Basic Studies on Auricular Movement as a Control Command for Functional Electrical Stimulation (FES) System

摘要

Functional electrical stimulation (FES) has been proposed as a technique that could restore the paralyzed motor functions of the patients who injured their upper motor neurons. In this paper, use of voluntary movement of the auricular was proposed as a control command for FES system. The movement may be used exclusively for controlling FES system, because it is seldom used in daily living. However, the percentage of persons who can move the auricular is small. In order to overcome this difficulty, a method of learning the movement was developed in this paper. The method was a training with electrical stimulation to the posterior auricular muscle and electromyogram (EMG) feedback. Three subjects attempted to learn the movement with this method, and two of them acquired the movement in a short term. Furthermore, in order to detect the auricular movement by EMG signal of the posterior auricular muscle, we studied the influence of other movements on the detection of the auricular movement. Power spectrum of noise during neck movement was distributed in lower frequency than that of the EMG signal. The noise during jaw movement was smaller in amplitude than the EMG signal. These experimental results suggested that the influence of both neck and jaw movements on detection of the auricular movement could be removed by appropriate signal processing. In addition, we also studied about fatigue characteristic of the posterior auricular muscle and reaction time of the auricular movement. It was difficult to move the auricular constantly over 1 minute, but it was probable to move it intermittently for 15 minutes. The reaction time of the movement was a little longer than that of finger movement. These suggested that the auricular movement could give short-time control commands repeatedly to FES system for long term.