“Sticking” aspects of a haptic device with part-locking programmable brakes

This paper outlines work on the development of a novel programmable rotary brake which can restrict motion of a mechanism moving in one direction whilst allowing free motion in other directions. The design, implementation and performance of a fully functional prototype are described along the work on incorporating the prototype into a 3 Degrees-Of-Freedom (DOF) haptic device. The ability of the haptic device to constrain the motion of the end-effector to point-constraint was investigated and the experiments have shown that the haptic device can implement virtual constraints without the need for a force sensor. The experiments also show that when an advanced control scheme is used the virtual wall is not felt as “sticky”.