Design for Saving Energy of a Vertically Articulated Manipulator Using Spring and Mass Balancers

This paper discusses a design method for optimal counterbalances and motors of a vertically articulated manipulator with 3 links in order to save the dissipated energy. A spring-balancer and a mass-balancer are mounted on the second and the third link respectively to make compensation for gravity force. The optimal design of the manipulator is performed by minimizing of the maximum eigenvalue consisted of the inertia of motors and a mass-balancer, the torque constants and the armature resistances of the motors. The constraint condition, which the motor should depend on, is derived from the equation that the starting current equals the maximum peak current. The manipulator system with the optimal spring-balancer and mass-balancer is designed and compared to one with two mass-balancers and one without balancers. The total weight and the dissipated energy of the optimally designed manipulator can be decreased remarkably.