Operating Strategy in PHOENIX’s Attitude Determination and Control Subsystem

Abstract

The 2U CubeSat project PHOENIX is being developed at NCKU as part of the QB50 mission The objective of the QB50 mission is to study the key constituents in lower thermosphere (90-320km) as well as serving as a platform for in-orbit technology demonstration In order to reach this objective attitude determination and control is required to perform precise stabilization and control the satellite to the desired orientation This thesis discusses the entire development process of Attitude Determination and Control Subsystem (ADCS) for the PHOENIX CubeSat with emphasis on the control strategy design and verification methods Starting from Software-in-the-Loop simulation software based on MATLAB/Simulink is utilized for the analysis of the operation procedure in both the Preliminary Design Stage (PDR) and Critical Design Review (CDR) stage The optimal combination of estimators and controllers are designed and implemented into ADCS flight software: ADCS task which is part of the flight software in the PHOENIX On-Board Data Handling (OBDH) board The ADCS task is divided into four parts: initialization process stabilization process magnetometer deployment process and anomaly handling The first two are in charge of decreasing the satellite angular velocity and reorienting itself into 3-axis stabilization mode The magnetometer deployment process comprise the verification and calibration procedure of the magnetometer after it is deployed The anomaly handling recovers the CubeSat from any unexpected scenario by activating the stabilization procedure autonomously Reference functional tests are applied on the sensors and actuators module to ensure their quality for the space mission With the view to thoroughly and effectively test the ADCS software the mission simulation has been conducted in different mission scenarios so that those functions related to ADCS could be analyzed and verified This testing implements a set of Electrical Ground Support Equipment (EGSE) to simulate several pseudo ADCS sensor data which will be read by to OBDH and test by the ADCS flight software to overcome the restriction in the laboratory environment that is not able to generate the real sensor measurement in space In conclusion the mission simulation not only provide an insight into the operating strategy but also a powerful approach to verify both the hardware and software functionality

Date of Award	2016 Aug 11
Original language	English
Supervisor	Jyh-Chin Juang (Supervisor)