1. High Resolution AMR Compass Honeywell Dr. Andy Peczalski Professor Beth Stadler Pat Albersman Jeff Aymond Dan Beckvall Marcus Ellson Patrick Hermans

2. Agenda Honeywell Introduction/Abstract – Marcus E MATLAB Simulations – Marcus E Software – Pat H Hardware – Jeff A Testing – Pat A Results – Dan B

3. Abstract Honeywell This project’s purpose is to improve the accuracy of a digital compass by using multiple compass IC’s. These will work together to collectively improve the accuracy of the overall system.

4. Abstract Honeywell One benchmark is to try to increase the accuracy of the system by the number of sensors used. Increased precision and repeatability is also desired.

5. Abstract Honeywell Customized hardware is necessary to implement the multiple sensor system. Customized software to manage the implementation is also necessary.

6. MATLAB Honeywell Used to simulate single and multiple sensors before our hardware was complete Provided a vehicle to test the performance of our heading calculation algorithms 1702 lines of MATLAB simulations

7. Sensor Placement The placement of the sensors must create a system accurate across 360 degrees Each individual bridge of each sensor can be simulated independently in MATLAB Multiple arrangements can be simulated to determine the best implementation Honeywell

8. Orientation Simulations Single IC Senor Output Wave Form: Honeywell Data Appears Evenly Spaced ICs at: 0, 36, 72, 108, 144, 180, 216, 252, 288, 324 Degrees

9. Orientation Simulations Single IC Senor Output Wave Form: Honeywell Data Evenly Spaced ICs at: 0, 9, 18, 27, 36, 45, 54, 63, 72, 81 Degrees

10. Software Honeywell Three software realms involved with this project: MATLAB C VB

11. C Written in MPLab – Version 8.0 CCS complier – Version 4 Run on PIC 18f4550 1326 Lines of C – 2532 Lines of Assembly Honeywell

12. Sensor Communication Sensor Commands – Heading Adjusted voltages Raw voltages – Calibrate – Re-address – Number of Summed measurements Honeywell

13. Serial Communication Allows Compass to display results Very helpful in debugging Allows for VB to control sensor Easy to implement in CCS 115200 Baud allowable from the 20Mhz crystal Honeywell

16. Weighted Averaging Honeywell

18. VB Provides an end-user interface Synchronizes the compass and the rotation table Allows for automated data acquisition Provides a repeatable test benching system Requires a third board to handle adjusted ground on PMC 4733 Lines Honeywell

21. Personal Computer (VB) PIC18F4520 (C) PMC Controller Rot. Table Sensors Serial I2C Parallel

22. Final Hardware Honeywell Abstract Initial Design Problems with Initial Design Changes Made Proposed Final Design

23. Abstract One compass, two boards – Main Board Microcontroller – Daughter Board Sensors Honeywell

24. Initial Design Honeywell Main Board

25. Essentially a controller board – Microcontroller – RS-232 Communication – I 2 C Communication – Interfacing Daughter Board Front Panel Honeywell

26. Initial Design Honeywell Daughter Board

27. Three functional systems – Sensor array – Power MUX – Laser Honeywell

28. Constraint: One of the dimensions must be less than 3.5” – Opening of zero-gauss chamber is 3.5” in diameter Honeywell 3.492” 3.132” Daughter Board Dimensions

29. Constraint: One of the dimensions must be less than 3.5” – Opening of gauss-free chamber is 3.5” in diameter Honeywell 3.132” 0.73” The Daughter Board meets size requirements Daughter Board Dimensions

30. Honeywell Ground Data Clock Power Feedback Networks Decoupling Capacitor LED Daughter Board HMC6352

31. Honeywell Daughter Board I 2 C Bus Data Clock

32. Design challenge: – Need to assign unique address to each sensor – Each sensor is factory installed with address 0x42 – In order to change addresses, a command must be sent to a sensor on the bus – This command message contains: – How to change address of individual sensor if every sensor is receiving the command? Honeywell Daughter Board Power MUX StartAddress[Ack]Command[Ack]Stop

33. Solution: Need to isolate communication to individual sensor How? – Burn-in Socket – Use a network of jumpers – Multiplex I 2 C to each sensor – Multiplex power to each sensor Honeywell Daughter Board Power MUX Photo taken from http://www.locknest.com/newsite/products/qfn/index.htm

