Department of Ecology and Evolutionary Biology, University of California, Irvine, CA 92697, USA.
Biol Lett. 2011 Jun 23;7(3):384-6. doi: 10.1098/rsbl.2010.1029. Epub 2010 Dec 8.
Lever systems within a skeleton transmit force with a capacity determined by the mechanical advantage, A. A is the distance from input force to a joint, divided by the distance from the joint to the output force. A lever with a relatively high A in static equilibrium has a great capacity to generate force but moves a load over a small distance. Therefore, the geometry of a skeletal lever presents a trade-off between force and speed under quasi-static conditions. The present study considers skeletal dynamics that do not assume static equilibrium by modelling kicking by a locust leg, which is powered by stored elastic energy. This model predicts that the output force of this lever is proportional to A, but its maximum speed is independent of A. Therefore, no trade-off between force and velocity exists in a lever system with spring-mass dynamics. This demonstrates that the motion of a skeleton depends on the major forces that govern its dynamics and cannot be inferred from skeletal geometry alone.
骨骼中的杠杆系统通过机械优势 A 来传递力，A 是输入力到关节的距离除以关节到输出力的距离。在静态平衡中，具有相对较高 A 的杠杆具有产生力的巨大能力，但只能移动负载一小段距离。因此，骨骼杠杆的几何形状在准静态条件下在力和速度之间呈现出一种权衡。本研究通过对蝗虫腿部踢腿的建模来考虑不假设静态平衡的骨骼动力学，蝗虫腿部由储存的弹性能量提供动力。该模型预测，这种杠杆的输出力与 A 成正比，但最大速度与 A 无关。因此，在具有弹簧质量动力学的杠杆系统中，不存在力与速度之间的权衡。这表明骨骼的运动取决于控制其动力学的主要力，而不能仅从骨骼几何形状推断出来。
