In aquatic pedestrian locomotion the dynamics of terrestrial and aquatic environments are coupled. Here we study terrestrial running and aquatic punting locomotion of the marine-living crab Pachygrapsus marmoratus . We detected both active and passive phases of running and punting through the observation of crab locomotory behaviour in standardized settings and by three-dimensional kinematic analysis of its dynamic gaits using high-speed video cameras. Variations in different stride parameters were studied and compared. The comparison was done based on the dimensionless parameter the Froude number ( Fr ) to account for the effect of buoyancy and size variability among the crabs. The underwater spring-loaded inverted pendulum (USLIP) model better fitted the dynamics of aquatic punting. USLIP takes account of the damping effect of the aquatic environment, a variable not considered by the spring-loaded inverted pendulum (SLIP) model in reduced gravity. Our results highli...

中文翻译：

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潮间带大理石蟹 (Pachygrapsus marmoratus) 的运动行为支持水下弹簧加载倒立摆作为动物平底船的基本模型。

在水上行人运动中，陆地和水生环境的动态是耦合的。在这里，我们研究了海生蟹 Pachygrapsus marmoratus 的陆上奔跑和水上漂流运动。我们通过在标准化环境中观察螃蟹的运动行为以及使用高速摄像机对其动态步态进行三维运动学分析，检测到了奔跑和弃船的主动和被动阶段。研究和比较了不同步幅参数的变化。比较是基于无量纲参数弗劳德数 (Fr) 进行的，以说明螃蟹之间浮力和大小可变性的影响。水下弹簧加载倒立摆 (USLIP) 模型更适合水上平底船的动力学。USLIP 考虑了水生环境的阻尼效应，这是弹簧加载倒立摆 (SLIP) 模型在重力降低时未考虑的变量。我们的结果高度...