KR102727548B1 - Noise control apparatus, and method of controlling thereof - Google Patents

Abstract

A noise control device and a control method thereof are disclosed. The noise control device according to one aspect may include: a communication unit that receives a problem frequency or a reference signal from a reference sensor provided on a case including a vibrator; and a control unit that calculates an adaptive filter value through adaptive control logic based on one of the problem frequency and the reference signal and a noise signal received from an error sensor, and generates a driving signal based on the calculated adaptive filter value to control the vibrator.

Description

{NOISE CONTROL APPARATUS, AND METHOD OF CONTROLLING THEREOF}

The present invention relates to a noise control device for reducing noise, and a control method thereof.

In a factory, mechanical equipment may be installed to perform various tasks, and noise may be generated due to such mechanical equipment. In this case, the noise generated in the factory is often amplified due to the structure of the mechanical equipment itself. For example, in the case of a machine tool that performs reciprocating cutting or rotary cutting, the noise is amplified and radiated as the internal excitation source, such as a motor, excites the surrounding machine parts and cases.

In general, in order to reduce noise radiated from the vibration of a source inside a factory, a method of passively reducing noise is used by attaching vibration-proof rubber, vibration-isolating structural mounts, vibration absorbing devices (e.g., mass dampers, or dynamic absorbers) to the outside or inside of the machine equipment. However, there are disadvantages such as increased weight of the machine equipment due to attachment of the devices and restrictions on the design of the machine equipment.

In addition, most of the noise signals inside the factory radiated due to vibration of the base are generated during structural transmission and are mainly low-frequency band signals, but there is a disadvantage that the noise signal reduction effect due to attachment of the aforementioned vibration-proof rubber, vibration-isolating structure mount, etc. is large in the high-frequency band. Accordingly, research is being conducted to reduce noise caused by vibration of machinery equipment inside the factory.

One aspect of the disclosed invention provides a noise control device and a control method thereof for reducing noise caused by structural transmission.

A noise control device according to one side comprises: a memory storing information on a frequency of a noise signal according to a vibration of a previously measured excitation source, a frequency of a previously measured noise signal in a factory, and a natural frequency of the excitation source; a reference signal generating unit comparing the frequency of the noise signal according to the vibration of the excitation source, the frequency of the noise signal in the factory, and the natural frequency of the excitation source to determine at least one target frequency from among a plurality of problem frequencies, and generating a reference signal based on the determined at least one target frequency; and a control unit inputting the generated reference signal as an argument of an adaptive control logic to calculate an adaptive filter value, and generating a driving signal based on the calculated filter value to control the excitation source. and the reference signal generating unit determines, if there is a frequency close to a preset frequency range, the frequency close to the preset frequency range as a first-priority problem frequency, determines the frequency of the noise signal in the factory as a second-priority problem frequency among the frequencies outside the preset frequency range, determines the natural frequency of the excitation source as a third-priority problem frequency, and determines a preset number of problem frequencies as target frequencies according to priority among the plurality of problem frequencies.

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In addition, the control unit can transmit the driving signal to the operating amplifier, and the operating amplifier can apply a driving voltage to the exciter based on the driving signal.

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In addition, on one side of the case including the above-described source, a plurality of candidate attachment locations are provided, and the control unit can generate a noise transfer function on the source attached to each of the plurality of candidate attachment locations, and determine at least one location among the plurality of attachment location candidates as the attachment location based on the noise transfer function.

Additionally, the plurality of problem frequencies can be determined within a preset problem frequency band.

A method for controlling a noise control device according to one aspect includes: a step of comparing a frequency of a noise signal according to a vibration of a pre-measured excitation source, a frequency of a pre-measured noise signal in a factory, and a natural frequency of the excitation source to determine at least one target frequency from among a plurality of problem frequencies; a step of generating a reference signal based on the at least one target frequency determined; and a step of calculating an adaptive filter value by inputting the generated reference signal as an argument in an adaptive control logic, and generating a driving signal based on the calculated filter value to control the exciter; wherein the determining step may include determining a frequency that is close to a preset frequency range, if there is a frequency that is close to the preset frequency range, as a first-priority problem frequency; determining the frequency of the noise signal in the factory as a second-priority problem frequency among frequencies outside the preset frequency range; determining the natural frequency of the excitation source as a third-priority problem frequency; and determining a preset number of problem frequencies as target frequencies according to priorities from among the plurality of problem frequencies.

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In addition, the controlling step may further include a step of controlling the operating amplifier to apply a driving voltage to the exciter through the driving signal.

