Bilateral control without force sensor for surgical assist robot

Recently, robot systems which support surgery are actively developed. Although force sensation is indispensable for surgeon to operate minimally invasive surgery safely, conventional robot systems cannot transmit force sensation. In this paper, it aims at developing the technology for transmitting force sensation in medical treatment without a force sensor in consideration of safety. Our proposed method is based on "symmetric position servo type bilateral control", which control rule needs not any force sensors. However, it has a problem that large force is required for the operation due to the influence of robot dynamics. To solve this problem, control input based on the information of acceleration and velocity of master and slave is added, and control rule is switched according to the state of the estimated environment. In the experiment using a robot of multiple degrees of freedom, it is confirmed that the influence of robot dynamics can be reduced. In addition, an excellent bilateral control with small operation force is achieved by the proposed method without using a force sensor.