CAPE Buoy

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University of Louisiana at Lafayette Senior Design Project

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  • CAPE Buoy

    1. 1. Members: John DeBlanc Elias Ellsworth Peter Bankole Luis Chinchilla Mentors: Nick Pugh Mark Fenstermaker Satellite Communications Buoy Senior Design II Fall 2008
    2. 2. Outline <ul><li>Introduction </li></ul><ul><li>Purpose </li></ul><ul><li>Functional Specifications </li></ul><ul><li>High Level Block Diagram </li></ul><ul><li>Introduction to Buoy System Model </li></ul><ul><li>Satellite Access Scheme </li></ul><ul><li>Data Budget </li></ul><ul><li>Sensor Subsystem </li></ul><ul><li>Link Budget </li></ul><ul><li>Communications Subsystem </li></ul><ul><li>Power Budget </li></ul><ul><li>Power Subsystem </li></ul><ul><li>Onboard Computer </li></ul><ul><li>Mechanical Subsystem </li></ul><ul><li>Summary </li></ul><ul><li>Acknowledgments </li></ul>
    3. 3. Introduction <ul><li>This design project will develop a satellite communications buoy. </li></ul><ul><li>This buoy will communicate with a Low Earth Orbiting (LEO) CubeSat; namely, the C.A.P.E. II </li></ul><ul><li>This project will combine the desirable features of satellite communications and low power requirements for future buoys and other remote applications. </li></ul>
    4. 4. Purpose <ul><li>Gather environmental data and then upload it to the C.A.P.E. II. </li></ul><ul><li>Demonstrate the usefulness of CubeSats in the area of data collection and forwarding. </li></ul><ul><li>Create a new arena for opportunities and applications within the CubeSat community. </li></ul><ul><li>Open doors for future University of Louisiana at Lafayette senior design teams that could develop other terrestrial applications with satellite link functionality. </li></ul>
    5. 5. Functional Specifications Environment Large Body Of Water Potentially Harsh Weather Buoy Compatible w/ Naval Academy Buoy On-board GPS Receiver Memory > 100 Megabits Data Interface (I2C) Low Cost 4) Sunlight 1) Environmental Data 2) Location 3) Time 5) Satellite Commands Inputs 1) 145MHz and/or 435MHz Transmission Frequency 2) Sufficient Transmission Power To Close Link With CAPE2 3) Transmit Location, Time, and Environmental Data Outputs Power System Solar/Batteries
    6. 6. High Level Block Diagram TX TX RX RX Sensors GPS PIC External Memory Solar Cells Batteries Power System TNC Radio Mechanical PVC Structure
    7. 7. Buoy System Model Data Budget How much data is collected? Comm. Budget How much signal is needed? Power Budget How much power is required?
    8. 8. Satellite Access Scheme Beacon Buoy “ Aloha?” Beacon &quot;aloha&quot; every 4 minutes. If acknowledged by satellite, upload weather data. Wait 24 hours until next satellite contact attempt. Satellite
    9. 9. <ul><li>The buoy will measure 8 environmental variables plus GPS location and time </li></ul><ul><li>If the buoy measures these variables 24 times a day, we collect about 1.4kilobytes </li></ul>Data Budget
    10. 10. <ul><li>Anemometer </li></ul><ul><li>Compass </li></ul><ul><li>Water Temp </li></ul><ul><li>Humidity </li></ul>Sensors <ul><li>Wind Vane </li></ul><ul><li>Air Temp </li></ul><ul><li>Pressure </li></ul><ul><li>Salinity </li></ul>
