BUZZSAT CONTROL SYSTEM

BUZZSAT CONTROL SYSTEM RECIEVING SIGNAL TO TRANSMITEARTH NOT SEEN SEE EARTH TRANSMIT BEACON

Control System Architecture

Hardware Needs 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 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 Determination Best Altitude For Satellite Easiest And Cheapest Access Of Space Is Within 450 Km above Earth (Low Earth Orbit or LEO) Easiest And Cheapest Access Of Space Is Within 450 Km above Earth (Low Earth Orbit or LEO) Determination of Orbit 45 Degrees Inclination 45 Degrees Inclination Passes Over Atlanta In Order To Receive Signal From Satellite Passes Over Atlanta In Order To Receive Signal From Satellite Magnetic Field Measurement In Orbit

Magnetic Field Effect On Earth Varies Accordingly To Four Factors Altitude Altitude Longitude Longitude Latitude Latitude Time Time Why Is It Important? Helps Determine The Effect Of the Satellite Guidance System In Respect To The Torque Created By The Magnetic Field Helps Determine The Effect Of the Satellite Guidance System In Respect To The Torque Created By The Magnetic Field

Determination Of The Orbit Trajectory By using a crude method of plotting the orbit, it is possible to determine where the satellite will travel across the earth From this information obtained, valuable data can be gathered such as the magnetic field effect in retrospect to the location of the satellite

Final Orbit Trajectory With Magnetic Field

Magnetic Field Chart

Torque Calculation With some formulas to obtain torque from magnetic field we can get the overall estimation of the torque exerted on the satellite

Attitude Control System  Function:  Controls satellite i. Motion ii. orientation  Why control orientation?  To get a better signal from antennas  Motions causing de- orientation:  Spin  Rotation  Procession

Attitude Control System  Different ACSs  3-axis stabilization (Roll, Pitch, and Yaw)  Permanent magnet (Easiest)  Electromagnet (Best Combination)  Why electromagnet?  Simple design  Low cost  Better controlled field  No flipping over poles

Attitude Control System  Design  800 turns 32 AWG enamel coated wire  10.5 in diameter, 2.5 in width  500 ohm resistance, 30 mA current  15V supplied from solar panels  Plastic insulation from satellite body  Current is switched on and off through Power MOSFET’s  Mounted to satellite by metal brackets

Attitude Control System  Torque calculations  Magnetic field for 800 rings of wire  Magnetic dipole moment of coil  Torque of earth’s field on satellite  Time calculations – 90 0 ( π/2) deviation  Satellite’s estimated moment of inertia  Rotational acceleration  Time for re-positioning  M=satellite mass, n=# of wire loops, μ o =permeability, R=coil radius, i=current through wire, A=area inside coil

Attitude Control System  Results  Coil exhibits slow movement and large oscillation about field axis

IR Sensors IntroductionFunctionality Selection Process Testing Procedure Integration

IR Sensors--Introduction Taking into account the Inverse Square Law, at 400km from earth, IR sensors will distinguish the sun from the earth using 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 & Design Using IR sensors that will check for radiation at ~10 micron, the electromagnetic torquing device will rotate the satellite… IR ( ) km 6371 km 55°

IR Sensors--Functionality …so that the transmission link will be pointed towards earth. R RR R R R

IR Sensors--Selection Process  X X    X    

IR Sensors--Testing procedure General hot/cold Soldering iron ( 0.19 mV ~ 3.30 mV ) Soldering iron ( 0.19 mV ~ 3.30 mV ) Cold aluminum can ( 0.07 mV ) Cold aluminum can ( 0.07 mV ) Ambient environment Sky ( mV ~ mV) Sky ( mV ~ mV) Ground ( mV ~ mV) Ground ( mV ~ mV) Extreme temperature Propane Torch( mV) Propane Torch( mV) Freezer at -80  C ( mV  0 mV) Freezer at -80  C ( mV  0 mV)

IR Sensors--Integration An 351 op-amp will be used to magnify the voltage output of the IR detector

System Integration The magnetic coil and transmitter switch work very well on the Control Board. Integration with the receiver board worked well with the proto-board, but we are still waiting for a full integration test with them. Earth Tracking System works, but full integration into the spacecraft will have to wait for future semester.

Future Plans and Options for Buzzsat Calibrate and fully test IR sensors and connection to ADC system. Add new polar coordinate axis of rotation for pointing the transmitter. θ instead of just φ. Would be beneficial to add AE to project for this more complex mechanical control system (momentum wheel) 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)

Budgetary Breakdown ITEM REAL COST COST TO PROJECT PIC μC $8.50Sampled UTMC μC $2500 (2 units) Donation (2 units) Northrop Grumman EEPROM $3000Donation Perkin Elmer Thermopile $15 (10 units) $180 (10 units + shipping) Magnetic Torquer $65$65 Printed Circuit Board $180$180 μC/EEPROM Programmer $100$100 Instrumentation Amps $50$50 Various other components $50Sampled Totals$8,603.50$585

Control 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