Flocks of Swimming Micro-robots with Long-range Hydrodynamic Interaction and Objectives

这个项目将创造一群游泳机器人，它们在高粘性的流体环境中工作，并协同影响。由于尺寸对不同流体力的相对贡献的影响，微米级机器人在水中的行为类似于厘米级机器人在粘性流体（如玉米糖浆或机油）中的行为。高粘性流体也可以模拟像沙子这样的颗粒介质中的运动。高粘度的一个影响是，一个机器人的运动可能会影响到许多身长之外的其他机器人。因此，这个项目将为考虑到这些相互作用的大型游泳机器人群创造新的轨迹规划和运动控制方法。两种可选择的控制模式将是本研究的重点。首先是最大限度地发挥游群的远距离效应，从而增强流体环境的混合性。二是最小化远程影响，使机器人群能够隐身移动。这些群的一些潜在应用包括油箱的机器人检查，环境监测和修复，以及血管中的多剂药物输送系统。本项目涉及多学科，从基础流体力学到机器人设计与控制。与这一多学科建议有关的研究和教育活动预计将使广泛的受众能够接触到这一主题，包括传统上代表性不足的群体和与国家工业有关的工程社区。创造能够在高粘性环境中移动和翻滚的人造游泳者带来了许多根本性的挑战。长期水动力相互作用非线性耦合了群体游泳者的推进功能，对粘性状态下的游泳有显著影响。长时间的流体动力相互作用很容易引起混沌，并导致不可预测的集体行为。该项目解决了非线性水动力相互作用下的第一个三维控制游泳者群。作为基准，实验将使用一个名为Quadroar的游泳者进行，并研究该游泳者在（准）周期和混沌群体行为之间切换的能力。将执行两项基本任务：(i)对群进行主动最优控制，以在背景流体中实现最高的混合效率（混沌混合模式）；（ii）对一个群体进行主动控制，使水动力相互作用相互抵消，即游泳者在对周围流体干扰最小的情况下聚集，并保持隐身（隐蔽群体模式）。这些模式为环境中介机器人群体定义了新的群体目标。

This project will create flocks of swimming robots that operate in, and cooperatively influence, highly viscous fluid environments. Because of the effect of size on the relative contributions of different fluid forces, micrometer-scale robots in water behave similarly to centimeter-scale robots in viscous fluids such as corn syrup or motor oil. High viscous fluids can also model movement in granular media like sand. One effect of high viscosity is that the movement of one robot may affect other robots many body lengths distant. Thus this project will create new methods of trajectory planning and motion control for large flocks of swimming robots that take these interactions into account. Two selectable modes of control will be the focus of this study. The first is to maximize the long-range effects of the swimming flock, so as to enhance mixing of the fluid environment. The second is to minimize long-range effects, so as to allow stealthy movement of the robot flock. Some potential applications of these flocks include robotic inspection of oil tanks, environmental monitoring and remediation, and multi-agent drug delivery systems in blood vessels. This project is multidisciplinary covering from fundamental fluid mechanics to robot design and control. The research and educational activities associated with this multidisciplinary proposal are expected to make the subject accessible to a broad audience including traditionally under-represented groups and engineering community affiliated with national industries.The creation of artificial swimmers capable of moving and tumbling in highly viscous environments poses numerous fundamental challenges. Swimming in viscous regimes is significantly affected by long-range hydrodynamic interactions that nonlinearly couple the propulsion function of swimmers in a swarm. Long-range hydrodynamic interactions can easily induce chaos, and lead to unpredictable collective behaviors. This project addresses the first three-dimensional controlled flock of swimmers under nonlinear hydrodynamic interactions. As a benchmark, experiments will be conducted using a swimmer called Quadroar, and the capability of this swimmer to switch between (quasi) periodic and chaotic group behaviors will be investigated. Two fundamental missions will be implemented: (i) Active optimal control of a flock to achieve the highest mixing efficiency in the background fluid (Chaotic Mixing mode); and (ii) Active control of a flock such that hydrodynamic interactions cancel each other, that is, swimmers flock with minimally disturbing the surrounding fluid, and remain stealth (Concealed Swarm mode). These modes define new group objectives for environment-mediated robotic swarms.