Sliding Mode Observer Design for Flexible Joint Manipulators

For an industrial robot with flexible joint characteristics, accurate measurement of the position and speed of the link-side information is extremely difficult and costly. The purpose of this study was to design a robust sliding mode observer which can exact estimate the link´s state information in the case of only motor position measurement. In the design process of the sliding mode observer, nonlinear uncertainty of the system was separated into two parts: the parameter uncertainty and estimation error, which Based on the flexible joint robot dynamics property. The stability of observer was proved by Lyapunov function, and the appropriate observer gain was obtained by solving the algebraic Riccati equation. The simulation results shown that, the observer accurate estimated the speed and position of the link-side of the flexible joint robot under the condition of only measure position information of the motor position.