Team ESAT Preliminary Design Review
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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.

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

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Team ESAT Preliminary Design Review Team ESAT Preliminary Design Review Presentation Transcript

  • Preliminary Design ReviewTeam ESAT
    Caleb Carroll
    Marc Cattrell
    Elliot Chalfant
    Luke Dornon
    Zach Vander Laan
    David Zilz
    Advisors:
    Dr. Hank Voss
    Mr. Jeff Dailey
    Taylor University
    Junior Engineering Project
    PicoSatellite
    1
  • What is a PicoSatellite?
    Satellite some where between 0.1-1 kg
    Often flown in groups of 3 or more
    How Does is differ from a regular satellite?
    Lower Orbit
    Able to reach unexplored areas of Atmosphere
    Lower Cost
    Introduction
    2
  • TubeSat
    Able to fit into tube for InterOrbital Flight
    Deployable from tube ready for orbit
    Withstand launch conditions
    CubeSat
    Constellation of PicoSatellites
    Fit 4-5 smaller satellites into CubeSat
    Project Scope
    3
  • Why are we doing this?
    Small Size/Weight/Cost
    Modular
    (Compatibility w/ other system)
    Stability Control
    Power Management
    Solution for Thermal
    Problems
    Scientific Instruments
    Project Requirement
    4
  • Work Breakdown Structure
    5
  • Block Diagram
    6
  • System Requirements
    7
  • GOAL: Stabilize satellite and meet attitude control objectives using magnetic stabilization
    What are attitude control issues to consider?
    • Antenna orientation
    • Sensor orientation (Plasma Probe, Magnetometer)
    • Power constraints (Solar Panels)
    • Aerodynamics
    1.7 Attitude Control
    8
  • Permanent Magnet
    2 Permanent Magnets (perpendicular orientation)
    Motor-controlled Magnet
    Permanent Magnet with Magnetic Torquer
    Magnetic Torquers for 3 axes
    Reaction Wheels / Thrusters
    Gravity Gradient Boom
    Attitude Control - Options
    9
  • Solar panels on both sides of satellite
    From power standpoint do not need to control satellite’s roll
    Advice from Taylor Engineering alum
    Strongly urged us to scale back scope of project
    Simple magnetic stabilization would be sufficiently difficult for semester - long project
     Use permanent magnet as method of attitude control
    Attitude Control – Narrowing the Scope
    10
  • Attitude Control – How Does a Permanent Magnet Work?
    • Earth modeled as a dipole magnet with roughly 11 degree angle of declination from geographical poles.
    • Magnetic torque due to interaction between permanent magnet and Earth’s magnetic field
    • Need magnetic torque to be greater than any other torque on satellite
    • Satellite will track the magnetic field of the Earth, rotating twice per orbit.
    [1]
    [2]
    11
  • At orbit of r=310km and T=1000K:
    For altitudes below 500km, drag force dominates all other forces (such as radiation) [3]
    Permanent magnet controls 2 axes (pitch and yaw) but roll appears to be unconstrained.
    While satellite may be able to roll over equator, it will not be able to do so near the poles
     Drag force constrains the 3rd axis
    Two surfaces of satellite will be in Ram direction during different parts of orbit
    These surfaces due to drag force are working against magnetic torque
    How large are these torques in a worst case scenario?
    Attitude Control – The Drag Force
    12
  • Worst case scenario for torque due to drag force:
    10’’ x .583’’ surface
    Highly concentrated group of molecules hit only one half of the surface
    Magnetic torque must be greater than this torque for optimal attitude control at this altitude
    Attitude Control – Calculating Drag Force Torque
    13
    • Proposed experimental setup:
    Measure the torsional spring constant of a thin stainless steel wire
    Hang magnet from wire and find equilibrium point at which torsional torque equals magnetic torque
    Using the equation we will know the value of the magnetic torque.
    Using we can find the value of the dipole moment (mu).
