A realization of multilateral force feedback control for cooperative motion

This paper proposes a novel control design for multilateral system considering different degrees of freedom (DOF) and structure. The conventional coordinate transformation with respect to the Cartesian coordinate system is not always suitable for bilateral and/or multilateral control for dexterous tasks, including grasping motion. This paper introduces spatial mode transformation, which is corresponding to human's tasks. The spatial modes are abstracted by using mode quarry matrices. The order of the mode quarry matrices means the task DOF, and the decoupled modes correspond to "translational task," "rotating task," "grasping task," and so on. Thus, the problems for motion integration of different DOF and structure are solved to design a multilateral controller in the spatial mode coordinate systems. Furthermore, the proposed multilateral control is designed based on acceleration control to realize both the force servoing and the position regulator for action-reaction law in remote environment simultaneously. The proposed multilateral control is applied for a multimaster/single-slave system, where the DOF is different from each other. As a result, a complicated task for the slave system is easily realized by two master systems with vivid force feedback based on modal control design of the multilateral system. The experimental results show viability of the proposed method.