An engineering professor at the University of Texas at Dallas applied robot control theory to enable powered prosthetics to dynamically respond to the wearer’s environment and help amputees walk. The robotic leg wearers were able to walk on a moving treadmill almost as quickly as an able-bodied person.
“We borrowed from robot control theory to create a simple, effective new way to analyze the human gait cycle,” said Dr. Robert Gregg, a faculty member in theErik Jonsson School of Engineering and Computer Science and lead author of the paper. “Our approach resulted in a method for controlling powered prostheses for amputees to help them move in a more stable, natural way than current prostheses.”
Control engineers view the human gait cycle through the lens of time — the interval at which each movement in the walking cycle needs to occur. Gregg, an assistant professor of bioengineering and mechanical engineering, proposed a new way to view and study the process of human walking: measuring a single variable that represents the motion of the body. In this study, that variable was the center of pressure on the foot, which moves from heel to toe through the gait cycle.
Gregg first tested his theory on computer models, and then with three above-knee amputee participants at the Rehabilitation Institute of Chicago. He implemented his algorithms with sensors measuring the center of pressure on a powered prosthesis. Inputted with only the user’s height, weight and dimension of the residual thigh into his algorithm, the prosthesis was configured for each subject in about 15 minutes. Subjects then walked on the ground and on a treadmill moving at increasing speeds.
