Abstract

Two methods for the estimation of the conduction velocity (CV) in the muscle fiber, using an array of surface Electromyography (SEMG) signals, are presented. This work is based on a constrained time delay estimation. Firstly, the coarse delays between all pairs of signals in the array are determined using correlation, producing a vector of delays (unconstrained estimator). Secondly , a fine estimation is carried out using the latter vector as data and the Chasles relations as constraints, in order to minimize the error produced in the first estimation. The first method uses the Lagrangian multiplier, the second includes the constraints in a Best Linear Unbiased Estimator (BLUE) and tends to the Maximum Likelihood Estimator (MLE). The estimator variances on simulated signals are compared with the Cramer-Rao Lower Bound (CRLB) of a MLE. A continuous CV estimation is obtained using a parabolic interpolation of the cross-correlation functions. The methods, applied to arrays of real SEMG signals, gave velocities in the range of 2.3 to 4.8 m/s.