Multiple-channel electromyogram (EMG) amplitude estimators incorporating temporal whitening filters and/or spatial uncorrelation filters contain a characterization of the EMG waveform (specifically, auto- and cross-correlation information) which may vary with joint angle. This paper reports on an experimental study which investigated the influence of joint angle on these EMG amplitude estimators. It was found that little or no relative improvement in estimator performance resulted from altering either temporal whitening or spatial uncorrelation filters as a function of joint angle. Also, the absolute performance level of these estimators did not vary with joint angle.

IEEE Transactions on Biomedical Engineering, Vol. 45, No. 5, pp. 664-668, 1998