Date of Award

Spring 2022

Document Type

Thesis - Open Access

Degree Name

Master of Science in Aerospace Engineering

Department

Aerospace Engineering

Committee Chair

Dr. Dongeun Seo

First Committee Member

Dr. Morad Nazari

Second Committee Member

Dr. Richard Prazenica

Third Committee Member

Dr. James W. Gregory

Fourth Committee Member

Dr. Christopher Grant

Abstract

This research is focused on the design of controllers for stabilizing a launch vehicle with an internally originating torque. The motivation for this research arises from the new development of rocket engines which swirl combustion gases to gain combustion stability benefits, and in the case of hybrid rocket engines, fuel regression benefits as well. The stability of the launch vehicle dynamics due to the internal torque has not been discussed before. To the author’s knowledge, this is the first research to address the stabilization problem of the launch vehicle with internal torque. Due to the new design/characteristics of these engines, there are not many research articles on the proposed topic and the exact internal dynamics remains mostly unknown, so this research focuses on designing controllers with the ability to compensate for unknown torques. In order to develop the controllers, this research also designs a dynamics model for these launch vehicles, where the changing location of the center of mass is shown through simulation to be negligible for a real hybrid launch vehicle. Due to the proprietary nature of the exact launch vehicle data, a launch vehicle that is based on the approximate real data of a real hybrid launch vehicle was developed for the simulation of the controllers that are designed in this research. The proposed controllers include a linear quadratic regulator, PD-type controller, affine parameter-dependent Lyapunov function based controller, and an adaptive controller. These controllers must meet the goal of stabilizing the launch vehicle within the main engine’s burn time. This constraint allows for these controllers to be implemented on either the first or upper stages of a launch vehicle. This research shows that the linear quadratic regulator, PD-type controller, and adaptive controller all provide adequate control over the launch vehicle with an engine originating internal toque. The performance of all four proposed controllers is demonstrated by numerical simulations. This research concludes with the recommendation of either the LQR controller or the PD-type controller for a launch vehicle similar to the one developed here. Future research may include the acquisition of real internal torque data from one of the institutions that is currently researching the design of swirl combustion engines. This data would be used to design an internal torque model for the engine, which would then be used in the equations of motion of the launch vehicle and the subsequent controller designs.

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