KR20240159285A - Device and Method for Active Noise Cancelling of Vehicle according to Road Surface Change - Google Patents

Abstract

A method and device for active noise control of a vehicle according to changes in road surfaces are disclosed.
According to one aspect of the present invention, a computer-implemented method for active noise control of a vehicle according to changes in road surfaces is provided, comprising: a step of detecting changes in the road surface according to movement of the vehicle; and a step of applying a common filter coefficient set stored in advance in an adaptive filter within a noise control system of the vehicle in response to detecting the changes in the road surface.

Description

{Device and Method for Active Noise Cancelling of Vehicle according to Road Surface Change}

Embodiments of the present invention relate to a method and device for active noise control of a vehicle according to changes in road surfaces.

The content described below merely provides background information related to the present embodiment and does not constitute prior art.

When a vehicle is driven, airborne noise and structural noise are generated in the vehicle. For example, noise generated by the vehicle's engine, noise generated by friction between the vehicle and the road, vibration transmitted through the suspension, and wind noise generated by the wind are generated.

As a method for reducing such noise, there is a passive noise control method that installs sound-absorbing materials inside the vehicle to absorb noise, and an active noise control (ANC) method that uses a noise control signal that has a phase opposite to that of the noise.

Passive noise control methods have limitations in adaptively eliminating various noises, so research on active noise control methods is actively being conducted. In particular, the Road-noise Active Noise Control (RANC) method for eliminating road noise from vehicles is attracting attention.

To perform active noise control, the vehicle's noise control system generates a noise control signal that has the same amplitude as the vehicle's interior noise but has an opposite phase to the interior noise, and outputs the noise control signal to the interior of the vehicle, thereby canceling out the interior noise.

The adaptive filter that generates the noise control signal in the noise control system is periodically updated according to the environmental conditions of the vehicle. For example, when the vehicle moves from a first road surface to a second road surface, the adaptive filter generates the noise control signal based on the signals according to the second road surface.

When the environmental conditions of the vehicle change, the coefficients of the conventional adaptive filter are initialized to 0. However, if the adaptive filter is initialized to 0 every time the environmental conditions of the vehicle change, the active noise control performance of the noise control system may deteriorate momentarily and abnormal noise may occur.

The main purpose of embodiments of the present invention is to provide an active noise control method and device for improving the convergence speed of an adaptive filter, preventing divergence of an adaptive filter, and preventing occurrence of abnormal noise when a road surface changes due to movement of a vehicle.

The problems to be solved by the present invention are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

According to one aspect of the present invention, a computer-implemented method for active noise control of a vehicle according to changes in road surfaces is provided, the method including: a step of detecting changes in the road surface according to movement of the vehicle; and a step of applying a common filter coefficient set stored in advance in an adaptive filter within a noise control system of the vehicle in response to detecting the changes in the road surface.

According to another aspect of the present invention, a device for active noise control of a vehicle according to a change in a road surface, comprising: a memory storing commands; and at least one processor, wherein the at least one processor detects a change in a road surface according to a movement of the vehicle by executing the commands, and applies a common filter coefficient set stored in advance in an adaptive filter within a noise control system of the vehicle in response to the detection of the change in the road surface.

As described above, according to one embodiment of the present invention, when the road surface changes due to the movement of a vehicle, the convergence speed of an adaptive filter can be improved, divergence of the adaptive filter can be prevented, and occurrence of abnormal noise can be prevented.

The effects of the present disclosure are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description below.

FIG. 1 is a schematic diagram illustrating components of a vehicle according to one embodiment of the present invention.
FIG. 2 is a drawing exemplarily shown to explain a noise control method according to one embodiment of the present invention.
Figure 3 is a configuration diagram of a noise control algorithm according to one embodiment of the present invention.
FIG. 4 is a configuration diagram of a portion of a noise control system according to one embodiment of the present invention.
Figure 5 is a flowchart of an active noise control method for a vehicle according to one embodiment of the present invention.

Hereinafter, some embodiments of the present disclosure will be described in detail using exemplary drawings. When adding reference numerals to components of each drawing, it should be noted that the same numerals are used for identical components as much as possible even if they are shown in different drawings. In addition, when describing the present disclosure, if it is determined that a specific description of a related known configuration or function may obscure the gist of the present disclosure, the detailed description thereof will be omitted.

