Design of a linear haptic display based on approximate straight line mechanisms

In this paper, we study a class of one degree-of-freedom mechanisms in order to design linear haptic interfaces. They allow to perform straight line motions with only revolute joints, thus limiting the friction that characterizes linear bearings. We particularly describe the characteristics of these systems and their good properties to design haptic displays: parallel architecture, very good linearity, good use of the actuator torque. The Hoeken's mechanism which has the best characteristics to build a direct drive general purpose haptic display is selected. We present the fabricated prototype and its evaluation in terms of bandwidth, Coulomb friction and apparent mass.