ERATO Synergistic Project, JST, Laboratory for Intelligent Systems and Informatics, Department of Mechano-Informatics, Graduate School of Information Science and Technology, University of Tokyo Bunkyo-ku, Tokyo, Japan.
Front Neurorobot. 2009 Oct 29;3:2. doi: 10.3389/neuro.12.002.2009. eCollection 2009.
Pattern generators found in the spinal cord are no more seen as simple rhythmic oscillators for motion control. Indeed, they achieve flexible and dynamical coordination in interaction with the body and the environment dynamics giving to rise motor synergies. Discovering the mechanisms underlying the control of motor synergies constitutes an important research question not only for neuroscience but also for robotics: the motors coordination of high dimensional robotic systems is still a drawback and new control methods based on biological solutions may reduce their overall complexity. We propose to model the flexible combination of motor synergies in embodied systems via partial phase synchronization of distributed chaotic systems; for specific coupling strength, chaotic systems are able to phase synchronize their dynamics to the resonant frequencies of one external force. We take advantage of this property to explore and exploit the intrinsic dynamics of one specified embodied system. In two experiments with bipedal walkers, we show how motor synergies emerge when the controllers phase synchronize to the body's dynamics, entraining it to its intrinsic behavioral patterns. This stage is characterized by directed information flow from the sensors to the motors exhibiting the optimal situation when the body dynamics drive the controllers (mutual entrainment). Based on our results, we discuss the relevance of our findings for modeling the modular control of distributed pattern generators exhibited in the spinal cord, and for exploring the motor synergies in robots.
脊髓中的模式发生器不再被视为运动控制的简单节奏振荡器。事实上，它们与身体和环境动力学相互作用，实现了灵活和动态的协调，从而产生运动协同作用。发现控制运动协同作用的机制不仅是神经科学的重要研究问题，也是机器人学的重要研究问题：高维机器人系统的电机协调仍然是一个缺点，基于生物解决方案的新控制方法可能会降低它们的整体复杂性。我们提出通过分布式混沌系统的部分相位同步来对体现系统中的运动协同作用进行灵活组合建模；对于特定的耦合强度，混沌系统能够将其动力学与外部力的共振频率进行相位同步。我们利用这一特性来探索和利用特定体现系统的内在动力学。在两个双足步行者的实验中，我们展示了当控制器相位同步到身体的动力学时，运动协同作用是如何出现的，从而使身体遵循其内在的行为模式。这个阶段的特点是从传感器到电机的有向信息流，当身体动力学驱动控制器时（相互同步）表现出最佳情况。基于我们的结果，我们讨论了我们的发现对于模拟脊髓中分布式模式发生器的模块化控制以及探索机器人中的运动协同作用的相关性。
