Maykranz Daniel, Seyfarth Andre
Locomotion Laboratory Magdalenenstr. 27, 64289 Darmstadt, Germany.
J Theor Biol. 2014 May 21;349:44-9. doi: 10.1016/j.jtbi.2014.01.029. Epub 2014 Jan 31.
The spring loaded inverted pendulum (SLIP) model is widely used to predict and explain basic characteristics of human walking and running. Its periodic running solutions can be mirrored at the instant of the vertical orientation of the leg and thus are symmetric between landing and take-off. In contrast, human running shows asymmetries between touchdown and take-off (e.g. shorter brake than push duration, greater mean ground reaction force during braking phase). Yet it is not fully understood whether these asymmetries are caused by asymmetric muscle properties (e.g. velocity-dependent force generation) or the asymmetric lever arm system in the human leg. We extend the SLIP model by a foot segment and a compliant ankle joint. This represents the extended foot contact and the displacement of the center of pressure during contact. With this model we investigate to which extent the landing-take off asymmetry in legged locomotion is caused by this asymmetric lever arm system. We find similar landing-take off asymmetries as in human running suggesting that the asymmetric lever arm system contributes to the asymmetry.
弹簧加载倒立摆（SLIP）模型被广泛用于预测和解释人类行走与跑步的基本特征。其周期性跑步解决方案在腿部垂直方向瞬间可镜像，因此在着陆和起飞之间是对称的。相比之下，人类跑步在触地和起飞之间表现出不对称性（例如制动时间比推动时间短，制动阶段平均地面反作用力更大）。然而，目前尚不完全清楚这些不对称性是由不对称的肌肉特性（例如速度依赖的力产生）还是人类腿部的不对称杠杆臂系统引起的。我们通过一个足部节段和一个柔顺踝关节扩展了SLIP模型。这代表了扩展的足部接触以及接触过程中压力中心的位移。利用这个模型，我们研究有腿运动中的着陆 - 起飞不对称性在多大程度上是由这种不对称杠杆臂系统引起的。我们发现与人类跑步中类似的着陆 - 起飞不对称性，这表明不对称杠杆臂系统导致了这种不对称性。
