Researchers at several of the Center for Compact and Efficient Fluid Power (CCEFP) institutions—University of Illinois, University of Minnesota, Milwaukee School of Engineering, Georgia Institute of Technology, and North Carolina A & T—are working on the development of the next generation AFO that will push the limits of fluid power technology. These innovative projects will lead to the development of a miniature and integrated power supply, actuators, valves, transmission lines and housing, while also addressing specific issues related to the development of novel powered exoskeletons to assist persons with disabilities.
Test bed 6, the Portable Powered Ankle Foot Orthosis (PPAFO) was recently successfully demonstrated to provide functional assistance on two individuals with lower leg weakness. One participant suffered from plantarflexor (calf muscle) weakness due to a spinal injury and could no longer generate torque at the ankle to push his toes down. This impairment affected his ability to propel himself forward while walking – thus making extended walking an exhausting task. The other individual had a form of muscular dystrophy, a disorder that caused weakness in both the calf and shin muscles, i.e., both plantarflexor and dorsiflexor muscles. Dorsiflexor impairment can limit the ability to pull the toes up during swing – thus creating a potential tripping hazard.
During testing, the PPAFO was able to provide functional assistance to both subjects. Although the PPAFO was not capable of providing enough power to fully restore normal propulsive torque, it was able to generate modest power for propulsive assistance. For the individual with plantarflexor weakness, this added plantarflexor torque resulted in increased single leg support time on the assisted side and demonstrated a more normal ankle motion. For the individual with dorsiflexor weakness, the PPAFO also successfully controlled the motion of the foot during swing. This assistance eliminated a potential tripping hazard by keeping the toes from contacting the ground. These experimental results demonstrated that the PPAFO was capable of providing untethered functional assistance for people with walking disabilities.
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