Modeling FES Actuation and Control of Multisegment Limb Movements

Functional Electrical Stimulation (FES) has been demonstrated as a promising technique for restoring motor function to otherwise paralyzed limbs. Though much progress remains in the technological arena to improve stimulation delivery systems, similar efforts must be directed to the equally-important problem of coordinating the complex, dynamically-coupled system of interconnected body segments. In present clinical studies, open-loop muscle stimulation (i.e. control) patterns are typically prescribed via a painstaking trial-and-error process. If FES is ever to become a viable means of restoring upright ambulation, hand function, and the like, our ability to control the simultaneous motions of many segments will be crucial. Through dynamic musculoskeletal modeling, we have the opportunity to study the coordination problem without the constraints imposed by present limitations in stimulation technology. Our modeling studies have focused upon: (a) the development of improved musculotendon actuator and joint models, (b) characterizing the complex system of interconnected body segments and the effects of muscle contractions on body-segment accelerations, and (c) developing techniques for controlling electrically-stimulated limb movements.