buzzsat control system. buzzsat control system recieving signal to transmitearth not seen see earth...
TRANSCRIPT
BUZZSAT
CONTROL SYSTEM
BUZZSAT
CONTROL SYSTEMRECIEVING SIGNAL TO TRANSMITEARTH NOT SEENSEE EARTHTRANSMIT BEACON
Control System Electronics(CSE)
Digital Inputfrom ReceiverTransmitter
Power Microcontroller
Transmitter
ReceiverPower
ControlSystemPower
Attitude Control System (ACS)
ElectromagneticTorque System
4
Earth Tracker
Controlled PowerACS
Power
Control System ArchitectureControl System Architecture
Hardware Needs
18F452
CM8870 DTMFDecoder
MAX232 LineLev el Conv erter
5
2
IRDetector
Low PassFilter
Network7 IR Detector
MOSFET PowerSwitches
2
• 18F452 Main Controller
• CM8870 DTMF Decoder
• UART in PIC, MAX232 Serial Port Line Level Converter
•MOSFET Power Switches
• Amplifier for IR Detector Voltage feed into 7 kHz Low Pass Filter
Printed Circuit Board
IR Detectors
MOSFET Switches
Serial Port
IR Sensor Low Pass Filters
DTMF Decoder
PIC18F452
Normal Software Tasks
• Starts up and initializes all the necessary hardware inside the PIC…
•ADC for IR Sensors
•PORT I/O for DTMF Decoder
•DTMF Interrupt
Power Up
INIT
LOOPREAD_DTMF
-Print Debug to Serial Port
Decoded DTMFValue
Toggle Transmitter
ToggleMagnetouquer 2
1
• Controller waits in LOOP mode until DTMF Decoder generates interrupt
•Reads received value
•Toggles respective power line
•Prints action to the serial port
• LOOP would be changed to SLEEP in flight mode for power saving.
Hardware & Software Improvement
• Hardware
•Watchdog/Reset Circuit
•Power Switch for each IC
•Power Multiplexer for IR Detectors
•Telemetry
• Software
•SLEEP Mode
•Algorithm for IR Detector Monitoring and Magnet Use
•Telemetry
Orbit DeterminationOrbit Determination
Best Altitude For SatelliteBest Altitude For Satellite Easiest And Cheapest Easiest And Cheapest
Access Of Space Is Within Access Of Space Is Within 450 Km above Earth (Low 450 Km above Earth (Low Earth Orbit or LEO)Earth Orbit or LEO)
Determination of OrbitDetermination of Orbit 45 Degrees Inclination45 Degrees Inclination Passes Over Atlanta In Passes Over Atlanta In
Order To Receive Signal Order To Receive Signal From SatelliteFrom Satellite
Magnetic Field Magnetic Field Measurement In OrbitMeasurement In Orbit
Magnetic Field Effect On EarthMagnetic Field Effect On EarthVaries Accordingly To Four FactorsVaries Accordingly To Four Factors
Altitude Altitude LongitudeLongitude Latitude Latitude TimeTime
Why Is It Important?Why Is It Important? Helps Determine The Effect Of the Satellite Guidance System In Respect To The Torque Helps Determine The Effect Of the Satellite Guidance System In Respect To The Torque
Created By The Magnetic FieldCreated By The Magnetic Field
Determination Of The Orbit Determination Of The Orbit TrajectoryTrajectory
By using a crude method of plotting the orbit, it is possible to By using a crude method of plotting the orbit, it is possible to determine where the satellite will travel across the earthdetermine where the satellite will travel across the earthFrom this information obtained, valuable data can be gathered such From this information obtained, valuable data can be gathered such as the magnetic field effect in retrospect to the location of the as the magnetic field effect in retrospect to the location of the satellitesatellite
Final Orbit Trajectory With Final Orbit Trajectory With Magnetic Field Magnetic Field
Magnetic Field ChartMagnetic Field Chart
Torque CalculationTorque Calculation