In describing components of embodiments according to the present disclosure, symbols such as first, second, i), ii), a), b), etc. may be used. These symbols are only for distinguishing the components from other components, and the nature or order or sequence of the components is not limited by the symbols. When a part in the specification is said to "include" or "provide" a component, this does not mean that other components are excluded, but rather that other components can be further included, unless explicitly stated otherwise.

Each component of the device or method according to the present invention may be implemented as hardware or software, or as a combination of hardware and software. In addition, the function of each component may be implemented as software, and a microprocessor may be implemented to execute the function of the software corresponding to each component.

FIG. 1 is a schematic diagram illustrating components of a vehicle according to one embodiment of the present invention.

Referring to FIG. 1, a vehicle (10) is illustrated that includes wheels (100), suspension devices (110), reference sensors (120), microphones (130), a controller (140), speakers (150), and an axle (160). The number and arrangement positions of the plurality of components in FIG. 1 correspond to one embodiment, and the number and positions of the components may be different in other embodiments.

The vehicle (10) includes a chassis on which accessories necessary for driving are mounted, and a noise control system that performs active noise control. The vehicle (10) may further include at least one of a power unit, a steering unit, or a braking unit.

The chassis of the vehicle (10) includes wheels (100) of the vehicle (10), and the wheels (100) include front wheels respectively arranged on the left and right sides of the front, and rear wheels respectively arranged on the left and right sides of the rear of the vehicle (10). The chassis of the vehicle (10) may further include an axle (160) as a power transmission means, suspension devices (110) as a vibration mitigation means, and a body. Here, the suspension devices (110) are devices that mitigate vibration or shock of the vehicle (10). Specifically, while the vehicle (10) is driving, vibration due to the road surface is applied to the vehicle (10). The suspension devices (110) mitigate vibration applied to the vehicle (10) by using springs, air suspension, or the like. The suspension devices (110) can improve the riding comfort of passengers riding in the vehicle (10) by mitigating shock.

However, noise may be generated inside the vehicle (10) by the suspension devices (110). Specifically, the suspension devices (110) can alleviate large vibrations applied to the vehicle (10), but it is difficult to eliminate minute vibrations generated by friction between the wheels (100) and the road surface. These minute vibrations generate noise inside the vehicle (10) through the suspension devices (110). Furthermore, noise generated by friction between the wheels (100) and the road surface, noise generated by the engine as a power unit, or wind noise generated by the wind may be introduced into the vehicle (10).

To eliminate noise inside the vehicle (10), the vehicle (10) may include a noise control system. The noise control system of the vehicle (10) may attenuate noise by using a noise control signal having the same amplitude as the noise signal for noise inside the vehicle (10) but having a phase opposite to the phase of the noise signal.

For this purpose, the noise control system includes reference sensors (120), microphones (130), a controller (140), and speakers (150). The noise control system may further include an amplifier (AMP) for audio reproduction.

The reference sensors (120) generate a reference signal representing vibrations caused by friction between the wheels (100) and the road surface, and transmit the reference signal to the controller (140). At this time, the reference sensors (120) transmit the reference signal in the form of an analog signal to the controller (140). Alternatively, the reference sensors (120) may convert the reference signal into a digital signal, and transmit the converted digital signal to the controller (140).

Here, the reference sensors (120) may be accelerometers. An accelerometer is a device that generates an acceleration signal representing the acceleration of a vehicle (10). The accelerometer is used to measure vibration of the vehicle (10). In other words, the reference sensors (120) may generate reference signals according to the vibration of the vehicle (10), and the reference signals represent acceleration signals. The reference sensors (120) are three-axis accelerometers that may measure vibration along three vertical axes.

Reference sensors (120) may be placed on the suspension devices (110), on a connecting mechanism connecting the wheels (100) and the axle (160), or on the vehicle body.

The noise control system may use at least one of a gyro sensor, a motion sensor, a displacement sensor, a torque sensor, or a microphone as a reference sensor to measure vibration of the vehicle (10).

Microphones (130) detect sound inside the vehicle (10). Microphones (130) can detect noise inside the vehicle (10). For example, microphones (130) can measure sound pressure of about 20 Hz to 20 kHz, which is a human audible frequency band. The range of the audible frequency of microphones (130) can be narrower or wider. In one embodiment, microphones (130) can measure noise introduced into the vehicle (10) by friction between wheels (100) and the road surface.

