Date and time
Thursday, October 22, 2020
10:00am - 12:00pm

Zoom Meeting (Information posted at the end of the announcement)

Human interaction & gait strategy with tightly-coupled lower-extremity systems

Interest in the use of exoskeletons (wearable robotic devices tightly-coupled to the user's body) for human gait augmentation has soared recently, with exoskeletons into design, control, and use efficacy. Use cases span many fields, from military (e.g. load carriage assistance) to medicine (e.g. gait rehabilitation or restoration) and industry (e.g. injury prevention).  Evaluating the human factors of human-exoskeleton interaction is an essential next step. Unexplained variation in gait strategy and adaptation observed across individual operators must be better understood to enable safe and efficacious exoskeleton use.

Cognitive fit is an individuals' understanding and ability to safely and effectively operate a system. Exoskeletons and similar tightly-coupled lower-extremity (TCLE) systems entail new interaction modalities that may affect cognitive fit. This thesis explores how cognitive factors and alternative interaction modalities impact individuals' gait and task performance. Two studies were conducted, one evaluating a cognitive function, inhibitory control, with interaction modalities relevant to TCLE system use, i.e. with tactile cues and lower-extremity response. Second, the Human-Exoskeleton Strategy & Adaptation (HESA) study was implemented, in which individuals completed baseline tasks assessing cognitive factors, specifically inhibitory control and attention, then walked with an ankle exoskeleton.

Evaluation of inhibitory control with tactile cues and lower-extremity responses resulted in decreased response times and accuracy in task performance. A probe of attention in the HESA study showed changing gait characteristics under increased attentional loads, in particular at slower walking speeds and with a secondary task. Individualized variation in exoskeleton gait using spatiotemporal gait characteristics was explicitly presented for the first time, showing that individuals initially prioritize stability and coordination with an ankle exoskeleton differently. Finally, select cognitive factors were found to be related to individuals' exoskeleton gait strategy. 

Differences in baseline factors like inhibitory control and ability to perform tasks under divided attention impact individuals' cognitive fit with exoskeleton systems. This individualized variation, as well as broader population patterns, should inform exoskeleton design and training by encouraging gait strategies that support desired exoskeleton use goals. For example, stroke patients using an exoskeleton to restore their gait and mitigate fall risk should prioritize stability during system use, while factory workers should be instructed to prioritize coordination to minimize injury risk. This thesis provides insight into human-exoskeleton interaction that can enable user safety and task efficacy with exoskeletons and related TCLE systems. 

Thesis Supervisor:
Leia Stirling, PhD
Associate Professor of IOE, University of Michigan

Thesis Committee Chair:
Julie Shah, PhD
Associate Professor of Aeronautics & Astronautics, MIT

Thesis Readers:
Ryan McKindles, PhD
Assistant Group Leader, Human Health & Performance Systems, MIT Lincoln Laboratory

Danielle Wood, PhD
Assistant Professor of Media Arts & Sciences and Aeronautics & Astronautics, MIT


Zoom invitation - 

Aditi Gupta is inviting you to a scheduled Zoom meeting.

Topic: Aditi Gupta Thesis Defense
Time: Oct 22, 2020 10:00 AM Eastern Time (US and Canada)

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