Robust nonlinear control for flexible joint robot manipulators

The robust nonlinear control method is proposed for the robot manipulators with joint flexibility based on the nonlinear H-infinity control method and the saturation control method. In contrast with the previous research, the control computation time is improved by modifying the input structure to the feed-forward and feed-back control input type. The nonlinear matrix inequality and robust input structures are changed to get the nominal parameter and desire states. So, the control system is no longer need to calculate dynamic equation and the optimization solution of the nonlinear matrix in equality in real time. In the event, the robust input does not dependent to the system parameter bounded range. The control system just need the feedback information of velocity and position of motor and link side by defining the upper bounded function of acceleration information. The robust performance of the proposed control method is verified through a series of computer simulation of a 2-DOF robot manipulator with joint flexibility.