1. Final Presentation April 19, 2010 Contactless Angular Position Sensor Team: Eugene Sandberg, Christine Bratton, Matt Landry, Aram Lee, Jeremy Lewis Faculty Advisor: Dr. Robert B. Reese ECE Department, Mississippi State University

2. Team Members Eugene Sandberg Computer Engineer Tasks: -Construct Test Setup -Program Microchip -Website -Populate the PCB Christine Bratton Electrical Engineer Tasks: -Research Magnets and Sensors -Program Microchip -Output Stage -Layout Design Aram Lee Electrical Engineer Tasks: -Research Magnets and Sensors -Program Microchip -Populate the PCB Jeremy Lewis Computer Engineer Tasks: -Construct Test Setup -Layout Design -Packaging Matt Landry Electrical Engineer Tasks: -Research Magnets and Sensors -Output Stage -Packaging -Layout Design

3. Outline Problem Statement Solution Diagram Constraints Initial Testing Populating the PCB Calibration Final Packaging Costs Video

4. The Problem Endcap/SensorA-Arm

5. Problem With Current Design The current sensor has reliability problems. It is not known for sure, but it could be due to the mechanical linkage between the sensor and A-arm. Desired: A contactless sensor solution.

6. Solution - Hall Effect Sensor

7. Solution Overview Magnet Generates a magnetic field. Sensor Outputs a signal relative to angular position of magnetic field. Microprocessor Processes the signal from the sensor. DAC/Amp Outputs analog voltage. (0-24V)

8. Constraints Technical Constraints Practical Constraints

9. Technical Constraints The CAPS must be driven by a 24 volt input and output a linear DC voltage ranging from 0 to 24 V. -Complete  The CAPS must draw less than 24 mA. -Satisfactory  -Actual draw is ~60 mA

10. Technical Constraints The CAPS must operate between -40 to 70 degrees Celsius and also meet MIL-STD-810 vibration requirements. -Not tested The CAPS must be accurate to.1 degrees and measure an angle of 90 degrees. -Complete  -Angle range changed to 17 to 68.7 degrees

11. Practical Constraints Sustainability – The CAPS must be contactless. -Complete 

12. Practical Constraints Compatibility – Must Fit in End Cap – Same Casing – Complete 

13. Initial Testing Old Sensor DegreeOutput(V)Ideal-out(V)Error(%)Error(degree) 170.030.00N/A0.065 201.341.403.940.118 253.663.721.610.129 306.066.050.250.032 358.558.372.150.387 4010.6310.700.610.140 4512.9513.020.540.151 5015.4215.350.490.161 5517.6117.670.340.129 6020.00 0.030.011 Maximum Error (degree)=0.387 Current:0.02A Resistance:1~1013ohm OldNew Max Error (degree)=0.3870.075 Current (mA)=2060

14. Initial Testing Right-Side-CalibrationLeft-Side-Calibration DegreeOutput(V)Ideal-out(V)Error(%)Error(degree)DegreeOutput(V)Ideal-out(V)Error(%)Error(degree) 170.030.00N/A0.065170.030.00N/A0.065 201.431.402.510.075201.431.402.510.075 253.733.720.270.022253.713.720.270.022 306.066.050.250.032306.066.050.250.032 358.398.370.240.043358.398.370.240.043 4010.7210.700.230.0544010.70 0.050.011 4513.0513.020.230.0654513.0513.020.230.065 5015.3715.350.160.0545015.3715.350.160.054 5517.6617.670.060.0225517.6617.670.060.022 6020.00 0.030.0116020.00 0.030.011 6522.3022.320.090.0436522.3022.320.090.043 Maximum Error (degree)=0.075Maximum Error (degree)=0.075 Current:0.04~0.06A Startup=0.1A Melexis 90316 Hall Effect Sensor

15. Packaging

16. PCB Layout Voltage Regulators Op-amp Melexis Hall Effect Sensor PIC24F and DAC Each board about 0.8” x 0.8”

17. Populated PCBs The extra three wires are for in-circuit programming of the sensor’s microcontroller firmware.

18. Calibration Initial magnet position unknown, and rotation direction different based on left/right side installation With A-Arm in neutral position, calibration sets vehicle side and records magnet position in non-volatile storage. External calibration box is used for this purposes, uses existing 3-wire interface; mode entered if supply voltage 6v to 10v instead of 24v. LEDs show calibration status, and switch selects left/right side.

19. _ Testing-Calibration Box 50 kHz 30 kHz 20 kHz Left side Right side Success Calibration Box Sensor

20. Final Packaging Costs QuantityPart NumberNamePrice per partTotal 1 MAX6341ESA+ND Voltage Referance $17.12 1 LM7321MA-ND OPAMP $2.51 1MMBT3904TPMSDKR-BJT $0.32 1 MAX5312EAE+-ND DAC $11.79 1PIC24FJ64GA002-E/ML-NDPIC24 $5.02 1DMN3404LDICT-NDSingle Mosfet $0.50 1LM2937IMP-12CT-NDVoltage Reg 12 $2.06 1LM2937IMP-5.0CT-NDVoltage Reg 5 $2.06 1LM3940IMP-3.3CT-NDVoltage Reg 3.3 $1.89 1 BZT52C10S-FDIDKR-ND Diode $0.44 11 Various Various Capacitors $0.45 $4.95 10 Various Various Resistors $0.15 $1.50 2IRF7303QTRPBFCT-NDDouble Mosfet $1.46 $2.92 1 Custom Fabricated Cylindar Metal Housing $900.00 1 One set of 4 PCB's$30$30.00 $965.96

21. Videos Sensor operation outside of hub housing Sensor installed into hub housing Sensor installation into A-ARM Sensor operation in A-ARM before calibration Calibration procedure Sensor operation in A-ARM after calibration

22. Videos

23. References Karahalis, Alex. “Contacless Angular Position Sensor.” August 11, 2009. SPG Media Group Ltd. “Stryker 8-Wheel Drive Armoured Combat Vehicles, USA.” 2009. [Online]. Available: http://www.army-technology.com/projects/stryker/ [Accessed: August 30, 2009]. Quasdorf, Joachim. “A Case Study: MR vs. Hall Effect for Position Sensing.” [Online]. Available: http://www.sensorsmag.com/sensors/article/ [Accessed: October 2009].