Electrohydraulic Transmission System for Minimally Invasive Robotics

It is a well-known fact that minimally invasive surgery (MIS) has many benefits, e.g., unnecessary trauma and blood loss can be minimized by opening tiny surgery scars, recovery process of patients can be lessened, and the possibilities of complications can be decreased. Although robots are widely used in MIS due to their fundamental superiorities such as high precision, current surgery robots mainly suffer from absence/limitation of haptic feedback during operation. This paper proposes a novel electrohydraulic haptic transmission system to improve the haptic feedback of a surgery robot. This new device replaces the highly nonlinear mechanical friction of thrust wire by viscous friction and avoids the backlash due to the incompressibility of fluid. Moreover, since the fluid is constantly occupying the entire volume of the hydraulic tube, the system behavior during bending of the tube can be modeled much easier than the thrust wire, for which position, shape, and bending angles of the inner wire inside the outer tube are hardly predictable. The validity of the proposal and its superiorities over conventional transmission mechanisms, such as thrust wire, are experimentally verified.