A State Synchronization Controller for Functional Electrical Stimulation-Based Telerehabilitation

A position-synchronization controller for functional electrical stimulation (FES)-based telerehabilitation was designed. The developed controller synchronizes an FES-driven human limb with a remote physical therapist’s manipulator despite constant bilateral communication delays. The control design overcomes a major stability analysis challenge: the unknown and unstructured nonlinearities in the FES-driven musculoskeletal dynamics. To address this challenge, the nonlinear muscle model was estimated through two neural networks with online update laws. A Lyapunov-based stability analysis was used to prove the globally uniformly ultimately bounded tracking performance. The control performance of the state synchronization controller is depicted using a simulation of an FES-elicited elbow extension that is remotely controlled by a manipulator.