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Perspectives on Walking in an Environment

BM 526 Project. Perspectives on Walking in an Environment. Işık Barış Fidaner. BM 526 Project. ?. Human. Walking. Environment. Gait. Locomotion. A walking human being. ____ Central Nervous System. Body. Soul. Walking - Bird’s eye view. Central Nervous System (CNS). output

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Perspectives on Walking in an Environment

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  1. BM 526 Project Perspectives on Walkingin an Environment Işık Barış Fidaner

  2. BM 526 Project ? Human Walking Environment Gait Locomotion

  3. A walking human being ____ Central Nervous System Body Soul

  4. Walking - Bird’s eye view CentralNervousSystem (CNS) output channels input channels Body situated in the Environment

  5. Outputs of CNS • Motor signals • Contract muscles to move forward while controlling the body posture • Auxilliary signals • Movements to enhance the input • Lifting head to see your path

  6. Inputs to the CNS • Visual • Spatiotemporal awareness to predict near future • Audio • Musical sounds to regulate the sense of time • External forces • Ground reactions to optimize energy consumption • Balance • Anxiety, fear of falling to increase posture control

  7. Visual awareness • Threephases of locomotion: • Perceptionandprocessingof thevisualinformation(ppphase) • Executethemovement(motor phase) • Examinetheconsequencesandadaptyourbehavior (Meschner 2008)

  8. Visual awareness • Every pp phase must end before corresponding motor phase begins • Perceptions are buffered in short-term memory (Meschner 2008)

  9. Visual awareness • Locomotion is a complexvariablebehavioralcontingency • Sharessamestructurewithotheractivitiesthatrequire “thinkingahead” such as • Readingoutloud • Dancing • Foraging (Meschner 2008)

  10. Effect of music and rhythm • Effect of music vs. raw metronome ranging through 50 to 190 BPM on walking vs. tapping finger, in terms of • Synchronization • Adapting walking tempo to the music • Spatialization • Effect on walking style, speed, step length etc. (Styns et al. 2007)

  11. Effect of music and rhythm • Synchronization • Bettersync in tapping • An optimum musical tempoexiststhatmaximizessync in walking(near 120 BPM) • Spatialization • Musicmakes us walkfaster, comparedtorawmetronome at same tempo • An optimum walking tempoexiststhatmaximizes step size(alsonear 120 BPM) (Styns et al. 2007)

  12. Resonance behavior • Step sizeresonateswithwalking tempo • Accordingto • fundamentalfrequency • damping factor • 2 Hz (=120 BPM) resonancefrequency in thelong-termenergyspectrum(Dougall et al. 2005) • Spontaneousorself-selected tempo of humanlocomotion (Styns et al. 2007)

  13. External forces • Groundreactionforceacts on our body throughfeet • Body forceacts on theground • GRF on a solidground: • GRF does not varywith time • Musclesreacttopreserve body posture • GRF on a flexibleground: • Oscillating in vertical, anterior-posteriororlateralcomponents • Walkingstyleandtempo adaptstothe time dynamics of GRF (Racic et al. May 2009)

  14. The Millennium Bridge • Opening ceremony in London, June 2000 (Racic et al. May 2009)

  15. The Millennium Bridge • Lateraloscillationupto7 cm! • Spontaneouswalking tempo • Vertical / Anterior: 2 Hz • Lateralcomponent: 1 Hz • Samewiththebridge’snaturalfrequency of lateraloscillation! • Peoplesynchronizedtheir tempo toeachotherandthebridge, forming a positivefeedbackloop (Racic et al. May 2009)

  16. External forces • Forceplates • Recordssinglesteps • Instrumentedtreadmill • Records a sequence of steps • Verticalandlateral GRF increasewithspeed • Anterior GRF reaches a maximum at 5.6 kmph(spontaneousspeed) • Time / frequencydomain • Deterministic / stochasticmodels (Racic et al. May 2009)

  17. Effect of anxiety, fear of falling • Old and young subjects • Each stands on the platform • Higher or lower platform • At the edge or at the middle • Recorded for each trial: • Galvanic skin conductance (GSC) to infer anxiety • Body center of mass (COM) and center of pressure (COP) to estimate motor behavior (Brown et al. 2006)

  18. Effect of anxiety, fear of falling • Standing on theedge, orhigherplatformscaused: • Increased GSC (anxiety) • Decreasedmean COM andCOP in anteriordirection(leaningbackwards) • Decreasedstdev of COP and COM (morecontrol) • Increase in meanpowerfrequency of COP • (c) and (d) Increasedstiffness in anklejoint (Brown et al. 2006)

  19. Effect of anxiety, fear of falling • No significant change dueto age difference • Standing near height or edges causes anxiety • Anxiety causes increasedcontrol on body posture • Contrary to previous work, fear may be beneficial to protect one’s body from falling (Brown et al. 2006)

  20. Conclusion: • Buffering, spatiotemporalawareness • Resonancein step size, optimum tempo of walking • Synchronizetostructure, positivefeedbackloop • Anxiety, fear of falling, increasedcontrol Biomechanics Behavioral science Musicology Civil engineering Psychology ….?

  21. Conclusion: • Different perspectives, separate disciplines • Common object of study • Multidisciplinary studies of walking Human Biomechanics Behavioral science Musicology Civil engineering Psychology ….?

  22. BM 526 Project Perspectives on Walkingin an Environment Işık Barış Fidaner

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