Collaborative Research: Assistive Robotics and Functional Electrical Stimulation - A Synergistic Combination to Reanimate Paralyzed Arms

People who are paralyzed from the shoulders down rely on 24-hour care to complete basic daily activities. Restoring arm and hand function would greatly increase their independence. Assistive robotics and functional electrical stimulation can potentially restore arm and hand function, but each has significant drawbacks.

The objective of this project is to develop a cooperative control strategy for functional elbow and wrist movements in people with high cervical spinal cord injuries using functional electrical stimulation and a robotic exoskeleton. The results of the project will help move functional electrical stimulation and upper limb robotics from laboratory assistive technologies to wearable devices used for everyday tasks by people with full-arm paralysis.

The complementary strengths of functional electrical stimulation (FES) and assistive robotics can potentially enable people with high tetraplegia to independently feed and groom themselves. FES provides free power using a person’s own muscles but cannot sufficiently control all joints simultaneously due to permanent denervation of some muscles. Assistive robots can provide additional power and control, but can be rigid, bulky, and heavy.

This project's objective is to develop a cooperative control strategy that demonstrates functional elbow and wrist movements in people with high tetraplegia using a hybrid FES+rigid support robot. By maximizing the utility of muscles activated by FES, the proposed hybrid strategy will reduce the need for robot power and size, paving the way for using FES with soft wearable robotics.

This project will use a rigid robot as the testbed for developing cooperative control strategies, allowing for exploration of the entire design space for future development of soft wearable exosuits coupled with FES. FES+robot assisted muscle-induced torques will be measured in real time during elbow and wrist movements. This information will feed into a coordinated FES+robot control scheme that aims to decrease robot work while maintaining tracking accuracy.

Performance and robustness of the control scheme will be benchmarked for varying robot capabilities during a self-feeding task. The outcome will be a model, mapping robot capabilities to task completion success, to be used to design future wearable hybrid FES-robotic systems for upper limb movement restoration. These advances will open up new research horizons in commanding and controlling hybrid neuroprostheses that could not otherwise be achieved.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.