When a noise control signal is output into the interior of a vehicle (10) for noise control, the microphones (130) can measure noise signals remaining in the interior of the vehicle (10) in an environment where the interior noise of the vehicle (10) is removed by the noise control signal. The residual noise is measured as an error signal or residual signal by the microphones (130). The error signal can be used as information for determining whether the noise inside the vehicle (10) has been normally reduced or removed.

When audio signals are further output into the interior of the vehicle (10), the acoustic signals of the microphones (130) may include error signals and audio signals.

The controller (140) generates a noise control signal for removing noise inside the vehicle based on the reference signal and error signal of the reference sensors (120). The controller (140) can generate a noise control signal having the same amplitude as the amplitude of the noise signal but having a phase opposite to the phase of the noise signal. The controller (140) can convert the reference signal and error signal, which are analog signals, into digital signals and generate a noise control signal from the converted digital signals.

When the noise control system includes an amplifier, the amplifier receives a noise control signal from the controller (140), receives an audio signal from an AVN (Audio, Video, Navigation) device, mixes the noise control signal and the audio signal, and outputs the mixed signal through a speaker.

An amplifier can control the amplitude of a mixed signal by using amplifiers. The amplifiers can include vacuum tubes or transistors to amplify the power of the mixed signal.

The speakers (150) receive a mixed signal, which is an electrical signal, from an amplifier or a noise control signal from a controller (140), and output the mixed signal or noise control signal in the form of sound waves inside the vehicle (10). The noise inside the vehicle (10) can be reduced or eliminated by the output of the mixed speakers (150). In particular, the noise can be maximally reduced at the microphones (130) or at the location of the passenger's ears.

The speakers (150) can output noise control signals only to specific passengers. Specifically, the speakers (150) can cause constructive interference or destructive interference at the ear positions of specific passengers by outputting noise control signals with different phases at multiple locations within the vehicle (10).

FIG. 2 is a drawing exemplarily shown to explain a noise control method according to one embodiment of the present invention.

Referring to FIG. 2, the vehicle noise control system includes a sensor (210), a controller (220), a speaker (230), and a microphone (240).

The noise control system of the vehicle can eliminate noise inside the vehicle by outputting a noise control signal generated based on a reference signal of the sensor (210). Furthermore, the noise control system can eliminate noise inside the vehicle to the maximum extent by using the residual noise remaining after noise removal as feedback.

Specifically, while a vehicle is driving, vibrations are generated by friction between the vehicle and the road surface, and the generated vibrations cause noise inside the vehicle.

The controller (220) obtains a reference signal detected by the sensor (210) and generates a noise control signal for reducing noise inside the vehicle based on the reference signal. The noise control signal is a signal having the same amplitude as the noise signal but having an opposite phase to the noise signal. The controller (220) outputs the noise control signal through the speaker (230).

The controller (220) can generate a noise control signal by applying an adaptive filter to the reference signal. Specifically, the controller (220) can determine coefficients of an adaptive filter (often referred to as a W-filter) based on the error signal(s) and the reference signal(s) according to an algorithm such as least mean square (LMS) or filtered-x least mean square (FxLMS), which are well known in the art. The noise control signal is generated by the adaptive filter based on the reference signal or a combination of reference signals. When the noise control signal is reproduced through the speaker (230), the sound pressure level of the road noise at the location of the speaker (230) is reduced.

Here, the path between the sensor (210) and the speaker (230) is called the primary path or main acoustic path. The primary path is a model representing the acoustic transmission characteristics from the sensor (210) to the speaker (230). The controller (220) can generate a noise control signal by considering the transfer function and delay time for the primary path.

However, despite the output of the noise control signal to remove the noise, residual noise may occur at the listening position of the passenger. For example, since the noise control signal output from the speaker (230) changes in the process of being transmitted to the listening position of the passenger, the noise may not be completely removed at the position of the passenger's ear. Furthermore, since the noise control signal generated from the controller (220) changes while passing through the amplifier or speaker (230), the noise may not be completely removed at the listening position of the passenger. This residual noise may be expressed as an error signal representing the difference between the noise signal and the changed noise control signal at the listening position of the passenger.

To remove residual noise, the noise control system can measure the residual noise using a microphone (240). The path between the speaker (230) and the microphone (40) is called a secondary path.

