Posture Control of Two Link Torque Unit Manipulator Considering Influence of Viscous Friction on Joints

Abstract

In this research, we consider a posture control problem of a planar two-link torque unit manipulator under a viscous friction condition. The torque unit is a module that consists of an electric motor and a reaction wheel. The friction caused by the presence of a viscous environment cannot be ignored in the real system. In this report, we first clarify the relation between the angle of links and the angular momentum of the reaction wheels under the viscous friction condition. Next, we try to control the first link at an arbitrary reference position without taking into consideration the angle of the second link. The angle of the first link can be controlled by changing the viscous friction condition between the first link and the base. Moreover, we attempt to control the second link at an arbitrary reference position by using the residual angular momentum of the reaction wheel at the second link. Finally, we demonstrate the feasibility of the proposed method by conducting a verification experiment.