NON-ISOMETRIC NEUROMUSCULAR ELECTRICAL STIMULATION VIA NON-MODEL BASED NONLINEAR CONTROL METHODS By KEITH STEGATH A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE

of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science NON-ISOMETRIC NEUROMUSCULAR ELECTRICAL STIMULATION VIA NON-MODEL BASED NONLINEAR CONTROL METHODS By Keith Stegath December 2007 Chair: Warren E. Dixon Major: Mechanical Engineering For people afflicted with neuromuscular disorders such as stroke or spinal cord injuries, there has been limited success by engineers and biological researchers to artificially control the afflicted person’s muscles with neuromuscular electrical stimulation (NMES). NMES is the application of an electrical current via internal or external electrodes which results in a muscle contraction. NMES is currently prescribed to treat muscle atrophy and impaired motor control associated with orthopedic and neurological damage, circulatory impairments, joint motion dysfunction, postural disorders, swelling and inflammatory reactions, slow-to-heal wounds and ulcers, and incontinence. The development of NMES as a neuroprosthesis has grown rapidly because of the potential improvement in the activities of daily living for individuals with movement disorders such as stroke and spinal cord injuries. Researchers have mainly focused on two methods to deliver the electrical signal to the muscle, direct nerve stimulation with electrodes inserted through the skin or implanted under the skin, and surface stimulation where adhesive-backed electrodes are placed on the skin. While each method has its advantages and