Beijing Computational Science Research Center, Haidian District, Beijing 100193, People's Republic of China.
Bioinspir Biomim. 2018 May 8;13(4):046001. doi: 10.1088/1748-3190/aab805.
In undulatory locomotion, torques along the body are required to overcome external forces from the environment and bend the body. These torques are usually generated by muscles in animals and closely related to muscle activations. In previous studies, researchers observed a single traveling wave pattern of the torque or muscle activation, but the formation of the torque pattern is still not well understood. To elucidate the formation of the torque pattern required by external resistive forces and the transition as kinematic parameters vary, we use simplistic resistive force theory models of self-propelled, steady undulatory locomotors and examine the spatio-temporal variation of the internal torque. We find that the internal torque has a traveling wave pattern with a decreasing speed normalized by the curvature speed as the wave number (the number of wavelengths on the locomotor's body) increases from 0.5 to 1.8. As the wave number increases to 2 and greater values, the torque transitions into a two-wave-like pattern and complex patterns. Using phasor diagram analysis, we reveal that the formation and transitions of the pattern are consequences of the integration and cancellation of force phasors.
在波动式运动中，需要沿着身体产生扭矩来克服环境的外力并弯曲身体。这些扭矩通常由动物体内的肌肉产生，与肌肉活动密切相关。在之前的研究中，研究人员观察到扭矩或肌肉活动的单一行进波模式，但扭矩模式的形成仍未得到很好的理解。为了阐明外部阻力所需的扭矩模式的形成以及运动学参数变化时的过渡，我们使用自主推进的、稳定波动式运动器的简化阻力理论模型，并检查内部扭矩的时空变化。我们发现，内部扭矩具有行进波模式，其速度随着波数（运动器体上的波长数）从 0.5 增加到 1.8 而按曲率速度归一化减小。当波数增加到 2 及更大的值时，扭矩过渡为两波类似的模式和复杂的模式。通过相量图分析，我们揭示了模式的形成和过渡是力相量的积分和抵消的结果。
