Date of Award


Degree Name

Doctor of Philosophy


Mechanical and Aerospace Engineering

First Advisor

Dr. Kapseong Ro

Second Advisor

Dr. James W. Kamman

Third Advisor

Dr. Koorosh Nagshineh

Fourth Advisor

Dr. Ikhlas Abdel-Qader


An active stabilization method for an aerial refueling drogue used in probe-drogue refueling system is presented in this study. The present refueling drogue exhibits an unstable motion due to various turbulent natures, which results in high failure rates and sometimes catastrophic accidents. Although it is considered a routine procedure for human pilot, the workload for mid-air refueling is highly demanding and autonomous operation is by no means a simple task. With rapidly growing use of unmanned aerial vehicles, autonomous aerial refueling is identified as one of essential technologies in future aviation. The present research is a pioneering work in active drogue stabilization that includes conceptual design of a controllable drogue, comprehensive dynamic wind tunnel experiments including a scale model prototype manufacturing, mathematical modeling and feedback control, and hardware-in-the-loop simulation.

A set of four aerodynamic control surfaces is implemented to minimize the level of modification necessary for the current hose-drogue refueling system. An inertial measurement unit is adopted as a primary sensor to detect the drogue motion. To verify the system performance, a four degrees-of-freedom dynamic test rig system is fabricated for wind tunnel experiment. This system is composed of a rigid link and the controllable drogue, and a representative mathematical model is constructed based on the multi-body dynamic analysis with experimentally measured data. A feedback control law is implemented to a custom designed avionics hardware. An artificial gust generator is fabricated to create turbulent flow field in the wind tunnel, and is quantified by a five-hole probe system. The results from the closed-loop, hardware-in-the-loop simulation test indicates that the proposed concept reduces the drogue motion up to 90%.

Access Setting

Dissertation-Open Access