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UTARI Seminar: Dr. Robert Gregg

UTARI Seminar

The UTARI Seminar will be held Friday, March 29th, at noon (12pm).

Each seminar highlights a different speaker who will discuss their latest research projects, cutting-edge technology or what is happening within certain technological industries. These industries include biomedical technologies or microsystems, assistive technologies, automation and intelligent systems, unmanned systems, advanced manufacturing and composite materials.


Dr. Robert Gregg


From kinematic to energetic design and control of wearable robots for agile human locomotion


Emerging robotic prostheses and orthoses can actively assist individuals with limb loss or stroke to achieve greater mobility, but current devices are limited to performing a small set of pre-defined motions. This talk will present three recent developments toward agile wearable robots: 1) user-synchronized kinematic control of powered prostheses, 2) optimal design of series elastic actuators for a wide range of activities, and 3) design of partial-assist exoskeletons that control body energy rather than kinematics. Typically, finite state machines are used to switch controllers between discrete phases of the gait cycle and between different tasks, but this approach cannot continuously synchronize the robot’s motion to the timing or activity of the human user. This talk will first present a continuous parameterization of human joint kinematics based on a phase variable that robustly represents the timing of the human gait cycle and task variables representing ground slope and walking speed. This parameterization is employed for user-synchronized control of a powered knee-ankle prosthesis, which enables above-knee amputee subjects to walk at variable speeds/inclines with reduced compensations of intact joints. To fully leverage this control approach, prosthetic legs must be designed to efficiently perform a wide range of activities while satisfying actuator constraints. A convex optimization framework will be introduced for the design of series elastic actuators that utilize nonlinear elasticity to minimize energy consumption and extend the range of achievable tasks. While these methods reproduce missing joint function, a different design and control philosophy is needed for exoskeletons that assist existing joint function. This talk will describe an energetic control paradigm for exoskeletons to alter the human body’s dynamics without prescribing joint kinematics. This control approach requires highly backdrivable actuators to facilitate voluntary human motion, motivating its implementation in exoskeletons with quasi direct-drive actuators. Applications in stroke, osteoarthritis, and elderly assist will be discussed.


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. Dr. Gregg directs the Locomotor Control Systems Laboratory, which conducts research on the control mechanisms of bipedal locomotion with applications to wearable and autonomous robots. He is a recipient of the Eugene McDermott Endowed Professorship, NSF CAREER Award, NIH Director’s New Innovator Award, and Career Award at the Scientific Interface from the Burroughs Wellcome Fund. Dr. Gregg is a Senior Member of the IEEE.




12pm - 1pm


7300 Jack Newell Boulevard South
Fort Worth, TX 76118-7115