CN-116895271-B - Active noise reduction system

CN116895271BCN 116895271 BCN116895271 BCN 116895271BCN-116895271-B

Abstract

The present invention relates to an active noise reduction system that reduces noise in an internal space of a moving body. The active noise reduction system includes a controller configured to control the cancellation sound output device. The controller is configured to generate a first cancellation estimation signal as an estimation signal of the cancellation sound at the position of the error detector based on the reference signal, generate a second cancellation estimation signal as an estimation signal of the cancellation sound at the head position of the occupant by adjusting a time delay and an amplitude of the first cancellation estimation signal based on the reference distance, and update a control filter for controlling the cancellation sound output device based on the second cancellation estimation signal.

Inventors

WANG XUN
INOUE TOSHIRO

Assignees

本田技研工业株式会社

Dates

Publication Date: 20260505
Application Date: 20230310
Priority Date: 20220330

Claims (7)

1. An active noise reduction system for reducing noise in an interior space of a mobile body, the active noise reduction system comprising: A reference signal generator configured to generate a reference signal corresponding to the noise; a cancellation sound output device configured to output a cancellation sound for canceling the noise; An error detector configured to detect an error between the noise and the cancellation sound, and generate an error signal corresponding to the error; A reference distance detector configured to detect a reference distance as a distance from the canceling sound output device to a head position of the occupant, and A controller configured to control the cancellation sound output device based on the reference signal, the error signal, and the reference distance, Wherein the controller is configured to: generating a first cancellation estimate signal based on the reference signal, the first cancellation estimate signal being an estimate signal of the cancellation sound at the position of the error detector; Generating a second cancellation estimation signal by adjusting a time delay and an amplitude of the first cancellation estimation signal based on the reference distance, the second cancellation estimation signal being an estimation signal of the cancellation sound at the head position of the occupant, and Updating a control filter based on the second cancellation estimation signal, the control filter being a filter for controlling the cancellation sound output device.
2. The active noise reduction system of claim 1, wherein the controller is configured to: Setting a correction coefficient corresponding to the reference distance, and The update amount of the control filter is corrected by multiplying the update amount of the control filter by the correction coefficient.
3. The active noise reduction system of claim 2, wherein the controller is configured to adjust the amplitude of the first cancellation estimate signal by using an amplitude adjustment coefficient that decreases as the reference distance increases, and The correction coefficient is set to the inverse of the amplitude adjustment coefficient.
4. The active noise reduction system of claim 2, wherein the controller is configured to adjust the amplitude of the first cancellation estimate signal by using an amplitude adjustment coefficient that decreases as the reference distance increases, and The correction coefficient is set such that the product of the amplitude adjustment coefficient and the correction coefficient is less than 1.
5. The active noise reduction system of claim 2, wherein the controller is configured to store a correction coefficient table defining a relationship between the reference distance and the correction coefficient.
6. The active noise reduction system of any of claims 1 to 5, wherein the controller is configured to: updating the estimated value of the transfer characteristic of the canceling sound, and The first cancellation estimation signal is generated by correcting the reference signal based on the updated estimation value of the transfer characteristic of the cancellation sound.
7. The active noise reduction system according to any one of claims 1 to 5, wherein the cancellation sound output device and the error detector are mounted in a headrest of an occupant seat provided in the interior space, and The controller is configured to generate the second cancellation estimate signal by adjusting only the time delay and the amplitude of the first cancellation estimate signal.

Description

Active noise reduction system Technical Field The present invention relates to an active noise reduction system that reduces noise by canceling acoustic interference noise in opposite phases to the noise. Background Generally, active noise reduction systems reduce noise by canceling acoustic interference noise in opposite phase to the noise. For example, the active noise reduction system includes a cancellation sound output device configured to output a cancellation sound to cancel noise, an error detector configured to detect an error between the noise and the cancellation sound and generate an error signal corresponding to the error, and a controller configured to control the cancellation sound output device based on the error signal. For example, JP2021-162849A discloses a speaker that outputs a cancellation sound, a microphone that outputs an error signal, and an active noise controller that generates a control signal for causing the speaker to output the cancellation sound based on the error signal. In the conventional active noise reduction system, an area having a high control effect (high noise reduction effect) is limited to a part of an area around an error detector such as a microphone. Therefore, if the head position of the occupant is changed, noise at the head position of the occupant may not be sufficiently reduced. Disclosure of Invention In view of the above background, an object of the present invention is to provide an inexpensive active noise reduction system capable of effectively reducing noise at the head position of an occupant even if the head position of the occupant changes. In order to achieve such an object, one aspect of the present invention provides an active noise reduction system 11 for reducing noise in an interior space (cabin 5) of a mobile body (vehicle 1), comprising a reference signal generator (vibration sensor 12) configured to generate a reference signal corresponding to the noise; a cancellation sound output device (speaker 13) configured to output a cancellation sound for canceling the noise, an error detector (error microphone 14) configured to detect an error between the noise and the cancellation sound and generate an error signal corresponding to the error, a reference distance detector 15 configured to detect a reference distance that is a distance from the cancellation sound output device to a head position of an occupant, and a controller 16 configured to control the cancellation sound output device based on the reference signal, the error signal, and the reference distance, wherein the controller is configured to generate a first cancellation estimation signal that is an estimation signal of the cancellation sound at a position of the error detector, generate a second cancellation estimation signal that is a time delay and an amplitude of the cancellation estimation signal by adjusting the first cancellation estimation signal based on the reference distance, based on the second cancellation estimation signal, and based on the update of the head estimation signal of the occupant, the control filter is a filter for controlling the canceling sound output device. According to this aspect, by updating the control filter based on the second cancellation estimation signal (the estimation signal of the cancellation sound at the head position of the occupant), the characteristic of the control filter can be changed to follow the change in the head position of the occupant. Therefore, even if the head position of the occupant changes, noise at the head position of the occupant can be effectively reduced. Further, the second cancellation estimate signal is generated by adjusting the time delay and amplitude of the first cancellation estimate signal (the estimate signal of the cancellation sound at the position of the error detector). Therefore, it is not necessary to use a filter with a high computational load to generate the second cancellation estimation signal. Thus, the computational load of the controller may be reduced, and the controller may be composed of a relatively inexpensive processor. In the above aspect, preferably, the controller is configured to set a correction coefficient corresponding to the reference distance, and correct the update amount of the control filter by multiplying the update amount of the control filter by the correction coefficient. According to this aspect, the update amount of the control filter can be adjusted according to the reference distance, so that the update amount of the control filter can be maintained at an appropriate value. In the above aspect, preferably, the controller is configured to adjust the amplitude of the first cancellation estimation signal by using an amplitude adjustment coefficient that decreases as the reference distance increases, and the correction coefficient is set to the inverse of the amplitude adjustment coefficient. According to this aspect, in the case where the amplitude adjustment coefficient