Robust nonlinear observer for flexible joint robot manipulators with only motor position measurement

Abstract

This paper proposes a design method of sliding mode observer for flexible joint robot manipulators. The proposed observer structure is the conventional Luenberger observer with additional switching element that is a role to attenuate system uncertainties and modeling errors. During sliding, the design method is that the nonlinear function due to system uncertainty in sliding mode observer is divides into the parameter distinction and estimation error elements by using the Lipschitz condition. From the design method, this paper proves relation of the asymptotical stability and robustness of overall system according to the positive nonlinear gain of switching element. The proposed observer accurately estimates the velocity and position of link side in the flexible joint robot using only motor position measurement. In the simulation result, the performance and robustness of proposed sliding mode observer is verified and compared with the high gain observer.