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In addition, on one side of the case including the above-described source, a plurality of candidate attachment locations are provided, and the controlling step may further include a step of generating a noise transfer function on a source attached to each of the plurality of candidate attachment locations, and determining at least one location among the plurality of attachment location candidates as the attachment location based on the noise transfer function.

Additionally, the plurality of problem frequencies can be determined within a preset problem frequency band.

The noise control device and its control method according to the embodiment can effectively reduce noise of mechanical equipment without attaching a separate device, such as the aforementioned vibration-proof rubber, to the mechanical equipment.

In addition, the noise control device and its control method according to the embodiment can generate a virtual reference signal and effectively reduce noise of mechanical equipment based on the generated reference signal.

Figure 1 is a diagram schematically illustrating an internal factory environment according to one embodiment.
FIG. 2 is a schematic diagram illustrating a control block diagram of a case including a noise control device and a driving source according to one embodiment.
FIG. 3 is a diagram illustrating a case and an error sensor placed in an internal factory environment according to one embodiment.
FIG. 4 is a drawing for explaining a case in which an attachment position of a vibration generator is set in a case according to one embodiment.
FIG. 5 is a block diagram illustrating an adaptive control logic according to one embodiment.
Figure 6 is a diagram schematically illustrating a noise transfer function according to one embodiment.
FIG. 7 is a schematic diagram of a control block diagram of a case including a noise control device and a source for controlling noise by generating a virtual reference signal according to an embodiment other than FIG. 2.
FIG. 8 is a diagram for explaining the operation flow of a noise control system according to one embodiment.
FIG. 9 is a drawing for explaining the operation flow of a noise control system according to a different embodiment from FIG. 8.

Figure 1 is a diagram schematically illustrating an internal factory environment according to one embodiment.

Various noise sources may be provided inside a factory. Here, the noise sources may include various types of mechanical equipment that generate noise. For example, noise sources (N1, N2, N3) that can perform various tasks as shown in Fig. 1 may be provided inside a factory.

However, most of the noise signals generated by the noise sources (N1, N2, N3) installed in the factory are structure-borne noise signals generated due to the structure of the noise sources themselves. These structure-borne noise signals are often amplified by vibrations according to the structure of the noise sources (N1, N2, N3) themselves. In other words, noise signals can be induced or amplified by vibrations. For example, when the excitation source installed inside the noise sources (N1, N2, N3) vibrates, the machine parts, cases, etc. surrounding the excitation source vibrate together, and the noise signal is amplified.

In general, in order to reduce noise signals, vibration-insulating materials that induce noise signals are added to the noise source (N1, N2, N3), or sound-absorbing materials are added. However, in these cases, there is a disadvantage in that the effect on structure-borne sound is low. In particular, in the case of noise signals in the low-frequency band, there is a disadvantage in that the blocking effect using existing sound-absorbing materials is low.

A noise control device according to an embodiment can attach a vibrator to a transmission path of a noise signal transmitted by vibration, for example, to a source of vibration or a case to which the source of vibration is attached, and then apply active control logic. Accordingly, the noise control device according to the embodiment can reduce structure-borne noise by operating the vibrator by continuously updating a filter value so that a noise signal of an error sensor is minimized through the active control logic. Hereinafter, the noise control device will be described in more detail.

FIG. 2 is a schematic diagram of a control block diagram of a noise control system including a case including a noise control device and a vibration source according to one embodiment, and FIG. 3 is a diagram illustrating a case and an error sensor placed in an internal factory environment according to one embodiment. In addition, FIG. 4 is a diagram for explaining a case of setting an attachment position of a vibration source to a case according to one embodiment, FIG. 5 is a diagram illustrating a block diagram of an adaptive control logic according to one embodiment, and FIG. 6 is a diagram schematically illustrating a noise transfer function according to one embodiment. Hereinafter, they will be described together to prevent duplication of explanation.

Referring to FIG. 2, the noise control system may include an error sensor (E), a noise control device (100), an operating amplifier (A), and a case (C) to which an exciter (200) is attached. The error sensor (E), the noise control device (100), the operating amplifier (A), and the case (C) may be electrically connected. Here, the electrical connection may include not only a case where it is connected via a wired line, that is, a case where it is connected via a wired communication network, but also all cases where it is connected via a wireless communication network, and there is no limitation.

Referring to FIG. 2, the noise control device (100a) is illustrated as including a communication unit (110) and a control unit (120), but is not limited thereto, and may be implemented to include at least one of an error sensor (E) and an operating amplifier (A), and so on. Hereinafter, each component constituting the noise control system will be described.

