Preliminary design and simulation of a pneumatic, stored-energy, hybrid orthosis for gait restoration

Loss of mobility due to lower limb paralysis is a common result of thoracic level spinal cord injury (SCI). Functional electrical stimulation (FES) can restore primitive gait in the vicinity of a wheelchair by using electrical stimulation to generate muscle contractions. A new concept for FES-assisted gait is presented that combines electrical stimulation with an orthosis that contains a fluid power system to store and transfer energy during the gait cycle. The Energy Storage Orthosis (ESO) can be driven through a complete gait cycle using only stimulation of the quadriceps muscles. The conceptual design of the ESO was completed and implemented in a dynamic simulation model and in a benchtop prototype for engineering measurements. No studies were conducted with human subjects. The results demonstrate the potential of the ESO concept and the validity of the simulation model as a means for designing the system.