title: Constructing predictive models of human running.
abstract: Running is an essential mode of human locomotion, during which ballistic aerial phases alternate with phases when a single foot contacts the ground. The spring-loaded inverted pendulum (SLIP) provides a starting point for modelling running, and generates ground reaction forces that resemble those of the centre of mass (CoM) of a human runner. Here, we show that while SLIP reproduces within-step kinematics of the CoM in three dimensions, it fails to reproduce stability and predict future motions. We construct SLIP control models using data-driven Floquet analysis, and show how these models may be used to obtain predictive models of human running with six additional states comprising the position and velocity of the swing-leg ankle. Our methods are general, and may be applied to any rhythmic physical system. We provide an approach for identifying an event-driven linear controller that approximates an observed stabilization strategy, and for producing a reduced-state model which closely recovers the observed dynamics.
authors.affiliation: Institute for Sport Science, Technical University Darmstadt, Magdalenenstr. 27, 64289 Darmstadt, Germany mmaus@sport.tu-darmstadt.de.
authors.forename: Horst-Moritz
authors.initials: HM
authors.lastname: Maus
authors.affiliation: Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI, USA.
authors.forename: Shai
authors.initials: S
authors.lastname: Revzen
authors.affiliation: Department of Mathematics, Cornell University, Malott Hall, Ithaca, NY, USA.
authors.forename: John
authors.initials: J
authors.lastname: Guckenheimer
authors.affiliation: Institute for Sport Science, Technical University Darmstadt, Magdalenenstr. 27, 64289 Darmstadt, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Ludwig
authors.affiliation: Department of Computer Science and Automation, Technische Universität Ilmenau, Ilmenau, Germany.
authors.forename: Johann
authors.initials: J
authors.lastname: Reger
authors.affiliation: Institute for Sport Science, Technical University Darmstadt, Magdalenenstr. 27, 64289 Darmstadt, Germany.
authors.forename: Andre
authors.initials: A
authors.lastname: Seyfarth
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena / Q000502:physiology; D006801:Humans; D008297:Male; D008954:Models, Biological; D011237:Predictive Value of Tests; D012420:Running / Q000502:physiology*
keywords: data-driven models; human running; spring-mass model; stabilization; template models