Unsteady aerodynamic modeling of Aerobat using lifting line theory and Wagner's function

TL;DR

This paper presents a simplified unsteady aerodynamic model for flapping wings using lifting line theory and Wagner's function, enabling efficient simulation and analysis of wake effects in bat-inspired robots.

Contribution

It introduces a state-space aerodynamic force model based on classical theories, reducing computational complexity for simulating unsteady wing aerodynamics.

Findings

Model aligns well with experimental data

Enables wake-based gait analysis

Supports aerodynamic performance optimization

Abstract

Flying animals possess highly complex physical characteristics and are capable of performing agile maneuvers using their wings. The flapping wings generate complex wake structures that influence the aerodynamic forces, which can be difficult to model. While it is possible to model these forces using fluid-structure interaction, it is very computationally expensive and difficult to formulate. In this paper, we follow a simpler approach by deriving the aerodynamic forces using a relatively small number of states and presenting them in a simple state-space form. The formulation utilizes Prandtl's lifting line theory and Wagner's function to determine the unsteady aerodynamic forces acting on the wing in a simulation, which then are compared to experimental data of the bat-inspired robot called the Aerobat. The simulated trailing-edge vortex shedding can be evaluated from this model, which then can be analyzed for a wake-based gait design approach to improve the aerodynamic performance of the robot.