Frequency selective active adaptive control system

• US 5,710,822 A
• Filed: 11/07/1995
• Issued: 01/20/1998
• Est. Priority Date: 11/07/1995
• Status: Expired due to Term

• Current Assignee: Digisonix Incorporated, Lord Corporation (Parker-Hannifin Corporation)
• Original Assignee: Digisonix Incorporated, Lord Corporation (Parker-Hannifin Corporation)
• Inventors: Steenhagen, Shawn K., Delfosse, Kent F., Southward, Steve C.
• Primary Examiner(s): Isen, Forester W.
• Application Number:
  US08/553,186
• Time in Patent Office: 805 Days
• Field of Search: 381/71, 381/94
• US Class Current: 381/71.12
• CPC Class Codes: G10K 11/17817 between the output signals and the error signals, i.e. secondary path
• CPC Class Codes: G10K 11/17833 by using a self-diagnostic function or a malfunction prevention function, e.g. detecting abnormal output levels
• CPC Class Codes: G10K 11/1785 Methods, e.g. algorithms; Devices G10K11/1781, G10K11/1783 take precedence
• CPC Class Codes: G10K 11/17854 the filter being an adaptive filter
• CPC Class Codes: G10K 11/17879 using both a reference signal and an error signal
• CPC Class Codes: G10K 11/17881 the reference signal being an acoustic signal, e.g. recorded with a microphone
• CPC Class Codes: G10K 2210/117 Nonlinear
• CPC Class Codes: G10K 2210/3028 Filtering, e.g. Kalman filters or special analogue or digital filters
• CPC Class Codes: G10K 2210/3039 Nonlinear, e.g. clipping, numerical truncation, thresholding or variable input and output gain
• CPC Class Codes: G10K 2210/3049 Random noise used, e.g. in model identification

Abstract

An active adaptive control system and method has frequency dependent filtering with a transfer characteristic which is a function of a frequency dependent shaped power limitation characteristic maximizing usage of available output transducer authority. Band separation is provided for different tones. Power limit partitioning is provided for effectively distributing power between correction tones to maximize model performance.

Claims

1. An active adaptive control method comprising introducing a control signal from an output transducer to combine with a system input signal and yield a system output signal, sensing said system output signal with an error transducer providing an error signal, providing an adaptive filter model having a model input from a reference signal correlated to said system input signal, and a model output outputting a correction signal to said output transducer to introduce said control signal according to a weight update signal, adaptively leaking said weight update signal as a function of said correction signal relative to a given peak value according to a desired peak value signal such that said correction signal adaptively converges to a value limited by said peak value, filtering said correction signal by a filter having a transfer characteristic which is a function of a frequency dependent shaped power limitation characteristic maximizing usage of available output transducer authority.

2. The method according to claim 1 wherein said transfer characteristic of said filter is an inverse function of said frequency dependent shaped power limitation characteristic.

3. The method according to claim 2 wherein said transfer characteristic of said filter is the inverse of said frequency dependent shaped power limitation characteristic.

4. The method according to claim 2 comprising comparing said correction signal against said desired peak value signal at a comparator to control adaptive leakage of said weight update signal, and supplying said correction signal to said comparator through said filter.

5. The method according to claim 4 comprising modeling said output transducer and the error path between said output transducer and said error transducer with a second adaptive filter model having a model input from an auxiliary noise source uncorrelated with said system input signal, summing the output of said auxiliary noise source and said correction signal from said model output of said first model and supplying the resultant sum to said output transducer, to afford a post-summed correction signal after passage through said summer, and a pre-summed correction signal prior to passage through said summer, comparing said pre-summed correction signal against said desired peak value signal at said comparator to control adaptive leakage of said weight update signal, filtering said pre-summed correction signal through said filter prior to said comparing.

6. The method according to claim 1 wherein said transfer characteristic of said filter is a direct function of said frequency dependent shaped power limitation characteristic.

7. The method according to claim 6 wherein said transfer characteristic of said filter is said frequency dependent shaped power limitation characteristic.

