Abstract: The structure of a welding robot is designed to overcome the problem of low strength in traditional tandem welding robots caused by placing the motors on revolute joints. The forward and inverse kinematic problems are solved using the D-H method and the inverse transform method, respectively. The inverse solution of the points on the locus is obtained by polynomial-fitting with Matlab. Thus the input functions are described with a polynomial, providing a simple method to design the control system. The method in a mechanism simulation is verified by Pro/E.

Key words: inverse, kinematics, polynomial-fitting, trajectory-planning, welding robot