The controller (220) receives an error signal as feedback from the microphone (240), and updates the filter coefficients of the adaptive filter using the acoustic transfer characteristics of the secondary path, the reference signal, and the error signal. The controller (220) generates a noise control signal by applying the updated coefficients of the adaptive filter to the reference signal. The noise control signal has an ideal waveform such that when it passes through the amplifier and is reproduced through the speakers (150), an offset sound that is substantially opposite in phase and equal in magnitude to the road noise heard by the passengers in the vehicle cabin is generated near the passengers' ears and the microphones (130). The offset sound from the speakers (150) meets the road noise near the microphones (130) in the vehicle cabin, and can lower the sound pressure level caused by the road noise at this location. That is, the secondary path-based noise control signal can reduce noise and residual noise at the location of the microphone (240). The closer the microphone (240) is to the passenger's listening position, the closer the microphone (240) can measure the noise to the residual noise at the passenger's listening position. If the microphone (240) is placed close to the passenger's ear position, it is advantageous in eliminating the residual noise.

Meanwhile, the vehicle's noise control system can model the secondary path more accurately by using a virtual microphone. The controller (220) can obtain accurate information on the sound transmission characteristics between the speaker (230) and the passenger's listening position based on the signal measured by the virtual microphone.

Through the above process, the vehicle's noise control system can further reduce residual noise at the position of the passenger's ears, and the performance of active noise control can be improved.

Figure 3 is a configuration diagram of a noise control algorithm according to one embodiment of the present invention.

Referring to FIG. 3, a primary path (310), a secondary path (320), a controller (330), an adaptive filter (332), a secondary path model (334), and an adaptive filter controller (336) are illustrated.

The noise control algorithm illustrated in Fig. 3 is a single-channel feedforward FxLMS algorithm. In other embodiments, multi-channel structures with many additional channels, many additional microphones, and many additional speakers may also be employed and algorithms for these may be employed. For example, 12 acceleration sensors and 8 speakers may be employed. Accordingly, multiple second-order path models and adaptive filters may be utilized.

The reference signal x(n) is sensed by the sensor. For example, the reference signal x(n) may be a measurement signal of an accelerometer or a measurement signal of a vibration sensor. The reference signal x(n) becomes a noise signal d(n) through the primary path (310).

The primary path (310) represents a reference sensor and speaker path. The acoustic transfer characteristics P(z) of the primary path (310) can be derived from the relationship between the reference signal x(n) and the noise signal d(n). For example, the transfer function of the primary path (310) can be calculated from the frequency response function of the reference signal x(n) and the noise signal d(n). As the acoustic transfer characteristics of the primary path (310), 'd(n)/x(n)' can be used. In this specification, the acoustic transfer characteristics can be used interchangeably with the transfer function.

The noise signal d(n) is the noise at the location that the controller (330) wants to control. For example, the noise signal d(n) represents the noise at the location of the passenger's ear or the noise at the location of the microphone. Here, the location of the microphone can be approximated as the location of the passenger's ear, which is the noise control point.

The controller (330) generates a noise control signal y(n) using the reference signal x(n) and the error signal e(n) to remove the noise signal d(n). The noise control signal y(n) is a signal for removing or attenuating the noise signal d(n).

The controller (330) can generate the noise control signal y(n) using an adaptive control algorithm. For example, the controller (330) can use various algorithms such as FxLMS (Filtered-input Least Mean Square), FxNLMS (Filtered-input Normalized Least Mean Square), FxRLS (Filtered-input Recursive Least Square), and FxNRLS (Filtered-input Normalized Recursive Least Square).

Specifically, the controller (330) may utilize an adaptive filter (332), a second-order path model (334), and an adaptive filter controller (336) to generate a noise control signal y(n).

The adaptive filter (332) receives a reference signal x(n) and generates a noise control signal y(n) for controlling a noise signal d(n). The transfer function of the adaptive filter (332) can be expressed as W(z), and the transfer function W(z) of the adaptive filter (332) can represent at least one filter coefficient. Here, the filter coefficients can configure a filter coefficient set in units of 256, and can configure a plurality of filter coefficient sets. The adaptive filter (332) can include 96 filter coefficient sets, which are multiplication values between 12 reference sensors and 8 speakers. The noise control signal y(n) can be derived by a convolution operation between the reference signal x(n) and the transfer function W(z) of the adaptive filter (332).

