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Helmet Locating and Tracking System

Helmet Locating and Tracking System. Kim Bongen, Greg Insana, Fengjia Liu ECE 445 Spring 2011 Team #16 TA Advisor: Xiangyu Ding. Outline. Part 1: Introduction Part 2: Hardware Part 3: Processing Part 4: Display Part 5: Results. Introduction Hardware Processing Display

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Helmet Locating and Tracking System

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  1. Helmet Locating and Tracking System Kim Bongen, Greg Insana, Fengjia Liu ECE 445 Spring 2011 Team #16 TA Advisor: Xiangyu Ding

  2. Outline Part 1: IntroductionPart 2: HardwarePart 3: ProcessingPart 4: DisplayPart 5: Results • Introduction • Hardware • Processing • Display • Summary & Concluding Remarks

  3. Background and Motivation Part 1: IntroductionPart 2: HardwarePart 3: ProcessingPart 4: DisplayPart 5: Results • Background • Evolution of military avionics • Helmet-mounted Displays (HMD’s) • Motivation • Partnership with industry • Exploring military technology

  4. Product features Sense the elevation, azimuth and tilt of a pilot's head/helmet relative to the cockpit Compatible with the Scorpion Helmet Mounted Cueing System Compact & lightweight Product Benefits Increased tracking accuracy over current solutions Cost-efficient components and design Project Objective Part 1: IntroductionPart 2: HardwarePart 3: ProcessingPart 4: DisplayPart 5: Results

  5. Ethical Considerations Part 1: IntroductionPart 2: HardwarePart 3: ProcessingPart 4: DisplayPart 5: Results • Acknowledge key outside contributions • Bill Haynes and Gentex Corp • Mark Smart & ECE Parts Shop Staff • Communication with Gentex Corp • Design and product quality

  6. Key Sensor Board Components Part 1: IntroductionPart 2: HardwarePart 3: ProcessingPart 4: DisplayPart 5: Results • 3-axis Accelerometer/Magnetometer • Linear acceleration • Magnetic field • 3-axis Gyroscope • Angular acceleration • GPS Chip

  7. PCB Design and Fabrication Part 1: IntroductionPart 2: HardwarePart 3: ProcessingPart 4: DisplayPart 5: Results • Designed using EAGLE editor 4.61r2 • Dimensions: 2.4x2.4 in • Predominantly one-sided design

  8. PCB – Top Side Part 1: IntroductionPart 2: HardwarePart 3: ProcessingPart 4: DisplayPart 5: Results

  9. PCB – Bottom Side Part 1: IntroductionPart 2: HardwarePart 3: ProcessingPart 4: DisplayPart 5: Results

  10. Sensor Board Testing Part 1: IntroductionPart 2: HardwarePart 3: ProcessingPart 4: DisplayPart 5: Results • General Procedure • Voltage at source and ground lines • Output Test • Accuracy Test • Drift Test • Debugging • Components • Accelerometer/Magnetometer • Gyroscope • PCB

  11. PCB Testing Part 1: IntroductionPart 2: HardwarePart 3: ProcessingPart 4: DisplayPart 5: Results • Ensure all wires functioned as intended • Utilized digital multimeter to measure resistance on voltage, ground, and data lines

  12. PCB Testing Results (Voltage and Ground) Part 1: IntroductionPart 2: HardwarePart 3: ProcessingPart 4: DisplayPart 5: Results

  13. PCB Testing Results (Resistors and Top Wires) Part 1: IntroductionPart 2: HardwarePart 3: ProcessingPart 4: DisplayPart 5: Results

  14. Interfacing Part 1: IntroductionPart 2: HardwarePart 3: ProcessingPart 4: DisplayPart 5: Results • Digital outputs from chip • I2C Protocol • 16-bit signed values for all three coordinates • Linear acceleration from accelerometer in m/s2 • Angular velocity from gyroscope in deg/s • FPGA • Controls I2C clock and data lines • Stores settings for the operation of the chips

  15. Major Components Part 1: IntroductionPart 2: HardwarePart 3: ProcessingPart 4: DisplayPart 5: Results • I2C Communicator • Writes appropriate settings to control registers on the chip • Continuously reads the output from the output registers • Calibration • Removes the constant offset from the output of the chips • Conversion • Converts the output to useable units • Integration • Compares the current input with the previous inputs to compute the integral for all three coordinates

  16. Plane Transformation Problem Part 1: IntroductionPart 2: HardwarePart 3: ProcessingPart 4: DisplayPart 5: Results za za Zw Zw ya ya xa xa Yw Yw Xw Xw Z Angle: 0o Z Angle: -45o

