The Rbow--a sensor bow



in action

The Rbow, constructed by Dan Trueman and Perry Cook, consists of a traditional violin bow with motion sensors (a biaxial accelerometer, mounted at the frog) and pressure sensors (mounted between the hair and the stick in two locations). It can be played by itself, using the shoulder or other surface as a point of resistance, or on any violin. Trueman uses it primarily with a six-string, solid-body electric violin, and in combination with pitch, amplitude, and overtone detection of the electric violin signal.

The Rbow was motivated by Trueman's frustration with conventional interface devices available to the violinist; footpedals seem crude and awkward as expressive instruments in comparison to the bowed string. By itself, the Rbow suggests a variety of kinds of physical interaction with electronic sound; moving the frog in various positions, which may require moving the entire body, and simply pressing the bow in various locations, all are effective ways of physically playing the Rbow.

In this way, the Rbow transforms the violinist into a kind of dancer, and requires Trueman to modify his traditional violin technique. When played with the electric violin, this often creates an interesting technical conflict--certain techniques, while effective for the Rbow, may be useless for playing the electric violin, and vice-versa. Finding points of cross-section, where playing both instruments simultaneously is physically and musically fulfilling, is one of the fascinating challenges presented by the Rbow.

The Rbow also offers mapping flexibility; the sensor data can be interpreted in many ways, and these interpretations can change over the course of a performance, phrase, or even within a gesture. One particularly compelling mapping attaches virtual shakers to the bow, encouraging the performer to shake and gyrate in various ways to control the energy and resonances of the shakers. In combination with analysis of the violin's audio signal, the Rbow makes for an effective controller of both physical models and realtime granular delay techniques; Trueman makes extensive use of the PeRColate toolkit in MSP which includes both of these kinds of synthesis and signal processing techniques.