Prototype System Design and Experimental Validation of Gait-Oriented EMG Bridge for Volitional Motion Function Rebuilding of Paralyzed Leg

The voluntary participation of paralyzed patients is crucial for the neuromuscular electrical stimulation (NMES) therapy. In this paper, an NMES technique based on surface electromyogram (sEMG) communication between healthy side and affected side of hemiplegic patients, called gait-oriented EMG bridging (EMGB), is proposed to realize the motion of paralyzed leg under the stimulation of the volitional sEMG signal of healthy leg. The sample entropy algorithm is used to detect the onset and offset of agonist sEMG in the healthy side, which triggers or ends the recording of agonist sEMG. The MAV/NSS co-modulation (MNDC) algorithm is used to modulate a various frequency and pulse width of stimulation according to the recording agonist sEMG. The stimulation is triggered by the onset of antagonistic sEMG in healthy side to stimulate the target affected muscles. A prototype gait-oriented EMGB system was developed for real time control of dorsiflexion and plantarflexion in sitting position. The experimental results indicated that alternate ankle motions can be achieved successfully. The angle trajectory of ankle can be reproduced alternately with a latency within 300 ms and a maximum cross-correlation coefficient > 0.82.