A Prototype Attitude Determination System for High Altitude Research Balloons

1. Catholic University of America A Prototype Attitude Determination System for High Altitude Research Balloons Erin Doody, Fernando Esteves, Devon Gonteski, Michael Lamos, Jason Quisberth, Peter Schramm, Raissa Silva, Gary Uritskiy, Patricia Yoritomo

2. Mission Overview *

3. Table of Contents • Mission Overview • Components • Theory and Concepts • Expected Results • System Overview • Block Diagrams • Mass Budget • Subsystem Design • Star Camera • Flight Computer • Pressure Vessel • Electrical Box • Gyros • Prototyping Plan • Assembly and Testing • Management Plan • Schedule • Budget • Task Distribution • Contact Matrix

4. Mission Overview Overall goal: Design, fabricate, test, and launch a system that collects data • 20kg payload • Measure altitude to arc-second precision • Use of commercially available and low-cost components • Meets Columbia Scientific Balloon Facility (CSBF) requirements • Meets Undergraduate Student Instrument Project (USIP)

5. Main Components • Daytime-Capable Star Camera • Gyroscopes • Tilt Sensors • Flight Computer • Magnetometer • Clinometer • Thermometer • Pressure Vessel • Box

6. Theory & Concepts • Electrical engineering, Mechanical engineering, and applied physics ideas and concepts will be used to order to construct, build, test, and fly payload • heat transfer • signal processing and filtering • thermodynamics • Knowledge of computer programming languages such as python will be used in order to operate the electronic components. • Similar projects are seen on the HASP carrier by NASA BPO and LaSPACE • Successful flights and good data are signs that this project is feasible within the timeline given

7. Expected Results To develop a low-cost, low-mass system for real-time attitude determination • Using of individual sensors including a daytime-capable digital star camera, MEMS gryoscopes, magnetometers, and tilt sensors (clinometers). • The fast, relative sensors (gyroscopes) that are continuously updated by the slower, absolute sensors (star camera, magnetometers). The integration of the gyro output will demonstrate real-time attitude determination to arc-second or better precision.

8. System Overview *

9. System Level Block Diagram AAS – Absolute Attitude Sensing CCM – Climate Control and Monitor MP – Mounting Plate PV – Pressure Vessel RAS – Relative Attitude Sensing SP – Signal Processing UB – Unpressurized Box VRB – Voltage Regulator Board *

10. System Concept of Operations *

11. Mass Budget *

12. SubsystemDesign *

13. Star Camera DesignLens *

14. Star Camera Lens Section • This system is design with the intent to to capture images of stars in both the day and night during flight • One of the requirements for the lens is that it must capture a minimum of 4 stars in the pipeline. • By choosing a lens with a greater area we see an increase in performance by a factor of 1.36. • Another advantage of the smaller f-stop lens is the size of the filter, 72mm vs. 58mm. The larger diameter lens provides a larger area and gives us a larger area of usable frame. • Even though the f/1.2 lens is heavier (545g vs. 290g) the HASP payload bay that we have acquired is 20Kg, well within our current estimate of 3.54Kg. *

15. Lens: Trade Studies Product Chosen: EF 50mm f/1.2L USM Standard & Medium Telephoto • Focal Length & Maximum Aperture -50mm f/1.2 • Lens Construction -8 elements in 6 groups • Diagonal Angle of View -46° (with full-frame cameras) • Focus Adjustment AF with full-time manual • Closest Focusing Distance -1.48 ft. / 0.45m • Filter Size -72mm • Max. Diameter x Length, Weight- 3.4 in. x 2.6 in./85.4mm x 65.5mm,19.2 oz./545g (lens only) *

16. Star Camera DesignCamera Body *

17. Camera Body Design Section • The camera body will be connected to the computer through the means of a USB 2.0 cable. • The software that will facilitate the communication between the flight computer is called gphoto2 and it will give use the ability to cycle shutter speed in flight • The photos that will be take will be sent to the external hardrive. • The reason for choosing the Canon 7D was that it is one of the only camera that is compatible with the gphoto2 software. • This limited the cameras that we could research thus almost forcing us to choose the 7D. *

