This prototype of a transfemoral prosthesis uses muscle actuators to drive the knee and ankle motion. Photograph courtesy of UA.
Xiangrong Shen, PhD, an assistant professor of mechanical engineering in The University of Alabama (UA), Tuscaloosa, College of Engineering, has received a $424,000 National Science Foundation (NSF) Faculty Early Career Development (CAREER) Award to further his work on a robotic prosthesis that could help individuals with amputations walk better.
Shen’s approach to robotic prostheses uses rocket fuel, a compound monopropellant, to power an artificial muscle. The use of this fuel allows for a lightweight prosthesis that stores enough energy to operate for daily use. This pneumatic system replaces the motor used in current powered prostheses. Shen said his system is proving to be lighter, more powerful, and more compact than current designs. He has successfully demonstrated the basic concept of the actuator and how to use it to drive a robotic joint, but said more research remains before testing can begin.
“This is a relatively new system,” Shen said. “There are some problems in putting the prosthesis into clinical use because the components of the prosthesis are still being developed. In our research, the long-term goal is to develop powered prostheses with comparable appearance and functionality as human limbs.”
Shen is also working on an electromyography neural interface that will allow the user to move the prosthesis. The interface reads the muscle-activating neural signal through electrodes placed on the surfaces of the remaining muscles in the residual limb. Although individuals with amputations have had the joints driven by these muscle removed, the muscle signal is still there, which can generate the commands to drive the prosthesis. He is also developing a fault-tolerant control structure for the electromyography controls, which is a kind of backup system that reconfigures the controller in the event of failure to prevent falls.
Editor’s note: This story was adapted from materials provided by UA.
