A Motion Control Method of Multi-joint Robots Utilizing Stiffness Adaptation for Energy Saving

Abstract

This paper investigates a new motion control method of multi-joint robots utilizing stiffness adjustment of mechanical elastic elements for the purpose of energy saving. This control method is designed to realize a condition similar to resonance of linear systems by the stiffness adjustment, even though the controlled systems have nonlinear dynamics and multi degree-of-freedom. The control method has two control objectives. One is to realize trajectory tracking control. The other is to reduce actuator torque as much as possible by the stiffness adjustment. This controller does not require exact parameter values of the controlled systems. Some fundamental parts of stability analysis and an energy saving effect are discussed mathematically. Some simulation results demonstrate the effectiveness of the proposed control method.