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Team ESAT Preliminary Design Review


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This is the slide show from our preliminary design review for our Junior Engineering Project.

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Team ESAT Preliminary Design Review

  1. 1. Preliminary Design ReviewTeam ESAT<br />Caleb Carroll<br />Marc Cattrell<br />Elliot Chalfant<br />Luke Dornon<br />Zach Vander Laan<br />David Zilz<br />Advisors:<br />Dr. Hank Voss<br />Mr. Jeff Dailey<br />Taylor University<br />Junior Engineering Project<br />PicoSatellite<br />1<br />
  2. 2. What is a PicoSatellite?<br />Satellite some where between 0.1-1 kg<br />Often flown in groups of 3 or more<br />How Does is differ from a regular satellite?<br />Lower Orbit<br />Able to reach unexplored areas of Atmosphere<br />Lower Cost<br />Introduction<br />2<br />
  3. 3. TubeSat<br />Able to fit into tube for InterOrbital Flight<br />Deployable from tube ready for orbit<br />Withstand launch conditions<br />CubeSat<br />Constellation of PicoSatellites<br />Fit 4-5 smaller satellites into CubeSat<br />Project Scope<br />3<br />
  4. 4. Why are we doing this?<br />Small Size/Weight/Cost<br />Modular <br />(Compatibility w/ other system)<br />Stability Control<br />Power Management<br />Solution for Thermal <br />Problems<br />Scientific Instruments<br />Project Requirement<br />4<br />
  5. 5. Work Breakdown Structure<br />5<br />
  6. 6. Block Diagram<br />6<br />
  7. 7. System Requirements<br />7<br />
  8. 8. GOAL: Stabilize satellite and meet attitude control objectives using magnetic stabilization<br />What are attitude control issues to consider?<br /><ul><li>Antenna orientation
  9. 9. Sensor orientation (Plasma Probe, Magnetometer)
  10. 10. Power constraints (Solar Panels)
  11. 11. Aerodynamics</li></ul>1.7 Attitude Control <br />8<br />
  12. 12. Permanent Magnet<br />2 Permanent Magnets (perpendicular orientation)<br />Motor-controlled Magnet<br />Permanent Magnet with Magnetic Torquer<br />Magnetic Torquers for 3 axes<br />Reaction Wheels / Thrusters<br />Gravity Gradient Boom<br />Attitude Control - Options<br />9<br />
  13. 13. Solar panels on both sides of satellite<br />From power standpoint do not need to control satellite’s roll<br />Advice from Taylor Engineering alum <br />Strongly urged us to scale back scope of project<br />Simple magnetic stabilization would be sufficiently difficult for semester - long project<br /> Use permanent magnet as method of attitude control<br />Attitude Control – Narrowing the Scope<br />10<br />
  14. 14. Attitude Control – How Does a Permanent Magnet Work?<br /><ul><li>Earth modeled as a dipole magnet with roughly 11 degree angle of declination from geographical poles.
  15. 15. Magnetic torque due to interaction between permanent magnet and Earth’s magnetic field
  16. 16. Need magnetic torque to be greater than any other torque on satellite
  17. 17. Satellite will track the magnetic field of the Earth, rotating twice per orbit.</li></ul>[1]<br />[2]<br />11<br />
  18. 18. At orbit of r=310km and T=1000K:<br />For altitudes below 500km, drag force dominates all other forces (such as radiation) [3]<br />Permanent magnet controls 2 axes (pitch and yaw) but roll appears to be unconstrained. <br />While satellite may be able to roll over equator, it will not be able to do so near the poles<br /> Drag force constrains the 3rd axis<br />Two surfaces of satellite will be in Ram direction during different parts of orbit <br />These surfaces due to drag force are working against magnetic torque<br />How large are these torques in a worst case scenario?<br />Attitude Control – The Drag Force<br />12<br />
  19. 19. Worst case scenario for torque due to drag force: <br />10’’ x .583’’ surface <br />Highly concentrated group of molecules hit only one half of the surface<br />Magnetic torque must be greater than this torque for optimal attitude control at this altitude<br />Attitude Control – Calculating Drag Force Torque<br />13<br />
