Date of Award

9-2024

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Department of Aeronautics and Astronautics

First Advisor

David H. Curtis, PhD

Abstract

On-orbit inspection is a rapidly growing mission that enables extending the life of aging legacy space systems through refueling, replacing, or upgrading components. For an inspection operation, multiple agents taking observations simultaneously can more quickly map an RSO and assure an inspection is complete regardless of RSO dynamics. A multi-agent guidance, navigation, and control (GNC) scheme must be designed with cooperation in mind to achieve inspection objectives, while leveraging the unique capabilities of a distributed inspection system. This work splits the GNC system into two parts composed of an offline guidance scheme for translational reference trajectory generation and an online navigation and control loop for reference trajectory tracking and constrained attitude control.

The offline guidance scheme centers on the formulation of optimal control problems (OCPs) in two types: continuous control and NMC-based trajectories. The solution of these OCPs is handled either by transcribing via pseudospectral collocation and then solving with an interior point nonlinear program (NLP) solver or by directly formulating as a static NLP. A novel method for evaluating information gain is proposed that incorporates viewing angle and lighting conditions to evaluate the quality of the information that could be gleaned from the images obtained. Online navigation and control are achieved by leveraging real-time capable factor graph methods, LQR reference trajectory tracking control, and APF-based constrained attitude control. The online scheme is demonstrated to provide a reliable method for tracking a reference trajectory while adhering to the attitude requirements of an inspection mission. Several example scenarios are explored to demonstrate the efficacy of this proposed offline-online hybrid approach and the implemented methods.

AFIT Designator

AFIT-ENY-DS-24-S-128

Comments

A 12-month embargo was observed for posting this work on AFIT Scholar.

Distribution Statement A, Approved for Public Release. PA case number on file.

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