抄録
This paper presents an identification process of viscoelasticity of a revolute joint of a simple one-link robot. This revolute joint has no viscoelastic property in itself due to a pully or a ball bearing incorporated in the joint axis. However, there exists virtual viscoelastic characteristic in the joint by placing antagonistic mechanism made with a pair of pneumatic artificial muscles. In this paper, first we generate contraction forces by applying compressed air to the pair of artificial muscles in order to maintain initial orientation of the robot and to increase joint stiffness. In that situation, an external force is applied to head of the joint so as to ingenerate 7°-rotational angle. Subsequently, slight vibration of the joint is caused by the release of the external force. By applying non-linear least-squares method to the joint angle data obtained from the vibration, virtual viscoelasticity of the joint can be easily identified. Finally, we reveal the existence of linear and non-linear properties of viscoelasticity according to the amount of the contraction of artificial muscles.
