Massaging human feet by a redundant manipulator equipped with a tactile sensor

Reflexology is a kind of assisting physical care through massaging or applying pressure to parts of the feet where will reflect an image of the human body in order to improve general health of the human. Based on this principle, we propose a new application of 7-DOF(degree of freedom) redundant manipulator to do the massaging work for human feet with the tactile sensor equipped to the end-effector. To facilitate the flexible and dexterous manipulation of redundant manipulator, the hybrid impedance control is adopted and extended to include the null space motion, not only to generate a desired motion of the end-effector, but also manage the contact force between the end-effector and the human feet. In order to improve the safety and comfortability, the reactive forces of the tactile sensor cells are monitored and recorded. A real massaging experiment is carried out on the human feet and the results demonstrate the effectiveness of the proposed control system.