Fu Xun, Zhang Bohao, Weber Ceri J, Cooper Kimberly L, Vasudevan Ram, Moore Talia Y
Robotics, University of Michigan, Ann Arbor, MI, USA.
Department of Cell and Developmental Biology, University of California San Diego, La Jolla, CA, USA.
J R Soc Interface. 2025 Feb;22(223):20240355. doi: 10.1098/rsif.2024.0355. Epub 2025 Feb 5.
Tails used as inertial appendages induce body rotations of animals and robots-a phenomenon that is governed largely by the ratio of the body and tail moments of inertia. However, vertebrate tails have more degrees of freedom (e.g. number of joints and rotational axes) than most current theoretical models and robotic tails. To understand how morphology affects inertial appendage function, we developed an optimization-based approach that finds the maximally effective tail trajectory and measures error from a target trajectory. For tails of equal total length and mass, increasing the number of equal-length joints increased the complexity of maximally effective tail motions. When we optimized the relative lengths of tail bones while keeping the total tail length, mass and number of joints the same, this optimization-based approach found that the lengths matched the pattern found in the tail bones of mammals specialized for inertial manoeuvring. In both experiments, adding joints enhanced the performance of the inertial appendage, but with diminishing returns, largely due to the total control effort constraint. This optimization-based simulation can compare the maximum performance of diverse inertial appendages that dynamically vary in a moment of inertia in three-dimensional space, predict inertial capabilities from skeletal data and inform the design of robotic inertial appendages.
用作惯性附属物的尾巴会引起动物和机器人的身体旋转——这一现象在很大程度上受身体和尾巴转动惯量之比的支配。然而，脊椎动物的尾巴比大多数当前的理论模型和机器人尾巴具有更多的自由度（例如关节数量和旋转轴数量）。为了理解形态如何影响惯性附属物的功能，我们开发了一种基于优化的方法，该方法可找到最大有效尾巴轨迹并测量与目标轨迹的误差。对于总长度和质量相等的尾巴，增加等长关节的数量会增加最大有效尾巴运动的复杂性。当我们在保持尾巴总长度、质量和关节数量不变的情况下优化尾骨的相对长度时，这种基于优化的方法发现这些长度与专门用于惯性 maneuvering 的哺乳动物尾骨中发现的模式相匹配。在这两个实验中，增加关节增强了惯性附属物的性能，但收益递减，这主要是由于总控制努力的限制。这种基于优化的模拟可以比较在三维空间中转动惯量动态变化的各种惯性附属物的最大性能，从骨骼数据预测惯性能力，并为机器人惯性附属物的设计提供信息。
