Design and implementation of expressive footwear

As an outgrowth of our interest in dense wireless sensing and expressive applications of wearable computing, we have developed the world’s most versatile human-computer interface for the foot. By dense wireless sensing, we mean the remote acquisition of many different parameters with a compact, autonomous sensor cluster. We have developed such a low-power sensor card to measure over 16 continuous quantities and transmit them wirelessly to a remote base station, updating all variables at 50 Hz. We have integrated a pair of these devices onto the feet of dancers and athletes, measuring continuous pressure at 3 points near the toe, dynamic pressure at the heel, bidirectional bend of the sole, height of each foot off conducting strips in the stage, angular rate of each foot about the vertical, angular position of each foot about the Earth's local magnetic field, as well as their tilt and low-G acceleration, 3-axis shock acceleration (from kicks and jumps), and position (via an integrated sonar). This paper describes the sensor and electronics systems, then outlines several projects in which we have applied these shoes for interactive dance and the capture of high-level podiatric gesture. We conclude by outlining several footwear-unrelated applications of our sensor system.