The filter coefficients of the adaptive filter (332) are determined and updated by the adaptive filter controller (336). In particular, the adaptive filter controller (336) updates the filter coefficients by considering that the noise control signal y(n) is transformed by the secondary path (320) after being output from the speaker. Here, the secondary path (320) is a path between the speaker and the position of the passenger's ear. The position of the passenger's ear can be replaced with the position of the microphone.

First, the transfer function S'(z) of the secondary path model (334) representing the acoustic transfer characteristics for the secondary path (320) can be estimated in advance. For example, the secondary path model (334) can be estimated from the output of the speaker and the input of the microphone in a situation where there is no noise inside the vehicle. In addition to the modeling method described above, the secondary path (320) can be modeled by a method appropriate to a person skilled in the art among methods for modeling to best explain the physical phenomenon of an actual audio system.

The adaptive filter controller (336) receives the reference signal x'(n) filtered by the second-order path model (334) as input and the error signal e(n) of the microphone. Here, the error signal e(n) is the residual noise measured when the noise signal d(n) is canceled by the noise control signal y(n) at a noise control point such as the microphone position.

The adaptive filter controller (336) updates the filter coefficients of the adaptive filter (332) by applying the Least Mean Square (LMS) algorithm to the filtered reference signal x'(n) and the error signal e(n). The filter coefficients W(z) can be updated by the gradient descent method.

The updated adaptive filter (332) generates a noise control signal y(n) from the reference signal x(n). After updating the adaptive filter (332), the adaptive filter (332) generates a noise control signal y(n) such that the noise control signal y'(n) transformed by the secondary path (320) has the same amplitude and opposite phase as the noise signal d(n). In other words, the noise control signal y(n) generated by the updated adaptive filter (332) has the same amplitude and opposite phase as d(n) at the microphone location when passing through the secondary path (320).

Therefore, the error signal e(n) measured by the microphone position is minimized.

Through this process, the controller (330) can adaptively generate a noise control signal y(n) even if at least one of the reference signal x(n), the noise signal d(n), or the secondary path (320) changes.

FIG. 4 is a configuration diagram of a portion of a noise control system according to one embodiment of the present invention.

Referring to FIG. 4, the noise control system includes a controller (430). The controller (430) includes an adaptive filter (432), a secondary path model (434), an adaptive filter controller (436), and a detector (438). Here, the adaptive filter (432) and the secondary path model (434) are identical to the adaptive filter (332) and the secondary path model (334) in FIG. 3, respectively. The adaptive filter (432) generates a noise control signal y(n) by applying a set of filter coefficients to a reference signal x(n) so as to reduce an error signal e(n).

When a vehicle moves from one road surface to another, the noise control performance of the controller (430) may deteriorate momentarily. Specifically, when the road surface on which the vehicle is driving changes, the reference signal changes significantly. When the non-updated filter coefficient set of the adaptive filter (432) is applied to the changed reference signal, the error signal may increase. In particular, a conventional noise control system may initialize the filter coefficient set to 0 when the reference signal or the error signal becomes larger than a preset size. However, the error signal may increase further. Thereafter, as the adaptive filter (432) is adaptively updated to the changed road surface, the error signal gradually decreases. In this way, the noise control performance of the noise control system may decrease between the time point of the road surface change and the time point of convergence of the adaptive filter (432).

Meanwhile, the adaptive filter (432) has a common characteristic when it is adapted to various road surfaces. Specifically, the filter coefficient set of the adaptive filter (432) converges to a different result for each road surface. That is, the filter coefficient set converged with respect to one road surface is different from the filter coefficient set converged with respect to another road surface. However, the filter coefficient set of the adaptive filter (432) has a common distribution before it converges for each road surface. For example, the filter coefficient set updated five times while the vehicle moves on the first road surface is similar to the filter coefficient set updated four times while the vehicle moves on the second road surface. In other words, although the adaptation results of the filter coefficient set for various road surfaces are different, the filter coefficient set has a similar distribution at a certain point in the road surface-specific adaptation process. Separately, the filter coefficient set sequentially adapted to various road surfaces has a similar distribution even if the order is changed. For example, the results in which the filter coefficient set is sequentially adapted to the first, second, and third road surfaces are similar to the results in which the filter coefficient set is sequentially adapted to the third, second, and first road surfaces.