8. The method according to claim 6 comprising supplying said correction signal through said filter to said output transducer, to afford a post-filtered correction signal after passage through said filter, and a pre-filtered correction signal prior to passage through said filter, comparing said pre-filtered correction signal against said desired peak value signal at a comparator to control adaptive leakage of said weight update signal.

9. The method according to claim 8 comprising modeling said output transducer and the error path between said output transducer and said error transducer with a second adaptive filter model having a model input from an auxiliary noise source uncorrelated with said system input signal, summing the output of said auxiliary noise source and said pre-filtered correction signal from said model output of said first model and supplying the resultant sum to said filter, to afford a post-summed pre-filtered correction signal after passage through said summer and prior to passage through said filter, and a pre-summed pre-filtered correction signal prior to passage through said summer and prior to passage through said filter, comparing said pre-filtered pre-summed correction signal against said desired peak value signal at said comparator to control adaptive leakage of said weight update signal.

10. An active adaptive control method comprising introducing a control signal from an output transducer to combine with a system input signal and yield a system output signal, sensing said system output signal with an error transducer providing an error signal, providing an adaptive filter model having a model input from a reference signal correlated to said system input signal, and a model output outputting a correction signal to said output transducer to introduce said control signal according to a weight update signal, adaptively leaking said weight update signal as a function of said correction signal relative to a given peak value according to a desired peak value signal such that said correction signal adaptively converges to a value limited by said peak value, varying said desired peak value signal according to frequency.

11. The method according to claim 10 comprising comparing said correction signal against said desired peak value signal at a comparator to control adaptive leakage of said weight update signal, providing a frequency transfer function controlling said peak value of said desired peak value signal.

12. The method according to claim 10 comprising modeling said output transducer and the error path between said output transducer and said error transducer with a second adaptive filter model having a model input from an auxiliary noise source uncorrelated with said system input signal, summing the output of said auxiliary noise source and said correction signal from said model output, to afford a post-summed correction signal after said summing, and a pre-summed correction signal prior to said summing, supplying said post-summed correction signal to said output transducer, comparing said pre-summed correction signal against said desired peak value signal at a comparator to control adaptive leakage of said weight update signal.

13. An active adaptive control method for a system input signal having a plurality of tones, comprising separating said system input signal into at least first and second input tones, introducing a control signal from an output transducer to combine with said system input signal and yield a system output signal, sensing said system output signal with an error transducer providing an error signal, providing a first adaptive filter model having a model input from a first reference signal correlated to said first input tone, and a model output outputting a first correction signal to said output transducer to introduce said control signal according to a first weight update signal, adaptively leaking said first weight update signal as a function of said first correction signal relative to a first given peak value according to a first desired peak value signal such that said first correction signal adaptively converges to a value limited by said first peak value, providing a second adaptive filter model having a model input from a second reference signal correlated to said second input tone, and a model output outputting a second correction signal to said output transducer to introduce said control signal according to a second weight update signal, adaptively leaking said second weight update signal as a function of said second correction signal relative to a second given peak value according to a second desired peak value signal such that said second correction signal adaptively converges to a value limited by said second peak value.

14. The method according to claim 13 comprising filtering each of said first and second correction signals with a frequency dependent transfer characteristic.

15. The method according to claim 14 comprising determining a frequency dependent shaped power limitation characteristic maximizing usage of available output transducer authority, and filtering each of said first and second correction signals with a filter having a transfer characteristic which is a function of said frequency dependent shaped power limitation characteristic.

16. The method according to claim 15 wherein each of said filters has a transfer characteristic which is an inverse function of said frequency dependent shaped power limitation characteristic.

17. The method according to claim 15 comprising providing a first said filter filtering said first correction signal, to afford a post-filtered first correction signal after passage through said first filter, and a pre-filtered first correction signal prior to passage through said first filter, providing a second filter filtering said second correction signal, to afford a post-filtered second correction signal after passage through said second filter, and a pre-filtered second correction signal prior to passage through said second filter, comparing said first post-filtered correction signal against said first desired peak value signal at a first comparator to control adaptive leakage of said first weight update signal, comparing said second post-filtered correction signal against said second desired peak value signal at a second comparator to control adaptive leakage of said second weight update signal.