The error sensor (E) can receive various noise signals generated within the factory. For example, the error sensor (E) can include a microphone. The error sensor (E) can receive various noise signals through the microphone and convert them into electrical signals. The error signal (E) can transmit the converted electrical signals to the noise control device (100a).

According to one embodiment, the error sensor (E) can receive an error signal. Accordingly, the sound control device (100a) according to the embodiment can continuously track the noise inside the factory and minimize the noise by inputting the error signal received through the error sensor (E) as an argument to the adaptive control logic and updating the adaptive filter value. A detailed description thereof will be given later.

The error sensor (E) can be located anywhere inside the factory. For example, the error sensor (E) can be located anywhere where it can receive noise generated from one of the multiple noise sources (N1, N2, N3) provided inside the factory as shown in Fig. 3. Meanwhile, the case (C) described below means the outer layer surrounding the machine equipment or the machine equipment itself.

The case (C) may include a source (1) for generating vibrations to drive the machine, a machine part (2) provided inside the case (C), and a reference sensor (3). Here, the machine part (2) is depicted as a block as shown in Fig. 2 for easier diagramming, but the inside of the actual case (C) may not exist in the form shown in Fig. 2.

The driving source (1) is a noise source that causes factory noise, and may refer to a device that generates vibration by generating driving force, such as a motor, for example. In addition, the driving source (1) may include all devices that generate driving force for performing various tasks within the factory, and there is no limitation.

The excitation source (1) and the machine part (2) are mechanically connected, so that the machine part (2) directly transmits the vibration generated from the excitation source (1) to the case (C), and the case (C) amplifies the vibration and radiates it as a noise signal.

The case (C) can be used to perform various tasks, including the actuator (1) and the machine part (2). At this time, the case (C) according to the embodiment is further provided with a reference sensor (3), which receives noise radiated from the case (C) and converts it into an electrical signal to generate a reference signal, i.e., a reference signal.

There is no limitation on whether the reference sensor (3) and the excitation source (1) can be mechanically or electrically connected.

For example, the reference sensor (3) may include a microphone. The reference sensor (3) may receive a noise signal radiated from the case (C1) through the microphone and convert it into an electrical signal. The reference sensor (3) may transmit the converted electrical signal to the noise control device (100). At this time, there is no limitation on the mounting location of the reference sensor (3), such as being mounted on one side of the case (C1). As described below, the noise control device (100a) may appropriately drive the exciter (200) to appropriately shield noise by continuously updating the filter value based on the reference signal.

The reference sensor (3) can derive at least one problem frequency from a noise signal received through a microphone. For example, the reference sensor (3) can derive at least one problem frequency by analyzing the frequency of the noise signal. Here, the problem frequency is a main frequency that causes noise among the frequencies constituting the noise signal, and in particular, can be a frequency of a signal generated by structural resonance.

The problem frequency band for determining the problem frequency can be preset, and the reference sensor (3) can derive the problem frequency using information about the preset problem frequency band. For example, the problem frequency band is a frequency band of a noise signal mainly generated by vibration, and can correspond to a low frequency band. In one embodiment, the problem frequency band can be preset as a band between 50 Hz and 100 Hz, but is not limited thereto.

As another example, the reference sensor (3) may include an encoder. In this case, the encoder may be attached to the excitation source (1), and the reference sensor (3) may measure the driving pulse of the excitation source (1) received from the encoder and derive at least one problem frequency based thereon.

Meanwhile, the subject of the operation for deriving the problem frequency is not limited to the reference sensor (3), and as will be described later, there is no limitation as the control unit (120) of the noise control device (100a) may derive at least one problem frequency from the noise signal received from the reference sensor (3).

Meanwhile, a vibrator (200) may be attached to a case (C1) according to an embodiment. At this time, there is no limitation that the vibrator (200) may be attached to the outside of the case (C1) or to the inside of the case (C1).

The exciter (200) is a device for suppressing vibrations that generate noise, and can be classified into a mechanical exciter, an electric exciter, and a hydraulic exciter depending on the operating method. The exciter (200) described below can be implemented through at least one of the operating methods described above, and there is no limitation.

As described later, the exciter (200) receives a driving signal from the operating amplifier (A) and generates vibration based on the received driving signal, thereby canceling out at least one of the vibration of the case (C1) and the vibration of the exciter (1) inside the case (C1). Accordingly, noise can be reduced as the vibration of the case (C1) or the vibration of the exciter (1) inside the case (C1) is suppressed.

