism. These key modes related to the dynamic accuracy could be picked up by comparison between the modal test of the moving-platform and the modal test of the robot. The applicability and efficiency of this technique is validated by the dynamic test of the Diamond robot.A new mathematical model is developed to modify element parameters by means of the static FEM technique. This mathematical model is general to modify parameters efficiently according to multiple requisitions. Moreover, the dynamic model is modified in conformity to the test model by dynamic modification technique. The modified model takes on the same characteristic as the actual robot approximately and has enough accuracy to optimization.An integration of genetic algorithm (GA) and classic arithmetic is investigated to search the overall solution of the optimization which gets the better dynamic accuracy of the Diamond 600 robot's by means of parameters modification. The GA avoided the local optimization, but it gets approximate one which is used as the initial basic feasible solution to seek out the global solution by classic arithmetic in succession.An advanced dynamics index is proposed in virtue of modal shape classification, which is used to evaluate the dynamics of a mechanism with time-varying modal parameter. By means of the comparison between two indices of the original robot and the improved one, it is identifiable that the optimization improved the dynamic performance of the robot.