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Active Noise Control in an Automobile for Road Noise

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Active Noise Control for Road Noise Demonstration Vehcle Results

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Active Noise Control in an Automobile for Road Noise

  1. 1. On-Road Demonstration of Noise Control in a Passenger Automobile – Part 2 Active 04 Williamsburg, VA, USA September 20-22, 2004 Christopher G. Park Christopher R. Fuller James P. Carneal Vanessa Collin John T. Long Robert E. Powell Joseph L. Schmidt Tech 1872 “ Others”
  2. 2. Where is Part 1? C.G. Park, C.R. Fuller, M. Kidner, “Evaluation and Demonstration of Advanced Active Noise Control in a Passenger Automobile”, Proceedings of Active 02 , pp. 275-284. <ul><li>Vehicle Characterization </li></ul><ul><li>Architecture Optimization </li></ul><ul><li>Preliminary System Performance </li></ul>
  3. 3. Outline of Part 2 Motivation for another demonstration Technology Overview On-road performance Concluding Remarks
  4. 4. The Need for ANC in Automobiles Specific noise problem Vehicle “booming” Broadband road noise <ul><li>Driver fatigue/comfort </li></ul><ul><li>Reduced background noise for communications </li></ul><ul><li>In car entertainment </li></ul><ul><li>Perception of quality </li></ul>
  5. 5. Car and Driver (March 2003) Jaguar S-type (7 th of 7) “ Ride quality… in the top half of the class. Impact noise is surprisingly high, though.” Lincoln LS V8 (6 th of 7) “ You hear every impact of the tires… and you hear little rattles.” Mercedes-Benz E320 (1 st of 7) “ Lows: … lots of road noise.”
  6. 6. Is ANC in Automobiles Practical? The move from laboratory to product has been slower than anticipated. Current DSP technology is on the verge of being cost effective for the large computational requirements of broadband ANC. Passive methods are reaching their limits due to weight considerations, package requirements, and conflicting design constraints. ANC incorporation of the audio systems amplifiers, speakers, wiring and connectors in addition to shared use of some input transducers and error sensors will allow the ANC system to have a more attractive variable cost.
  7. 7. Technology Overview Sound Management System Performance sensor Disturbance sensor Speaker rough road = unwanted interior noise A Sound Management System supplements the passive sound package to enable improved tailoring of the interior acoustic response beyond passive design limitations. Further, the system authority can be redistributed throughout vehicle development to address response characteristic issues that are otherwise costly to modify through passive hardware and tooling changes.
  8. 8. Implemented ANC System Modified Filtered-X LMS algorithm. “ Large” number of sensors and actuators. Multi-DSP (TI C6701) controller. Laboratory grade sensors and a trunk load of equipment.
  9. 9. On-Road Performance <ul><li>2 different vehicles </li></ul><ul><li>Low and mid-frequency performance </li></ul><ul><li>Parallel control system performance </li></ul><ul><li>2 road surfaces </li></ul><ul><li>Pragmatic concerns (e.g. system initialization) </li></ul>
  10. 10. Vehicles <ul><li>Vehicle #1 </li></ul><ul><li>Production passenger automobile </li></ul><ul><li>“ Design optimization” platform </li></ul><ul><li>Proof-of-concept installation </li></ul><ul><li>Trunk full of electronics </li></ul><ul><li>Vehicle #2 </li></ul><ul><li>Same make but different generation of vehicle #1 </li></ul><ul><li>ANC system installed without design re-optimization </li></ul><ul><li>Production quality integration of sensors and actuators </li></ul><ul><li>Turn-key automation </li></ul><ul><li>Trunk full of electronics </li></ul>
  11. 11. Low Frequency Performance in Vehicle #1 Cabin averaged performance rough road (-5.4 dB) Control off Control on
  12. 12. Vehicle #1 Seat-by-Seat Performance Frequency (Hz)
  13. 13. Mid- and Mixed Frequency Performance in Vehicle #1 Control Off Mid-Frequency ANC Combined Low/Mid ANC Cabin averaged performance rough road (-2.4 / -5.6 dB)
  14. 14. Low Frequency Performance in Vehicle #2 Cabin averaged performance rough road (-3.5 dB) Electrical noise Loss of performance due to an actuator change
  15. 15. Low Frequency Performance in Vehicle #2 Cabin averaged performance coarse road (-3.0 dB) Note: Several actuators were saturated during this run.
  16. 16. System Initialization in Vehicle #1 Initial cabin averaged performance rough road (no intrusive system ID)
  17. 17. Concluding Remarks Achieved substantial attenuation of low frequency road noise: 3.6 dB(A) broadband with upwards of 10 dB narrowband attenuation Demonstrated architecture performance robustness from one vehicle to another of the same make but different sound package. Demonstrated the viability of using two parallel and independent controllers to target different spectral content. Pragmatic issues did not pose an implementation barrier during preliminary field trials of the technology.