Phanindra Tallapragada
Phanindra Tallapragada, an assistant professor of mechanical engineering, has won a grant to support the project “Mechanics of Locomotion with Nonholonomic Constraints in a Fluid”. The grant will be funded by the Dynamics, Control and Systems Diagnostics (DCSD) program, which is part of the Civil, Mechanical and Manufacturing Innovation (CMMI) division at the NSF.
This award supports fundamental research into the interactions of a fish-like body with a surrounding fluid, and the ways in which motion of the body can transfer energy and momentum for propulsion and maneuverability. The research builds upon recent results that show how the complex dynamics of certain types of fish-like bodies can be captured in the form of a relatively tractable nonholonomic constraint, that is, an algebraic relationship between the velocities of different parts of the system. This project will generalize and extend the consequences of this result, and clarify the variables that govern this class of fluid-structure interaction. Robotic platforms will be built to experimentally validate the theoretical insights. The ability to precisely maneuver small aquatic robots has many important applications, including the inspection of underwater structures, environmental monitoring, and underwater exploration. The results of this project will lead to improved design of aquatic robots with different shapes, sizes and propulsion mechanisms. The natural appeal of fish-like robots will be leveraged to recruit members of underrepresented groups into engineering, to develop attractive independent research projects for undergraduate students, and to demonstrate and motivate key aspects of fluid mechanics in undergraduate courses. The project provides a rich multidisciplinary research education and training environment, demonstrating synergy between subjects, including fluid mechanics, nonlinear dynamics, geometric mechanics, and control theory, which are rarely connected at the undergraduate level.
The motion of a fish-like body in water is governed by the changes in its shape, the creation of vorticity and the interaction of the body with such vorticity. The creation of vorticity imposes a nonholonomic constraint on the motion of the body. The primary aim of the research supported by this award is to create a mathematical framework that can illuminate the interplay of abstract shape variables and nonholonomic constraints on the motion of a body in water. Shape variables will take form of internal masses and rotors. The constraints in the form of vorticity creation will be modeled using discrete vortex approximations. Such models with the novel interpretation of vortex shedding as a nonholonomic constraint are well suited to understand and emulate the efficiency and maneuverability of fish, to investigate gaits and to design control algorithms for an aquatic robot. Aquatic robots propelled and maneuvered entirely via internal rotors or moving masses will be designed and provide a platform to validate the theoretical results.
