Seyfarth André, Geyer Hartmut, Herr Hugh
Artificial Intelligence Laboratory, Cambridge, MA 02139, USA.
J Exp Biol. 2003 Aug;206(Pt 15):2547-55. doi: 10.1242/jeb.00463.
In running, the spring-like axial behavior of stance limbs is a well-known and remarkably general feature. Here we consider how the rotational behavior of limbs affects running stability. It is commonly observed that running animals retract their limbs just prior to ground contact, moving each foot rearward towards the ground. In this study, we employ a conservative spring-mass model to test the effects of swing-leg retraction on running stability. A feed-forward control scheme is applied where the swing-leg is retracted at constant angular velocity throughout the second half of the swing phase. The control scheme allows the spring-mass system to automatically adapt the angle of attack in response to disturbances in forward speed and stance-limb stiffness. Using a return map to investigate system stability, we propose an optimal swing-leg retraction model for the stabilization of flight phase apex height. The results of this study indicate that swing-leg retraction significantly improves the stability of spring-mass running, suggesting that swing-phase limb dynamics may play an important role in the stabilization of running animals.
在奔跑过程中，支撑肢体类似弹簧的轴向行为是一个广为人知且非常普遍的特征。在此，我们探讨肢体的旋转行为如何影响奔跑稳定性。人们通常观察到，奔跑的动物在即将触地之前会收回肢体，将每只脚向后朝着地面移动。在本研究中，我们采用一个保守的弹簧 - 质量模型来测试摆动腿收回对奔跑稳定性的影响。应用一种前馈控制方案，在摆动阶段的后半段以恒定角速度收回摆动腿。该控制方案使弹簧 - 质量系统能够根据前进速度和支撑肢体刚度的干扰自动调整攻角。通过使用返回映射来研究系统稳定性，我们提出了一个用于稳定飞行阶段顶点高度的最佳摆动腿收回模型。本研究结果表明，摆动腿收回显著提高了弹簧 - 质量模型奔跑的稳定性，这表明摆动阶段肢体动力学可能在奔跑动物的稳定中发挥重要作用。
