Abstract
This paper represents newly developed 4-degrees-of-freedom (4-DOF) haptic master associated with controllable magnetorheological (MR) fluid for robot-assisted minimally invasive surgery (RMIS). In RMIS, the proposed master can be used as a haptic interface in order to restore sense of touch, including recovery of kinesthetic and kinetic information. By utilizing MR fluid, the proposed haptic master can easily generate bi- directional repulsive torque. The proposed master is composed of two actuators: MR bi-directional clutch with planetary gear system and MR clutch with bevel gear system. After explaining the mechanism of MR haptic master, the torque models of MR actuators are mathematically derived on basis of Bingham model. In order to evaluate the performance of the proposed haptic device, a torque tracking experiment is implemented. The desired torque trajectory is achieved by PID controller. In order to verify efficacy of the proposed haptic master, desired force and actual one are compared in time domain. In addition, to simulate a human organ in the virtual space, experiment takes advantage of a volumetric deformable object rendered with spring-damper mass model in real time. An operator can manipulate a virtual slave on the screen with the haptic master, and desired force and torque are produced from the contact between the virtual slave and the objects.