    11. 11. <ul><li>The wind speed would be detected using </li></ul><ul><li>3 cups anemometer assembly and </li></ul><ul><li>a 0H090U Hall Effect Transistor </li></ul><ul><li>The 3 cups anemometer assembly as a magnet in its center. The magnets would be used to detect the rotations of the cups. </li></ul><ul><li>Calculation </li></ul><ul><li>v(m/s) = 2*pi*f ( r ) </li></ul><ul><li>r = radius from center of shaft to </li></ul><ul><li>center of cups. </li></ul><ul><li>r = 0.053mm </li></ul><ul><li>v = velocity in meters/sec </li></ul>Anemometer
    12. 12. <ul><li>The wind vane includes a 5k Dual Wiper </li></ul><ul><li>Potentiometer which uses a 540 degree </li></ul><ul><li>format and analog input range – 0 to 5V </li></ul><ul><li>It would also include a tail and a pointer that would point in the direction of the wind. The Tail and the pointer will help rotate the potentiometer to the direction of the wind. </li></ul><ul><li>A 3 Axis digital Compass (TTL) is used </li></ul><ul><li>to orient the wind direction to its true </li></ul><ul><li>north </li></ul>Wind Vane
    13. 13. <ul><li>Features: </li></ul><ul><li>- Azimuth </li></ul><ul><li>- Inclination (Pitch and Roll) </li></ul><ul><li>- 3 Axis magnetic sensors from Honeywell </li></ul><ul><li>- 3 Axis Accelerometers(G) from ST Microelectronics </li></ul><ul><li>- 24 bit differential Analog to Digital Converter from Analog Devices </li></ul><ul><li>- Four sentence formats for data parsing </li></ul><ul><li>- Tera Terminal software for COM </li></ul><ul><li>- Multiple baud rate(4800, 9600, 14400, 192000, 38400, 57600, 115200) </li></ul><ul><li>- Built in Temperature Sensor (-40C to 85C) for compass board </li></ul>(0S500-T) 3 Axis Compass (TTL)
    14. 14. <ul><li>A DS1621 DIP Temperature Sensor </li></ul><ul><li>is used to determine the air temperature sensor. It ranges from -55C to 125C and it uses I2C communication bus to communicate with a data handling system </li></ul><ul><li>The DS1621 is placed inside a non- conducting epoxy for the water temperature Sensor </li></ul>Air / Water Temperature Sensor
    15. 15. <ul><li>The humidity of the air would be detected using dry and wet bulb thermometers </li></ul><ul><li>The humidity is calculated based on a comparison between the wet bulb temperature and the dry bulb temperature. This method is used for some psychrometers. </li></ul>Humidity Sensor
    16. 16. <ul><li>The MPX4115AP Pressure Sensor would be </li></ul><ul><li>used to measure air pressure. It ranges from </li></ul><ul><li>15 to 115kpa </li></ul><ul><li>A 0.17 ID, 0.25 OD POLYETH TUBE would used as an atmospheric vent </li></ul>Pressure Sensor
    17. 17. <ul><li>Requires two electrodes mounted </li></ul><ul><li>inside PVC </li></ul><ul><li>Uses IRF7831 MOSFET Switch to </li></ul><ul><li>turn on sensors </li></ul><ul><li>MAX4372 Op. Amplifier for voltage </li></ul><ul><li>Output: 0 to 5v range for ADC </li></ul><ul><li>conversion </li></ul><ul><li>The salinity would be determined by </li></ul><ul><li>finding a relationship between the </li></ul><ul><li>voltages and salinity through a graph. </li></ul><ul><li>A mathematical formula would be </li></ul><ul><li>derived from the graph because the </li></ul><ul><li>voltages are proportional to the </li></ul><ul><li>salinity </li></ul>Salinity Sensor
    18. 18. Link Budget
    19. 19. Communications – Link Testing ¼ Wave Antenna – 6W TX Power Naval Academy LEO PCSAT Antenna Polarization
