kysat -2: status report and overview of c&dh and...

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Jason Rexroat University of Kentucky Kevin Brown Morehead State UniversityTwyman Clements Kentucky Space LLC

KySat-2: Status Report and Overview of C&DH and Communications Systems Design

� Mission Goals� Board Stackup� Attitude Control System� Communications System� Command and Data Handling System� Image Processing Unit� Operations

3/16/162014 CubeSat Developer's Workshop KySat-22

Overview

� Goals:� Continue the goals of KySat-1

� Educational/Public Outreach through photos and sensor data for K-12

� Distributed processing architecture� Stellar Gyroscope Payload

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KySat-2 Mission

2014 CubeSat Developer's Workshop KySat-2

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Board Stackup

EPS

C&DH

Imaging  System

Phasing  Board

Deployment  Board Camera  

Structure

Battery  Holding

Radio

2014 CubeSat Developer's Workshop KySat-2

� Passive magnetic stabilization� Permanent neodymium magnets on z-axis, hysteresis material

on x-y plane� Required magnetics found using Smart NanosatelliteAttitude

Propagator (SNAP) developed by University of Kentucky

3/16/162014 CubeSat Developer's Workshop KySat-25

Attitude Control

� AstroDev Lithium-1 UHF Radio� 9600 baud� FSK modulation� UHF: 437.405 MHz� AX.25 packets� 1.5W transmit power

� Quad monopole antenna in omni-directional configuration

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Communications System

2014 CubeSat Developer's Workshop KySat-2

� Created by the Space Systems Lab

� Leverages aspects of Space Plug-and-play Avionics protocol (SPA)� SPA-1L for CubeLab Bus on

International Space Station� COSMIAC’s Trailblazer CubeSat

� Distributed processing architecture� SDM-L – mission processor� LASIMs – subsystem interface

processors

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Command & Data Handling System

2014 CubeSat Developer's Workshop KySat-2

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Final Design

UART

UART

SD  Card

Real  Time  Clock

EPSSolar  Boards

EPS  Interface  

uC

Camera  Interface  

uC

I2C

I2C  Bus

Subsystem  InferfacesPower

Gyroscope

Sensors

SPI

Beagle  BoardCamera

Imaging

Radio  Interface  

uC

Radio

Comms

UART

Heartbeat  Monitor

Sensor  Interface  

uC

I2C

File  System Command  Handling

State  Machine

SPA  I2C  Network

SPI

Timekeeping

External  Watchdog  Timer

GPIO8051F120

Magnetometer

Interface  uC  Hard  Reset

3.3V

5 February 2013

2014 CubeSat Developer's Workshop KySat-2

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C&DH Hardware

8051F120

8051F9308051F930

8051F930

8051F930

Radio LASIM

EPS LASIM

Sensor LASIM

IPU LASIM

SDM-L

2014 CubeSat Developer's Workshop KySat-2

RTC

External WDT

SD Storage

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Software ArchitectureMission-Specific

Hardware-Specific

2014 CubeSat Developer's Workshop KySat-2

� Strengths� Custom PCB allowed for

full functionality control� Programming API allowed

for multiple students to seamlessly develop LASIM code

� Hardware requirements abstracted from task execution

� Challenges� Initial need for time-

consuming PCB revisions� Added software

complexity to implement networked bus

� Hardware bottleneck introduced latency in software transactions

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KySat-2 C&DH Architecture

2014 CubeSat Developer's Workshop KySat-2

� BeagleBoard-xM� 5MP CMOS Sensor� Gain and exposure control� OpenCV image processing

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Image Processing Unit

2014 CubeSat Developer's Workshop KySat-2

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Stellar Gyroscope ExamplesRotation Estimate = 0.99975°, Actual Rotation = 1.0027°

Detected Stars in first frameDetected Stars in second framePaired stars using RANSAC

Rotation Estimate = 4.7519°, Actual Rotation = 1.0027°

Detected Stars in first frameDetected Stars in second framePaired stars using RANSAC

Detected Stars in first frameDetected Stars in second framePaired stars using RANSAC

Detected Stars in first frameDetected Stars in second framePaired stars using RANSAC

2014 CubeSat Developer's Workshop KySat-2

� Two KySat-2 models built: “Luke” and “Leia” in July and August 2013

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KySat-2 Integration

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Launch� KySat-2 “Leia” launched on

November 19, 2013� Wallops Flight Facility, VA� Orbital Sciences Minotaur-I

� 500km circular orbit, 40.5 degree inclination

� First contact made by RA4CTR in Russia 1.5 hours later:

2014 CubeSat Developer's Workshop KySat-2

� Two ground stations at UK� VHF/UHF roof-mounted Yagi antennas with azimuth/elevation rotor

control, SatPC32 and Ham Radio Deluxe automatic tracking software

� Three ground stations at MSU� VHF/UHF Yagi antennas� 21m parabolic dish

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Ground Stations

� wxPython-based GUI� Large user base with plenty of libraries and examples

� Cross-platform compatibility

� Master Ground Station Software� For UK and MSU ground teams

� Full command set, image processing, C&DH scheduler debugging

� Scripting: can read Python scripts to automate passes, make decisions based on satellite response

� In conjunction with ground station automation, can completely schedule and automate data collection

� HAM Ground Station Software� Decodes beacons, limited transmit functionality, automatically sends beacons to server at

Kentucky Space

� Available at: ssl.engineering.uky.edu/amateur-radio-operators

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Operations

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� Collected over 12,000 unique beacons since launch

� Distributed network maintenance and data transfer verified and nominal

� Power system persistence, power budget verified� Communications downlink verified� Mission clock ran continuously to Launch + 110 days

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Operations

Sync characters, data type, and size

Spacecraft Time

Telemetry: Battery voltages, regulator currents, solar panel voltages and currents, state flags

Checksums

2014 CubeSat Developer's Workshop KySat-2

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International Beacons

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Large scale Battery String Voltage – 80 days

2014 CubeSat Developer's Workshop KySat-2

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Small scale Battery String Voltage – 80 days

2014 CubeSat Developer's Workshop KySat-2

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Solar Cell Current – 80 days

Uplink

3/16/162014 CubeSat Developer's Workshop KySat-224

� Excellent downlink, but some problems with uplink limiting commanding and science operations

Image credit: Colin Hurst VK5HI

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Battery Voltage Anomaly – 110 days

� Suspected cause: X4.9 solar flare on 25 February, largest of 2014

� Simulations show that KySat-2 was in the sun for the event

3/16/162014 CubeSat Developer's Workshop KySat-226

Battery Voltage Anomaly Cause

Image from: http://www.tesis.lebedev.ru/en/sun_flares.html?m=2&d=25&y=2014

Jason  Rexroatjason.rexroat@uky.edu

Space  Systems  LaboratoryUniversity  of  Kentucky

Thank You

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Twyman Clementstclements@kentuckyspace.com

Kentucky  Space,  LLC