18. The method according to claim 17 comprising summing said first and second pre-filtered correction signals and supplying the resultant sum to said output transducer.

19. The method according to claim 17 comprising modeling said output transducer and the error path between said output transducer and said error transducer with a third adaptive filter model having a model input from an auxiliary noise source uncorrelated with said system input signal, and summing the output of said auxiliary noise source with said first and second pre-filtered correction signals and supplying the resultant sum to said output transducer.

20. The method according to claim 13 comprising filtering the input to said output transducer with a frequency dependent transfer characteristic.

21. The method according to claim 20 comprising determining a frequency dependent shaped power limitation characteristic maximizing usage of available output transducer authority, and filtering the input to said output transducer with a filter having a transfer characteristic which is a function of said frequency dependent shaped power limitation characteristic.

22. The method according to claim 21 wherein said transfer characteristic of said filter is a direct function of said frequency dependent shaped power limitation characteristic.

23. The method according to claim 21 comprising summing said first and second correction signals and supplying the resultant sum as a summed correction signal through said filter to said output transducer, to afford first and second pre-summed correction signals prior to said summing, and a post-summed correction signal after said summing and before passage through said filter.

24. The method according to claim 23 comprising comparing said first pre-summed correction signal against said first desired peak value signal at a first comparator to control adaptive leakage of said first weight update signal, and comparing said second pre-summed correction signal against said second desired peak value signal at a second comparator to control adaptive leakage of said second weight update signal.

25. The method according to claim 13 comprising summing said first and second correction signals and supplying the resultant sum as a summed correction signal to said output transducer, to afford a post-summed correction signal after said summing, and first and second pre-summed correction signals prior to said summing, comparing said first pre-summed correction signal against said first desired peak value signal at a first comparator to control adaptive leakage of said first weight update signal, comparing said second pre-summed correction signal against said second desired peak value signal at a second comparator to control adaptive leakage of said second weight update signal.

26. The method according to claim 25 comprising determining a frequency dependent shaped power limitation characteristic maximizing usage of available output transducer authority, and filtering said post-summed correction signal supplied to said output transducer by a filter having a transfer characteristic which is a function of said frequency dependent shaped power limitation characteristic.

27. The method according to claim 26 comprising modeling said output transducer and the error path between said output transducer and said error transducer with a third adaptive filter model having a model input from an auxiliary noise source uncorrelated to said system input signal, and comprising summing the output of said auxiliary noise source with the outputs of said first and second models and filtering the output resultant sum by through said filter before passage to said output transducer.

28. The method according to claim 13 comprising varying each of said first and second desired peak value signals according to frequency.

29. The method according to claim 28 comprising comparing said first Correction signal against said first desired peak value signal at a first comparator to control adaptive leakage of said first weight update signal, comparing said second correction signal against said second desired peak value signal at a second comparator to control adaptive leakage of said second weight update signal, providing a first frequency transfer function varying said first desired peak value signal according to frequency, and providing a second frequency transfer function varying said second desired peak value signal according to frequency.

30. The method according to claim 28 comprising modeling said output transducer and the error path between said output transducer and said error transducer with a third adaptive filter model having a model input from an auxiliary noise source uncorrelated to said system input signal, summing the output of said auxiliary noise source and said first and second correction signals, to afford a post-summed correction signal supplied to said output transducer, a first pre-summed correction signal, and a second pre-summed correction signal, comparing said first pre-summed correction signal against said frequency dependent first desired peak value signal at a first comparator to control adaptive leakage of said first weight update signal, comparing said second pre-summed correction signal against said frequency dependent second desired peak value signal at a second comparator to control adaptive leakage of said second weight update signal.

