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Active Noise Cancellation For the GM Equinox

Active Noise Cancellation For the GM Equinox. Organization. Advisor: Dr. Nicolas Younan. Summary. Problem. Design and build a small, affordable, portable system to actively cancel periodic noise in a vehicle cabin as perceived by the driver. Solution.

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Active Noise Cancellation For the GM Equinox

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  1. Active Noise CancellationFor the GM Equinox

  2. Organization Advisor: Dr. Nicolas Younan

  3. Summary Problem Design and build a small, affordable, portable system to actively cancel periodic noise in a vehicle cabin as perceived by the driver. Solution • Design and test on a readily available vehicle (1999 Chrysler Cirrus). • Ensure the system is portable.

  4. Why Active Noise Control? • High Frequencies • narrow wavelength • respond well to passive cancellation • Low Frequencies • wider wavelength • respond poorly to passive cancellation • respond well to active cancellation

  5. Overview

  6. Design Constraints • Operational Frequency Range: 50Hz to 1000Hz • Quantization: 16 bits • Sample Rate: 8.00kHz (internal rate of 2kHz) • Attenuation: >= 5dB • Response Time: <= 1s • Cost: < $500 • Power: • Microphones: 9V - supplied by daughter card • Board: 5V - regulated from vehicle’s supply • Reliability: lifetime of the vehicle • Size: module smaller than 9” x 5” x 4” • Safety: upper limit on output power

  7. For Senior Design II… • Adjust algorithm to handle multiple inputs, multiple outputs • Adjust algorithm to cancel only periodic noises • Upgrade algorithm to a Block LMS algorithm and variable adaptation constants • Create PCB layout design • Packaging

  8. For Senior Design II… • Adjust algorithm to handle multiple inputs, multiple outputs • Adjust algorithm to cancel only periodic noises • Upgrade algorithm to a Block LMS algorithm and variable adaptation constants • Create PCB layout design • Packaging

  9. Multi-Error LMS • To globally minimize noise over an array of error sensors • Two error sensors, two secondary sources, and four possible paths • Sum of the errors than more important than any individual error

  10. For Senior Design II… • Adjust algorithm to handle multiple inputs, multiple outputs • Adjust algorithm to cancel only periodic noises • Upgrade algorithm to a Block LMS algorithm and variable adaptation constants • Create PCB layout design • Packaging

  11. Synthetic Reference/Plant Estimation Block

  12. Adaptation Constant μ = 0.0001 μ = 0.0007 Sound levels at cancellation region (over 10 seconds)

  13. For Senior Design II… • Adjust algorithm to handle multiple inputs, multiple outputs • Adjust algorithm to cancel only periodic noises • Upgrade algorithm to a Block LMS algorithm and variable adaptation constants • Create PCB layout design • Packaging

  14. Improvement Highlights • Block processing reduces computation • Internal downsampling improves accuracy while further reducing computation • Anti-aliasing prevents input/output at undesirable frequencies • Synthetic reference signal

  15. Test Procedure • Feed white noise into vehicle cabin to determine acoustics of vehicle. • Record noise before activation of Active Noise Cancellation system. • Activate cancellation signal. • Record noise level with Active Noise Cancellation system on.

  16. Results (Pure Sinusoids) Left microphone PICTURE here. Right microphone Sound levels at cancellation region

  17. Results (Engine Noise) Left microphone PICTURE here. Right microphone Sound levels at cancellation region

  18. Analysis Attenuation (dB) • Results for both cases greater than twice the requirement (5dB).

  19. For Senior Design II… • Adjust algorithm to handle multiple inputs, multiple outputs • Adjust algorithm to cancel only periodic noises • Upgrade algorithm to a Block LMS algorithm and variable adaptation constants • Create PCB layout design • Packaging

  20. PCB Design • Using existing development board • Incorporate daughtercard - Voltage regulation - Preamplification - Biasing for microphone

  21. Daughtercard Schematic

  22. Daughtercard Layout

  23. Packaging • Encased both development board and daughtercard in individual aluminum chassis • Connected power and audio inputs • Chassis doubles as RF shielding and physical protection

  24. Working Prototype Full System Daughtercard

  25. Cost Analysis (Prototype)

  26. Cost Analysis (Mass Production)

  27. Summary • Feasible for Challenge-X Vehicle • Results Dependant upon engine • More noise means more cancellation

  28. Acknowledgements • Dr. Younan • Dr. Molen • Dr. Bruce • Dr. Harden

  29. Questions?

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