Bilateral control for omnidirectional bending motion of the DSD forceps teleoperation system with time varying delay

Recently, robotic surgical support systems are in clinical use for minimally invasive surgery. We have developed a multi-DOF robotic forceps manipulator using a novel omnidirectional bending mechanism, and for the developed robotic forceps manipulator, we proposed a passivity based bilateral control that enables motion scaling in both position tracking and force tracking, and guarantees the stability of the teleoperation system in the presence of constant time delay, so far. In this paper, the passivity based bilateral control is improved so as to guarantee the stability of the teleoperation system not only in the presence of the constant time delay but also in the presence of the time varying delay. However, the proposed bilateral control law is applicable only to the one DOF bending motion of the robotic forceps. Therefore, using the change of coordinates, the proposed bilateral control scheme is extended so that it may become applicable to the omnidirectional bending motion of the robotic forceps. In order to verify the effectiveness of the proposed control scheme, experimental works were carried out for the developed robotic forceps.