Collaborative Research: Unsteady Hydrodynamics and Geometric Control of Pisciform Locomotion

University Of California-Irvine, Irvine CA

Investigators

Abstract

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.