  17. Plane Transformation Part 1: IntroductionPart 2: HardwarePart 3: ProcessingPart 4: DisplayPart 5: Results • Transforms the acceleration values from the chip plane to the world plane • Uses angles from the gyroscope • Needs sine and cosine values provided by a look-up table

  18. Block Diagram Part 1: IntroductionPart 2: HardwarePart 3: ProcessingPart 4: DisplayPart 5: Results Integration I2C Calibration Conversion Gyroscope Calibration Conversion I2C Plane Transformation Integration Integration Accelerometer

  19. Block Diagram Part 1: IntroductionPart 2: HardwarePart 3: ProcessingPart 4: DisplayPart 5: Results x, y, z 16-bits each x, y, z 32-bits each clock, data 1-bit each Integration I2C Calibration Conversion Gyroscope Calibration Conversion I2C Plane Transformation Integration Integration Accelerometer clock, data 1-bit each x, y, z 32-bits each x, y, z 16-bits each

  20. Numeric Display Part 1: IntroductionPart 2: HardwarePart 3: ProcessingPart 4: DisplayPart 5: Results • Switches select data to be displayed • Data needed to be converted to binary coded decimal (BCD) • Data then sent to display in ASCII • 2x16 line display – with labels can only fit 5 digits of x, y, and z

  21. Start Does the MSB = 1? Yes No Sign is negative Sign is positive Convert data to positive binary representation Shift in MSB Is this the final bit? Are any of the BCD digits > 5? No Yes No Add 3 to any BCD digit >5 Yes End Numeric Display Part 1: IntroductionPart 2: HardwarePart 3: ProcessingPart 4: DisplayPart 5: Results BCD Conversion • “shift, add three” algorithm • Mathematical simplification of the subtract 10, add 16 method. • Example: Twelve = 1100 => 0001 0010

  22. Graphical Display Part 1: IntroductionPart 2: HardwarePart 3: ProcessingPart 4: DisplayPart 5: Results • Implemented via the VGA port on DE2 board • Switches used to select which value to control the ball • Acceleration • Velocity • Position • Angle

  23. Computation Testing Part 1: IntroductionPart 2: HardwarePart 3: ProcessingPart 4: DisplayPart 5: Results • Simulations verify theoretical functionality of all entities • Drift from first level integration depends on calibration • Increases linearly with time • Approximately 20 mm/s per second and 20 millidegrees per second • Drift from second integration depends on first level • Increases quadratically with time

  24. Statistics Part 1: IntroductionPart 2: HardwarePart 3: ProcessingPart 4: DisplayPart 5: Results Sampling rate: 41.56 Hz • I2C Communication: 240.6 µs (every 100th data point is used) Computation Times: • Calibration: 40 ns • Conversion: 80 ns • Integration: 500 ns • Plane Transformation: 180 ns • Total comp time with partial functionality: 1.12 µs • Total estimated time with full functionality: 1.92 µs

  25. FPGA Benefits and Limitations Part 1: IntroductionPart 2: HardwarePart 3: ProcessingPart 4: DisplayPart 5: Results Benefits • Easily adaptable to existing systems. • Speed • Size and weight • Familiarity Limitations • Embedded multipliers • Rounding Error • Available memory for look-up table

  26. Challenges Part 1: IntroductionPart 2: HardwarePart 3: ProcessingPart 4: DisplayPart 5: Results Embedded Multipliers • Altera DE2 has 70 9-bit multipliers • 16-bit multiplication for conversion • Requires 2 multipliers for the 2 sensors, done on all 3 coordinates  12 multipliers • 32-bit multiplication for integration • Requires 4 multipliers done on all 3 coordinates • once for gyroscope, twice for accelerometer  36 multipliers • 16-bit multiplication for plane transformation • Requires 2 multipliers for every multiplication done within the rotation matrix • Result  56 multipliers Total Multipliers: 104/70

  27. Challenges Part 1: IntroductionPart 2: HardwarePart 3: ProcessingPart 4: DisplayPart 5: Results Rounding Error • Any division done results in rounding error • Minimized by using smaller units (micrometers and microdegrees) • Smaller units  more bits to store number  more multipliers • Inaccurate calculations can lead to drift

  28. Recommendations Part 1: IntroductionPart 2: HardwarePart 3: ProcessingPart 4: DisplayPart 5: Results • Use specialized FPGA circuit • Focus on components used in circuit (multipliers) • Consider using computer for computations • More processing power • Signal processing to get better results • Determine if the propagation delay is small enough • Investigate floating point

  29. Special Thanks • Bill Haynes & Gentex Corp • Mark Smart & ECE Parts Shop Staff • Xiangyu Ding

  30. Finis

  31. General Outline Introduction Objective Review Original Design Describe project build and functional tests Discuss successes and challenges Other tests Recommendations Developmental Notes

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