Meanwhile, in order to more effectively cancel out noise, the attachment location of the exciter (200) according to the embodiment can be preset. As described below, a group of attachment location candidates is set on the case (C1), and then the exciter can be attached to a position corresponding to a plurality of the set attachment location candidates. Accordingly, the noise control device (100a) according to the embodiment can generate a noise transfer function at each of the attachment location candidates through prior measurement.

The noise control device (100a) can set the attachment location with the highest sensitivity in the problem noise band as the attachment location of the exciter (200) based on the generated noise transfer function. Then, a user, for example, a factory manager or an employee, can effectively block noise by attaching the exciter (200) to the selected attachment location. In other words, the noise control device (100a) according to the embodiment can maximize the noise reduction effect by selecting the optimal attachment location. A detailed description of this will be provided later.

Referring to FIG. 2, the noise control device (100a) may include a communication unit (110) and a control unit (120). At this time, the communication unit (110) and the control unit (120) may be operated through a processor capable of various calculation processing, such as an MCU (Micro Control Unit, MCU).

The communication unit (110) and the control unit (120) may be implemented separately and included in the noise control device (100a). Alternatively, the communication unit (110) and the control unit (120) may be integrated into a single component and included in the noise control device. For example, the communication unit (110) and the control unit (120) may be integrated into a system on chip (SOC) and included in the noise control device (100a), and so on, without limitation.

The communication unit (110) can exchange various signals with an external device through at least one of a wired communication method and a wireless communication method. For example, the communication unit (110) can include at least one of a wired communication module and a wireless communication module. Here, the wired communication module means a module that supports wired communication. The wired communication method can include a method of transmitting and receiving wired signals through a wired cable, such as HDMI (high definition multimedia interface), PCI (Peripheral Component Interconnect), PCI-express, and USB (Universe Serial Bus), and in addition, various wired communication methods known to those skilled in the art can be included.

Meanwhile, the wireless communication module refers to a module that supports wireless communication. Wireless communication methods may include wireless communication methods that transmit and receive wireless signals via a base station, such as LTE (long-term evolution), LTE-A (LTE Advance), CDMA (code division multiple access), and WCDMA (wideband CDMA), as well as methods that transmit and receive wireless signals with an external device within a certain distance, such as Wireless LAN, Wi-Fi, Bluetooth, Z-wave, Zigbee, BLE (Bluetooth Low Energy), and NFC (Near Field Communication). Here, the wireless signal may include various forms of data according to voice call signals, video call call signals, or text/multimedia message transmission and reception.

The wired communication module may correspond to an integrated chip (IC) or IC package in which communication modules supporting one or more wired communication methods are integrated, and the wireless communication module may correspond to an integrated chip (IC) or IC package in which communication modules supporting one or more wireless communication methods are integrated.

For example, the communication unit (110) can receive a reference signal from the reference sensor (3) via a wired/wireless communication network. In one embodiment, the communication unit (110) can periodically receive a reference signal from the reference sensor (3) according to a preset cycle. Accordingly, the control unit (120) inputs the reference signal received by the communication unit (110) into the adaptive control logic, thereby continuously updating the adaptive filter value, thereby adaptively reducing noise. In another embodiment, the communication unit (110) can receive a reference signal from the reference sensor when a user requests, and so on, without limitation.

Meanwhile, a control unit (120) may be provided in the noise control device (100a). The control unit (120) may control the overall operation of components within the noise control device (100a).

The control unit (120) may include a memory (121) in which control data for noise control is previously stored, and a processor (125) that performs a series of operations based on the control data previously stored in the memory (121) to generate a control signal, and controls the operation of not only components within the noise control device but also external components through the generated control signal.

The memory (121) may be implemented through at least one type of storage medium among a memory type (flash memory type), a hard disk type, a multimedia card micro type, a card type memory (for example, an SD or XD memory, etc.), a Random Access Memory (RAM), a Static Random Access Memory (SRAM), a ROM (Read-Only Memory), an Electrically Erasable Programmable Read-Only Memory (EEPROM), a Programmable Read-Only Memory (PROM), a magnetic memory, a magnetic disk, and an optical disk. However, the present invention is not limited thereto, and may be implemented in any other form known in the art.