18. Camera Body: Trade Study Product Chosen: *

19. AAS: Risk Matrix AAS.RSK.1: Mission objectives aren't met if the Star Camera overheats. AAS.RSK.2: Mission objectives are affected if the Star Camera parameters had not been set right. AAS.RSK.3: Mission objectives aren't met if the Camera fails to communicate with the flight computer. AAS.RSK.4: Mission objectives are affected if the camera lens becomes obstructed *

20. Flight Computer Design *

21. Flight Computer Design Section • The flight computer will be responsible for the data acquisition and signal processing. It should have a good processing potential, enough I/O ports to connect all devices, compact size and be robust to different environments. • The first option we consider for the flight computer was a ASUS laptop. It had all the processing potential we need and I/O ports. However, it had some disadvantages such as high price, big size, power consuming and produces too much heat. • Single board computers are a very compact and cheap option that have also a great processing potential. The BeagleBoard-xM (the flight computer selected) have all the capacities we need for a very good price. It has 512 MB DDR memory, 1 GHz ARM Cortex-A8 processor, provides 4 USB ports and runs differents versions of linux. *

22. Flight Computer: Trade Studies • Show rationale for you choices in components. You basically weigh your options against your requirements and what each component can offer. Don’t forget things like: availability, cost, and prior knowledge. I recommend an online search for examples if you are unsure, or contact me. *

23. Subsystem Design Section • This section is where you explain how each subsystem was designed • Start with your organization chart with each of your subsystems labeled • Discuss how you researched components that would meet your requirements • Show trade studies if necessary, and if you show them, be prepared to explain the scoring and categories • The most important part is explaining how you reached your major design decisions in each subsystem • After explaining components, discuss any risks associated with this subsystem *

24. SP: Risk Matrix SP.RSK.1: Mission objectives aren't met if the computer or the PSyncADC board overheats. SP.RSK.2: Mission objectives aren't met if the flight computer fails in communicating to the PSyncADC. SP.RSK.3: Mission objectives aren't met if the flight computer fails in processing sensor data. SP.RSK.4: Mission objectives will be affected if bad sensor data is not filtered. SP.RSK.5: Mission objectives will be affected if the hard drive gets damaged on landing. *

25. Pressure Vessel and Electrical Box Design *

26. Subsystem Overview – Block Diagram Pressure Vessel and Electrical Box • The pressure vessel will connect to the electrical box that will connect to the large payload (carrier) Pressure Vessel Electrical Box Carrier *

27. Pressure Vessel Pressure Vessel • Top view • Side view Star Camera Flight Computer Hard drive *

28. Electrical Box Electrical Box • Top View • Side View Gyro Board P-Sync *

29. EPS: Trade Studies • Show rationale for you choices in components. You basically weigh your options against your requirements and what each component can offer. Don’t forget things like: availability, cost, and prior knowledge. I recommend an online search for examples if you are unsure, or contact me. • You should have completed a trade study for each block, but you only need to present the 2-3 most important. • Numbers are relatively subjective, but 10 should represent a perfect fit, 5 will work, but is not desirable, and 0 does NOT meet expectations. • The component with the highest average should drive your choice for design. *

30. PV: Risk Matrix PV.RSK.1: Mission objectives aren't met if the pressure vessel leaks. PV.RSK.2: Mission objectives aren't met if pressure vessel opens entirely/explode. PV.RSK.3: Mission objectives are affected if the pressure vessel could not provide the right pressure. PV.RSK.4: Mission objectives are affected if the pressure vessel detached from other components PV.RSK.5: Mission objectives are affected if the pressure vessel gets dented after landing. *

31. CCM: Risk Matrix CCM.RSK.1: Mission objectives are affected if heaters could not provide enough energy. CCM.RSK.2: Mission objectives are affected if thermometers fails to measure data correctly. CCM.RSK.3: Mission objectives are affected if heaters fails provide excessive energy; *

