Improvement of tactile sensation of a bilateral forceps robot by a switching virtual model

Interest in tele-operation started many decades ago. Today, tele-operation is becoming a reality with improved tele-communication systems. Bilateral control is also a subset of tele-operation. Usually in bilateral control, force position information is exchanged between a master and a slave. This structure successfully transmits tactile sensation from the slave environment to the master operator. A bilateral control system is capable of transmitting tactile sensation to the master side. This capability is also known as the transparency of the system. If bilateral control is used in a surgery, ideally the medical doctor should sense the feeling coming from the body tissue together with the reaction force of the special surgical tool. We have previously proposed a method to eliminate the special surgical tool with a simple tool tip and a virtual tool model. However, a physical tool as well as the proposed virtual tool add impedance to the system. Even if a virtual model is used, impedances are essential to carry out the tool action. In this paper, a novel method is proposed to switch off and on the virtual tool model when the tool action can be replaced by the environmental reaction forces. An experiment was carried out using a bilaterally controlled forceps robot. Results show the applicability of the idea.