NSF grant will help fund engineering professor’s research of bio-inspired micro-air vehicles

These high-speed video snapshots of a monarch in flight were captured in UAH’s ATOM Lab, which provides high-speed, low-latency, real-time three-dimensional tracking of freely moving objects. Its 33 Vicon T40 infrared cameras can track 50 unique objects at up to 370 frames per second with a latency of 5 milliseconds, and a spatial resolution of 1.5 mm.

Dr. Chang-kwon Kang, an assistant professor in the Department of Mechanical and Aerospace Engineering at The University of Alabama in Huntsville (UAH), was awarded a three-year, $276,876 grant by the National Science Foundation (NSF) for his proposal entitled "Dynamics and Control of Long Range Micro Air Vehicles Inspired by Monarch Butterflies." The project will study the biomechanics of monarch butterfly flight, with the goal of creating engineered flight vehicles with unprecedented capabilities.

"I am very happy with his grant. NSF awards are outcomes of a very competitive review process, and this is a great recognition of the work that we have done so far," says Dr. Kang, who is also the recipient of a 2018 NASA Innovative Advanced Concepts award for his proposal on Marsbees. "With this award we can continue making scientific discoveries related to bio-inspired engineering and the development of bio-inspired micro-air vehicles."

The NSF grant will support research already underway at UAH’s Autonomous Tracking Optical Measurement (ATOM) Lab, where Dr. Kang and associate department chair Dr. Brian Landrum are focused on biological and bio-inspired flight, fluid-structure interaction, moving boundaries, and design optimization using computational and experimental methods. The pair is particularly interested in monarch butterflies, whose distinguishing characteristics include the slow flapping tempo of their wings, their wing flexibility, and the mechanical coupling of their wing and body movements. "They also fly at relatively high altitudes," says Dr. Kang. "Glider pilots have observed Monarch butterflies soaring on thermal currents at altitudes up to 1,250 m, and their overwintering grounds are at altitudes of up to 3,300 m."

For this particular project, Dr. Kang and Dr. Taeyoung Lee, an expert in the dynamics and control of aerospace systems at George Washington University, are hoping to uncover the physical mechanisms underlying the monarch’s highly efficient flight with the help from a multidisciplinary team of researchers with expertise in computational mechanics, biological experiments, fluid dynamics, and nonlinear controls. "The primary scientific objective is to test the hypothesis that high-altitude flight is a critical component to the long-range flight characteristics of the monarch butterfly," says Dr. Kang. "This will be achieved with a series of experimental, computational, and theoretical research efforts."

First, the team will use the ATOM Lab’s high-tech motion-capture system to measure the flight maneuvers of live monarchs at various altitudes. These measurements will then be validated with computational fluid dynamics simulations for the unsteady viscous flows around flexible flapping wings integrated with a multibody dynamics model representing the thorax and the abdomen deformation. The resulting aerodynamic model, says Dr. Kang, will be "approximated by an artificial neural network for real-time dynamic simulation, from which a nonlinear feedback control system will be constructed via Floquet-Lypuanov theory" The fidelity of the computational dynamic model and the feedback control system will also be verified to provide a comprehensive analysis of the low-frequency flapping dynamics of an articulated, flexible multibody system representing the remarkable flight characteristics of monarch butterflies.

Ultimately, the team plans to apply their findings to the creation of transformative, bio-inspired micro-air vehicles with enhanced flight efficiency and superior flight range. "These vehicles will enhance national security by allowing long-term surveillance of large areas and by providing long-range reconnoitering capacity for search and rescue," says Dr. Kang. "They will also improve the national quality of life by enabling long-term monitoring of environmental hazards." There’s even something in it for the monarchs, he adds. "Our research will help contribute to the understanding of their migration patterns, thereby supporting the conservation of this endangered species."