Characterization of surface electromyography patterns of healthy and incomplete spinal cord injury subjects interacting with an upper-extremity exoskeleton

Abstract

Abstract-Rehabilitation exoskeletons may make use of myoelectric control to restore in patients with significant motor impairment following a spinal cord injury (SCI) a sense of volitional control over their limb -a crucial component for recovery of movement. Little investigation has been done into the feasibility of using surface electromyography (sEMG) as an exoskeleton control interface for SCI patients, whose impairment manifests in a highly variable way across the patient population. We have demonstrated that by using only a small subset of features extracted from eight bipolar electrodes recording on the upper arm and forearm muscles, we can achieve high predictive accuracy for the intended direction of motion. Five healthy subjects and two SCI subjects performed voluntary isometric contractions while wearing an exoskeleton for the wrist and elbow joints, generating six distinct single and multi-DoF motions in a total of sixteen possible directions. Using linear discriminant analysis, classification performance was then evaluated using randomly selected holdout test data from the same recording session. Commonalities across subjects, both healthy and SCI, were analyzed at the levels of selected features and the values of commonly selected features. Future work will be to investigate group-specific classification of SCI subjects' intended movements for use in the real-time control of a rehabilitation exoskeleton.

A Review on Design of Upper Limb Exoskeletons

“…Reference [164] has used FSR sensors for the payload estimation of robotic exoskeleton. Moreover, force sensors including FSRs and load cells are being used to measure the interaction pressure over the whole contact area between the upper limb and exoskeleton [48,50,55,79,165,166]. Besides, several studies have proposed neural/muscular sensing and shown its significance for exoskeleton control.…”

“…The complex relative movements between the radial and ulna bones make it difficult to develop a mechanism which can precisely replicate the forearm supination/pronation. Few studies [6,22,33,34,50,58,70,72,167] have presented a design that can actively support the users in executing forearm supination/pronation by taking into account the effect of radial/ulnar deviation.…”

“…The FMG-based technique to control the exoskeleton robots is only useful in specific applications such as carrying heavy loads, but the idea of implementing this method for ADL and rehabilitation is not possible. To overcome this issue [50,182,183], EMG signals can be used to estimate the required assistance level in rehabilitation or assistive applications. Moreover, EMG based control methods are not very effective in case of tremor or spasticity.…”

A Bowden Cable-Based Series Elastic Actuation Module for Assessing the Human Wrist

“…To measure passivity, two bipolar surface electromyography (sEMG) electrodes were used. Each sEMG electrode was located on the user's forearm to measure muscle activity related to wrist flexion and extension, using electrode placements similar to [23] (see Fig. 8).…”

Payload estimation using forcemyography sensors for control of upper-body exoskeleton in load carrying assistance

“…The implementation of this method for daily routine activities or factory tasks is not feasible, where the user carries objects of different attributes. To overcome this challenge, Electromyography (EMG) based estimation methods are used instead to determine joint torques and provide assistance through exoskeletons McDonald et al (2017); Mangukiya et al (2017); Leonardis et al (2015); Abdallah et al (2017); Mghames et al (2017); Tang et al (2014); Rahman et al (2015); Li et al (2013); Kiguchi and Hayashi (2012). In these methods the assistance to each joint is provided by analyzing the muscle activities of its prime mover muscle group.…”