32. VRB: Risk Matrix VRB.RSK.1: Mission objectives aren't met if power supply cannot give enough power for the whole system. VRB.RSK.2: Mission objectives are affected if voltage regulation board fails in provide the correct voltage. VRB.RSK.3: Mission objectives aren't met if power supplies excessive amounts of current. *

33. UB: Risk Matrix PV.RSK.1: Mission objectives are affected if the unpressured box opens. PV.RSK.2: Mission objectives are affected if the unpressured box gets damage. *

34. Gyro Selection *

35. Gyro Overview – Block Diagram • Show your subsystems, now with more detail inside the boxes, and the connections between them *

36. Subsystem Design Section • This section is where you explain how each subsystem was designed • Start with your organization chart with each of your subsystems labeled • Discuss how you researched components that would meet your requirements • Show trade studies if necessary, and if you show them, be prepared to explain the scoring and categories • The most important part is explaining how you reached your major design decisions in each subsystem • After explaining components, discuss any risks associated with this subsystem *

37. Gyro: Trade Studies • Show rationale for you choices in components. You basically weigh your options against your requirements and what each component can offer. Don’t forget things like: availability, cost, and prior knowledge. I recommend an online search for examples if you are unsure, or contact me. *

38. RAS: Risk Matrix RAS.RSK.1: Mission objectives are affected if a gyro fails or sends corrupted data to signal processing. RAS.RSK.2: Mission objectives are affected if the Magnetometer fails or sends corrupted data to signal processing. AAS.RSK.3: Mission objectives are affected if the Clinometer fails or sends corrupted data to signal processing. *

39. Prototype Assembly and Testing

40. Payload Prototype Assembly • Construct metal box of identical dimensions to actual payload in order to test different part positioning • Things to consider: • Positioning of all the parts relative to each other • Vacuum chamber integrity • Insulation positioning

41. Sensor Testing • Once all the parts are hooked up together and functioning, the multiple sensors present on the payload must be tested • Things to consider • Sensor calibration • Sensor positioning within the payload • Reliability and accuracy of each sensor

42. Gyroscope Testing • After the completion of gyro fabrication, test all gyros for proper functioning separately, then together as a system to guarantee that each board operates both by itself and in a system • The accuracy and precision of the final gyroscope unit will be measured in a variety of tests

43. Temperature Regulation Requirements • The payload electronic parts must remain in a certain temperature range to ensure proper function • Temperature of the electric board(s) must be above 5°C but below 60°C • To ensure this is met, the prototype of the payload must be put under extensive testing in extreme temperature conditions

44. Important Factors to consider • Insulation – a insulating layer must be present to slow down heat dissipation from and into the vessel • Ventilation – there must be circulation in the payload to ensure that the hottest parts do not overheat too quickly • Thermostat heating – we plan on having an on-board thermostat with a heating element to heat up the system if the air inside goes too low

45. Testing the Prototype • There are two conditions under which the system must be able to function • Room temperature: the heat dissipation from the prototype vessel must be great enough so that it does not overheat, which means the excessive insulation must be avoided • Upper stratosphere temperature (-5°C): the thermostat must be able to heat the system in the case in which the heat from the functioning parts is insufficient to maintain functional temperature

46. Final testing • Once the payload prototype is fully assembled and all its parts are functional, it is important to leave the entire system running for several days at a time to identify any weak links in the physical and software design • Running for long testing periods will reveal elusive coding bugs, design flaws, and system glitches that could potentially occur in flight

47. Project Management Plan

49. Schedule

50. Work Breakdown Structure Pressure Vessel: • Trade studies • Designs and brainstorming • Sketch SolidWorks drawings • Electronic simulation and testing in SolidWorks • Purchase materials • Preliminary fabrication process • Thermal testing and insulation design • Test preliminary fabrication design • Final compiling with electrical components Unpressurized Box • Trade studies • Designs and brainstorming • Sketch SolidWorks drawings • Electronic simulation and testing in SolidWorks • Purchase materials • Preliminary fabrication process • Thermal testing and insulation design • Test preliminary fabrication design • Final compiling with electrical components