34. We chose to multiplex power – Advantages Saves power Simplifies troubleshooting – Disadvantages Signal loss through MUX Other unknowns… Honeywell Daughter Board Power MUX

35. Problems with Initial Design Problems – Main Board None – Daughter Board I 2 C bus – When powered off, the sensors interfere with I 2 C bus – 5V data signal is pulled down to 2.5V – Therefore communication will not work – Problems not related to design Sensor 3 will not communicate Will not hinder project; algorithm will still work Slight loss of sensitivity at sensor 3’s axes of sensitivity (27° and 117 °) Honeywell

36. Changes to Initial Design I 2 C bus fix – Remove MUX and feed power to all sensors – Cut I 2 C traces – Add jumpers to I 2 C vias and address them one by one – Connect all jumpers to I 2 C bus Honeywell

37. Changes to Initial Design Other changes – No laser mount Laser mounted directly to plexi-glass case Saves cost ($25) Honeywell

38. Changes to Initial Design Other changes – Main Board Layout Honeywell BeforeAfter

39. Proposed Final Design Due to I 2 C bus issues, our current design does not work Two options 1.Power all sensors and use burn-in or jumpers socket to isolate sensors 2.Multiplex I 2 C bus Honeywell

40. Proposed Final Design Option 1: Power all sensors and use socket/jumpers Advantages – No MUX needed Reduces surface area of board Reduces signal loss of MUX – Sleep mode on sensors Save power I 2 C bus has not been tested in this mode Honeywell

41. Proposed Final Design Option 1: Power all sensors and use socket/jumpers Disadvantages – Sockets can be expensive – Footprint of HMC6352 is not common Hard to find socket – No disadvantages if we add jumpers Honeywell

42. Proposed Final Design Option 2: Multiplex I 2 C bus Advantages – No need for a socket – Sleep mode to save power (not tested) Disadvantages – Side effects of multiplexing I 2 C unknown Honeywell

43. Testing Honeywell Prototype Final

44. Test Setup Honeywell

45. Accuracy Honeywell Precision Repeatability Compare ß field Compare

46. Prototype Testing Honeywell Given one sensor CCS compiler

47. Final Testing Honeywell Elements of Final testing Pretesting (zero gauss values) Pretesting (offsets) Testing (accuracy, precision, repeatability)

48. Pre-testing (zero gauss) 1.Place sensors in the zero gauss chamber 2.Rotate 360 deg. while taking readings 3.Analyze data and get zero gauss values Honeywell

49. Pre-testing (offsets) 1.Place sensors in artificial magnetic field 2.Run VB script that finds sensor locations Finds zero gauss value of each chip Works using relativity Bang bang control 3.Analyze data and find chip placements 4.Hardcode this to software Honeywell

50. Raw voltage readings with offsets

51. Honeywell Raw voltage readings with offsets

52. Accuracy Test Procedure 1.Determine the B field Find the zero crossing on each axis B field should be 90 degrees from zero crossing Average the 20 axes results 2.Take measurement 3.Compare result to actual 4.Rotate to different position 5.Repeat steps 2-5 Honeywell 23 deg 113 deg

53. Results Honeywell Results Comprise of: Determining Specs Comparison of Specs to Controls Ways to improve Future for Nanowires?

54. Results: Specs - Repeatability Comprised of 5 readings taken at 0, 90, 180,270 Our Product: Min = +- 0.015 Max = +-0.089 Control: Min = +- 0.033 Max = +-0.051 Honeywell = +- 0.030 Max = +- 0.120 Honeywell

55. Results: Specs - Precision Honeywell

56. Results: Specs - Accuracy Honeywell

57. How Can We Improve Currently using arcTan(x/y) to compute heading – This assumes we have X and Y which need to be 90 degrees apart – In practice this is not true, we found this is actually only within +-8 degrees Use different algorithms, better weighting More Sensors Honeywell

58. Future For Nanowires? Nanowires are inherently less accurate Means greater room for improvement Small enough to use more than 10 bridges Weighting should have more of an effect Will have completely different obstacles All in all, from the results of this feasibility test they look very promising Honeywell

59. Conclusion Honeywell Questions/ Comments? Demo Upstairs?