Lateral undulation of the flexible spine of sprawling posture vertebrates

Wang, Wei; Ji, Aihong; Manoonpong, Poramate; Shen, Huan; Hu, Jie; Dai, Zhendong; Yu, Zhengtao

doi:10.1007/s00359-018-1275-z

Cited by 19 publications

(14 citation statements)

References 74 publications

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“…We developed an agile climbing robot capable of climbing rough or compliant, vertical and inclined surfaces based on the running trot of climbing geckos (figure 1 and electronic supplementary material, figure S1). It is driven via lateral flexion, with diagonal pairs of limbs contacting the surface in unison following biomechanical patterns in lizards (figure 1c) [32,35]. Each foot of the robot uses a four-bar linkage system to simultaneously royalsocietypublishing.org/journal/rspb Proc.…”

Section: Methods (A) Development Of the Bioinspired Climbing Robotmentioning

confidence: 99%

“…Multiple hypotheses have been developed to explain the role the spine might play in sprawled locomotion: it may speed up locomotion [4,26,27]; increase turning ability [16,28]; stabilize the body to prevent slipping [18,29] or alternatively enhance energy efficiency while moving [30,31]. However, it is difficult to investigate this variation since changes in spine use are often coupled with variation in limb development making comparative studies difficult [23,32].…”

Section: (C) Altering the Range Of Motionmentioning

confidence: 99%

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Using a biologically mimicking climbing robot to explore the performance landscape of climbing in lizards

et al. 2021

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Locomotion is a key aspect associated with ecologically relevant tasks for many organisms, therefore, survival often depends on their ability to perform well at these tasks. Despite this significance, we have little idea how different performance tasks are weighted when increased performance in one task comes at the cost of decreased performance in another. Additionally, the ability for natural systems to become optimized to perform a specific task can be limited by structural, historic or functional constraints. Climbing lizards provide a good example of these constraints as climbing ability likely requires the optimization of tasks which may conflict with one another such as increasing speed, avoiding falls and reducing the cost of transport (COT). Understanding how modifications to the lizard bauplan can influence these tasks may allow us to understand the relative weighting of different performance objectives among species. Here, we reconstruct multiple performance landscapes of climbing locomotion using a 10 d.f. robot based upon the lizard bauplan, including an actuated spine, shoulders and feet, the latter which interlock with the surface via claws. This design allows us to independently vary speed, foot angles and range of motion (ROM), while simultaneously collecting data on climbed distance, stability and efficiency. We first demonstrate a trade-off between speed and stability, with high speeds resulting in decreased stability and low speeds an increased COT. By varying foot orientation of fore- and hindfeet independently, we found geckos converge on a narrow optimum of foot angles (fore 20°, hind 100°) for both speed and stability, but avoid a secondary wider optimum (fore −20°, hind −50°) highlighting a possible constraint. Modifying the spine and limb ROM revealed a gradient in performance. Evolutionary modifications in movement among extant species over time appear to follow this gradient towards areas which promote speed and efficiency.

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Section: Methods (A) Development Of the Bioinspired Climbing Robotmentioning

confidence: 99%

Section: (C) Altering the Range Of Motionmentioning

confidence: 99%

Using a biologically mimicking climbing robot to explore the performance landscape of climbing in lizards

et al. 2021

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“…Multiple hypotheses have been developed to explain the role the spine might play in sprawled locomotion: it may speed up locomotion (4,29,30); increase turning ability (17,31); stabilize the body to prevent slipping (13,32); or alternatively enhance energy efficiency while moving (33). However, it is difficult to investigate this variation since changes in spine use is often coupled with variation in limb development making comparative studies difficult (11,27).…”

Section: Resultsmentioning

confidence: 99%

“…We developed an agile climbing robot capable of climbing rough or compliant, vertical, and inclined surfaces based on the running trot of climbing geckos (Extended Data Figure S1). It is driven via lateral flexion, with diagonal pairs of limbs contacting the surface in unison following biomechanical patterns in lizards (10,11). Each foot of the robot uses a 4-bar linkage system to simultaneously raise and push, or lower and pull the foot to engage the claws, mimicking the directional dependent adhesive systems of insects and lizards (12).…”

