Ultrasonic position measurement and its applications to human interface

This paper presents a two-dimensional position measuring method and its applications to human interface. It is based on the principle of ultrasonic position measurement by phase difference. In the conventional method, position is computed by triangulation with the absolute distance between transmitter and sensor; on the other hand, in our method, it is computed with the phase difference between the waves received by two pairs of sensors. By attaching a transmitter to an adequate device, various kinds of motor actions of a computer user are available to screen pointing by the device, which allows the user various pointing styles such as “mouse-like” one and “pen-like” one. First, the principle and the formulas of ultrasonic position measurement by phase difference are introduced. Second, trial construction of the pointing system is described, and performance of the pointing system is investigated. Last, some examples of pointing devices with various pointing styles are realized, and experiments on the efficiency of pointing tasks with computer users are carried out to conclude that the pointing system is suitable for practical use