The memory (121) may store control programs, control data, etc. for controlling components or external components of the noise control device (100a). In addition, various data for controlling noise may be stored in the memory (121). For example, the memory (121) may store data in the form of an algorithm or program regarding an adaptive control logic that continuously updates a filter value based on a reference signal to gradually reduce noise. Accordingly, the processor (125) may determine a filter value based on the data stored in the memory, and control the driving of the excitation source by applying a driving voltage to the operating amplifier. In addition, the memory (121) may store various data for controlling the overall operation for gradually reducing noise, and there is no limitation. Hereinafter, the processor (125) will be described.

The processor (125) can perform a series of processing to control the overall operation of the internal components of the noise control device (100a) and/or the external components of the noise control device (100).

For example, the processor (125) can generate a control signal and control the operation of the communication unit (110) through the generated control signal, thereby transmitting and receiving signals containing various data with an external device.

The processor (125) can control the communication unit (110) to receive a reference signal from the reference sensor (3). Then, the processor (125) can derive at least one problem frequency based on the received reference signal. Alternatively, the processor (125) can control the communication unit (110) to receive data about at least one problem frequency derived by the reference sensor (3) from the reference sensor (3).

The processor (125) can minimize noise through an open-loop type adaptive control logic that feeds back a reference signal or a problem frequency derived from the reference signal. Hereinafter, the adaptive control logic will be briefly described.

Referring to Fig. 5, a signal x(n) can be input to the adaptive control logic. At this time, the signal x(n) may be the reference signal itself, or may be a signal related to at least one problem frequency derived from the reference signal.

Meanwhile, the signal x(n) may be transmitted to the error sensor (E) through the internal environment of the factory, as illustrated in Fig. 3. At this time, the signal x(n) may be deformed due to the internal environment, vibration generated from an external device, or noise. Therefore, the signal d(n) input to the error sensor (E) may be the same as or different from x(n). Here, d(n) is also called a primary signal.

Therefore, if the factor that transforms x(n) is expressed as a transfer function P(z), then, as illustrated in FIG. 4, x(n) can be expressed as being transformed into d(n) via the primary path transfer function P(z). In one embodiment, the primary path may correspond to a path between an area where an exciter (1) is provided or an area where a case (C) including an exciter (1) is located and an area where an error sensor (E) is provided, and d(n) can be expressed as x(n)*P(n). Here, P(z) is also called a primary path transfer function, but is also called a primary path transfer function. n corresponds to time, and z corresponds to frequency.

Meanwhile, if the path between the area where the exciter (200) is provided and the area where the error sensor (E) is provided is called a secondary path, the signal caused by the vibration of the exciter (200) can be input to the error sensor (E) through the secondary path transfer function S(z).

In general, noise is minimized as the difference between the signal d(n) through the primary path and the signal y'(n) through the secondary path, that is, the error signal e(n), approaches 0.

In other words, the error signal e(n) is the difference between the signal through the first path and the signal through the second path, and can be expressed as in the following mathematical expression 1.

At this time, the control block according to the embodiment can apply the estimated transfer function for the secondary path to x(n) and use it as an argument when designing an adaptive filter. Here, the estimated transfer function for the secondary path is also called a secondary path compensation filter.

Referring to Figure 4, stands for the estimated transfer function for the second path. In other words, stands for the transfer function for the second-order path predicted in advance.

For example, data on the estimated transfer function for the secondary path may be determined in advance through modeling and stored in the memory (121) of the noise control device (100a). Alternatively, data on the estimated transfer function for the secondary path may be stored in an external server, etc., and the communication unit (110) may receive the aforementioned data from an external server through a wired/wireless communication network, etc., without limitation.

In order to offset noise signals that change according to the environment within the factory, the influence of the secondary path must be considered in advance. For example, the noise control device (100a) according to the embodiment can calculate the influence of the secondary path in advance based on the filtered-X LMS (FxLMS) algorithm, which is one example of an adaptive control algorithm, and control the operation of the exciter (200) based on the calculation result.

Unlike the LMS algorithm, which uses the input, i.e. the reference signal, directly as an argument of the adaptive filter, the FxLMS algorithm uses the reference signal as a modeled second-order path function. , and can be used as an input value of the FxLMS adaptive filter algorithm, i.e., as an argument of the adaptive filter.

The processor (125) can obtain the effect of actually eliminating the influence of the secondary path by reflecting the secondary path in advance using the modeled secondary path estimation transfer function. At this time, the adaptive filter value can be expressed as in the following mathematical expression 2.

Here, n represents time, w(n) represents the filter coefficient at time n, and w(n+1) represents the updated filter coefficient at time n+1. In addition, x'(n) represents the reference signal that has passed through the second-order compensation filter. In addition, μ represents the step size, which is a scale factor at the time of update.

