OPTIMUM GEOMETRIC DESIGN FOR ROBOT ARM WITH GEOMETRIC RESTRICTIONS BY MEANS OF A HYBRID ALGORITHM

In the present paper an optimisation algorithm is described to find out the geometric design parameters of an open loop spatial robot with 3 revolute joints in the presence of geometric restrictions of the links. The design variables include the base position, the geometry of the links and the joint angles of the robot and are calculated so that the manipulator will be able to place its end-effector at prescribed positions, avoiding simultaneously singular configurations and geometrical restrictions among the links. The developed algorithm uses the Denavit-Hartenberg parameters and 4x4 homogeneous matrices to obtain the kinematic equations of the robot. The optimisation problem is solved with a hybrid method that combines a genetic algorithm, a quasi-Newton algorithm and a constraints handling method. To examine the efficiency of the method, numerical examples for 1, 3 and 5 prescribed positions of the end-effector are applied.