  20. 20. <ul><li>Proposed experimental setup:</li></ul>Measure the torsional spring constant of a thin stainless steel wire <br />Hang magnet from wire and find equilibrium point at which torsional torque equals magnetic torque<br />Using the equation we will know the value of the magnetic torque.<br />Using we can find the value of the dipole moment (mu).<br />Find the magnetic torques at every location of the orbit<br />6) Repeat process to finalize magnet choice<br />Attitude Control – Choosing a Magnet<br />14<br />
  21. 21. Experimental Refinement<br />Oscillation Damping<br />Viscous fluid<br />Hysteresis Rod<br />Magnetic Placement<br />Orbit Simulation<br />Time Spent / Usefulness tradeoff <br />Attitude Control – Issues to Consider<br />15<br />
  22. 22. [1]<br />[2] Bopp, Matthew, and Jonathan Messer. An Analysis of Magnetic Attitude Control of Low Earth Orbit Nano-satellites with Application for the BUSAT. BUSAT. Attitude Control and Determination Subsystem. Web. 01 Mar. 2010.<br />[3] Fundamentals of Space systems<br />[4] Physics for Scientists and Engineers (Giancoli)<br />Works Cited<br />16<br />
  23. 23. 1.2 Mechanical Design<br />DESIGN 1:<br /><ul><li> ROUGH TUBESAT DIMENSIONAL CONSTRAINTS
  26. 26. MAXIMIZE PANEL #</li></li></ul><li>DESIGN 2:<br /><ul><li> SOLAR PANEL DIMENSIONAL CONSTRAINTS
  29. 29. MAXIMIZE PANEL #</li></li></ul><li>DESIGN 3:<br /><ul><li> SOLAR PANEL + ANTENNAE CONSTRAINTS
  31. 31. # PANEL REDUCTION</li></li></ul><li>DESIGN 4:<br /><ul><li> REPLACE WIRE-WRAP ANTENNAE WITH PATCH
  33. 33. # PANEL REDUCTION</li></li></ul><li>Purpose:<br />Fly sensors in a Low Altitude Orbit<br />Observe “Good Science” from these sensors<br />Basic Purpose of Flying a Satellite<br />What We Will Be Flying:<br />Two Plasma Probes<br />One Magnetometer<br />1.6 Sensors<br />22<br />
  34. 34. What We Expect to Find<br />Current From<br /> Charged Particles<br />Graph Shows Current vs. Swept Bias Voltage<br />23<br />
  35. 35. Plot of a Log Scale<br />Electron Temperature<br />Temperature of Given Electron Distribution<br />Plasma Potential<br />Average Electric Potential Between Particles<br />What Do We Use This For?<br />24<br />
  36. 36. Sensor System Block Diagram<br />To Command Interface <br /><ul><li>Able to Connect Directly to Main Interface
  37. 37. Built on Individual Circuits
  38. 38. Ease of Transferability
  39. 39. Redundant System</li></ul>To Command Interface <br />Magnetic Field <br /> Readings<br />Plasma Readings<br />25<br />
  40. 40. Deployable Sensor Booms<br />Fiberglass Rod<br />Langmuir Plasma Probes<br />Magnetometer<br />Folding Sensor Booms<br />Plate Plasma Probes<br />1cm x 3cm Gold Plated Units<br />Coaxial Cable Directly Through Wall<br />Opposite Corners of Satellite<br />History of Design<br />26<br />
  41. 41. Electrical Schematic<br />27<br />
  42. 42. Past:<br />Decide on Final Design of Probes<br />Right Now:<br />Have Electrical Schematic<br />Have most of the parts<br />Next Step:<br />Assemble Circuitry<br />Test Circuitry<br />Timeline<br />28<br />
  43. 43. Collecting Good Data<br />Staying Out of Wake<br />Far enough away from craft<br />Transmitting Data Back to<br /> Earth for Analysis<br />Long Enough Orbit for Good Results<br />Stable Flight Thanks to Attitude Control<br />Issues/Risk Assessment<br />29<br />
  44. 44. Power management concept<br />Energy supplied by GaAs solar panels<br />Energy stored in batteries<br />Energy provided to entire electrical system for in-flight operation<br />1.5 Power Management<br />30<br />
  45. 45. Goals:<br />Determine power supply capabilities of solar panels and batteries<br />Regulate power usage in the satellite for maximum data acquisition/transmission<br />Requirements<br />Supply sufficient power for operation of essential satellite systems<br />Sustain power supply for estimated 3 month flight<br />Power Management Objectives<br />31<br />
  46. 46. Power Supply Diagram<br />32<br />
  47. 47. Power Usage Diagram<br />33<br />
  48. 48. Batteries<br />4V Batteries<br />Rated for 875mAhr (3500mWhr)<br />Solar Cells<br />Rated for 14mA/ square cm at 2V<br />Our cells can provide 400mA max (800mW)<br />Power Supply Specifications<br />34<br />
  49. 49. Assumptions used to create a baseline power supply estimate:<br />Solar panels produce full current when pointed at the sun within a 45 degree angle.<br />Atmospheric reduction of solar energy is negligible.<br />Satellite follows a polar orbit.<br />Satellite attitude is primarily controlled by a fixed magnet aligning with earth’s magnetic field.<br />Solar Panel Power Estimation <br />35<br />