31. The method according to claim 13 comprising separating said error signal into at least first and second error tones corresponding respectively to said first and second input tones, and combining said first reference signal with said first error tone to provide said first weight update signal, and combining said second reference signal with said second error tone to provide said second weight update signal.

32. The method according to claim 31 comprising providing said first error tone from a first error transducer, and providing said second error tone from a second error transducer.

33. The method according to claim 13 comprising variably balancing leakage of said first and second weight update signals to partition power distribution among said first and second correction signals to limit cumulative power to said output transducer.

34. The method according to claim 33 comprising determining an admissable region of values in a plot of said first correction signal versus said second correction signal, and coordinating control of leakage of said first and second weight update signals to maintain said first and second correction signals in said admissable region.

35. The method according to claim 34 comprising determining the boundary of said admissable region along a boundary line according to the sum of said first and second correction signals being equal to a predetermined maximum value.

36. The method according to claim 34 comprising determining the boundary of said admissable region along a boundary line and determining the optimum point on said boundary line for balancing said first and second desired peak value signals from a starting point off of said boundary line comprising projecting from said starting point to said boundary line along a projection line intersecting and perpendicular to said boundary line, the intersection of said projection line and said boundary line being said optimum point.

37. The method according to claim 34 comprising determining the boundary of said admissable region along a boundary line and maintaining said first and second correction signals on said boundary line.

38. The method according to claim 34 comprising determining the boundary of said admissable region along a boundary line and determining the optimum point on said boundary line for balancing said first and second desired peak value signals from a starting point off of said boundary line comprising projecting from said starting point to said boundary line along a projection line extending from the origin of said plot through said starting point and intersecting said boundary line, the intersection of said projection line and said boundary line being said optimum point.

39. The method according to claim 34 comprising determining the boundary of said admissable region along a boundary line and determining the optimum point on said boundary line for balancing said first and second desired peak value signals from a starting point off of said boundary line comprising determining an error surface around said starting point and projecting from said starting point to said boundary line along a projection line intersecting said boundary line and tangent to said error surface, the intersection of said projection line and said boundary line being said optimum point.

40. An active adaptive control system comprising an output transducer introducing a control signal to combine with a system input signal and yield a system output signal, an error transducer sensing said system output signal and providing an error signal, an adaptive filter model having a model input from a reference signal correlated to said system input signal, and a model output outputting a correction signal to said output transducer to introduce said control signal according to a weight update signal, adaptive leak means adaptively leaking said weight update signal as a function of said correction signal relative to a given peak value according to a desired peak value signal such that said correction signal adaptively converges to a value limited by said peak value, a filter filtering said correction signal by a transfer characteristic which is a function of a frequency dependent shaped power limitation characteristic maximizing usage of available output transducer authority.

41. The system according to claim 40 wherein said filter has a transfer characteristic which is an inverse function of said frequency dependent shaped power limitation characteristic.

42. The system according to claim 41 wherein said filter has a transfer characteristic which is the inverse of said frequency dependent shaped power limitation characteristic.

43. The system according to claim 41 comprising a comparator comparing said correction signal against said desired peak value signal to control adaptive leakage of said weight update signal, and wherein said correction signal from said output of said model is supplied through said filter to said comparator.

44. The system according to claim 43 comprising a second adaptive filter model modeling said output transducer and the error path between said output transducer and said error transducer, said second adaptive filter model having a model input from an auxiliary noise source uncorrelated with said system input signal, a summer summing the output of said auxiliary noise source and said correction signal from said model output of said first mentioned model and supplying the resultant sum to said output transducer, to afford a post-summed correction signal after passage through said summer, and a pre-summed correction signal prior to passage through said summer, a comparator comparing said pre-summed correction signal against said desired peak value signal to control adaptive leakage of said weight update signal, wherein said pre-summed correction signal is supplied through said filter to said comparator.

45. The system according to claim 40 wherein said filter has a transfer characteristic which is a direct function of said frequency dependent shaped power limitation characteristic.

46. The system according to claim 45 wherein said filter has a transfer characteristic which is said frequency dependent shaped power limitation characteristic.

