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Dec 12, 2022 372 likes •599 views

Reducing the energy cost of human walking using an unpowered exoskeleton [Collins, Wiggin & Sawicki (2015) Nature ] Steve Collins Associate Professor Mechanical Engineering & Robotics Institute Carnegie Mellon University Steve Collins

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Steve Collins  Carnegie Mellon University  biomechatronics.cit.cmu.edu  stevecollins@cmu.edu

Reducing the energy cost of human walking using an unpowered exoskeleton

Steve Collins Associate Professor Mechanical Engineering & Robotics Institute Carnegie Mellon University

[Collins, Wiggin & Sawicki (2015) Nature]

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Steve Collins  Carnegie Mellon University  biomechatronics.cit.cmu.edu  stevecollins@cmu.edu

Humans are expert at walking efficiently. Walking is still most energy-intensive activity. Challenge: Reduce energy cost of normal walking.

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Steve Collins  Carnegie Mellon University  biomechatronics.cit.cmu.edu  stevecollins@cmu.edu

Initial attempts, 1800’s and 1900’s

[Yagn (1890) Patent; Seireg (1971); GE Hardiman (1965)]

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Steve Collins  Carnegie Mellon University  biomechatronics.cit.cmu.edu  stevecollins@cmu.edu

Recent serious attempts

[Zoss et al. (2006); van Dijk et al. (2011); Cherry et al. (2009); Charalambous et al. (2012)]

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Steve Collins  Carnegie Mellon University  biomechatronics.cit.cmu.edu  stevecollins@cmu.edu

Success with powered devices, 2013—2014

[Malcolm et al. (2013); Mooney et al. (2014)]

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Steve Collins  Carnegie Mellon University  biomechatronics.cit.cmu.edu  stevecollins@cmu.edu

Energy flow in steady-state, level walking

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Steve Collins  Carnegie Mellon University  biomechatronics.cit.cmu.edu  stevecollins@cmu.edu

Wasted energy: Muscle inefficiencies.

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Steve Collins  Carnegie Mellon University  biomechatronics.cit.cmu.edu  stevecollins@cmu.edu

Related unpowered successes, 2006—2012

[Rome et al. (2006); Franz et al. (2012); Donelan et al. (2008); Grabowski et al. (2009)]

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Steve Collins  Carnegie Mellon University  biomechatronics.cit.cmu.edu  stevecollins@cmu.edu [Collins, Wiggin & Sawicki (2015) Nature]

Our Device: Passive Exoskeleton Targets Calves

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Steve Collins  Carnegie Mellon University  biomechatronics.cit.cmu.edu  stevecollins@cmu.edu [Collins, Wiggin & Sawicki (2015) Nature]

Our Device: Passive Exoskeleton Targets Calves

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Steve Collins  Carnegie Mellon University  biomechatronics.cit.cmu.edu  stevecollins@cmu.edu

Beating evolution: More efficient walking

[Collins, Wiggin & Sawicki (2015) Nature]

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Steve Collins  Carnegie Mellon University  biomechatronics.cit.cmu.edu  stevecollins@cmu.edu

Does 7% matter?: Yes.

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Steve Collins  Carnegie Mellon University  biomechatronics.cit.cmu.edu  stevecollins@cmu.edu

How? Reduced muscle force

[Collins, Wiggin & Sawicki (2015) Nature]

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Steve Collins  Carnegie Mellon University  biomechatronics.cit.cmu.edu  stevecollins@cmu.edu

How? Reduced muscle activation

[Collins, Wiggin & Sawicki (2015) Nature]

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Steve Collins  Carnegie Mellon University  biomechatronics.cit.cmu.edu  stevecollins@cmu.edu

How? Probably not muscle work

[Collins, Wiggin & Sawicki (2015) Nature]

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Steve Collins  Carnegie Mellon University  biomechatronics.cit.cmu.edu  stevecollins@cmu.edu

How? Not center of mass work

[Collins, Wiggin & Sawicki (2015) Nature]

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Steve Collins  Carnegie Mellon University  biomechatronics.cit.cmu.edu  stevecollins@cmu.edu

Why back up? Calf muscle-tendon dynamics

[Collins, Wiggin & Sawicki (2015) Nature]

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Steve Collins  Carnegie Mellon University  biomechatronics.cit.cmu.edu  stevecollins@cmu.edu

Why back up? Knee moments

[Collins, Wiggin & Sawicki (2015) Nature]

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Steve Collins  Carnegie Mellon University  biomechatronics.cit.cmu.edu  stevecollins@cmu.edu

Conclusions:

1. Efficiency of human gait can be improved
2. Key: biomechanics knowledge (not tech)
3. Formula: lightweight + medium force (+ work)

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Steve Collins  Carnegie Mellon University  biomechatronics.cit.cmu.edu  stevecollins@cmu.edu

Discussion.

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Steve Collins  Carnegie Mellon University  biomechatronics.cit.cmu.edu  stevecollins@cmu.edu