Loading Events

« All Events

  • This event has passed.

Spring 2018 GRASP Seminar Series: Robert Gregg, University of Texas at Dallas, “Towards Unified Control of Powered Prosthetic Legs with User-Synchronized Timing and Task Adaptations”

February 9, 2018 @ 11:00 am - 12:00 pm


The human gait cycle is typically viewed as a periodic sequence of discrete events, starting with heel contact during initial stance and ending with knee extension during late swing. This convention has informed the design of control strategies for powered prosthetic legs, which almost universally switch between multiple distinct controllers through the gait cycle based on a finite state machine. Human locomotion is further discretized into a small set of task-specific finite state machines, e.g., one for uphill and one for downhill. However, this discrete methodology cannot synchronize to the continuous motions of the user or adapt to the continuum of user activities. Instead of discretely representing human locomotion, this talk will present a continuous parameterization of human gait based on 1) a phase variable that robustly represents the timing of human joint patterns, and 2) task variables that parameterize kinematic adaptations to ground slope and walking speed. A unifying prosthetic leg controller is then designed around this continuous parameterization to synchronize prosthetic joint patterns with the timing and activity of the human user. The viability of this approach is demonstrated by experiments with above-knee amputee subjects walking on a powered knee-ankle prosthesis at variable speeds and inclines. Volitional control is demonstrated through non-rhythmic activities such as forward/backward stepping and kicking a ball. Ongoing work in the design of high-performance prosthetic legs with low-impedance actuators will be also presented, followed by applications in powered orthoses for stroke gait.


- Learn More

Robert D. Gregg IV received the B.S. degree in electrical engineering and computer sciences from the University of California, Berkeley in 2006 and the M.S. and Ph.D. degrees in electrical and computer engineering from the University of Illinois at Urbana-Champaign in 2007 and 2010, respectively. He joined the Departments of Bioengineering and Mechanical Engineering at the University of Texas at Dallas (UTD) as an Assistant Professor in June 2013 with an adjunct appointment at the UT Southwestern Medical Center. Prior to joining UTD, he was a Research Scientist at the Rehabilitation Institute of Chicago and a Postdoctoral Fellow at Northwestern University. His research concerns the control mechanisms of bipedal locomotion with application to wearable control systems, including prostheses and orthoses. Dr. Gregg is a recipient of the NSF CAREER Award, the NIH Director’s New Innovator Award, and the Career Award at the Scientific Interface from the Burroughs Wellcome Fund. Dr. Gregg is a Senior Member of the IEEE Control Systems Society and the IEEE Robotics & Automation Society.


February 9, 2018
11:00 am - 12:00 pm
Event Category: