Selection of muscle and nerve-cuff electrodes for FES using a customizable musculoskeletal model

Neuroprosthetic systems based on functional electrical stimulation (FES) aim to restore motor function to individuals with various levels of paralysis due to spinal cord injury (SCI). Identifying the optimal set of electrodes to be included in the neuroprosthesis is a complicated problem, since it depends on the characteristics of the specific individual, such as the level of injury and remaining muscle force, the movements the FES system aims to restore, and the hardware limitations, i.e. the number and type of electrodes available. In order to simplify this procedure, an electrode-selection method has been developed that uses a musculoskeletal model with parameters that simulate the characteristics of the prospective FES user. The candidate sets for stimulation are created based on the requirements of the person, and the hardware limitations of the proposed system. Using each of the candidate sets, a number of inverse-dynamic simulations are performed to determine if the target movements can be accomplished. The set that allows the most movements to be performed is chosen as the optimal set for stimulation. The technique is demonstrated here in a system recently developed by our research group to restore whole-arm movement to an individual with high level tetraplegia.