Title :
Artificial neural network control of FES in paraplegics for patient responsive ambulation
Author :
Graupe, Daniel ; Kordylewski, Hubert
Author_Institution :
Dept. of Electr. Eng. & Comput. Sci., Illinois Univ., Chicago, IL, USA
fDate :
7/1/1995 12:00:00 AM
Abstract :
Describes a binary adaptive resonance theory (ART-1)-based artificial neural network (ANN) adapted for controlling functional electrical stimulation (FES) to facilitate patient-responsive ambulation by paralyzed patients with spinal cord injures. This network is to serve as a controller in an FES system developed by the first author which is presently in use by 300 patients worldwide (still without ANN control) and which was the first and the only FES system approved by the FDA. The proposed neural network discriminates above-lesion upper-trunk electromyographic (EMG) time series to activate standing and walking functions under FES and controls FES stimuli levels using response-EMG signals. For this particular application, the authors introduce several modifications of the ART-1 for pattern recognition and classification. First, a modified on-line learning rule is proposed. The new rule assures bidirectorial modification of the stored patterns and prevents noise interference. Second, a new reset rule is proposed which prevents "exact matching" when the input is a subset of the chosen pattern. The authors show the applicability of a single ART-1-based structure to solving two problems, namely, 1) signal pattern recognition and classification, and 2) control. This also facilitates ambulation of paraplegics under FES, with adequate patient interaction in initial system training, retraining the network when needed, and in allowing patient\´s manual override in the ease of error, where any manual override serves as a retraining input to the neural network. Thus, the practical control problems (arising in actual independent patient ambulation via FES) were all satisfied by a relatively simple ANN design.
Keywords :
adaptive resonance theory; biocontrol; biomechanics; muscle; neurophysiology; orthotics; above-lesion upper-trunk electromyographic time series; adequate patient interaction; artificial neural network control; bidirectorial modification; binary adaptive resonance theory; functional electrical stimulation control; independent patient ambulation; manual override; modified on-line learning rule; noise interference; paralyzed patients; paraplegics; patient responsive ambulation; reset rule; retraining input; signal pattern recognition; spinal cord injures; system training; Adaptive control; Artificial neural networks; Control systems; Electromyography; Neural networks; Neuromuscular stimulation; Pattern recognition; Programmable control; Resonance; Spinal cord; Electric Stimulation Therapy; Electromyography; Humans; Locomotion; Neural Networks (Computer); Paraplegia; Pattern Recognition, Automated; Spinal Cord Injuries;
Journal_Title :
Biomedical Engineering, IEEE Transactions on