With some formulas With some formulas to obtain torque from to obtain torque from magnetic field we can magnetic field we can get the overall get the overall estimation of the estimation of the torque exerted on the torque exerted on the satellitesatellite
earthearth uBuB
BRniAu32
Attitude Control SystemAttitude Control System Function:Function:
Controls satelliteControls satellitei.i. MotionMotionii.ii. orientationorientation
Why control orientation?Why control orientation? To get a better signal from To get a better signal from
antennasantennas Motions causing de-Motions causing de-
orientation:orientation: SpinSpin RotationRotation ProcessionProcession
Attitude Control SystemAttitude Control System
Different ACSsDifferent ACSs 3-axis stabilization (Roll, Pitch, and Yaw)3-axis stabilization (Roll, Pitch, and Yaw) Permanent magnet (Easiest)Permanent magnet (Easiest) Electromagnet (Best Combination)Electromagnet (Best Combination)
Why electromagnet?Why electromagnet? Simple designSimple design Low costLow cost Better controlled fieldBetter controlled field No flipping over polesNo flipping over poles
Attitude Control SystemAttitude Control System
DesignDesign 800 turns 32 AWG enamel coated 800 turns 32 AWG enamel coated
wirewire 10.5 in diameter, 2.5 in width10.5 in diameter, 2.5 in width 500 ohm resistance, 30 mA 500 ohm resistance, 30 mA
currentcurrent 15V supplied from solar panels15V supplied from solar panels Plastic insulation from satellite Plastic insulation from satellite
bodybody Current is switched on and off Current is switched on and off
through Power MOSFET’sthrough Power MOSFET’s Mounted to satellite by metal Mounted to satellite by metal
brackets brackets
Attitude Control SystemAttitude Control System
Torque calculationsTorque calculations Magnetic field for 800 rings of wireMagnetic field for 800 rings of wire
Magnetic dipole moment of coilMagnetic dipole moment of coil
Torque of earth’s field on satelliteTorque of earth’s field on satellite
Time calculations – 90Time calculations – 900 0 (( π/2 π/2) deviation) deviation Satellite’s estimated moment of inertiaSatellite’s estimated moment of inertia
Rotational accelerationRotational acceleration
Time for re-positioning Time for re-positioning
M=satellite mass, n=# of wire loops, M=satellite mass, n=# of wire loops, μμoo=permeability, R=coil radius, i=current =permeability, R=coil radius, i=current through wire, A=area inside coilthrough wire, A=area inside coil
R
iB
2
800
BRniAu32
earthearth uBuB
2
2MRI I
t
Attitude Control SystemAttitude Control System
st 38min
Results
Coil exhibits slow movement and large oscillation about field axis
st 81max
IR SensorsIR Sensors
IntroductionIntroduction
FunctionalityFunctionality
Selection ProcessSelection Process
Testing ProcedureTesting Procedure
IntegrationIntegration
IR Sensors--IntroductionIR Sensors--Introduction
Taking into account the Inverse Square Law, at 400km from Taking into account the Inverse Square Law, at 400km from earth, IR sensors will distinguish the sun from the earth using earth, IR sensors will distinguish the sun from the earth using their different wavelength region of maximum intensity. their different wavelength region of maximum intensity.
Spectrum of the earth. The earth emits most of its radiation in a wavelength band between 0.5 and 30.0 micrometers (µm).
Spectrum of the sun. The sun emits most of its radiation in a wavelength band between 0.1 and 4.0 micrometers (µm).