47. The system according to claim 46 wherein said correction signal is supplied from said model output through said filter to said output transducer.

48. The system according to claim 45 wherein said filter filters said correction signal supplied to said output transducer, to afford a post-filtered correction signal after passage through said filter, and a pre-filtered correction signal prior to passage through said filter, a comparator comparing said pre-filtered correction signal against said desired peak value signal to control adaptive leakage of said weight update signal.

49. The system according to claim 48 comprising a second adaptive filter model modeling said output transducer and the error path between said output transducer and said error transducer, said second adaptive filter model having a model input from an auxiliary noise source uncorrelated with said system input signal, a summer summing the output of said auxiliary noise source with said pre-filtered correction signal and supplying the resultant sum to said filter.

50. An active adaptive control system comprising an output transducer introducing a control signal to combine with a system input signal and yield a system output signal, an error transducer sensing said system output signal and providing an error signal, an adaptive filter model having a model input from a reference signal correlated to said system input signal, and a model output outputting a correction signal to said output transducer to introduce said control signal according to a weight update signal, adaptive leak means adaptively leaking said weight update signal as a function of said correction signal relative to a given peak value according to a desired peak value signal such that said correction signal adaptively converges to a value limited by said peak value, frequency transfer means varying said desired peak value signal according to frequency.

51. The system according to claim 50 comprising a comparator comparing said correction signal against said desired peak value signal to control adaptive leakage of said weight update signal, said frequency transfer means controlling said peak value of said desired peak value signal.

52. The system according to claim 50 comprising a second adaptive filter model modeling said output transducer and the error path between said output transducer and said error transducer, said second adaptive filter model having a model input from an auxiliary noise source uncorrelated with said system input signal, a summer summing the output of said auxiliary noise source and said correction signal from said model output of said first mentioned model, to afford a post-summed correction signal after passage through said summer, and a pre-summed correction signal prior to passage through said summer, said post-summed correction signal being supplied to said output transducer, a comparator comparing said pre-summed correction signal against said desired peak value signal to control adaptive leakage of said weight update signal.

53. An active adaptive control system for a system input signal having a plurality of tones, comprising separating means separating said system input signal into at least first and second input tones, an output transducer introducing a control signal to combine with said system input signal and yield a system output signal, an error transducer sensing said system output signal and providing an error signal, a first adaptive filter model having a model input from a first reference signal correlated to said first input tone, and a model output outputting a first correction signal to said output transducer to introduce said control signal according to a first weight update signal, first adaptive leak means adaptively leaking said first update signal as a function of said first correction signal relative to a first given peak value according to a first desired peak value signal such that said first correction signal adaptively converges to a value limited by said first peak value, a second adaptive filter model having a model input from a second reference signal correlated to said second input tone, and a model output outputting a second correction signal to said output transducer to introduce said control signal according to a second weight update signal, second adaptive leak means adaptively leaking said second weight update signal as a function of said second correction signal relative to a second given peak value according to a second desired peak value signal such that said second correction signal adaptively converges to a value limited by said second peak value.

54. The system according to claim 53 comprising filter means filtering said first and second correction signals with a frequency dependent transfer characteristic.

55. The system according to claim 54 wherein said filter means has a transfer characteristic which is a function of a frequency dependent shaped power limitation characteristic maximizing usage of available output transducer authority.

56. The system according to claim 55 wherein said filter means comprises first and second filters each having a transfer characteristic which is an inverse function of said frequency dependent shaped power limitation characteristic.

57. The system according to claim 53 comprising a first filter filtering said first correction signal with a frequency dependent transfer characteristic, to afford a post-filtered first correction signal after passage through said first filter, and a pre-filtered first correction signal prior to passage through said first filter, a second filter filtering said second correction signal with a frequency dependent transfer characteristic, to afford a post-filtered second correction signal after passage through said second filter, and a pre-filtered second correction signal prior to passage through said second filter, a first comparator comparing said first post-filtered correction signal against said first desired peak value signal to control adaptive leakage of said first weight update signal, a second comparator comparing said second post-filtered correction signal against said desired peak value signal to control adaptive leakage of said second weight update signal.

