A closed-loop tactor frequency control system for vibrotactile feedback

In this paper, we address the problem of maintaining a precise frequency in vibrating motors for use as vibrotactile cueing devices. Our solution utilizes a piezoelectric film sensor that measures the motor frequency and uses a feedback-loop circuit to dynamically adjust the motor power to maintain the target frequency. We confirmed the accuracy of the film with a laser sensor and tested the ability of the feedback system to match a target frequency by changing the physical load placed on the motor. A user study showed that subjects perceived a difference in vibration intensity under loaded conditions with and without our compensation system, indicating the usefulness of such a feedback system on influencing perception. The results can help designers create better interfaces when vibrotactile cues are employed.