Design and control of a haptic knob

• The design and the fabrication of a haptic knob.
• The presentation of a position sensor based on force measurements with 3.6° accuracy.
• The modeling and the control of the vibration amplitude.
• The psychophysical experiment showing how haptic can increase user's accuracy in a pointing task.

Introducing haptic into tactile input interfaces allow users to really feel their action on the device they control by this way. In this paper, we achieve tactile stimulation by using the squeeze film effect. It is applied on a haptic knob, as those which control an MP3 player for example. We present our design procedure of the active surface and of the position sensor based on force measurement which achieves a resolution of 3.6°. We also show that stimuli are damped by fingertip, and a specific control loop with a response time of 2.5 ms has been achieved to tackle this problem. Finally, a psychophysical experiment was conducted showing how the haptic feedback can increase user's accuracy in a pointing task.