In order to utilize the adaptive characteristics of this adaptive filter (432), the noise control system stores a common filter coefficient set for various road surfaces in advance. Here, the common filter coefficient set is the result of the filter coefficient set of the adaptive filter (432) being updated for various road surfaces. The common filter coefficient set is determined during the vehicle driving test process and stored in advance.

Below, examples of generating a common filter coefficient set are described.

According to one embodiment of the present invention, a common filter coefficient set is determined based on a plurality of individual filter coefficient sets for a plurality of road surfaces. Here, each individual filter coefficient set is a result of updating an initial filter coefficient set defined for each road surface a preset number of times or for a preset time period. In particular, the initial filter coefficient set is a zero filter coefficient set, and the common filter coefficient set may be any one of the plurality of individual filter coefficient sets or an average of the plurality of individual filter coefficient sets. Specifically, when the vehicle is driving on a first road surface, the controller (430) obtains a first individual filter coefficient set by updating the zero filter coefficient set a preset number of times or for a preset time period based on a first acceleration signal and a first error signal. When the vehicle is driving on a second road surface, the controller (430) obtains a second individual filter coefficient set by updating the zero filter coefficient set based on a second acceleration signal and a second error signal. Through the iterative process for multiple surfaces, the controller (430) obtains a plurality of individual filter coefficient sets. The individual filter coefficient sets have similar distributions. Thereafter, the controller (430) stores one of the individual filter coefficient sets or the average of the individual filter coefficient sets as a common filter coefficient set.

According to another embodiment of the present invention, the common filter coefficient set is a result of sequentially adapting a predefined initial filter coefficient set to a plurality of road surfaces. Here, the initial filter coefficient set is a zero filter coefficient set. Specifically, the controller (430) updates the zero filter coefficient set based on a first acceleration signal and a first error signal of the vehicle on a first road surface. The zero filter coefficient set converges to a first individual filter coefficient set according to the update. The controller (430) obtains a second individual filter coefficient set by updating the first individual filter coefficient set based on a second acceleration signal and a second error signal of the vehicle on a second road surface. Thereafter, the controller (430) adapts the second individual filter coefficient set to a third road surface environment. Through an iterative process for various road surfaces, the controller (430) obtains a common filter coefficient set.

A common filter coefficient set is stored in advance in the memory of the controller (430). Thereafter, the common filter coefficient set is used according to changes in the road surface while the vehicle is driving.

Below, a noise control system using a common filter coefficient set is described.

The controller (430) detects changes in the road surface due to the movement of the vehicle, and applies a common filter coefficient set for various road surfaces to the adaptive filter (432) in response to the detected changes in the road surface.

The detector (438) detects changes in the road surface due to the movement of the vehicle.

As an example, the detector (438) can detect a change in the road surface on which the vehicle is driving based on at least one of the reference signal and the error signal. If the magnitude of the reference signal within a specific frequency band is greater than a preset first magnitude criterion, the detector (438) determines that the vehicle has moved from one road surface to another road surface. Alternatively, if the magnitude of the error signal within a specific frequency band is greater than a preset second magnitude criterion, the detector (438) determines that the vehicle has moved from one road surface to another road surface. Meanwhile, instead of the reference signal, a reference signal x'(n) filtered by the secondary path model (434) may be used.

As another example, the detector (438) can detect a change in the road surface on which the vehicle is driving based on the change amount of the filter coefficient set of the adaptive filter (432). In one update step, if the filter coefficient set of the adaptive filter (432) changes more than a preset change criterion, the detector (438) can detect a change in the road surface.

The adaptive filter controller (436) applies a set of common filter coefficients stored in advance in the adaptive filter (432) in response to detecting a change in the road surface.

According to one embodiment of the present invention, a common filter coefficient set is determined based on a plurality of individual filter coefficient sets for a plurality of road surfaces. Each individual filter coefficient set is a result of updating an initial filter coefficient set defined for each road surface a predetermined number of times or for a predetermined time period. Specifically, each individual filter coefficient set is a result of updating an initial filter coefficient set based on an acceleration signal and an error signal collected for each road surface. In addition, the initial filter coefficient set is a zero filter coefficient set in which the filter coefficients have a value of 0.

According to another embodiment of the present invention, the common filter coefficient set is a result of sequentially adapting a predefined initial filter coefficient set to a plurality of road surfaces.

