A Study of Stability and Workspace Decoupling Control Based on Robust Control in Multi-Degrees-of-Freedom Robot

Abstract

The paper describes a workspace force controller based on disturbance observer. In the multi-degrees-of-freedom robot, either joint space or workspace is selected to construct the disturbance observer. In case the disturbance observer is constructed in the joint space, the total stability of motion controller is independent of the configuration of robot. In the workspace observer-based motion controller, however, the total stability depends on the configuration of robot.
In the paper, the differences between the joint space observer and the workspace observer are shown from a viewpoint of the stability. Furthermore, the decoupling control strategy is discussed in the workspace. First, the observer-based system is analyzed in one-degree-of-freedom system. Secondly, we explain a basic structure of workspace motion controller based on the joint space observer and the workspace observer. Then the stability of each motion controller is considered. Several numerical results are also shown to confirm the theoretical analysis of the observer-based motion controller.