Development and Experimental Validation of a Haptic Compass Based on Asymmetric Torque Stimuli

This paper presents the design, control, and experimental validation of a haptic compass, designed as a guiding device for all environments. The proposed device uses the principle of asymmetric torques. Its design is based on a direct drive motor and a pre-calibrated open-loop control, which allows the generation of stimuli in a wide range of frequencies. User studies are presented and show optimum effectiveness in the frequency range 5-15
$\mathrm{\mathrm{Hz}\;a}$
nd for torques over
$40\; \mathrm{m}\mathrm{N}\mathrm{m}$
. The use of a haptic feedback proportional to the angle error is then shown to significantly improve the results. An experimental validation by a group of‘ subjects with the portable device using these stimuli is reported. The results show that all subjects met all route objectives with small lateral deviations (avg.
$\mathrm{0.39\;\mathrm{m}}$
).