Hybrid Impedance Control of Massage Considering Dynamic Interaction of Human and Robot Collaboration Systems

This paper proposes an intelligent massage control system that uses a multi-fingered robot hand with hybrid impedance control, which is able to recreate the movement and force of a human massage therapist. Therefore, various massage points, such as changes in the stiffness of human skin muscle, can be controlled by using an impedance control method. A hybrid impedance control, comprised of position-based and force-based control methods, was developed. The position-based impedance control is used to control the lateral position of massage on the human skin muscle. On the other hand, the force-based impedance control is used to control the force of the vertical direction on human skin muscle. This paper also identifies human skin muscle through robot perception of impedance to decide on the parameters of the impedance controller. A strategy using impedance control to implement an adaptive control system is presented, under the conditions of both soft and hard skin and muscle. The effectiveness of this massage control system using a multi-fingered robot hand with hybrid impedance control is demonstrated through realistic massage experiments involving pushing and rubbing motions.