Robust control and parameter estimation of robots with flexible joints

A decentralized control design is presented for industrial robots with flexibilities at the joints. Based on an independent joint robot model, a two-degree-of-freedom, linear compensator is proposed. The latter is designed based on the Youla parametrization yielding a stable compensator which effectively takes into account the oscillatory modes, and uses only measurable actuator signals (motor shaft position). Conditions for achieving global stability are given. A two-step estimation mechanism is applied for estimating the complete robot arm model´s parameters