Robust control by inverse optimal PID approach for flexible joint robot manipulator

Abstract

This paper proposes a robust inverse-optimal control for flexible joint robot manipulator in order to cope with parameter uncertainties. In the first step, a virtual control input was designed as PID form with 2 gain tuning conditions. In the second and third steps, the other virtual input and actual control torque were made using the saturation-type nonlinear control based on the Lyapunov's second method. The controller does not need information of acceleration and jerk of motor side as well as link side. In addition, the one is able to apply to actual robot controller by reducing calculation time caused by Nonlinear Matrix Inequality (NLMI) solving. The robustness was shown in the simulation result through 2-DOF robot manipulator which has flexible joint.