Gesture-Sensing for Musical Performance: A Percussive Interface


To create the next-generation Radio Drum. Note that ultimately it might not be a "Radio" Drum. The technology might end up being different. It must be a 3-dimensional controller that "doubles" as a drum. That is, it senses the space above a surface, but it also can be played like a drum, and identify "whacks" and different kinds of gestures, bounces, etc. It is a controller, and does not generate sound.


The fist-generation Radio Drum was designed by Bob Boie and built at Bell Labs in the mid-1980's as a "three-dimensional mouse." The Radio Drum uses capactive sensing; you use a radio frequency to measure capacitance. The two sticks are differentiated by using different frequencies for each one.

The Radio Drum itself could be called a "gesture sensor" that keeps constant track of the 3-dimensional spatial location of mallets in the following way: A small amount of wire is wrapped around the end of each of two sticks and acts as a conducting surface electrically driven by a radio frequency voltage source. The drum surface beneath the sticks receives the signal, and the x and y positions of the sticks are derived by determining the first moment of capacitance between the sticks and the surface below. The z position (height) is given by the reciprocal of the first moment. The greatest accuracy in z is in the region from about 5 cm above the surface and closer. The response time is between 5 and 10 msecs, but this latency can be lowered to below 5 msec. (For technical details see [Boie, et al 1989]).


We have several copies of the original Boie drum (in fact we have all of them still in existence), and we have a design for a "wireless" version in progress. The new prototype wireless sticks were made last year by some UVic engineering grad students, and I think we can finish at least a basic prototype of the wireless drum by the end of 1999. Then we can test it and see if it is good enough. If not, we might use another technology, or possibly use a hybrid -- for example, one sensor method for "whack" and one for "continuous" modes.


Temporal resolution: 1 millisecond latency

Spatial resolution: 1 millimeter resolution in x,y,z




written by Dr. A. Schloss, School of Music, UVic,