Referring to mathematical expression 2, the processor (125) according to the embodiment can continuously reflect the environmental change in the factory by updating the adaptive filter value based on the signals y'(n), and e(n) and the previous filter value w(n). The control block can continuously reduce the influence of the environmental change by updating the adaptive filter value according to the preset sampling rate. Here, the preset sampling rate may be set to correspond to the reference signal reception period, but is not limited thereto.

Meanwhile, the sound signal y(n) that has passed through the adaptive filter can be expressed as in the following mathematical expression 3.

At this time, the processor (125) can determine the adaptive filter value so that the error signal e(n) approaches 0. The characteristics of the noise source (N), the environment in which the noise is transmitted, etc. have characteristics that change over time, and thus the size, phase, and frequency components of the noise also change. Therefore, the noise control device (100) according to the embodiment can reflect environmental changes by applying an adaptive control algorithm that continuously updates the adaptive filter value.

The processor (125) can transmit the driving signal calculated with the updated filter value to the operating amplifier (A). Then, the operating amplifier (A) applies the driving voltage amplified based on the driving signal to the exciter (200), so that the exciter (200) can reduce noise caused by vibration of the exciter (1).

Meanwhile, the noise reduction effect may vary depending on the attachment location of the actuator (200). Therefore, the processor (125) according to the embodiment can check the noise reduction effect in a plurality of attachment location candidates and then set the optimal attachment location based on the check result.

Inside the case (C1), a motor (1a) may be provided as an example of a driving force (1). At this time, a plurality of driving forces may be respectively attached to a plurality of candidate attachment positions in the case (C1). Referring to Fig. 5, a group of attachment position candidates including six candidate attachment positions (H1, H2, H3, H4, H5, H6) may be provided on the case (C1), and a driving force may be attached to each of the candidate attachment positions (H1, H2, H3, H4, H5, H6).

The processor (125) can control a sample signal to be applied to a plurality of exciters through the operating amplifier (A) for pre-measurement. Here, the sample signal is for determining signal sensitivity in a problem noise band, and can correspond to a swept sine signal, a random signal, etc.

Then, the processor (125) can receive a sample signal reflecting the secondary path through the error signal and derive a noise transfer function based on this. For example, if a vibrator is attached to each of the six candidate attachment locations (H1, H2, H3, H4, H5, H6), the processor (125) can derive six noise transfer functions as shown in Fig. 6.

At this time, the processor (125) may set priorities in the order of highest sensitivity, that is, highest noise level, in the preset problem noise band (B), and then set attachment locations in the order of highest priority. For example, the processor (125) may set the first priority to the first candidate attachment location (H1) and the second priority to the third attachment location (H3). The processor (125) may provide the user with the number of attachment points of the vibrator (200). In one embodiment, the processor (125) may determine that the home appliance (200) is attached only to the first candidate attachment location (H1), or may determine that the vibrator (200) is attached to each of the first candidate attachment location (H1) and the third candidate attachment location (H3). The user may receive the pre-measurement result through the noise control device (100a) and attach the vibrator (200) to the case (C) in response to the pre-measurement result.

Meanwhile, if an adaptive control logic is to be used to continuously remove noise by continuously updating the filter value based on the reference signal, continuous reception of the reference signal is required, so the reference sensor (3) must be installed near the excitation source (1), for example, on one side of the case (C). In this case, there is a disadvantage in that the cost consumed for removing noise increases.

A noise control device (100a) according to an embodiment can reduce costs and enable a user to use the noise control device more simply by generating a virtual reference sensor and utilizing a virtual reference signal generated from the virtual reference sensor as an argument of an adaptive control logic even when the reference sensor (3) is not installed near a source of vibration (1). Hereinafter, a noise control device that generates a virtual reference sensor and utilizes a virtual reference signal generated from the virtual reference sensor as an argument of an adaptive control logic will be described.

FIG. 7 is a schematic diagram of a control block diagram of a case including a noise control device and a source for controlling noise by generating a virtual reference signal according to an embodiment other than FIG. 2.

Referring to FIG. 7, the noise control device (100b) may further include a reference signal generation unit (130) that generates a virtual reference signal, and thus, the reference sensor (3, FIG. 2) may be omitted in the case (C2) of FIG. 7.

The reference signal generation unit (130) can generate a virtual reference signal by analyzing the frequency of a signal measured in advance before performing real-time control.