58. The system according to claim 57 comprising a summer summing said first and second pre-filtered correction signals and supplying the resultant sum to said output transducer.

59. The system according to claim 58 comprising a third adaptive filter model modeling said output transducer and the error path between said output transducer and said error transducer, said third adaptive filter model having a model input from an auxiliary noise source uncorrelated with said system input signal, wherein said summer sums the output of said auxiliary noise source with said first and second pre-filtered correction signals and supplies the resultant sum to said output transducer.

60. The system according to claim 53 comprising a filter filtering the input to said output transducer with a frequency dependent transfer characteristic.

61. The system according to claim 60 wherein said filter has a transfer characteristic which is a function of a frequency dependent shaped power limitation characteristic maximizing usage of available output transducer authority.

62. The system according to claim 61 wherein said filter has a transfer characteristic which is a direct function of said frequency dependent shaped power limitation characteristic.

63. The system according to claim 62 wherein said filter has a transfer characteristic which is said frequency dependent shaped power limitation characteristic.

64. The system according to claim 60 comprising a summer summing said first and second correction signals and supplying the resultant sum as a summed correction signal to said output transducer, and wherein said filter filters said summed correction signal.

65. The system according to claim 53 comprising a summer summing said first and second correction signals and supplying the resultant sum as a summed correction signal to said output transducer, to afford a post-summed correction signal after passage through said summer, and first and second pre-summed correction signals prior to passage through said summer, a first comparator comparing said first pre-summed correction signal against said first desired peak value signal to control adaptive leakage of said first weight update signal, a second comparator comparing said second pre-summed correction signal against said second desired peak value signal to control adaptive leakage of said second weight update signal.

66. The system according to claim 65 comprising a filter filtering said post-summed correction signal supplied to said output transducer by a transfer characteristic which is a function of a frequency dependent shaped power limitation characteristic maximizing usage of available output transducer authority.

67. The system according to claim 66 comprising a third adaptive filter model modeling said output transducer and the error path between said output transducer and said error transducer, said third adaptive filter model having a model input from an auxiliary noise source uncorrelated with said system input signal, a summer summing the output of said auxiliary noise source with the outputs of said first and second models, and wherein said filter filters the output resultant sum from said summer by a transfer characteristic which is a direct function of said frequency dependent shaped power limitation characteristic before passage to said output transducer.

68. The system according to claim 53 comprising frequency transfer means varying said first and second desired peak value signals according to frequency.

69. The system according to claim 68 comprising a first comparator comparing said first correction signal against said first desired peak value signal to control adaptive leakage of said first weight update signal, a second comparator comparing said second correction signal against said second desired peak value signal to control adaptive leakage of said second weight update signal, a first frequency transfer function varying said first desired peak value signal according to frequency, and a second frequency transfer function varying said second desired peak value signal according to frequency.

70. The system according to claim 68 comprising a third adaptive filter model modeling said output transducer and the error path between said output transducer and said error transducer, said third adaptive filter model having a model input from an auxiliary noise source uncorrelated to said system input signal, a summer summing the output of said auxiliary noise source and said first and second correction signals, to afford a post-summed correction signal supplied to said output transducer, a first pre-summed correction signal, and a second pre-summed correction signal, a first comparator comparing said first pre-summed correction signal against said frequency dependent first desired peak value signal to control adaptive leakage of said first weight update signal, a second comparator comparing said second pre-summed correction signal against said frequency dependent second desired peak value signal to control adaptive leakage of said second weight update signal.

71. The system according to claim 53 comprising separating means separating said error signal into at least first and second error tones corresponding respectively to said first and second input tones, a first combiner combining said first reference signal with said first error tone to provide said first weight update signal, and a second combiner combining said second reference signal with said second error tone to provide said second weight update signal.

72. The system according to claim 71 comprising a first error transducer providing said first error tone, and a second error transducer providing said second error tone.