Simulating Push-Buttons Using a Haptic Display: Requirements on Force Resolution and Force-Displacement Curve

This paper presents the procedure and results of two experiments dealing with the force resolution of the human finger and with haptic demands on push-buttons. The outcome is used to specify design details of a novel approach to a flexible control panel. A haptic display controlled by a PC enables the simulation of push-buttons with programmable forcedisplacement curves. The “just noticeable force difference” is investigated by displaying a constant force with changing value in the middle of the stroke. On average the participants were able to perceive a sudden change of force larger than 100 mN. In relation to the reference forces between 0,5 and 2,5 N this equals a relative noticeable force difference of 20 to 5%. In the second experiment the participants could vary the force-displacement curve of the simulated button. They were asked to find a setting that provides a subjectively appropriate haptic feedback during the depressing.