Key points are not available for this paper at this time.
An ultrasonic position-sensing device has been designed which will allow a computer to determine periodically the x, y, and z coordinates of the tip of a pen-sized wand. The device can replace the lightpen and RAND Tablet for 2-D work, and extend the usefulness of such devices by virtue of the extra dimension available. The extremely large working space in which the WAND can operate allows it to be used for an entirely new set of pointing functions not directly connected with a display as well as the normal display control functions.
Lawrence G. Roberts (1966) studied this question.