Julia C. Bell

Date of Award

6-2021

Document Type

Thesis

Degree Name

Master of Science in Astronautical Engineering

Department

Department of Aeronautics and Astronautics

First Advisor

Costantinos Zagaris, PhD

Abstract

The evolving space environment has created a demand for autonomous spacecraft that can maneuver in complex and sometimes contentious environments. Constraint enforcement, such as an avoidance zone to prevent collision with a target, is a key component of autonomous control to ensure safety and performance requirements are met. Finite-horizon Model Predictive Control (MPC) is a popular control method due to its improved computation time while optimizing performance. Two areas of MPC in need of expansion are time-varying constraints and phase transitions in multi-phase applications. In this work, MPC is employed to track the reference trajectory of a multi-phase satellite inspection mission. During certain phases, conical and spherical constraints are activated to represent a sun vector keep-in-zone (KIZ) and a collision avoidance keep-out-zone (KOZ), respectively. The equations of motion follow the linearized Hill-Clohessey-Wiltshire (HCW) equations. The problem is solved to minimize control effort and tracking error using MPCTools, a control and estimation tool for dynamic models. Results are compared to the validated results from literature and found to be comparable in costs while lending flexibility to phase design.

AFIT Designator

AFIT-ENY-MS-21-J-094

DTIC Accession Number

AD1146495

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