Aquarium: A Fully Differentiable Fluid-Structure Interaction Solver for Robotics Applications

01/17/2023
by   Jeong Hun Lee, et al.
0

We present Aquarium, a differentiable fluid-structure interaction solver for robotics that offers stable simulation, accurate coupled robot-fluid physics, and full differentiability with respect to fluid states, robot states, and shape parameters. Aquarium achieves stable simulation with accurate flow physics by integrating over the discrete, incompressible Navier-Stokes equations directly using a fully-implicit Crank-Nicolson scheme with a second-order finite-volume spatial discretization. The robot and fluid physics are coupled using the immersed boundary method by formulating the no-slip condition as an equality constraint applied directly to the Navier-Stokes system. This choice of coupling allows the fluid-structure interaction to be posed and solved as a nonlinear optimization problem. This optimization-based formulation is then exploited using the implicit-function theorem to compute derivatives. The derivatives can then be passed to a gradient-based optimization or learning framework. We demonstrate Aquarium's ability to accurately simulate coupled fluid-solid physics with numerous examples, including a cylinder in free stream and a soft robotic tail with hardware validation. We also demonstrate Aquarium's ability to provide full, analytical gradients by performing both shape and gait optimization of a robotic fish tail to maximize generated thrust.

READ FULL TEXT

page 1

page 6

research
10/05/2017

A monolithic fluid-structure interaction formulation for solid and liquid membranes including free-surface contact

A unified fluid-structure interaction (FSI) formulation is presented for...
research
07/08/2020

Fully discrete loosely coupled Robin-Robin scheme for incompressible fluid-structure interaction: stability and error analysis

We consider a fully discrete loosely coupled scheme for incompressible f...
research
07/02/2019

Parallel time-stepping for fluid-structure interactions

We present a parallel time-stepping method for fluid-structure interacti...
research
04/20/2021

Vorticity Maximization of a Linear Fluid Flow via Volume Constrained and Perimeter Regularized Shape Optimization

We study an optimization problem that aims to determine the shape of an ...
research
08/09/2021

Maximizing Vortex for the Navier–Stokes Flow with a Convective Boundary Condition: A Shape Design Problem

In this study, a shape optimization problem for the two-dimensional stat...
research
06/01/2022

Control of Two-way Coupled Fluid Systems with Differentiable Solvers

We investigate the use of deep neural networks to control complex nonlin...

Please sign up or login with your details

Forgot password? Click here to reset