Bio-inspired swing leg control for spring-mass robots running on ground with unexpected height disturbance

Vejdani, Hamid; Blum, Yvonne; Daley, Monica A.; Hurst, Jonathan

doi:10.1088/1748-3182/8/4/046006

Cited by 31 publications

(38 citation statements)

References 38 publications

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“…Simple walking and running models have revealed that swing-leg velocity just before the stance transition influences numerous aspects of locomotor dynamics, including stability [14]–[16], [18], robustness [19], leg work [19], [20], disturbance rejection and collision impact energy losses [18]. Previous studies suggest these factors cannot be simultaneously optimized—resulting in a trade-off between two families of performance objectives: swing-leg velocity can be optimized to minimize peak forces, work and collision impacts [16], [18]–[20], or to provide stability, disturbance rejection and robustness of body centre of mass (CoM) dynamics [15], [16], [18]–[20], but not all simultaneously. Thus, a potential trade-off has emerged between optimal swing-leg trajectory to regulate leg loading for injury avoidance , or alternatively, to facilitate steady gait through disturbance rejection .…”

Section: Introductionmentioning

confidence: 99%

“…However, minimizing leg impacts and peak forces may also be critical, because animal legs have relatively constant safety factors in musculoskeletal structures around 2–4× the peak forces of steady locomotion [25], [26]. Perfect disturbance rejection can demand large leg forces [18]–[20], which could lead to musculoskeletal injury. Building legs to withstand very large forces would require carrying extra weight, so limited safety factors in animal legs may reflect a compromise between safety and economy.…”

Section: Introductionmentioning

confidence: 99%

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Swing-Leg Trajectory of Running Guinea Fowl Suggests Task-Level Priority of Force Regulation Rather than Disturbance Rejection

et al. 2014

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To achieve robust and stable legged locomotion in uneven terrain, animals must effectively coordinate limb swing and stance phases, which involve distinct yet coupled dynamics. Recent theoretical studies have highlighted the critical influence of swing-leg trajectory on stability, disturbance rejection, leg loading and economy of walking and running. Yet, simulations suggest that not all these factors can be simultaneously optimized. A potential trade-off arises between the optimal swing-leg trajectory for disturbance rejection (to maintain steady gait) versus regulation of leg loading (for injury avoidance and economy). Here we investigate how running guinea fowl manage this potential trade-off by comparing experimental data to predictions of hypothesis-based simulations of running over a terrain drop perturbation. We use a simple model to predict swing-leg trajectory and running dynamics. In simulations, we generate optimized swing-leg trajectories based upon specific hypotheses for task-level control priorities. We optimized swing trajectories to achieve i) constant peak force, ii) constant axial impulse, or iii) perfect disturbance rejection (steady gait) in the stance following a terrain drop. We compare simulation predictions to experimental data on guinea fowl running over a visible step down. Swing and stance dynamics of running guinea fowl closely match simulations optimized to regulate leg loading (priorities i and ii), and do not match the simulations optimized for disturbance rejection (priority iii). The simulations reinforce previous findings that swing-leg trajectory targeting disturbance rejection demands large increases in stance leg force following a terrain drop. Guinea fowl negotiate a downward step using unsteady dynamics with forward acceleration, and recover to steady gait in subsequent steps. Our results suggest that guinea fowl use swing-leg trajectory consistent with priority for load regulation, and not for steadiness of gait. Swing-leg trajectory optimized for load regulation may facilitate economy and injury avoidance in uneven terrain.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Swing-Leg Trajectory of Running Guinea Fowl Suggests Task-Level Priority of Force Regulation Rather than Disturbance Rejection

et al. 2014

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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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“…Leg retraction can affect the stability of the locomotor system (Blum et al, 2011(Blum et al, , 2010Seyfarth et al, 2003), the size of the disturbances a system can reject (Karssen et al, 2011) and the leg loading during a stance phase (Blum et al, 2014;Vejdani et al, 2013). Adjusting leg retraction velocity alters the landing posture, adjusting a trade-off between achieved successful stance phase versus reducing leg loading (Daley and Usherwood, 2010).…”

Section: Vision and Stabilitymentioning

confidence: 99%

Light level impacts locomotor biomechanics in a secondarily diurnal gecko,Rhoptropus afer

Birn-Jeffery

Higham

2016

Journal of Experimental Biology

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Locomotion through complex habitats relies on the continuous feedback from a number of sensory systems, including vision. Animals face a visual trade-off between acuity and light sensitivity that depends on light levels, which will dramatically impact the ability to process information and move quickly through a habitat, making ambient illumination an incredibly important ecological factor. Despite this, there is a paucity of data examining ambient light in the context of locomotor dynamics. There have been several independent transitions from the nocturnal ancestor to a diurnal activity pattern among geckos. We examined how ambient light level impacted the locomotor performance and high-speed three-dimensional kinematics of a secondarily diurnal, and cursorial, gecko (Rhoptropus afer) from Namibia. This species is active under foggy and sunny conditions, indicating that a range of ambient light conditions is experienced naturally. Locomotor speed was lowest in the 'no-light' condition compared with all other light intensities, occurring via a combination of shorter stride length and lower stride frequency. Additionally, the centre of mass was significantly lower, and the geckos were more sprawled, in the no-light condition relative to all of the higher light intensities. Locomotor behaviour is clearly sub-optimal under lower light conditions, suggesting that ecological conditions, such as very dense fog, might preclude the ability to run quickly during predator-prey interactions. The impact of ambient light on fitness should be explored further, especially in those groups that exhibit multiple transitions between diel activity patterns.

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Bio-inspired swing leg control for spring-mass robots running on ground with unexpected height disturbance

Cited by 31 publications

References 38 publications

Swing-Leg Trajectory of Running Guinea Fowl Suggests Task-Level Priority of Force Regulation Rather than Disturbance Rejection

Swing-Leg Trajectory of Running Guinea Fowl Suggests Task-Level Priority of Force Regulation Rather than Disturbance Rejection

SLIP with swing leg augmentation as a model for running

Light level impacts locomotor biomechanics in a secondarily diurnal gecko,Rhoptropus afer

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