    20. 20. Low power 3V Radio Handheld Radio Picopacket TNC-X Communications - Radio
    21. 21. Power Budget <ul><li>How did we go about designing the Power Subsystem? </li></ul>Total System Power Units Amount Total Onboard Computer Power PER DAY Watt-hours 0.3685176 Total Communication Power PER DAY Watt-hours 3.7863978 Total GPS Power PER DAY Watt-Hours 0.48 Total Sensor Power PER DAY Watt-Hours 0.1277 General System Power PER DAY Watt-hours 4.7626154
    22. 22. Power – Power Subsystem <ul><li>Batteries vs. Solar Panels + Batteries: </li></ul><ul><ul><li>Batteries have a limited lifetime. </li></ul></ul><ul><ul><li>Solar panels will provide a longer lifetime to batteries to satisfy the buoy’s power needs. </li></ul></ul><ul><li>Sealed Lead Acid Battery </li></ul><ul><ul><li>Poor weight-to-energy density </li></ul></ul><ul><ul><li>Inexpensive </li></ul></ul><ul><ul><li>Low-self discharge </li></ul></ul><ul><ul><li>Multiple Solar Panels </li></ul></ul><ul><ul><ul><li>Collect as much sunlight as possible </li></ul></ul></ul>
    23. 23. Power – Experiments <ul><li>Peak Power Point </li></ul><ul><ul><li>Use solar panels efficiently </li></ul></ul><ul><ul><li>Different Peak Power Points </li></ul></ul><ul><ul><ul><ul><li>Generic vs. Atlantic </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Which one is better? </li></ul></ul></ul></ul>Generic Atlantic
    24. 24. Power – Experiments Generic Atlantic Typical Voltage Volts 14.75 Typical Current Amps 0.09499 Typical Power Watts 1.40110 Time In Sun Per Day Hours 3.3 Power Per Day / Panel 1 (Direct Sunlight) AH 0.313467 Power Per Day / Panel 1 (Direct Sunlight) WH 4.62363825 Indirect Sunlight Percentage % 20.00% Power Per Day / Panel 2 (Indirect Sunlight) AH 0.0626934 Power Per Day / Panel 2 (Indirect Sunlight) WH 0.92472765 Indirect Sunlight Percentage % 20.00% Power Per Day / Panel 3 (Indirect Sunlight) AH 0.0626934 Power Per Day / Panel 3 (Indirect Sunlight) WH 0.92472765 Indirect Sunlight Percentage % 10.00% Power Per Day / Panel 4 (Indirect Sunlight) AH 0.0313467 Power Per Day / Panel 4 (Indirect Sunlight) WH 0.462363825 Total Power Generated Per Day (Amp-hours) AH 0.362054385 Total Power Generated Per Day (Watt-hours) WH 5.340302179 Typical Voltage Volts 12.65 Typical Current Amps 0.06235 Typical Power Watts 0.78873 Time In Sun Per Day Hours 3.3 Power Per Day / Panel 1 (Direct Sunlight) AH 0.205755 Power Per Day / Panel 1 (Direct Sunlight) WH 2.60280075 Indirect Sunlight Percentage % 20.00% Power Per Day / Panel 2 (Indirect Sunlight) AH 0.041151 Power Per Day / Panel 2 (Indirect Sunlight) WH 0.52056015 Indirect Sunlight Percentage % 20.00% Power Per Day / Panel 3 (Indirect Sunlight) AH 0.041151 Power Per Day / Panel 3 (Indirect Sunlight) WH 0.52056015 Indirect Sunlight Percentage % 10.00% Power Per Day / Panel 4 (Indirect Sunlight) AH 0.0205755 Power Per Day / Panel 4 (Indirect Sunlight) WH 0.260280075 Total Power Generated Per Day (Amp-hours) AH 0.237647025 Total Power Generated Per Day (Watt-hours) WH 3.006234866
    25. 25. Power – Regulating Power <ul><li>Step-down voltage : 12 V to 5 V </li></ul><ul><li>Linear Regulator vs. Switching Regulators: </li></ul><ul><li>Linear : </li></ul><ul><li>Take the difference between input and output voltages. </li></ul><ul><ul><li>Difference voltage is converted into thermal energy  Wasted as heat </li></ul></ul><ul><ul><li>Efficiencies: 14% to 40% </li></ul></ul><ul><li>Switching : </li></ul><ul><li>Takes small amounts of energy from input voltage and moves it to output. </li></ul><ul><ul><li>Relatively small energy loss. </li></ul></ul><ul><ul><li>Efficiencies: 70% to 85% </li></ul></ul><ul><ul><li>Conclusion : </li></ul></ul><ul><ul><ul><li>Switching Regulator Efficiency > Linear Regulator Efficiency. </li></ul></ul></ul>
