Abstract: In a haptic master-slave system the interaction forces between the slave and the environment are fed back to the surgeon through a haptic device providing a tactile sensation. The forces reflected to the master device should be accurately controlled because, as long as the surgeon is not grasping the haptic device, an uncontrolled motion of the slave can occur. In this paper a new master-slave control architecture allowing to avoid dangerous and uncontrolled slave motions is presented and discussed. The basic idea is to control the position of the device through a system able to generate forces on the master only when the surgeon is grasping this device. In this way, an external force applied to the slave has no effects on the master when the surgeon releases the haptic device, leaving the system in a stable configuration. Experimental tests for a 1
dof haptic device have been carried out showing the system is effective and provides an accurate tactile sensation.