The Indiana Center For Regenerative Medicine and Engineering Monthly Speaker Series

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Title: Assistive Robotics at Notre Dame: Toward Fluent Control of Lower-Limb Prostheses

Patrick Wensing, PhD is an Assistant Professor in the Department of Aerospace and Mechanical Engineering at the University of Notre Dame where he directs the Robotics, Optimization, and Assistive Mobility (ROAM) lab. He received his Ph.D. in Electrical and Computer Engineering from The Ohio State University in 2014, and completed Postdoctoral training at MIT in 2017. His research group at Notre Dame focuses on bringing new levels of mobility to autonomous robots and assistive devices (exoskeletons and prostheses). He currently serves as an Associate Editor for the IEEE Transactions on Robotics

Jim Schmiedeler, PhD, is a Professor and Associate Department Chair in Aerospace and Mechanical Engineering at the University of Notre Dame. He received the Ph.D. degree from The Ohio State University in mechanical engineering. Jim is a recipient of the Presidential Early Career Award for Scientists and Engineers (PECASE) and a fellow of the American Society of Mechanical Engineers. His research interests span legged robots and the biomechanics of human locomotion.

 Abstract

Powered lower-limb prostheses offer potential benefits over passive devices in terms of providing work when ascending stairs and contributing actively to balance. The interface between a user and a powered device, however, results in complex physical dynamics and motor adaptations that both shape and are shaped by the control strategy of the prosthesis. The first part of this talk will address ongoing work to enhance the control of powered transfemoral prostheses. The general approach is to use relatively compact models of the fundamental mechanics of human gait, termed template models, to coordinate machine response in synergy with task-level motor control goals. Data to be collected from experiments on natural human gait, non-amputee gait using a prosthesis with a bypass adapter, and amputee gait with passive and active prostheses will help quantitatively disambiguate between candidate template models of locomotion. The hypothesis is that these models reflect task-level human motor coordination goals, and because they are computationally tractable, can enable a new paradigm for real-time task-level control of powered prostheses. The second part of the talk will address ongoing parallel work to enhance the control of powered transtibial prostheses by exploring “hybrid volitional control.” Volitional control in general refers to control of a powered prosthesis based on some direct sensing of user intent. It can range from full volitional control, with the sensed intent directly mapped onto each powered degree of freedom, to partial volitional control, with algorithms interpreting higher-level intent from sensors to determine the individual joint motions. Non-volitional control strategies, which are independent of user input, are more common in current powered prostheses, but they limit functionality. Hybrid volitional control aims to maintain the robustness and reliability of these non-volitional approaches, while enabling a fuller repertoire of limb motion via some volitional control. The current challenge in this domain is to provide hybrid volitional control across the full gait cycle, not just confined to a single sub-phase. Overall, this complementary research at Notre Dame aims to make the interface with powered prostheses more fluent for users.