Collaborative Research: Unsteady Hydrodynamics and Geometric Control of Pisciform Locomotion

这一合作项目将通过对鱼形运动的研究，即通过研究鱼类动物使用的运动策略，改进流体中推进和控制的物理模型和控制设计方法的最先进水平。该项目平衡了基本分析、数值模拟和物理实验。这项工作的一个基石是开发一种模块化的生物运动模拟器(MBE)，该模拟器可以配置成展示各种不同的鱼形策略，从振荡运动(例如金枪鱼使用)到波动运动(例如鳗鱼使用)。这一结果将推动工程系统的能力，朝着在鱼类动物中看到的速度、灵活性、隐形、健壮性和效率的惊人能力迈进。以前的鱼形运动模型在很大程度上依赖于准稳定流动假设，未能捕捉到身体和流体之间重要的非稳定相互作用。这项工作将制定、识别和验证用于非定常流动效应的低维状态空间模型，并将该模型纳入几何控制框架，从而能够设计出最佳的形态和步态。具体地说，该研究计划将产生(I)非定常涡格法(UVLM)作为模拟鱼形运动的工具的评估，(Ii)实验验证的、关于水流中一系列移动翼片上的非定常作用力的降阶状态空间表示，(Iii)使用几何控制模型优化鱼形游泳者的形态和步态的方法，该几何控制模型已被修改为包括非定常流动效应，以及(Iv)使用MBE的拖曳实验的运动、力和可视化数据的参数存储库。

This collaborative project will improve the state-of-the-art of physical models and control design methods for propulsion and control in fluids, through the study of pisciform locomotion -- that is, through the study of movement strategies used by fishlike animals. The project balances fundamental analysis, numerical simulation, and physical experiments. A cornerstone of the effort is the development of a modular biolocomotion emulator (MBE) that can be configured to demonstrate the full spectrum of distinct pisciform strategies, from oscillatory locomotion (used, for example, by tuna) to undulatory locomotion (used, for example, by eels). The results will advance the capabilities of engineered systems, towards the astonishing capabilities for speed, agility, stealth, robustness, and efficiency seen in fishlike animals.Previous models of pisciform locomotion have largely relied on quasi-steady flow assumptions that fail to capture important unsteady interactions between the body and the fluid. This effort will formulate, identify and validate a low-dimensional, state space model for unsteady flow effects and incorporate that model into a geometric control framework that enables the design of optimum morphologies and gaits. Specifically, the research program will produce (i) an assessment of the unsteady vortex lattice method (UVLM) as a tool for modeling pisciform locomotion, (ii) an experimentally validated, reduced-order state space representation for the unsteady forces on a series of moving foils in a flow, (iii) methods for optimizing the morphology and gait of a pisciform swimmer using a geometric control model that has been amended to include unsteady flow effects, and (iv) a parametric repository of motion, force, and visualization data from towing experiments using the MBE.