Design and experimental implementation of a hybrid zero dynamics-based controller for planar bipeds with curved feet

Anne Elizabeth Martin, David C. Post, James P. Schmiedeler

    Research output: Contribution to journalArticle

    42 Citations (Scopus)

    Abstract

    This paper extends the use of virtual constraints and hybrid zero dynamics (HZD), a successful control strategy for point-foot bipeds, to the design of controllers for planar curved foot bipeds. Although the rolling contact constraint at the foot-ground interface increases complexity somewhat, the measure of local stability remains a function of configuration only, and a closed-form solution still determines the existence of a periodic orbit. The formulation is validated in experiment using the planar five-link biped ERNIE. While gaits designed for point feet yielded stable walking when ERNIE was equipped with curved feet, errors in both desired speed and joint tracking were significantly larger than for gaits designed for the correct radius curved feet. Thus, HZD-based control of this biped is shown to be robust to some modeling error in the foot radius, but at the same time, to require consideration of foot radius to achieve predictably reliable walking gaits. Additionally, under HZD-based control, this biped walked with lower specific energetic cost of transport and joint tracking errors for matched curved foot gait design and hardware compared to matched point-foot gait design and hardware.

    Original languageEnglish (US)
    Pages (from-to)988-1005
    Number of pages18
    JournalInternational Journal of Robotics Research
    Volume33
    Issue number7
    DOIs
    StatePublished - Jan 1 2014

    Fingerprint

    Gait
    Controller
    Controllers
    Zero
    Radius
    Hardware
    Orbits
    Modeling Error
    Local Stability
    Closed-form Solution
    Periodic Orbits
    Control Strategy
    Design
    Costs
    Contact
    Experiments
    Configuration
    Formulation
    Experiment

    All Science Journal Classification (ASJC) codes

    • Software
    • Modeling and Simulation
    • Mechanical Engineering
    • Electrical and Electronic Engineering
    • Artificial Intelligence
    • Applied Mathematics

    Cite this

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    abstract = "This paper extends the use of virtual constraints and hybrid zero dynamics (HZD), a successful control strategy for point-foot bipeds, to the design of controllers for planar curved foot bipeds. Although the rolling contact constraint at the foot-ground interface increases complexity somewhat, the measure of local stability remains a function of configuration only, and a closed-form solution still determines the existence of a periodic orbit. The formulation is validated in experiment using the planar five-link biped ERNIE. While gaits designed for point feet yielded stable walking when ERNIE was equipped with curved feet, errors in both desired speed and joint tracking were significantly larger than for gaits designed for the correct radius curved feet. Thus, HZD-based control of this biped is shown to be robust to some modeling error in the foot radius, but at the same time, to require consideration of foot radius to achieve predictably reliable walking gaits. Additionally, under HZD-based control, this biped walked with lower specific energetic cost of transport and joint tracking errors for matched curved foot gait design and hardware compared to matched point-foot gait design and hardware.",
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    Design and experimental implementation of a hybrid zero dynamics-based controller for planar bipeds with curved feet. / Martin, Anne Elizabeth; Post, David C.; Schmiedeler, James P.

    In: International Journal of Robotics Research, Vol. 33, No. 7, 01.01.2014, p. 988-1005.

    Research output: Contribution to journalArticle

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