Two new grants totaling $500,209 from the National Science Foundation (NSF) will help researchers at the University of Pittsburgh (Pitt) make strides in helping individuals with paraplegia walk while wearing an exoskeleton.
From left, Sharma with graduate students Nicholas Kirsch and Naji Alibeji examine a prototype of the PITT EXO, or Semi-Active Hybrid Orthosis. Photograph courtesy of Swanson School of Engineering/John Altdorfer.
Nitin Sharma, PhD, assistant professor of mechanical engineering and material science at Pitt’s Swanson School of Engineering, will lead the research. He will focus on optimizing the potential of two prevalent technologies used for mechanically assisted walking: functional electrical stimulation (FES), which uses low-level electrical currents to activate leg muscles, and powered exoskeletons, which use electric motors mounted on an external frame to move the wearer’s joints. The resulting hybrid aims to capitalize on the best of both systems.
“It’s like a hybrid car switching between a gas engine and an electric motor depending on circumstance,” said Sharma. “The algorithms we are developing determine when to use power from FES and when to use the power from the motors on the frame.”
The first grant comes from the General and Age-Related Disabilities Engineering Division of NSF. UNS: Optimal Adaptive Control Methods for a Hybrid Exoskeleton will investigate a new class of control algorithms that adapt to allocate optimized control inputs to FES and electric motors during single joint movements. The Civil, Mechanical and Manufacturing Innovation Division of the NSF will fund Coordinating Electrical Stimulation and Motor Assist in a Hybrid Neuroprosthesis Using Control Strategies Inspired by Human Motor Control. In this study, Sharma will research control algorithms to determine an optimal synergy between FES-induced multi-joint movements and movements aided by a powered exoskeleton. Both projects will examine the efficiency of exoskeleton technology for manufacturers hoping to develop new hybrid models that take advantage of FES technology, powered frames, and robotics.
“Current exoskeleton research is using devices completely powered by electric motors. They have huge battery packs and can only provide a maximum of about an hour of continuous walking. With FES, you are using a person’s own muscles to make that person walk. FES also has been shown clinically to improve cardiovascular fitness, increase muscle strength, and prevent atrophy,” said Sharma.
Editor’s note: This story was adapted from materials provided by Pitt.