Section: Development Of the Bio-inspired Climbing Robotmentioning

confidence: 99%

Using a biologically mimicking climbing robot to explore the performance landscape of climbing in lizards

Beck

Haagensen

Proost

et al. 2021

Preprint

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The life and death of an organism often depends on its ability to perform well at some ecologically relevant task. Yet despite this significance we have little idea how well species are optimised for competing locomotor tasks. Most scientists generally accept that the ability for natural systems to become optimised for a specific task is limited by structural, historic or functional constraints. Climbing lizards provide a good example of constraint where climbing ability requires the optimization of conflicting tasks such as speed, stability, or efficiency. Here we reconstruct multiple performance landscapes of climbing locomotion using a 10-DOF robot based upon the lizard bauplan, including an actuated spine, shoulders, and feet, the latter which interlock with the surface via claws. This design allows us to independently vary speed, foot angles, and range of motion, while simultaneously collecting data on climbed distance, stability and efficiency. We first demonstrate a trade-off between speed and stability with high speeds resulting in decreased stability and low speeds an increased cost of transport. By varying foot orientation of fore and hindfeet independently, we found geckos converge on a narrow optimum for both speed and stability, but avoid a secondary wider optimum highlighting a possible constraint. Modifying the spine and limb range of movement revealed a gradient in performance. Evolutionary modifications in movement among extant species appear to follow this gradient towards areas which promote speed and efficiency. This approach can give us a better understanding about locomotor optimization, and provide inspiration for industrial and search-and-rescue robots.Significance StatementClimbing requires the optimization of conflicting tasks such as speed, stability, or efficiency, but understanding the relative importance of these competing performance traits is difficult.We used a highly modular bio-inspired climbing robot to reconstruct performance landscapes for climbing lizards. We then compared the performance of extant species onto these and show strong congruence with lizard phenotypes and robotic optima.Using this method we can show why certain phenotypes are not present among extant species, illustrating why these would be potentially mal-adaptive.These principles may be useful to compare with relative rates of evolution along differing evolutionary histories. It also highlights the importance of biological inspiration towards the optimization of industrial climbing robots, which like lizards, must negotiate complex environments.

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“…Medial impulse scales α M ∼1.04 after taking duty factor into account, while lateral impulse of the hindlimb scales α M ∼1.3 , suggesting that these side-to-side forces may become more important at larger body sizes. The pattern of lateral undulation changes with speed [37][38][39][40] and may vary with body size. Proportionally, higher lateral GRFs and/or magnitudes of lateral undulation in larger sprawling animals may distribute peak forces away from the vertical, enabling them to generate sufficient locomotor force without dangerously high bone stresses in any one direction.…”

Section: Discussionmentioning

confidence: 99%

The scaling of ground reaction forces and duty factor in monitor lizards: implications for locomotion in sprawling tetrapods

et al. 2021

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Geometric scaling predicts a major challenge for legged, terrestrial locomotion. Locomotor support requirements scale identically with body mass ( α M 1 ), while force-generation capacity should scale α M 2/3 as it depends on muscle cross-sectional area. Mammals compensate with more upright limb postures at larger sizes, but it remains unknown how sprawling tetrapods deal with this challenge. Varanid lizards are an ideal group to address this question because they cover an enormous body size range while maintaining a similar bent-limb posture and body proportions. This study reports the scaling of ground reaction forces and duty factor for varanid lizards ranging from 7 g to 37 kg. Impulses (force×time) ( α M 0.99−1.34 ) and peak forces ( α M 0.73−1.00 ) scaled higher than expected. Duty factor scaled α M 0.04 and was higher for the hindlimb than the forelimb. The proportion of vertical impulse to total impulse increased with body size, and impulses decreased while peak forces increased with speed.

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Lateral undulation of the flexible spine of sprawling posture vertebrates

Cited by 19 publications

References 74 publications

Using a biologically mimicking climbing robot to explore the performance landscape of climbing in lizards

Using a biologically mimicking climbing robot to explore the performance landscape of climbing in lizards

Using a biologically mimicking climbing robot to explore the performance landscape of climbing in lizards

The scaling of ground reaction forces and duty factor in monitor lizards: implications for locomotion in sprawling tetrapods

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