Design, Manufacturing, Building and Testing Subsystems of Cube Satellite

Table of Contents

• Introduction
• Objectives
• Document road map
• Project layout
• Mission Analysis and Orbital Determination
• Introduction
• Problem Definition
• Survey’s Results
• Statistical analysis of the existing Cube Satellites
• Summary of cube satellite parameters
• Types of Orbits and Orbital Parameters Definition
• Classical Orbital Parameters
• Orbital Design
• Design Attempt
• Equations Used
• Orbit Propagator Survey
• Orbit Propagator
• Introduction
• SGP4 Model
• Perturbations considered in the model
• Two Line Elements
• Model characteristics
• Model Verification
• Disadvantages of SPG4 Model
• Cowell’s Method
• Acceleration Components
• Acceleration due to Non-spherical Earth Gravity
• Deceleration due to atmospheric drag
• Acceleration due to the sun and moon
• Advantages & Disadvantages of Cowell’s Method Propagator
• Implemented Propagator
• Method of calculation
• Propagator Interface
• References
• Electric Power
• Introduction
• Abstract
• EPS Requirements and Objectives
• EPS Constraints
• Mission Modes related to EPS
• Definitions
• Progress of the 2nd iteration
• Problems of the last year
• What to be done in 3rd iteration of EPS
• Survey on EPS Main Components
• Objective of survey
• Solar Panels
• Solar Cells type survey result
• Efficiency survey result
• Conclusion of solar cells survey
• Battery
• Battery survey results
• Conclusion on the battery survey
• Configuration
• Distributed VS Centralized System
• Conclusion on the survey of the architecture
• PPT VS DET System
• Results of the configuration review
• Conclusion of configuration survey
• Number of voltage buses survey
• Main components of EPS
• DC_DC Converters
• Buck Converter plus (low pass filter)
• Boost converter (step-up converter)
• Buck-boost converter
• Calculations of the Dc-Dc converter
• How to calculate the Dc-Dc converter calculations
• Charging Circuit (Step-up converters)
• MAX1811
• MCP73861 or MCP73863 family
• MAX1555
• LTC 3421
• Adjustable
• TPS61201DRCT
• TPS61202DRCT
• Low-Dropout Linear regulator (LDO)
• Discharging circuit (Step-down converter)
• LTC3414
• Solar cells
• Second iteration solar cells
• Third iteration solar cells
• Solar cell connections
• Solar Cells in Parallel
• Batteries
• One step-up converter per side
• Advantages:
• Disadvantage:
• One Step up converter for all sides
• Advantages:
• Disadvantage:
• Conclusion
• Step-Up DC-DC Converters Circuit
• MAX 756 circuit
• Basic Functionality of the step-up circuit
• Testing
• FirstTest (single MAX)
• Results
• Second Test (Multi-MAX) 3 Max
• Results
• Conclusion
• Note
• OBC Power Requirements
• Charging Circuits
• LM 317T
• Conclusion
• Charging Process
• Charging with MAX1555
• Testing
• Summer Tests
• Results
• Conclusion
• Charging with MCP73831
• Testing
• Results
• Conclusion
• Charge with Max1555
• Results

• Individual interfacing tests
• Command and Data Handling (CDH)
• The test
• Results
• Interface with communication subsystem
• Tests
• Receiving Signals
• Results
• Conclusion of receiving test
• Transmitting test
• Before solving
• After solving
• Test
• The interface with ADCS
• Interfacing with the whole subsystems
• Scenario

• The Switching techniques
• Relay
• Advantages
• Disadvantages
• Conclusion
• Transistors
• BJT (Bipolar junction transistor)
• NPN configuration as a switch
• Test 1
• Test 2
• Conclusion of test (1) and test (2)
• PNP Configuration as a switch
• Test 3
• Test 4
• Darlington Transistor
• Conclusion
• Test of switching between batteries in charging process

• Solar cells simulation
• Solar cells parametric coefficients
• Battery discharge simulation

• Solar panels
• Step-up regulators
• PCB’S
• Simulink
• Switching Controllers

Objectives and Key Themes

This document describes the third iteration of the Cairo University Cube Satellite, which focuses on the design, manufacturing, building, and testing of selected subsystems. The main objective of this project is to use low-cost, off-the-shelf components (COTS) and novel computing systems to develop a functional Cube Satellite capable of Earth imaging.

• Earth Imaging: The Cube Satellite is designed to capture and transmit images of the Earth's surface.
• COTS Utilization: The project prioritizes the use of commercially available, affordable components.
• Subsystem Integration: The document explores the integration of various subsystems, such as power, attitude control, and communications, into a cohesive system.
• Mission Analysis and Orbital Design: The project analyzes mission requirements and determines the most suitable orbit for the Cube Satellite.
• Data Handling and Communication: The document examines the software and hardware aspects of data collection, processing, and transmission.

Chapter Summaries

• Chapter 1: Introduction

This chapter outlines the objectives, organization, and overall scope of the project. It introduces the Cairo University Cube Satellite and highlights its goals and key features.

• Chapter 2: Mission Analysis and Orbital Determination

This chapter delves into the selection of the most appropriate orbit for the Cube Satellite. It discusses various orbital parameters, including inclination, altitude, and period, and analyzes the suitability of Sun-synchronous orbits for Earth imaging. It also reviews different orbit propagator models and their strengths and weaknesses.

• Chapter 3: Electric Power

This chapter focuses on the design and implementation of the Cube Satellite's electrical power system (EPS). It covers power generation through solar panels, power conditioning, power storage in batteries, and power distribution to other subsystems. The chapter explores different charging circuits, switching techniques, and power budget considerations.

• Chapter 4: Attitude Determination and Control

This chapter describes the attitude determination and control subsystem (ADCS) of the Cube Satellite. It discusses the use of sensors such as magnetometers, sun sensors, and gyroscopes to determine the satellite's orientation. The chapter examines various attitude determination algorithms and control actuators, including magnetorquers, and outlines the development of control algorithms.

• Chapter 5: Communications

This chapter focuses on the communication subsystem of the Cube Satellite. It explores different communication protocols such as AX.25 and discusses the implementation of these protocols on the satellite and ground station. The chapter also analyzes the efficiency and availability of the communication system.

• Chapter 6: Command and Data Handling

This chapter covers the command and data handling subsystem (CDH) of the Cube Satellite. It discusses the selection and implementation of an on-board computer (OBC), highlighting the role of the Beagle Bone Black as the chosen OBC. The chapter details the software architecture and operating modes of the CDH subsystem.

• Chapter 7: Structure

This chapter focuses on the structure subsystem of the Cube Satellite, which provides the framework for all other components. It examines different design concepts and materials, considering factors such as weight, strength, and thermal performance. The chapter explores the process of static and dynamic structural analysis and reviews the results of vibration testing.

• Chapter 8: Integration

This chapter covers the final stages of the project, where the subsystems are integrated into a complete functional Cube Satellite. It illustrates the assembly process, highlighting the interaction and compatibility between the subsystems. It also provides insights into the challenges and considerations associated with integration.

Keywords

This project focuses on the design and development of a Cube Satellite for Earth imaging using low-cost components and novel computing systems. Key themes include CubeSat technology, mission analysis, orbital determination, electrical power systems, attitude determination and control, communication protocols, command and data handling, structural design, and system integration. This project utilizes commercially available components, such as solar panels, batteries, sensors, microcontrollers, and transceivers, to achieve its objectives.