2025-03-19 カリフォルニア大学バークレー校 (UCB)
Sebastian Lee (top image) and Justin Yim (bottom)
＜関連情報＞
- https://news.berkeley.edu/2025/03/19/no-robot-can-match-a-squirrels-ability-to-leap-from-limb-to-limb-until-now/
- https://www.science.org/doi/10.1126/scirobotics.adq1949
- https://journals.biologists.com/jeb/article/doi/10.1242/jeb.249934/367220/Free-ranging-squirrels-perform-stable-above-branch
リスのバランス制御にヒントを得た、枝から枝へ跳躍・着地する単足ロボット Monopedal robot branch-to-branch leaping and landing inspired by squirrel balance control
Justin K. Yim, Eric K. Wang, Sebastian D. Lee, Nathaniel H. Hunt, […], and Ronald S. Fearing
Science Robotics Published:19 Mar 2025
DOI:https://doi.org/10.1126/scirobotics.adq1949
Abstract
Locomotors traversing arboreal environments must often leap across large gaps to land on small-diameter supports. Balancing these dynamic landings is challenging because of high incident momentum, restricted foothold options, and reduced capacity to produce reaction torques on narrow supports. We hypothesized that leg length control to enhance branch reaction control authority would markedly expand the range of successful landing conditions, drawing on the same powerful leg actuation required for leaping. Exploring this balance strategy, the monopedal robot Salto-1P demonstrates branch-to-branch leaps, including some upright balanced landings, despite negligible grasping torque. We also compared this landing strategy with the landings of squirrels, which similarly lack the grip strength found in other arboreal species. We demonstrate that greater radial force control reduces the inertial body torque and/or grasping torque at the support required to balance a given landing. Adding simple radial force balance control strategies to conventional balance controllers greatly expands potential landing conditions, increasing the range of initial angular momentum that can be balanced by 230 and 470% across ranges of landing angles for low-order models of the robot and squirrel, respectively.
リスの枝から枝への着地は、脚力と非包括的な足の回転力でバランスをとることで安定した Free-ranging squirrels perform stable, above-branch landings by balancing using leg force and nonprehensile foot torque
Sebastian D. Lee,Stanley Wang,Duyi Kuang,Eric K. Wang,Justin K. Yim,Nathaniel H. Hunt,Ronald S. Fearing,Hannah S. Stuart,Robert J. Full
Journal of Experimental Biology Published:27 February 2025
DOI:https://doi.org/10.1242/jeb.249934
For gap-crossing agility, arboreal animals require the ability to stabilize dynamic landings on branches. Despite lacking a prehensile grip, squirrels achieve stable landings using a palmar grasp. We investigated the landing dynamics of free-ranging fox squirrels (Sciurus niger) to uncover strategies for stable, above-branch landings. Using high-speed video and force-torque measurements in the sagittal plane, we quantified landing kinetics across gap distances. Squirrels rapidly managed >80% of the landing energy with their forelimbs. With larger gaps, peak leg force and foot torque increased. Alignment between forelimbs, velocity, and force increased, likely reducing joint moments. We tested control hypotheses based on an extensible pendulum model used in the physical, hopping robot named Salto. Squirrels stabilized off-target landings by modulating leg force and foot torque. To correct for undershooting, squirrels generated pull up torques and reduced leg force. For overshooting, squirrels generated braking torques and increased leg force. Embodying control principles in leg and foot design can enable stable landings in sparse environments for animals and robots alike, even those lacking prehensile grasps.
