Investigating Sea Lion Locomotion as the Basis for Shape Changing UUVs
Abstract
The objective of this work is to determine strategies for the propulsion and dynamics offlexible, shape changing unmanned underwater vehicles (UUVs) that can operate in and exploit high-energy environments with the potential for surf-to-land transitions. The basisfor an innovative UUV is the California sea lion (Zalophus californianus). This marine mammal displays morphological and behavioral characteristics~speed, agility, and flexibility~that allow it to operate in flow conditions that conform to projected naval operations.This study will provide us with a digital catalog of sea lion maneuvers and a detailed mathematical description of them. The study will initially focus on steady swimmingbehavior (the ~clap~) before progressing to include turning, accelerating and other advanced maneuvers. We will obtain both two- and three-dimensional data using three synchronized digital cameras. This required significant development of markerless threedimensionaltracking techniques for large free-swimming bodies.Once we gather kinematic data, we will determine the associated motion primitives and six-degree-of-freedom models and associated control strategies to translate these biological results to future flexible robotic vehicles. These models will use Poincare s equations, which area generalized form of Lagrange~s equations that are used to characterize the dynamical behavior of a variety of mechanical systems. Once this is done, the primary objective is to understand how body flexure can be used to enhance maneuvering capabilities of undersea vehicles. At the basic level, we propose to investigate how the extent to which the ability to bend and twist the flexible body enhances ~controllability.~This project is a natural, innovative extension of work on unsteady propulsion that has been carried out over the last decade. However, unlike previous results, which indicate that efficient underwater thrust production is at the cost of maneuverability and flexibility, the sea loin offers a potential paradigm wherein efficient, effective propulsion does not have to be dominated by heaving and pitching fins at a regular oscillatory frequency. Thus, it has the specific potential for creating efficient, robust underwater propulsion that can operate over a range of flow conditions and has the potential to movefrom the surf to the shore, an expressed mission of the Office of Naval Research (ONR). This project will have a strong scientific contribution, both in the physics that will be explored and the methods that will be developed. The main method developments are markerless, three-dimensional tracking of a large, freely swimming object (while methods exist for small-scale motion (insects) or highly predictable motions (human walking), these tools are not available for general locomotion with an unknowntrajectory). The physics we will explore, the efficient, pulsatile swimming of the sea lion that incorporates that reactions of the fins and flexing body, will explore a new paradigm of high performance biologically inspired locomotion. Finally, we will provide insight into the complex connection of fin, body forces and their control as necessary for a sea lion inspired UUV.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 03, 2017
- Source ID
- N000141712312
Entities
People
- Megan C. Leftwich
Organizations
- George Washington University
- Office of Naval Research
- United States Navy