    26. 26. Power – System Features <ul><li>-Controlled Solar Charging </li></ul><ul><li>-Prevent solar panels from overcharging batteries </li></ul><ul><li>-Using a MOSFET as a switch between solar panels and batteries </li></ul><ul><li>-Microcontroller will open / close switch depending on battery charge </li></ul><ul><li>-Control Other Subsystem’s Power </li></ul><ul><li>- Some components will not be used all the time. </li></ul><ul><li>- Use of MOSFETs as switches to selectively power buoy components </li></ul><ul><li>-Watchdog Timer </li></ul><ul><li>-Resets the Microcontroller </li></ul><ul><li>-Momentarily cuts the power to the Microcontroller and Subsystems </li></ul><ul><li>-Reset a latch up condition </li></ul>Battery D G Solar Panel S
    27. 27. Power – Final Calculations <ul><li>Despite conservative assumptions about sunshine per day and system inefficiencies this power system design exceeds the buoy's power requirements. </li></ul>Total System Power Units Amount General System Power PER DAY Watt-hours 4.7626154 Solar Power Harnessed PER DAY Watt-hours 5.340302179 Surplus Power From Sun Watt-hours 0.577686779
    28. 28. Onboard Computer Coordinating the Subsystems Sensors Power Comm Satellite Communications Weather Buoy
    29. 29. The Buoy State Machine
    30. 30. Data Gathering State Fetch current data from the environmental sensors and GPS <ul><li>struct ENVIRONS* GetEnvirons(); </li></ul><ul><li>Pressure (kPa), Humidity (%), Air Temperature (degrees), </li></ul><ul><li>Water Temperature (degrees), Salinity (mg/L), </li></ul><ul><li>Wind Speed (mph), and Wind Direction (N,S,W,E,NE,NW,SE,SW) </li></ul><ul><li>struct GPS* GetGPS(); </li></ul><ul><li>Time , Longitude , and Latitude </li></ul>
    31. 31. Aloha State Attempt to contact satellite Acknowledged Not Acknowledged
    32. 32. Data Tx State Upload environmental data to satellite [Buoy Address],[Date],[Time],[Latitude],[Longitude],A[Air Temperature],W[Water Temperature],H[Humidity],WS[Wind Speed],WD[Wind Direction],S[Salinity] 03,101809,053021.32,2501.23.N,9002.18.W,A088,W084,H060,WS015,WDNW,S32
    33. 33. Wait Short State Waiting between data gathering and alohas 60 Minutes 4 Minutes
    34. 34. Wait Long State Waiting while accumulating a 24 hour data set 60 Minutes 24 Hours
    35. 35. Power Management State Disable Solar Charging Enable Solar Charging Low Power Mode Cease Activity Until Voltage >= 12.4 100% Charge 80% Charge 30% Charge Regulate System Voltage
    36. 36. Mechanical - Construction Bending PVC for Solar Panel Mounts Final Result
    37. 37. Mechanical Antenna Solar Panels 3 ft Discus Aluminum Struts Payload
    38. 38. Mechanical - Stability Test Insert Video Here
    39. 39. Sensors Physical Mount
    40. 40. Summary
    41. 41. Acknowledgements <ul><li>Special Thanks to: </li></ul><ul><ul><li>Nick Pugh </li></ul></ul><ul><ul><li>Mark Fenstermaker </li></ul></ul><ul><ul><li>Fenstermaker and Associates </li></ul></ul><ul><ul><li>Dr. Zhongqi Pan </li></ul></ul>
    42. 42. Questions ?
