Optimal regulation of bipedal walking speed despite an unexpected bump in the road.

Bipedal locomotion may occur over imperfect surfaces with bumps or other features that disrupt steady gait. An unexpected bump in the road is generally expected to slow down most types of locomotion. On wheels, speed may be regained quite readily with "cruise control" performed in continuo...

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Main Authors: Osman Darici, Hakan Temeltas, Arthur D Kuo
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2018-01-01
Series:PLoS ONE
Online Access:http://europepmc.org/articles/PMC6157876?pdf=render
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author Osman Darici
Hakan Temeltas
Arthur D Kuo
author_facet Osman Darici
Hakan Temeltas
Arthur D Kuo
author_sort Osman Darici
collection DOAJ
description Bipedal locomotion may occur over imperfect surfaces with bumps or other features that disrupt steady gait. An unexpected bump in the road is generally expected to slow down most types of locomotion. On wheels, speed may be regained quite readily with "cruise control" performed in continuous time. But legged locomotion is less straightforward, because the stance leg may be under-actuated, and the continuous-time dynamics are periodically disrupted by discrete ground contact events. Those events may also afford good control opportunities, albeit subject to the delay between discrete opportunities. The regulation of walking speed should ideally use these opportunities to compensate for lost time, and with good economy if possible. However, the appropriate control strategy is unknown. Here we present how to restore speed and make up for time lost going over a bump in the road, through discrete, once-per-step control. We use a simple dynamic walking model to determine the optimal sequence of control actions-pushing off from the leg at the end of each stance phase-for fast response or best economy. A two-step, deadbeat sequence is the fastest possible response, and reasonably economical. Slower responses over more steps are more economical overall, but a bigger difference is that they demand considerably less peak power. A simple, reactive control strategy can thus compensate for an unexpected bump, with explicit trade-offs in time and work. Control of legged locomotion is not as straightforward as with wheels, but discrete control actions also allow for effective and economical reactions to imperfect terrain.
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spelling doaj.art-6a13124cb8c3411586fa41320ecc37e42022-12-21T19:44:22ZengPublic Library of Science (PLoS)PLoS ONE1932-62032018-01-01139e020420510.1371/journal.pone.0204205Optimal regulation of bipedal walking speed despite an unexpected bump in the road.Osman DariciHakan TemeltasArthur D KuoBipedal locomotion may occur over imperfect surfaces with bumps or other features that disrupt steady gait. An unexpected bump in the road is generally expected to slow down most types of locomotion. On wheels, speed may be regained quite readily with "cruise control" performed in continuous time. But legged locomotion is less straightforward, because the stance leg may be under-actuated, and the continuous-time dynamics are periodically disrupted by discrete ground contact events. Those events may also afford good control opportunities, albeit subject to the delay between discrete opportunities. The regulation of walking speed should ideally use these opportunities to compensate for lost time, and with good economy if possible. However, the appropriate control strategy is unknown. Here we present how to restore speed and make up for time lost going over a bump in the road, through discrete, once-per-step control. We use a simple dynamic walking model to determine the optimal sequence of control actions-pushing off from the leg at the end of each stance phase-for fast response or best economy. A two-step, deadbeat sequence is the fastest possible response, and reasonably economical. Slower responses over more steps are more economical overall, but a bigger difference is that they demand considerably less peak power. A simple, reactive control strategy can thus compensate for an unexpected bump, with explicit trade-offs in time and work. Control of legged locomotion is not as straightforward as with wheels, but discrete control actions also allow for effective and economical reactions to imperfect terrain.http://europepmc.org/articles/PMC6157876?pdf=render
spellingShingle Osman Darici
Hakan Temeltas
Arthur D Kuo
Optimal regulation of bipedal walking speed despite an unexpected bump in the road.
PLoS ONE
title Optimal regulation of bipedal walking speed despite an unexpected bump in the road.
title_full Optimal regulation of bipedal walking speed despite an unexpected bump in the road.
title_fullStr Optimal regulation of bipedal walking speed despite an unexpected bump in the road.
title_full_unstemmed Optimal regulation of bipedal walking speed despite an unexpected bump in the road.
title_short Optimal regulation of bipedal walking speed despite an unexpected bump in the road.
title_sort optimal regulation of bipedal walking speed despite an unexpected bump in the road
url http://europepmc.org/articles/PMC6157876?pdf=render
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