Research Article
Ken Nishihara and Kazuya Imaiz
Abstract
The methods to reconstruct motor commands, which control muscle contraction levels, by means of the computation of detected pulse density from a electromyography (EMG) signal was proposed. Moreover, the accuracy of reconstructing the motor commands with computer simulation was validated. Theoretical neural pulse trains in each of the motor neurons before and after synapse were generated from the specified time pattern of motor command for a muscle and the waveform of bipolar electrode EMG was synthesized. A tri-phasic waveform of the action potential was used for the synthesis. The locations of the motor units around the electrodes were assigned and the amplitude of the neural pulse trains in action potentials were attenuated according to the distances between the motor units and the electrodes. Then, pulse trains were detected from the synthesized EMG signal by pulse shaping, and the motor command of a whole muscle was reconstructed by measuring change in pulse density. The results showed that the reconstructed time pattern of the motor command corresponded fairly accurately to the theoretically generated one, except for a few missing pulses in the motor units far from the electrodes, and a few false pulses caused by interference between high density pulse trains. A direct approach to assessing the accuracy of reconstructing the motor commands was suggested with these methods.