A Note on the Time Constant in Low-Pass Filtering of Rectified Surface EMG

A procedure to obtain the optimal time constant in low-pass filtering of surface EMG has been developed. The performance index which determines the optimality of the time constant considers the sensitivity of the filter and the reproducibility of the filtered output. In our procedure, the optimal time constant can be easily calculated from a nonlinear equation which is characterized by the autocorrelation coefficient of the given muscular performance and the mean and variance of surface EMG in static contraction.