Initial Value Compensation for Optimal Digital Servosystem and Its Application

Abstract

Optimal digital servo system with initial value compensation and its application to design of variable speed path control of robot manipulator are proposed in this paper. Optimal servo system is applicable to the servo system with the arbitrary internal model. It is synthesized by extending type-1 optimal servo system synthesis method by means of augmented system.Strictly speaking, optimal servo system by means of augmented system is not guaranteed to be optimal till initial values of input variables are determined. Initial value compensation for input variables is necessary to synthesize an exact optimal servo system. The initial value compensation method for optimal digital servo system is proposed.The optimal digital repetitive control system includes a internal model of a generator of periodic signals in the closed-loop. It is a type of optimal digital servo system. In this paper, the optimal digital repetitive control system is applied to design of variable speed path control of robot manipulator. Trajectory planning method taking control ability of designed robot manipulator control system into account is combined with the repetitive control. Nonlinear compensation error and interference from the other arms are regarded as being equivalent disturbance signal and compensation action is applied by utilizing estimated value of the equivalent disturbance in discrete-time model. In simulation result, the effectiveness of proposed servo system with initial value compensation is confirmed.