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Development of an algorithm for generating a control signal for myoelectric prosthetic knee

Abstract:

Many advances have been done in the area of prosthetic devices for transfemoral amputees. One of the approaches in this field has been the use of EMG signals from the muscles, in order to identify the instant of gait cycle, as well as to generate a control signal for the prosthesis actuator. This kind of signals has a huge potential for controlling a prosthesis, but at the same time has several problems associated [1]. Until now, some of these problems remained unsolved and as a matter of fact, it has not been possible to use EMG signals for the control of a commercial prosthesis. Nowadays, research is being done at the Simón Bolívar University in Venezuela which aims at developing an A/K prosthesis. At this point, the idea is to try different approaches to the control problem, regarding specifically what kind of signals to use. One of the signals studied are the EMG signals. The present work pretends to show a methodology to make an algorithm that allows generating a control signal for a knee prosthesis. At present time, EMG signals from leg muscles of healthy persons have been captured, processed and analyzed. A threshold has been identified from which it is possible to generate a control signal of two states of activity ON/OFF. In other words, knowing this threshold it is possible to say when to block and unblock the prosthetic knee. The research will be continued, trying to generate a more complete algorithm which gives as output not a two-states control signal, but a continuous one. This would allow to position the knee in different angular positions and surely, would be an important outcome for the A/K prosthesis being developed. © Springer-Verlag Berlin Heidelberg 2007.