Keywords

Tethered UAV, Aerial monitoring, Regenerative braking, Quadrotor autogyro, Flight stability and control, Persistent aerial systems

Abstract

Tethered autogyros are promising platforms for persistent aerial surveillance because the tether enables long-duration deployment through mooring and bidirectional power transfer, while autorotating unpowered rotors use ambient wind to generate lift. This dissertation develops dynamic models and control strategies for a tethered quadrotor autogyro to evaluate its flight capability for aerial surveillance applications.

The study develops a hybrid modeling framework in which aerodynamic forces are represented in three dimensions while overall motion is restricted to the vertical plane. The model combines Lagrangian mechanics, Blade Element Momentum Theory, and catenary mechanics, and includes rotor-speed and blade flapping DoF. Numerical solutions of the equations of motion are used to investigate equilibrium characteristics, with results consistent with trends reported in the literature.

Using this hybrid model, a novel regenerative differential rotor braking method is investigated for pitch and altitude control. A two-loop feedback controller is developed, and closed-loop stability is analyzed. An adaptive control strategy is also developed to estimate the optimum operating point during flight using an equilibrium-based quadratic altitude–pitch relation, thereby enabling altitude regulation under varying wind conditions.

To capture the full flight dynamics, the hybrid model is then extended to a three-dimensional formulation that includes roll and yaw dynamics. This model is used to investigate attitude and altitude control through differential braking of alternate rotors, as well as switching from autorotative to powered flight during low-wind periods. Simulation results show that switching can maintain the desired altitude, supporting the feasibility of extended deployment under uncertain wind conditions.

Completion Date

2026

Semester

Spring

Committee Chair

Tuhin Das

Degree

Doctor of Philosophy (Ph.D.)

College

College of Engineering and Computer Science

Department

Mechanical and Aerospace Engineering

Format

PDF

Document Type

Dissertation

Identifier

DP0053223

Release Date

5-15-2027

Available for download on Saturday, May 15, 2027

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