Multivariable root loci of control systems of robot manipulators with flexible driving systems. Distortion feedback.

Abstract
Flexibility of driving systems produces robot arm vibration. Since vibration decreases the operation efficiency and quality, the prevention of such vibration becomes an important consideration in robot arm control. High-gain feedback of distortion in driving systems at each joint improves the oscillatory behavior of the robot system. By using a theory of multivariable root-loci, we present two propositions on the behavior of the closed-loop eigenvalues when the high-gain feedback of distortion is implemented.