    43. 43. Appendix <ul><li>Satellite Data Transmission </li></ul><ul><li>Salinity Testing Schematic </li></ul><ul><li>Power Subsystem Schematic </li></ul><ul><li>Sensors Subsystem Schematic </li></ul><ul><li>Main Board Schematic </li></ul><ul><li>Angle of Incidence </li></ul><ul><li>Buoy System Model Spreadsheet </li></ul><ul><li>Communication Subsystem Schematic </li></ul><ul><li>TNC - X Schematic </li></ul>
    44. 45. Satellite Data Transmission
    45. 46. Satellite Data Transmission
    46. 47. Satellite Data Transmission
    47. 48. Satellite Data Transmission
    48. 49. Satellite Data Transmission
    49. 50. Satellite Data Transmission
    50. 51. Satellite Data Transmission
    51. 52. Salinity Testing Schematic
    52. 53. Power Subsystem Schematic
    53. 54. Sensors Subsystem Schematic
    54. 55. Sensors Subsystem Schematic
    55. 56. Main Board Schematic
    56. 57. TNC- X Schematic
    57. 58. Angle of Incidence
    58. 59. Buoy System Model
    59. 60. Buoy System Model
    60. 61. Buoy System Model
    61. 62. Buoy System Model
    62. 63. Buoy System Model
    63. 64. Buoy System Model
    64. 65. Buoy System Model
    65. 66. Buoy System Model
    66. 67. Buoy System Model
    67. 68. Communications Subsystem Schematic
    68. 69. Transistors <ul><li>Bipolar Junction Transistors vs. Field Effect Transistors: </li></ul><ul><li>BJT : </li></ul><ul><li>Works by injecting electrons into the “Base” </li></ul><ul><ul><ul><li>Trigger that turns the transistor on / off </li></ul></ul></ul><ul><ul><ul><li>Thus, they require current to flow in order to keep transistor working </li></ul></ul></ul><ul><li>FET : </li></ul><ul><li>Voltage applied to the Gate controls the current flowing in the Source-Drain channel </li></ul><ul><ul><li>No more current is needed to keep transistor closed for the duration of time needed </li></ul></ul><ul><ul><li>Conclusion : </li></ul></ul><ul><ul><ul><li>BJTs are current-controlled valves & FETs are voltage-controlled valves. </li></ul></ul></ul><ul><ul><ul><li>Loss in power of a FET < Loss in power of a BJT. </li></ul></ul></ul>
    69. 70. Transistors <ul><li>Bipolar Junction Transistors vs. Field Effect Transistors: </li></ul><ul><ul><li>Conclusion : </li></ul></ul><ul><ul><ul><li>BJTs are current-controlled valves & FETs are voltage-controlled valves. </li></ul></ul></ul><ul><ul><ul><li>Loss in power of a FET < Loss in power of a BJT. </li></ul></ul></ul>
    70. 71. Regulators <ul><li>Linear Regulator vs. Switching Regulators: </li></ul><ul><li>Linear : </li></ul><ul><li>Take the difference between input and output voltages. </li></ul><ul><ul><li>Difference voltage is converted into thermal energy  Wasted as heat </li></ul></ul><ul><ul><li>Efficiencies: 14% to 40% </li></ul></ul><ul><li>Switching : </li></ul><ul><li>Takes small amounts of energy from input voltage and moves it to output. </li></ul><ul><ul><li>Relatively small energy loss. </li></ul></ul><ul><ul><li>Efficiencies: 70% to 85% </li></ul></ul><ul><ul><li>Conclusion : </li></ul></ul><ul><ul><ul><li>Switching Regulator Efficiency > Linear Regulator Efficiency. </li></ul></ul></ul>
    71. 72. Solar Panel Efficiency
    72. 73. Voltage Scalar
    73. 74. S D G V GS MOSFET as a Switch <ul><li>-Regions of Operation: </li></ul><ul><li>-Cutoff Region </li></ul><ul><li>-Triode Region </li></ul><ul><li>-Saturation Region </li></ul><ul><li>-For a Switch: Cutoff and Triode Regions are utilized. </li></ul><ul><li>-Cutoff occurs when  V GS < V T </li></ul><ul><li>- Device is turned off </li></ul><ul><li>-Triode occurs when  V GS > V T and V DS < V GS – V T </li></ul><ul><li>-Device is turned on </li></ul><ul><li>-V T is the Threshold voltage </li></ul><ul><li>-Established during device fabrication </li></ul><ul><li>-Typically lies between 0.5 V – 1.0 V </li></ul><ul><li>-MOSFET acts as a linear device: </li></ul><ul><li>-Linear resistor whose resistance can be modulated by changing V GS . </li></ul>V DS Solar Panels Driver
    74. 75. High-Side Driver <ul><li>-Essentially a specialized power amplifier </li></ul><ul><li>-Connected Between: </li></ul><ul><li>-Output of a Power Supply Controller  Microcontroller </li></ul><ul><li>-Power Switch it is driving  MOSFET </li></ul>Solar Panels Driver PIC S D G V GS
    75. 76. Charging Batteries

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