Route Guidance with a Vibro-tactile Waist Belt

Navigation in unfamiliar places is difficult, even if signposts are available they are located at fixed points, may be overseen when the area is crowded, and are impossible to use by blind people. Visual navigation devices make guidance information available at any place but are neither hands-free nor a solution for blind people. In order to tackle all of these problems, we experimented with vibro-tactile guidance cues. First we created an indoor navigation system consisting of position tracking hardware and a vibro-tactile waist belt that guides a person from waypoint to waypoint of a predetermined course. For that we used the 6DOF ultrasonic tracking system InterSense IS-900 and a waist belt composed of 8 C-2 tactor elements from Engineering Acoustics Inc. For the design of the vibro-tactile cues the following parameters have been used: (i) intensity (attenuation in dB), (ii) frequency, (iii) position (which tactor), (iv) vibro-tactile pattern. We started with a very simple notification pattern and then tried to improve walking speed and accuracy by adding distance information. We showed that with a tracking system working at centimeter accuracy, vibro-tactile cues alone allow for precise walking with an estimated average distance to the test course of only 20cm. Higher time-lag (around 750ms compared to 380ms) lead to significantly worse results. Distance information did not yet lead to increases in precision, this may be due the subtle nature of the chosen encoding scheme. However, it is possible that after a longer learning period participants can estimate distance. More details about the experiment setup and the first part of the results can be found in [1].