Advanced Swing Leg Control for Stable Locomotion

Blum, Yvonne; Rummel, Juergen; Seyfarth, André

doi:10.1007/978-3-540-74764-2_46

Cited by 19 publications

(16 citation statements)

References 8 publications

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“…Postural changes at the time of ground contact are mediated through leg retraction and leg length change during the late swing phase (Blum et al, 2007;Blum et al, 2010;Seyfarth et al, 2003). Consequently, the swing leg trajectory is a crucial control target for stability, robustness and injury avoidance in uneven terrain (Blum et al, 2007;Blum et al, 2011;Daley and Usherwood, 2010;Seyfarth et al, 2003).…”

Section: Evidence Of Anticipation and Active Controlmentioning

confidence: 99%

Birds achieve high robustness in uneven terrain through active control of landing conditions

Birn-Jeffery

Daley

2012

Journal of Experimental Biology

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SUMMARYWe understand little about how animals adjust locomotor behaviour to negotiate uneven terrain. The mechanical demands and constraints of such behaviours likely differ from uniform terrain locomotion. Here we investigated how common pheasants negotiate visible obstacles with heights from 10 to 50% of leg length. Our goal was to determine the neuro-mechanical strategies used to achieve robust stability, and address whether strategies vary with obstacle height. We found that control of landing conditions was crucial for minimising fluctuations in stance leg loading and work in uneven terrain. Variation in touchdown leg angle ( TD ) was correlated with the orientation of ground force during stance, and the angle between the leg and body velocity vector at touchdown ( TD ) was correlated with net limb work. Pheasants actively targeted obstacles to control body velocity and leg posture at touchdown to achieve nearly steady dynamics on the obstacle step. In the approach step to an obstacle, the birds produced net positive limb work to launch themselves upward. On the obstacle, body dynamics were similar to uniform terrain. Pheasants also increased swing leg retraction velocity during obstacle negotiation, which we suggest is an active strategy to minimise fluctuations in peak force and leg posture in uneven terrain. Thus, pheasants appear to achieve robustly stable locomotion through a combination of path planning using visual feedback and active adjustment of leg swing dynamics to control landing conditions. We suggest that strategies for robust stability are context specific, depending on the quality of sensory feedback available, especially visual input.

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Section: Evidence Of Anticipation and Active Controlmentioning

confidence: 99%

Birds achieve high robustness in uneven terrain through active control of landing conditions

Birn-Jeffery

Daley

2012

Journal of Experimental Biology

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“…Thus, increasing the pendulum length yields in slower motion 3 and consequently, steeper leg (smaller angle of attack) at touch down. It happens because of swing leg retraction which is observed already in human locomotion [19], [20], [21] and simulated models [22], [23], [13]. Eventually, smaller angle of attack reduces the forward speed [3] which means that the correlation between l p and V x should be around −1.…”

Section: System Analysismentioning

confidence: 91%

SLIP with swing leg augmentation as a model for running

Rashty

Sharbafi

Seyfarth

2014

2014 IEEE/RSJ International Conference on Intelligent Robots and Systems

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Abstract-Swing leg adjustment, repulsive leg function and balance are key elements in the control of bipedal locomotion. In simple gait models like spring-loaded inverted pendulum (SLIP), swing leg control can be applied to achieve stable running. The aim of this study is to investigate the ability of pendulum like swing leg motion for stabilizing running and reproducing a desired (human like) gait pattern. The employed running model consists of two sub-models: SLIP model for the stance phase and a pendulum based control for the swing phase. It is shown that with changing the pendulum length at each step, stable running gaits with widely different performances are achieved. The body vertical speed at take off is utilized as feedback information to tune the pendulum length as the control parameter. In particular, the effect of the pendulum length adjustment on the motion characteristics like horizontal speed, apex height and the stabilized system energy will be investigated. With this method key features of the human like swing leg motion e.g. leg retraction can be reproduced. Higher speeds correspond larger angular motion of each leg which is in agreement with experimental results in previous studies. The presented model also explains the swing-leg to stance-leg interaction mechanism which was not addressed in the underlying SLIP model. This conceptual model can be considered as a functional mechanical template for legged locomotion and can be used to build more complex models, e.g. having segmented legs or an upper body.

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“…Since 2003, there have been several studies to verify SLR as a control scheme in gait models and to find an optimal SLR speed for those models, [4][5][6][7][8] though literature on SLR in human motion is sparse. Swing-leg retraction was observed in Muybridge's images on human locomotion 9 and in some experimental studies accompanying papers focused on its presence in modeling.…”

Section: Introductionmentioning

confidence: 99%

Characterizing Swing-Leg Retraction in Human Locomotion

Poggensee¹,

Sharbafi²,

Seyfarth³

et al. 2014

Mobile Service Robotics

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Swing-leg retraction, the backward rotation of the swing leg just prior to ground contact, is observed in human locomotion. While several advantages of swingleg retraction, like gait stability and perturbation rejection, are shown by conceptual models, there is currently very little experimental data on swing-leg retraction in human motion. In this paper, kinematic data for twenty-eight subjects walking and running at different speeds are analyzed. Swing-leg retraction was shown to exist in walking and running at every non-zero speed. Additionally, swing-leg retraction speed and acceleration linearly increase with gait speed. At comparable gait speeds, swing-leg retraction speed is higher for running than for walking.

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Advanced Swing Leg Control for Stable Locomotion

Cited by 19 publications

References 8 publications

Birds achieve high robustness in uneven terrain through active control of landing conditions

Birds achieve high robustness in uneven terrain through active control of landing conditions

SLIP with swing leg augmentation as a model for running

Characterizing Swing-Leg Retraction in Human Locomotion

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