Quantifying dynamic stability and maneuverability in legged locomotion
Quantifying dynamic stability and maneuverability in legged locomotion
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DOI：
10.1093/icb/42.1.149
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发表时间：
2002-02-01
影响因子：
2.6
通讯作者：
Koditschek, D
中科院分区：
文献类型：
--
作者：
Full, RJ;Kubow, T;Koditschek, D
动物可以转向、闪避、俯冲、攀爬、转弯和突然停止。它们的稳定性和可操作性非常出色，但量化是一个挑战。正式的稳定性分析可以进行物种内部和物种之间的定量比较。稳定性分析与模板（作为控制指南的简单通用模型）结合使用可以得出可检验的功能假设。在不了解动物机械（肌肉骨骼）系统的情况下假设的神经控制模型可能会适得其反，甚至破坏稳定。由于系统是动态耦合的，通过一个方向的反射反馈主动校正的扰动可能会导致其他方向的扰动。从一个方向的扰动恢复的被动速率不同于其他方向的速率。我们假设动物可能在通过被动动力学快速恢复的方向（例如身体定向和旋转）施加较少的神经控制。相比之下，动物可能会通过被动动力学（例如前进速度和航向）对缓慢恢复或根本不恢复的方向施加更多的神经控制。当神经控制与机械系统的自然、被动动力学配合使用时，可以最好地增强稳定性。测量可操作性更具挑战性，需要新的通用指标。模板表明，对总力的简单分析和压力中心的量化可以得出有价值的假设，而运动学描述可能不充分。对稳定性和可操作性的研究与动物的行为和生态有直接关系，但如果要理解动物设计也至关重要。动物对于稳态、直线运动来说似乎严重过度，因为它们似乎拥有太多的神经元、肌肉、关节，甚至太多的附肢。动物运动的下一步是让动物受到扰动并揭示其所有部分的功能。
Animals can swerve, dodge, dive, climb, turn and stop abruptly. Their stability and maneuverability are remarkable, but a challenge to quantify. Formal stability analysis can allow for quantitative comparisons within and among species. Stability analysis used in concert with a template (a simple, general model that serves as a guide for control) can lead to testable hypotheses of function. Neural control models postulated without knowledge of the animal's mechanical (musculo-skeletal) system can be counterproductive and even destabilizing. Perturbations actively corrected by reflex feedback in one direction can result in perturbations in other directions because the system is coupled dynamically. The passive rate of recovery from a perturbation in one direction differs from rates in other directions. We hypothesize that animals might exert less neural control in directions that rapidly recover via passive dynamics (e.g., in body orientation and rotation). By contrast, animals are likely to exert more neural control in directions that recover slowly or not at all via passive dynamics (e.g., forward velocity and heading). Neural control best enhances stability when it works with the natural, passive dynamics of the mechanical system. Measuring maneuverability is more challenging and new, general metrics are needed. Templates reveal that simple analyses of summed forces and quantification of the center of pressure can lead to valuable hypotheses, whereas kinematic descriptions may be inadequate. The study of stability and maneuverability has direct relevance to the behavior and ecology of animals, but is also critical if animal design is to be understood. Animals appear to be grossly over-built for steady-state, straight-ahead locomotion, as they appear to possess too many neurons, muscles, joints and even too many appendages. The next step in animal locomotion is to subject animals to perturbations and reveal the function of all their parts.