The adaptive filter (432) generates a noise control signal by applying a common filter coefficient set to a reference signal. A noise control signal based on a common filter coefficient set can further reduce an error signal compared to a noise control signal based on a zero filter coefficient set.

Thereafter, when the vehicle is moving on a changed road surface, the controller (430) acquires an acceleration signal and an error signal. The controller (430) adaptively adjusts a common filter coefficient set of an adaptive filter (432) based on the acceleration signal and the error signal. The filter coefficient set of the adaptive filter (432) gradually converges. The adaptive filter (432) generates a noise control signal by applying the filter coefficient sets that are converging to a reference signal. As the adaptive filter (432) converges, the error signal also gradually decreases.

As described above, unlike the conventional noise control system in which a zero filter coefficient set, in which the filter coefficients have values of 0, is initially used, in the noise control system according to one embodiment of the present invention, a common filter coefficient set is used as the initial filter coefficient set of the adaptive filter (432). By using this common filter coefficient set, the controller (430) can prevent the divergence of the adaptive filter (432) and at the same time improve the convergence speed of the adaptive filter (432). Furthermore, the controller (430) can minimize the time during which the noise control performance deteriorates.

Figure 5 is a flowchart of an active noise control method for a vehicle according to one embodiment of the present invention.

Referring to Fig. 5, the controller of the vehicle's noise control system detects changes in the road surface due to the movement of the vehicle (S510).

The controller can detect changes in the road surface based on the magnitude of the reference signal, the magnitude of the error signal, or the amount of change in the adaptive filter within the noise control system.

In response to detecting a change in the road surface, the controller applies a common filter coefficient set stored in advance in an adaptive filter within the vehicle's noise control system (S520).

Here, according to one embodiment of the present invention, the common filter coefficient set is determined based on a plurality of individual filter coefficient sets for a plurality of road surfaces. Each individual filter coefficient set represents a result of updating a predefined initial filter coefficient set for each road surface a predefined number of times or a predefined time period. In particular, each individual filter coefficient set is a result of updating the initial filter coefficient set based on an acceleration signal and an error signal collected for each road surface. The initial filter coefficient set represents a zero filter coefficient set in which the filter coefficients have a value of 0. The controller can determine any one of the plurality of individual filter coefficient sets or an average of the plurality of individual filter coefficient sets as the common filter coefficient set.

According to another embodiment of the present invention, the common filter coefficient set may be the result of sequentially adapting a predefined initial filter coefficient set to a plurality of road surfaces. The order of the road surfaces may be set in various ways. That is, the common filter coefficient set may be obtained by sequentially converging the filter coefficient set of the adaptive filter to a plurality of road surfaces.

Thereafter, the controller acquires an acceleration signal and an error signal while the vehicle is moving on a changed road surface (S530).

Acceleration signals and error signals are signals collected by the acceleration sensor and microphone while the vehicle is moving on a changing road surface.

The controller adaptively adjusts a common filter coefficient set of the adaptive filter based on the acceleration signal and the error signal (S540).

The controller adjusts the common filter coefficient set applied to the adaptive filter so that the error signal is reduced. Accordingly, the filter coefficient set of the adaptive filter converges quickly. In particular, when the road surface changes, the common filter coefficient set, not the zero filter coefficient set, is applied to the adaptive filter, so that the convergence speed of the adaptive filter is improved. In addition, when the noise control signal generated by the adaptive filter to which the common filter coefficient set is applied is output through the speaker, it is possible to prevent abnormal noise from occurring in the vehicle. In addition, it is possible to prevent the adaptive filter from emitting.

Various implementations of the systems and techniques described herein can be implemented as digital electronic circuits, integrated circuits, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), computer hardware, firmware, software, and/or combinations thereof. These various implementations can include implementations of one or more computer programs executable on a programmable system. The programmable system includes at least one programmable processor (which may be a special purpose processor or a general purpose processor) coupled to receive data and instructions from, and transmit data and instructions to, a storage system, at least one input device, and at least one output device. Computer programs (also known as programs, software, software applications, or code) include instructions for the programmable processor and are stored on a "computer-readable medium."

