Estimation and share of environmental impedance using multiple robots for haptic broadcasting

Bilateral control system has been developed as a method to transmit tactile sense in order to be applied to handling radioactive material, operating unmanned underwater vehicles, space robotics, telesurgery, etc. Bilateral control system is able to transmit tactile sense to only one operator. To transmit tactile sense to multiple operators, multilateral control was expanded from bilateral control. However, tactile sense of environment which general multilateral control system transmits to an operator is significantly affected by other operators´ motion. This paper proposes a novel control system which transmits environmental impedance to multiple operators. The proposed system uses master-slave system consisting of multiple master robots and a single slave robot. Both position and force information is transmitted bi-directionally between each master robot and a slave in the proposed system, whereas the information is transmitted among all robots in general multilateral control system. In addition, a method to estimate environmental impedance given by spring-damper model is proposed, since the proposed control system requires real-time estimation of environmental impedance. The validity of the proposed system is confirmed by simulation and experiment.