Comments on "Upper Extremity Limb Function Discrimination Using EMG Signal Analysis" and the Relationship Between Parallel-Fltering and Hypothesis-Testing Limb Function Classifiers

A continuity which is not readily apparent exists between certain limb function classification algorithms based on time series models of the surface EMG for use in the control of prostheses and orthoses. Superficially, the parallel-filtering system proposed by Graupe et al. [1], [2] appears to be arbitrary, inconsistent, and ad hoc in nature, and has been criticized as such [3] . Doerschuk et al. independentty developed a multichannel decision algorithm for limb function descrinination within the framework of classical detection theory using multiple-hypothesis testing [3]. This conimtihication establishes the fundamental equivalence of the two algorithms by showing that the system advocated by Graupe is in actuality a degenerate form of that proposed by Doerschuk when conditions of equal residual variance and a priori probabilities are met. A theoretical basis for Graupe's system is presented and its relationship to the multiple hypothesis test of Doerschuk is derived which unifies the contributions of both groups.