    Find the magnetic torques at every location of the orbit
    6) Repeat process to finalize magnet choice
    Attitude Control – Choosing a Magnet
    14
  • Experimental Refinement
    Oscillation Damping
    Viscous fluid
    Hysteresis Rod
    Magnetic Placement
    Orbit Simulation
    Time Spent / Usefulness tradeoff
    Attitude Control – Issues to Consider
    15
  • [1] http://oceanexplorer.noaa.gov/explorations/05galapagos/logs/dec22/media/magfield_600.html
    [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.
    [3] Fundamentals of Space systems
    [4] Physics for Scientists and Engineers (Giancoli)
    Works Cited
    16
  • 1.2 Mechanical Design
    DESIGN 1:
    • ROUGH TUBESAT DIMENSIONAL CONSTRAINTS
    • THIN PC BOARD, TAPERED EDGES
  • DESIGN 2:
    • SOLAR PANEL DIMENSIONAL CONSTRAINTS
    • TWIN HINGED BOARDS
    • MAXIMIZE PANEL #
  • DESIGN 2:
    • SOLAR PANEL DIMENSIONAL CONSTRAINTS
    • TWIN HINGED BOARDS
    DESIGN 2:
    • SOLAR PANEL DIMENSIONAL CONSTRAINTS
    • TWIN HINGED BOARDS
    • MAXIMIZE PANEL #
  • DESIGN 3:
    • SOLAR PANEL + ANTENNAE CONSTRAINTS
    • CASING (E&M SHIELDING)
    • # PANEL REDUCTION
  • DESIGN 4:
    • REPLACE WIRE-WRAP ANTENNAE WITH PATCH
    • PRESERVE ENCLOSURE SYMMETRY
    • # PANEL REDUCTION
  • Purpose:
    Fly sensors in a Low Altitude Orbit
    Observe “Good Science” from these sensors
    Basic Purpose of Flying a Satellite
    What We Will Be Flying:
    Two Plasma Probes
    One Magnetometer
    1.6 Sensors
    22
  • What We Expect to Find
    Current From
    Charged Particles
    Graph Shows Current vs. Swept Bias Voltage
    23
  • Plot of a Log Scale
    Electron Temperature
    Temperature of Given Electron Distribution
    Plasma Potential
    Average Electric Potential Between Particles
    What Do We Use This For?
    24
  • Sensor System Block Diagram
    To Command Interface
    • Able to Connect Directly to Main Interface
    • Built on Individual Circuits
    • Ease of Transferability
    • Redundant System
    To Command Interface
    Magnetic Field
    Readings
    Plasma Readings
    25
  • Deployable Sensor Booms
    Fiberglass Rod
    Langmuir Plasma Probes
    Magnetometer
    Folding Sensor Booms
    Plate Plasma Probes
    1cm x 3cm Gold Plated Units
    Coaxial Cable Directly Through Wall
    Opposite Corners of Satellite
    History of Design
    26
  • Electrical Schematic
    27
  • Past:
    Decide on Final Design of Probes
    Right Now:
    Have Electrical Schematic
    Have most of the parts
    Next Step:
    Assemble Circuitry
    Test Circuitry
    Timeline
    28
  • Collecting Good Data
    Staying Out of Wake
    Far enough away from craft
    Transmitting Data Back to
    Earth for Analysis
    Long Enough Orbit for Good Results
    Stable Flight Thanks to Attitude Control
    Issues/Risk Assessment
    29
  • Power management concept
    Energy supplied by GaAs solar panels
    Energy stored in batteries
    Energy provided to entire electrical system for in-flight operation
    1.5 Power Management
    30
  • Goals:
    Determine power supply capabilities of solar panels and batteries
    Regulate power usage in the satellite for maximum data acquisition/transmission
    Requirements
    Supply sufficient power for operation of essential satellite systems
    Sustain power supply for estimated 3 month flight
    Power Management Objectives
    31
  • Power Supply Diagram
    32
  • Power Usage Diagram
    33
  • Batteries
    4V Batteries
    Rated for 875mAhr (3500mWhr)
    Solar Cells
    Rated for 14mA/ square cm at 2V
    Our cells can provide 400mA max (800mW)
    Power Supply Specifications
    34
  • Assumptions used to create a baseline power supply estimate:
    Solar panels produce full current when pointed at the sun within a 45 degree angle.
