Quadruped animals use not only their legs but also their trunks during walking and running. Although many previous studies have investigated the flexion, extension, and lateral bending of the trunk, few studies have investigated the body torsion, and its dynamic effects on locomotion thus remain unclear. In this study, we investigated the effects of body torsion on gait stability during trotting and pacing. Specifically, we constructed a simple model consisting of two rigid bodies connected via a torsional joint that has a torsional spring and four leg springs. We then derived periodic solutions for trotting and pacing and evaluated the stabilities of these motion types using a Poincaré map. We found that the moments of inertia of the bodies and the spring constant ratio of the torsional spring and the leg springs determine the stability of these periodic solutions. We then determined the stability conditions for these parameters and elucidated the relevant mechanisms. In additi...

中文翻译：

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基于简单分析模型的身体扭转柔韧性对小跑和起搏过程中稳定性的影响。

四足动物在行走和跑步时不仅使用腿，还使用躯干。虽然之前的许多研究已经研究了躯干的屈曲、伸展和侧弯，但很少有研究研究身体扭转，因此其对运动的动态影响仍不清楚。在这项研究中，我们研究了在小跑和踱步过程中身体扭转对步态稳定性的影响。具体来说，我们构建了一个简单的模型，该模型由两个刚体组成，这些刚体通过一个扭转关节连接，该扭转关节具有一个扭转弹簧和四个腿弹簧。然后我们推导出小跑和起搏的周期解，并使用庞加莱映射评估这些运动类型的稳定性。我们发现物体的转动惯量和扭簧和腿簧的弹簧常数比决定了这些周期解的稳定性。然后我们确定了这些参数的稳定性条件并阐明了相关机制。此外...