Active adaptive control system with weight update selective leakage

• US 5,586,190 A
• Filed: 06/23/1994
• Issued: 12/17/1996
• Est. Priority Date: 06/23/1994
• Status: Expired due to Term

• Current Assignee: Digisonix Incorporated
• Original Assignee: Digisonix Incorporated
• Inventors: Trantow, Jerry J., Finn, Brian M.
• Primary Examiner(s): Coles, Sr., Edward L.
• Assistant Examiner(s): Grant, II, Jerome
• Application Number:
  US08/264,510
• Time in Patent Office: 908 Days
• Field of Search: 381/71, 381/73.1, 381/94, 381/93
• US Class Current: 381/71.12
• 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 11/17854 the filter being an adaptive filter
• CPC Class Codes: G10K 11/17881 the reference signal being an acoustic signal, e.g. recorded with a microphone

Abstract

An active adaptive control system introduces a control signal from an output transducer (14) to combine with the system input signal (6) and yield a system output signal (8). An error transducer (16) senses the system output signal and provides an error signal (44). An adaptive filter model (40) has a model input from a reference signal (42) correlated to the system input signal, and an output outputting a correction signal (46) to the output transducer to introduce the control signal according to a weight update signal (74) provided by the product (from multiplier 72) of the reference signal and the error signal. Selective leakage of the weight update signal is provided in response to a given condition of a given parameter, preferably output power of the correction signal, to control performance of the model, to selectively degrade same according to need. Leakage is varied by multiplying a previous weight update value by a factor γ and adding the result to the product of the reference signal and error signal, and varying γ as a function of the correction signal.

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 an output outputting a correction signal to said output transducer to introduce said control signal according to a weight update signal, combining said reference signal and said error signal to provide said weight update signal, and providing selective leakage of said weight update signal in response to a given condition of a given parameter, to control performance of said model, and comprising varying said leakage as a discontinuous step function of said correction signal such that when said correction signal exceeds a given threshold, said leakage is abruptly, nonlinearly increased as a step function from a first lower level to a second higher level.

2. 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 an output outputting a correction signal to said output transducer to introduce said control signal according to a weight update signal, combining said reference signal and said error signal to provide said weight update signal, and providing selective leakage of said weight update signal in response to a given condition of a given parameter, to control performance of said model, and comprising varying said leakage as a continuous increasing function of said correction signal above a given threshold such that when said correction signal exceeds said given threshold, said leakage increases as a continuous function of said correction signal.

3. 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, output outputting a correction signal to said output transducer to introduce said control signal according to a weight update signal, combining said reference signal and said error signal to provide said weight update signal, and providing selective leakage of said weight update signal in response to a given condition of a given parameter, to control performance of said model, and comprising increasing said leakage linearly with increasing output power of said correction signal above a given threshold.

4. 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 an output outputting a correction signal to said output transducer to introduce said control signal according to a weight update signal, combining said reference signal and said error signal to provide said weight update signal, providing selective leakage of said weight update signal to degrade performance of said model, and adjustably varying said leakage to vary performance of said model, and comprising varying said leakage by multiplying a previous weight update value by a factor γ

and adding the result to the product of said reference signal and said error signal, and varying γ

as a function of said correction signal, varying γ

as a discontinuous step function of said correction signal such that when said correction signal exceeds a given threshold, γ

is abruptly, nonlinearly decreased as a step function from a first higher level to a second lower level, to thus abruptly, nonlinearly increase leakage from a first lower level to a second higher level.

5. 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 an output outputting a correction signal to said output transducer to introduce said control signal according to a weight update signal, combining said reference signal and said error signal to provide said weight update signal, providing selective leakage of said weight update signal to degrade performance of said model, and adjustably varying said leakage to vary performance of said model, and comprising varying said leakage by multiplying a previous weight update value by a factor γ

and adding the result to the product of said reference signal and said error signal, and varying γ

as a function of said correction signal, varying γ

as a continuous decreasing function of said correction signal above a given threshold such that when said correction signal exceeds said given threshold, γ

decreases as a continuous function of said correction signal, to thus increase leakage as a continuous function of said correction signal.

6. 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 an output outputting a correction signal to said output transducer to introduce said control signal according to a weight update signal, combining said reference signal and said error signal to provide said weight update signal, providing selective leakage of said weight update signal to degrade performance of said model, and adjustably varying said leakage to vary performance of said model, and comprising varying said leakage by multiplying a previous weight update value by a factor γ

and adding the result to the product of said reference signal and said error signal, and varying γ

as a function of said correction signal, decreasing γ

linearly with increasing output power of said correction signal above a given threshold, to thus increase leakage linearly with increasing output power of said correction signal above said given threshold.

7. 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 threshold to change leakage of said weight update signal when said correction signal exceeds said threshold.

8. The method according to claim 7 comprising adaptively leaking said weight update signal by leaking said weight update signal as a function of said correction signal and supplying the leaked weight update signal to said adaptive filter model to adapt said correction signal controlling leakage of said weight update signal.

9. The method according to claim 8 comprising leaking said weight update signal by multiplying a previous weight update value by a factor γ

and adding the result to the product of said reference signal and said error signal, and varying γ

as a function of said correction signal.