Date

2014

Document Type

Thesis

Degree

Master of Science

Department

Mechanical Engineering

First Adviser

Hart, Terry J.

Abstract

To further facilitate the development of the guidance, navigation, and control systems of the future extra-planetary vehicles, there is a need for a simplified, easy-to-repair test bed that is dynamically similar to the full scale spacecraft. To achieve such a platform, a 3:1 thrust-to-weight ratio modular simulator was designed. The simulator is constructed from high strength-low density composite materials coupled with hobby grade electronic motors and a custom flexible landing gear system to increase stability and reduce capsizing while landing.For attitude control, a nonlinear Fuzzy Logic style control system was developed and analyzed against more traditional PID style control schemes used in the past generations. This new style of controller offers increased performance in attitude control. After a comprehensive and complete simulation analysis, the fuzzy logic controller was implemented using the open source computer BeagleBone Black. Feedback was deliver by the use of an inertial measurement unit In addition to the development of a fuzzy logic attitude control system, work began on the development of a full guidance, navigation, and control (GNC) system. The GNC system that was developed was a trajectory controller in the form of a fuzzy logic cascade control law. The simplified control law was developed to mimic the control systems used in commercial aircraft autopilots, in which the trajectory is assumed to be 2D, where the spacecraft simulator remains pointing in the direction of its destination point. The controller was developed to accept different styles of trajectory and the entire system is modular in nature.From the simulation analysis of the closed-loop system, system level design specification were determined for the flight hardware. Ultimately, after programming the controller and integrating the electronics, it was determined the total time-delay of the system exceeded the design specification. Because of the hardware limitations, the attitude controller was, at best, n neutrally stable. Future work is proposed to integrate a real time microcontroller to account for the limitations of the BeagleBone and programming language chosen.

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