  50. 50. Baseline Solar Power<br />For a noon-midnight orbit satellite magnetic control causes solar panels to point away from the sun for a portion of a noon-midnight orbit in addition to the significant portion of orbit behind the earth’s shadow.<br />For a dawn-dusk orbit the sun’s rays come out of the screen and thus hit the satellite for its entire orbit.<br />Sunlight<br />Earth’s Shadow<br />Orbital Path<br />36<br />
  51. 51. Baseline Solar Power II<br />Sunlight<br />Direction of Satellite<br />Magnetic Field Line<br />Solar Cells Parallel to Sunlight<br />Solar Cells Perpendicular to Sunlight<br />With a single fixed magnet to control attitude, the satellite is free to rotate around magnetic field lines. Even when the field is perfectly perpendicular to the panels the rotation could cause the cells to see sunlight only 50% of the time (two sides have panels giving a 90 degree angle of effectiveness).<br />37<br />
  52. 52. Using all the previously discussed estimation factors, the baseline or minimum expected solar power can be calculated.<br />Baseline Solar Power III<br />38<br />
  53. 53. Based on our Solar Power estimates, the average solar power supply should be roughly 0.5W, but this will not be continuously available.<br />Our batteries must store power and supply it when the solar panels are inactive.<br />The number of batteries launched will depend on the space and weight restrictions of our satellite after other components are installed.<br />Batteries<br />39<br />
  54. 54. Power Usage Specifications<br />Total = 510 mW<br />40<br />
  55. 55. Our solar power estimates may prove to be too high for our real orbit.<br />Our transmission hardware requires large amounts of power compared to our supplies.<br />Aerodynamic forces may prevent rotation around the magnetic field lines resulting in solar cells never facing sunlight for up to a three month period.<br />Potential Issues<br />41<br />
  56. 56. Refine Power Supply Estimate<br />Measure actual solar cell power output over varying solar incidence angles<br />Refine orbit model following finalized attitude control design<br />Scheduled for the first 2 weeks of April<br />Optimize component duty cycles<br />Construction/Integration<br />Install power supply systems<br />Test functionality<br />Scheduled for final 2 weeks of April, first 2 weeks of May<br />Future Work<br />42<br />
  57. 57. 1.3 ESAT Communications System<br />Primary Link<br />Axonn satellite module<br /> Frequency range: 1611.25 – 1618.75 Mhz ( Globalstar )<br /> Data rate: 9600 144 Byte packet burst mode.<br /> Antenna: Compact microstrip patch antenna L1 band Gain: 5.7dB 25mm x 25mm x 2mm<br /> Current: 500mA (Tx)<br />Secondary Link<br />Maxstream spread spectrum module<br /> Frequency range: 902 – 928Mhz ( ISM band )<br /> Data rate: 9600 – 57.6kb<br /> Data encryption: 32bit<br /> Antenna: Collinear 7.5dB <br /> RF Power: 1W <br /> Current: 700mA (Tx)<br />Inventek GPS Module<br /> Firmware: Taylor HankEYE V2.1E ( No restrictions )<br /> Channel: 20<br /> Update rate: 20Hz<br /> Data rate: 115.2kb<br /> Current: 25mA<br /> Antenna: Active patch L1 band 28db gain 25mm x 25mm x 2mm<br />43<br />
  58. 58. ESAT Communications System<br />Globalstar satellite network<br />1611Mhz<br />ESAT<br />900Mhz<br />Globalstar Ground Station<br />Internet<br />Taylor Ground Station<br />44<br />
  59. 59. ESAT Communications System<br />Taylor ground station<br /> Communications: Dual Maxstream 900Mhz ISM Module<br /> Tracking: Az / Elv satellite antenna tracking system<br /> Antenna: 47dB Axial mode helical stack<br /> Software: Sequel server database / LabView user interface / AGI satellite interface<br />Communications protocol <br /> HawkEYE packet structure ( high speed micro burst packet )<br /> Packet size: 44 Byte<br /> CRC: 16 Bit<br /> GPS position<br /> Instrument data<br /> System data<br />45<br />
  60. 60. ESAT Control Module<br />46<br />
  61. 61. Next Steps<br />Attitude Control<br />Magnet Finalization<br />Experimental Refinement<br />Mechanical<br />Drawing Finalization<br />Enclosure <br />Sensors<br />Circuitry Finalization<br />Power Management<br />Final Power Calculations<br />Circuitry Construction<br />Communication<br />Circuitry Design and Testing<br />47<br />