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3/16/161
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
3/16/162014 CubeSat Developer's Workshop KySat-216
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
3/16/162014 CubeSat Developer's Workshop KySat-217
Operations
3/16/162014 CubeSat Developer's Workshop KySat-218
� 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
3/16/162014 CubeSat Developer's Workshop KySat-220
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
3/16/1623 2014 CubeSat Developer's Workshop KySat-2
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
3/16/162014 CubeSat Developer's Workshop KySat-225
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 [email protected]
Space Systems LaboratoryUniversity of Kentucky
Thank You
3/16/16 27
Twyman [email protected]
Kentucky Space, LLC