Decoupling design of robust control systems for SCARA robots using adaptive pole placement

SCARA robots generally have two revolute joints and one prismatic joint. One of the fundamental motions of the robots is horizontal transportation of a load by actuating the two revolute joints. Residual vibration of the prismatic joint generally occurs in the transportation, and it should be suppressed. In this paper, we propose an adaptive controller design for the transportation. The controlled object is modeled as a nonlinear double-input quadruple-output system with unknown load mass. The controlled object is separated into two single-input double-output systems which allows us to design an integral controller providing performance robustness with respect to the estimation error of the mass. Experimental results demonstrate the effectiveness of the proposed method.