IR Sensors--Functionality & IR Sensors--Functionality & DesignDesign
Using IR sensors that will check Using IR sensors that will check for radiation at ~10 micron, the for radiation at ~10 micron, the electromagnetic torquing device electromagnetic torquing device will rotate the satellite…will rotate the satellite…
IR
IR
IR
IR
IR
IRIR
IR (6371+400) km
6371 km
6371 km
55°
IR Sensors--FunctionalityIR Sensors--Functionality
……so that the transmission link will be pointed so that the transmission link will be pointed towards earth. towards earth. R
RR
R
RR
IR Sensors--Selection ProcessIR Sensors--Selection Process
MgCdTe (Rad-hard)
Pyroelectric
Thermopile
Wavelength (~10 m)
Price Availability Application
XX
X
IR Sensors--Testing procedureIR Sensors--Testing procedure
General hot/coldGeneral hot/cold Soldering iron Soldering iron ( 0.19 mV ~ 3.30 mV )( 0.19 mV ~ 3.30 mV ) Cold aluminum canCold aluminum can ( 0.07 mV )( 0.07 mV )
Ambient environmentAmbient environment Sky Sky ( 0.094 mV ~ 0.289 mV)( 0.094 mV ~ 0.289 mV) Ground Ground ( 0.135 mV ~ 0.161 ( 0.135 mV ~ 0.161
mV)mV)
Extreme temperatureExtreme temperature Propane TorchPropane Torch ( 3.137 mV)( 3.137 mV) Freezer at -80 Freezer at -80 C C ( 0.005 mV ( 0.005 mV 0 mV) 0 mV)
IR Sensors--IntegrationIR Sensors--Integration
An 351 op-amp will be used to magnify the voltage output of the IR detector
-+
-
1.2M
+
-1.2k
GND
5V DC
OUT
Connectors
System IntegrationSystem Integration
The magnetic coil and transmitter switch The magnetic coil and transmitter switch work very well on the Control Board. work very well on the Control Board.
Integration with the receiver board worked Integration with the receiver board worked well with the proto-board, but we are still well with the proto-board, but we are still waiting for a full integration test with them.waiting for a full integration test with them.
Earth Tracking System works, but full Earth Tracking System works, but full integration into the spacecraft will have to integration into the spacecraft will have to wait for future semester. wait for future semester.
Future Plans and Options for Future Plans and Options for BuzzsatBuzzsat
Calibrate and fully test IR sensors and connection to ADC system.Calibrate and fully test IR sensors and connection to ADC system.
θθφφ
Add new polar coordinate axis of rotation for pointing Add new polar coordinate axis of rotation for pointing the transmitter.the transmitter. θ θ instead of just instead of just φφ. Would be . Would be beneficial to add AE to project for this more complex beneficial to add AE to project for this more complex mechanical control system (momentum wheel)mechanical control system (momentum wheel)
Use MilSpec/RadHard parts and shielding techniques to space qualify the satellite.Use MilSpec/RadHard parts and shielding techniques to space qualify the satellite.Add GPS system for selective transmitting (i.e. only transmit over North America)Add GPS system for selective transmitting (i.e. only transmit over North America)
Budgetary BreakdownBudgetary BreakdownITEMITEM REAL COSTREAL COST COST TO PROJECTCOST TO PROJECT
PIC PIC μμCC $8.50$8.50 SampledSampled
UTMC UTMC μμCC $2500 (2 units)$2500 (2 units) Donation (2 units)Donation (2 units)
Northrop Grumman EEPROMNorthrop Grumman EEPROM $3000$3000 DonationDonation
Perkin Elmer ThermopilePerkin Elmer Thermopile $15 (10 units)$15 (10 units) $180 (10 units + shipping)$180 (10 units + shipping)
Magnetic TorquerMagnetic Torquer $65$65 $65$65
Printed Circuit BoardPrinted Circuit Board $180$180 $180$180
μμC/EEPROM ProgrammerC/EEPROM Programmer $100$100 $100$100
Instrumentation AmpsInstrumentation Amps $50$50 $50$50
Various other componentsVarious other components $50$50 SampledSampled
TotalsTotals $8,603.50 $8,603.50 $585$585
Control System SponsorsControl System Sponsors
Rad Hard EEPROM Valued at over $2200
$500 Check for various costs incurred
Professional Support from Radiation Expert
2 Rad Hard Microcontrollers Valued
at over $5000
IR Sensor Sampling $150 worth