ℋ∞-Controller Design Methods Applied to One Joint of a Flexible Industrial Manipulator

Abstract

Control of a flexible joint of an industrial manipulator using ℋ∞ design methods is presented. The considered design methods are i) mixed-ℋ∞ design, and ii) ℋ∞ loop shaping design. Two different controller configurations are examined: one uses only the actuator position, while the other uses the actuator position and the acceleration of the end-effector. The four resulting controllers are compared to a standard pid controller where only the actuator position is measured. The choices of the weighting functions are discussed in details. For the loop shaping design method, the acceleration measurement is required to improve the performance compared to the pid controller. For the mixed-**ℋ∞ method it is enough to have only the actuator position to get an improved performance. Model order reduction of the controllers is briefly discussed, which is important for implementation of the controllers in the robot control system.