A computer-readable recording medium includes any type of recording device that stores data that can be read by a computer system. Such a computer-readable recording medium can be a non-volatile or non-transitory medium, such as a ROM, a CD-ROM, a magnetic tape, a floppy disk, a memory card, a hard disk, a magneto-optical disk, a storage device, and may further include a transitory medium, such as a data transmission medium. In addition, the computer-readable recording medium can be distributed over a network-connected computer system, so that the computer-readable code can be stored and executed in a distributed manner.

Although the flowchart/timing diagram of this specification describes each process as being executed sequentially, this is only an illustrative description of the technical idea of one embodiment of the present disclosure. In other words, a person having ordinary skill in the art to which one embodiment of the present disclosure belongs may change and modify and apply various modifications and variations such as changing the order described in the flowchart/timing diagram and executing it or executing one or more of the processes in parallel without departing from the essential characteristics of one embodiment of the present disclosure. Therefore, the flowchart/timing diagram is not limited to a chronological order.

The above description is merely an illustrative description of the technical idea of the present embodiment, and those with ordinary skill in the art to which the present embodiment belongs may make various modifications and variations without departing from the essential characteristics of the present embodiment. Therefore, the present embodiments are not intended to limit the technical idea of the present embodiment, but to explain it, and the scope of the technical idea of the present embodiment is not limited by these embodiments. The protection scope of the present embodiment should be interpreted by the following claims, and all technical ideas within a scope equivalent thereto should be interpreted as being included in the scope of the rights of the present embodiment.

Claims (16)

In a computer implementation method for active noise control of a vehicle according to changes in road surface,
A step for detecting changes in the road surface due to the movement of the vehicle; and
In response to detecting the above road surface change, a step of applying a common filter coefficient set stored in advance in an adaptive filter within the noise control system of the vehicle.
A method including: In the first paragraph,
The above common filter coefficient set is,
It is determined based on multiple sets of individual filter coefficients for multiple road surfaces.
Each individual filter coefficient set is:
A method in which a predefined set of initial filter coefficients for each road surface is updated a predefined number of times or over a predefined time period. In the second paragraph,
Each individual filter coefficient set is:
A method for updating the initial filter coefficient set based on acceleration signals and error signals collected for each road surface. In the second paragraph,
The above common filter coefficient set is,
A method wherein any one of the plurality of individual filter coefficient sets is used, or an average of the plurality of individual filter coefficient sets is used. In the second paragraph,
The above initial filter coefficient set is,
A method of using a set of zero filter coefficients where the values of the filter coefficients are 0. In the first paragraph,
The above common filter coefficient set is,
A method that results from sequentially adapting a predefined set of initial filter coefficients to multiple road surfaces. In the first paragraph,
A step of acquiring an acceleration signal and an error signal while the vehicle is moving on a changed road surface; and
A step of adaptively adjusting the common filter coefficient set of the adaptive filter based on the acceleration signal and the error signal.
How to include more. In Article 7,
The above adjustment steps are:
A step of adjusting the common filter coefficient set so as to reduce the above error signal.
A method including: In a device for active noise control of a vehicle according to changes in road surface,
memory for storing commands; and
Containing at least one processor,
At least one processor executes the instructions,
Detect changes in road surface due to vehicle movement,
A device that applies a common filter coefficient set stored in advance in an adaptive filter within a noise control system of the vehicle in response to detecting the above road surface change. In Article 9,
The above common filter coefficient set is,
It is determined based on multiple sets of individual filter coefficients for multiple road surfaces.
Each individual filter coefficient set is:
A device that updates a predefined set of initial filter coefficients for each road surface a predefined number of times or over a predefined time period. In Article 10,
Each individual filter coefficient set is:
A device that updates the initial filter coefficient set based on acceleration signals and error signals collected for each road surface. In Article 10,
The above common filter coefficient set is,
A device which is one of the plurality of individual filter coefficient sets, or an average of the plurality of individual filter coefficient sets. In Article 10,
The above initial filter coefficient set is,
A device with a zero filter coefficient set where the values of the filter coefficients are 0. In Article 9,
The above common filter coefficient set is,
A device that is the result of sequentially adapting a predefined set of initial filter coefficients to multiple road surfaces. In Article 9,
At least one processor of the above,
Obtaining acceleration signals and error signals while the above vehicle is moving on a changed road surface,
A device adaptively adjusting the common filter coefficient set of the adaptive filter based on the acceleration signal and the error signal. In Article 15,
At least one processor of the above,
A device for adjusting the common filter coefficient set so as to reduce the above error signal.

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