For example, before performing real-time control, the reference signal generation unit (130) can measure noise signals and vibration signals of machine equipment, such as case (C2), in advance to derive respective frequencies. Then, the reference signal generation unit (130) can analyze each frequency to derive a problem frequency.

In addition, the reference signal generation unit (130) can derive the natural frequency, i.e., the natural frequency, of the case (C2). For example, the reference signal generation unit (130) can derive the problem frequency by performing a modal test on the exciter (1) or the case (C2) including the exciter (1) to identify the natural frequency of the exciter (1) or the case including the exciter (1).

The reference signal generation unit (130) can generate a target frequency candidate group including a plurality of derived problem frequencies. At this time, the reference signal generation unit (130) can set priorities for a plurality of problem frequencies included in the target frequency candidate group and select a target frequency according to the priorities. Here, the target frequency is a frequency that is the target of noise reduction, and the number of target frequencies can be set in advance.

As the number of target frequencies increases, the amount of computation required by the control unit (120) may increase. In addition, as the number of target frequencies increases unnecessarily, the noise control performance at important target frequencies may decrease. Therefore, the number of target frequencies may be preset based on the control performance of the noise control device, for example, the control unit, that is, the computational processing capability. In one embodiment, the number of target frequencies may be preset to 5 to 10, but is not limited thereto.

The reference signal generation unit (130) can determine the target frequency by setting priorities for problem frequencies according to preset criteria.

For example, in most cases where noise in a factory is the most problematic, the frequency of the noise signal due to the vibration of the exciter (1) and the frequency of at least one noise source provided in the factory may be close to a preset frequency range. Accordingly, information regarding the frequency of the noise signal due to the vibration of the exciter and the frequency of at least one noise source provided in the factory may be stored in the memory (121) of the noise control device (100b) through prior measurement.

In addition, information on the natural frequency of the excitation source measured in advance through a modal test can be stored in the memory (121) of the control device (100a). Accordingly, the reference signal generation unit (130) can analyze the frequency based on the information stored in the memory (121) to derive a plurality of problem frequencies, and then set priorities for the plurality of problem frequencies according to preset criteria.

For example, if there is a frequency that is close within a preset frequency range among the frequencies constituting the noise signal that has been measured in the factory, the frequencies constituting the noise signal due to the vibration of the exciter (1) that has been measured, and the natural frequency of the exciter (1), the reference signal generation unit (130) can set the frequency that is close within the preset frequency range as the first priority. The case where the noise signal becomes the biggest problem is when the frequencies constituting the noise signal due to the vibration of the exciter (1) and the frequencies constituting the noise signal within the factory are close. Therefore, the reference signal generation unit (130) can set the frequency that is close within the preset frequency range as the first priority among the frequencies constituting the noise signal due to the vibration of the exciter (1), the natural frequency of the exciter (1), and the frequencies constituting the noise signal within the factory.

In addition, the reference signal generation unit (130) can set the frequency of a noise signal in a factory with a high noise level among the frequencies outside the preset frequency range as a second-priority target frequency.

In addition, the reference signal generation unit (130) can set the natural frequency of the excitation source (1) that has little influence from noise but has a large amount of energy distributed as the third-priority target frequency as a result of analyzing the frequency caused by noise in the factory.

The reference signal generation unit (130) generates a harmonic function signal based on the set target frequency, and can utilize the generated harmonic function signal as a reference signal and an argument of the adaptive control logic. At this time, the initial harmonic function signal, i.e., the initial phase and initial amplitude of the signal x(n) initially input as an argument, can be updated by the filter value derived through the adaptive control logic, and therefore may be set to an arbitrary value.

The noise control device (100b) according to the embodiment can reduce the production cost of mechanical equipment by adaptively controlling the excitation source and reducing noise without the need to attach separate sound-absorbing and sound-proofing materials, vibration-proofing rubber, etc. In addition, the noise control device (100b) according to the embodiment can effectively reduce noise due to structural transmission that cannot be reduced by the aforementioned sound-absorbing and sound-proofing materials, vibration-proofing rubber, etc.

The noise control device (100b) of Fig. 7 further includes a reference signal generation unit (130) that generates a virtual reference signal, and the remaining components are the same as those of the noise control device (100a) of Fig. 2, so a detailed description thereof will be omitted. Hereinafter, the operation of the noise control system will be briefly described.

FIG. 8 is a diagram for explaining the operation flow of a noise control system according to one embodiment.

The noise control device and the reference are electrically connected to each other so that various data can be exchanged. Accordingly, referring to Fig. 8, the noise control device of the noise control system can receive a problem frequency or reference signal from a reference sensor provided on a case including a source of excitation (800).