    Atmospheric reduction of solar energy is negligible.
    Satellite follows a polar orbit.
    Satellite attitude is primarily controlled by a fixed magnet aligning with earth’s magnetic field.
    Solar Panel Power Estimation
    35
  • Baseline Solar Power
    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.
    For a dawn-dusk orbit the sun’s rays come out of the screen and thus hit the satellite for its entire orbit.
    Sunlight
    Earth’s Shadow
    Orbital Path
    36
  • Baseline Solar Power II
    Sunlight
    Direction of Satellite
    Magnetic Field Line
    Solar Cells Parallel to Sunlight
    Solar Cells Perpendicular to Sunlight
    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).
    37
  • Using all the previously discussed estimation factors, the baseline or minimum expected solar power can be calculated.
    Baseline Solar Power III
    38
  • Based on our Solar Power estimates, the average solar power supply should be roughly 0.5W, but this will not be continuously available.
    Our batteries must store power and supply it when the solar panels are inactive.
    The number of batteries launched will depend on the space and weight restrictions of our satellite after other components are installed.
    Batteries
    39
  • Power Usage Specifications
    Total = 510 mW
    40
  • Our solar power estimates may prove to be too high for our real orbit.
    Our transmission hardware requires large amounts of power compared to our supplies.
    Aerodynamic forces may prevent rotation around the magnetic field lines resulting in solar cells never facing sunlight for up to a three month period.
    Potential Issues
    41
  • Refine Power Supply Estimate
    Measure actual solar cell power output over varying solar incidence angles
    Refine orbit model following finalized attitude control design
    Scheduled for the first 2 weeks of April
    Optimize component duty cycles
    Construction/Integration
    Install power supply systems
    Test functionality
    Scheduled for final 2 weeks of April, first 2 weeks of May
    Future Work
    42
  • 1.3 ESAT Communications System
    Primary Link
    Axonn satellite module
    Frequency range: 1611.25 – 1618.75 Mhz ( Globalstar )
    Data rate: 9600 144 Byte packet burst mode.
    Antenna: Compact microstrip patch antenna L1 band Gain: 5.7dB 25mm x 25mm x 2mm
    Current: 500mA (Tx)
    Secondary Link
    Maxstream spread spectrum module
    Frequency range: 902 – 928Mhz ( ISM band )
    Data rate: 9600 – 57.6kb
    Data encryption: 32bit
    Antenna: Collinear 7.5dB
    RF Power: 1W
    Current: 700mA (Tx)
    Inventek GPS Module
    Firmware: Taylor HankEYE V2.1E ( No restrictions )
    Channel: 20
    Update rate: 20Hz
    Data rate: 115.2kb
    Current: 25mA
    Antenna: Active patch L1 band 28db gain 25mm x 25mm x 2mm
    43
  • ESAT Communications System
    Globalstar satellite network
    1611Mhz
    ESAT
    900Mhz
    Globalstar Ground Station
    Internet
    Taylor Ground Station
    44
  • ESAT Communications System
    Taylor ground station
    Communications: Dual Maxstream 900Mhz ISM Module
    Tracking: Az / Elv satellite antenna tracking system
    Antenna: 47dB Axial mode helical stack
    Software: Sequel server database / LabView user interface / AGI satellite interface
    Communications protocol
    HawkEYE packet structure ( high speed micro burst packet )
    Packet size: 44 Byte
    CRC: 16 Bit
    GPS position
    Instrument data
    System data
    45
  • ESAT Control Module
    46
  • Next Steps
    Attitude Control
    Magnet Finalization
    Experimental Refinement
    Mechanical
    Drawing Finalization
    Enclosure
    Sensors
    Circuitry Finalization
    Power Management
    Final Power Calculations
    Circuitry Construction
    Communication
    Circuitry Design and Testing
    47