A Describing Function Analysis of Tracking Performance Using Two Tactile Displays

A display consisting of two vibrators attached to the body was tested using three different error signal-to-vibration amplitude transformations. In addition, a novel ripple display consisting of seven sequentially activated air-jet stimulators was tested on a compensatory tracking task. For both displays the range of gains and body locations were determined by both describing-function and error-power analyses. The results showed that the two-vibrator display was equally effective on all five body areas tested, but that the ripple display produced best tracking performance only when widely spaced or situated on an anatomical landmark. The best ripple display, however, was better than the best vibrator display and provided tracking performance nearly equivalent to visual displays. It was found that the ripple display was not enhanced by apparent motion but produced equivalent operator time delays shorter than those measured with visual displays.