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Abstract ObjectivesDespite qualitative observations of wild primates pumping branches before leaping across gaps in the canopy, most studies have suggested that support compliance increases the energetic cost of arboreal leaping, thus limiting leaping performance. In this study, we quantified branch pumping behavior and tree swaying in wild primates to test the hypothesis that these behaviors improve leaping performance. Materials and MethodsWe recorded wild colobine monkeys crossing gaps in the canopy and quantitatively tracked the kinematics of both the monkey and the compliant support during behavioral sequences. We also empirically measured the compliance of a sample of locomotor supports in the monkeys' natural habitat, allowing us to quantify the resonant properties of substrates used during leaping. ResultsAnalyses of three recordings show that adult red colobus monkeys (Piliocolobus tephrosceles) use branch compliance to their advantage by actively pumping branches before leaping, augmenting their vertical velocity at take‐off. Quantitative modeling of branch resonance periods, based on empirical measurements of support compliance, suggests that monkeys specifically employed branch pumping on relatively thin branches with protracted periods of oscillation. Finally, an additional four recordings show that both red colobus and black and white colobus monkeys (Colobus guereza) utilize tree swaying to cross large gaps, augmenting horizontal velocity at take‐off. DiscussionThis deliberate branch manipulation to produce a mechanical effect for stronger propulsion is consistent with the framework of instrumental problem‐solving. To our knowledge, this is the first study of wild primates which quantitatively shows how compliant branches can be used advantageously to augment locomotor performance.
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This content will become publicly available on March 1, 2026
Unification of mathematical descriptions of compliant behavior centers with physical realizations of those behaviors
Abstract A more intuitive appreciation of spatial compliant behavior can be obtained through analysis and description of the behavior in terms of itscenters, specifically the center of stiffness, the center of compliance, and the center of elasticity. This paper investigates the properties of each of these centers. Necessary and sufficient conditions for the coincidence of these centers are identified. A physical appreciation of those compliant behaviors that have coincident centers is obtained in terms of restrictions on the geometry of topologically simple mechanisms that realize those behaviors. The results can be used in the design of compliant mechanisms for robotic manipulation, especially when the compliance is characterized by the location of its center.
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- Award ID(s):
- 2024554
- PAR ID:
- 10637314
- Publisher / Repository:
- Cambridge University Press
- Date Published:
- Journal Name:
- Robotica
- Volume:
- 43
- Issue:
- 3
- ISSN:
- 0263-5747
- Page Range / eLocation ID:
- 1171 to 1197
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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