SELF-CALIBRATING DIGITAL MYOPROCESSOR

ABSTRACT A myoelectric signal processing technique has been digitally implemented to provide realtime proportional control of a prosthetic elbow. This technique, previously implemented in analog circuitry, produced a five-fold improvement in the signal-to-noise ratio over the usual process of rectifying the signal from a single electrode pair and then smoothing it. This technique, which processes signals from four electrode pairs, applies a prewhitening transformation to the input signals in order to take advantage of the different information content of each signal. The prewhitening transformation matrix, which weights the signals with respect to each other, is calculated from the covariance matrix which characterizes the “cross talk” between signals and is different for each electrode set up. A major advantage of digital implementation is that this calibration is performed automatically. This adaptive, self-calibrating myoprocessor is an unique experimental facility. Its capabilities include the ability to maintain calibration under conditions of fatigue.