Control performance characteristics of myoelectric signal with additive interference.

Myoelectric signal is an important source of control information for powered prostheses. A commonly used performance measure for the signal processors of such control systems is the ratio of processor output mean to variance. This ratio (SNR) is a function of a number of factors including physiological parameters and additive interference. The paper investigates the effects of motor unit physiological parameters and interference on control performance, with particular reference to SNR. Performance equations are derived and verified with in vivo experiments. The results show a complex interaction among the physiological parameters and interference. A particular point of interest is the misleading SNR values that can occur under certain recruitment and interference conditions.