Design Optimization of a 3-D Three Cable Driven Manipulator

This paper presents simulation and optimization of a 3-D three cable driven manipulator. For some specific paths in the workspace volume, motions of the robot before optimization are simulated and tension in the cables and stiffness of the cable robot for various points on the paths are determined. By selecting a function which is related to the stiffness matrix of the robot and considering it as the objective function of genetic algorithm, vertical positions of the connection points on the base platform as the optimization variables for each point on the paths can be determined in a way that the related function of the robot is optimized and a tension reduction in all the cables can be observed for most of the paths. Finally, the results of using different kinds of objective functions derived from the stiffness matrix are presented for three different criteria: workspace volume, kinematic performance indices and actuating energy of the robot. The results indicate which function has the largest workspace volume with tension reduction property in all the three cables, which has the highest values for the kinematic performance indices and which has the lowest actuating energy.