Robust Vibration Control of Flexible Robot Arm Taking Account of an Uncertainty in Bending and Torsional Coupling

This paper presents a design procedure of H∞ controller for bending-torsional coupled vibration of fiexible robot arm. In the case that the robot arm does not hold the inertial center of the payload, it processes uncertain bending-torsional coupled vibrations which affect in the accuracy and the stability of the controller. In this research, H>∞ robust control design scheme taking account of parameter variations as structured uncertainties and model error of uncontrolled modes as unstructured uncertainties is utilized to describe the uncertainty in coupled vibration to guarantee robustness against such uncertainty. An experimental robot arm system is built and its parameters are identified by using Seto's method. A controller is obtained by applying the present design method. Control experiments are performed and the robustness of the synthesized controller to the parameter variations and model error are confirmed. The robustness of the obtained controller against uncertainty in coupled vibration is compared with ordinary H∞ controller. The superiority of the presented controller design method is certificated.