Tanikawa Toyoaki, Masuda Yoichi, Ishikawa Masato
Department of Mechanical Engineering, Osaka University, Suita, Japan.
Front Neurorobot. 2021 Apr 8;15:636864. doi: 10.3389/fnbot.2021.636864. eCollection 2021.
Spinal reflex is essential to the robust locomotion of quadruped animals. To investigate the reflex mechanisms, we developed a quadruped robot platform that emulates the neuromuscular dynamics of animals. The leg is designed to be highly back-drivable, and four Hill-type muscles and neuronal pathways are simulated on each leg using software. By searching for the reflex circuit that contributes to the generation of steady gait in cats through robotic experiments, we found a simple reflex circuit that could produce leg trajectories and a steady gait. In addition, this circuit can reproduce the experimental behavior observed in cats. As a major contribution of this study, we show that the underlying structure of the reflex circuit is the reciprocal coupling between extensor muscles via excitatory neural pathways. In the walking experiments on the robot, a steady gait and experimental behaviors of walking cats emerged from the reflex circuit without any central pattern generators. Furthermore, to take advantage of walking experiments using a neurophysiological robotic platform, we conducted experiments in which a part of the proposed reflex circuit was disconnected for a certain period of time during walking. The results showed that the prolongation of the stance phase caused by the reciprocal excitatory reflex contributed greatly to the generation of a steady gait.
脊髓反射对于四足动物稳健的运动至关重要。为了研究反射机制，我们开发了一个模拟动物神经肌肉动力学的四足机器人平台。腿部设计为具有高度的反向驱动性，并且使用软件在每条腿上模拟了四块希尔型肌肉和神经通路。通过机器人实验寻找有助于猫产生稳定步态的反射回路，我们发现了一个能产生腿部轨迹和稳定步态的简单反射回路。此外，该回路能够重现猫身上观察到的实验行为。作为本研究的一项主要贡献，我们表明反射回路的潜在结构是通过兴奋性神经通路实现的伸肌之间的相互耦合。在机器人的行走实验中，稳定的步态和行走猫的实验行为从反射回路中出现，而无需任何中枢模式发生器。此外，为了利用神经生理学机器人平台进行行走实验，我们进行了实验，在行走过程中，将所提出的反射回路的一部分断开一段时间。结果表明，由相互兴奋性反射引起的站立期延长对稳定步态的产生有很大贡献。