The noise control device can calculate an adaptive filter value through adaptive control logic based on one of the problem frequency and reference signal received from the reference sensor and the noise signal received from the error sensor (810).

For example, when a reference signal is received from a reference sensor, the noise control device can analyze the frequency of the reference signal to derive at least one problem frequency. Here, the problem frequency may mean a frequency with a large noise level in a preset problem frequency band. As another example, when the reference sensor analyzes the frequency of the reference signal received to derive a problem frequency and transmits information about the derived problem frequency to the noise control device, the noise control device may omit the problem frequency derivation process described above.

The noise control device can calculate an adaptive filter value by inputting a signal generated based on a problem frequency as an argument into the adaptive control logic. At this time, the adaptive control logic can mean a logic in which an adaptive filter value is updated by continuously inputting a reference signal that can change over time as an argument in the form of an open route.

The noise control device can control the exciter by generating a driving signal based on the calculated adaptive filter value (820). The noise control device, the operating amplifier, and the exciter are electrically connected to each other, so that various signals can be sent and received.

The noise control device can transmit a driving signal to the operating amplifier of the noise control system. Then, the operating amplifier can input a driving voltage amplified according to the driving signal to the exciter of the noise control system. Accordingly, the exciter can vibrate according to the driving voltage, and thus the vibration of the case or the exciter inside the case can be offset, so that noise can be reduced. Hereinafter, the operation flow of the noise control system that generates a virtual reference signal and calculates an adaptive filter value based on the virtual reference signal will be briefly described.

FIG. 9 is a drawing for explaining the operation flow of a noise control system according to a different embodiment from FIG. 8.

In the noise control system, unlike that shown in Fig. 2, the reference sensor may be omitted. In this case, the noise control system may derive a plurality of problem frequencies through pre-measurement, classify the plurality of problem frequencies according to priority, and then determine at least one problem frequency according to priority.

Referring to FIG. 9, the noise control device of the noise control system can compare the frequency of a noise signal according to the vibration of a previously measured source, the frequency of a previously measured noise signal in a factory, and the natural frequency of the source to determine at least one target frequency among a plurality of problem frequencies (900).

For example, a noise control device can receive noise signals according to vibration of a source and noise signals within a factory in advance through an error sensor. Then, the noise control device can analyze the frequencies of each of the noise signals according to vibration of a source measured in advance and noise signals within a factory to derive a problem frequency.

As another example, the noise control device can pre-analyze the natural frequency of the case through modal testing. The noise control device can derive the problem frequency based on the natural frequency of the case.

Then, the noise control device can set priorities by synthesizing the derived problem frequencies. Here, the target frequency is the frequency to be subject to noise reduction, and the number of target frequencies can be set in advance.

For example, the noise control device can generate a target frequency candidate group including a plurality of derived problem frequencies. At this time, the noise control device can set priorities for the plurality of problem frequencies included in the target frequency candidate group and select a target frequency according to the priorities.

The noise control device can prioritize multiple problem frequencies based on preset criteria.

The noise control device can compare the frequency of the noise signal according to the vibration of the excitation source, the frequency of the noise signal in the factory, and the natural frequency of the excitation source to determine whether there is a frequency that is close to a preset frequency range. If it is determined that there is a frequency that is close to a preset frequency range, the noise control device can determine the aforementioned frequency as a first-priority problem frequency.

Next, the noise control device can determine the frequency of the noise signal within the factory as the second-order problem frequency among the frequency of the noise signal according to the vibration of the excitation source, the frequency of the noise signal within the factory, and the natural frequency of the excitation source. In addition, the noise control device can determine the natural frequency of the excitation source as the third-order problem frequency.

The noise control device can determine target frequencies by priority according to a preset number of problem frequencies among multiple problem frequencies. For example, if the number of target frequencies is preset to N (N≥1), the noise control device can set only N problem frequencies as target frequencies according to priority.

The noise control device can generate a reference signal based on at least one target frequency determined (910). For example, the noise control device can generate a reference signal composed of a harmonic function based on at least one target frequency.

The noise control device can input a reference signal as an argument in the adaptive control logic, calculate an adaptive filter value, and generate a driving signal based on the calculated filter value to control the exciter (920). The noise control device, the operating amplifier, and the exciter are electrically connected to each other, so that various signals can be sent and received.

The noise control device can transmit a driving signal to the operating amplifier of the noise control system. Then, the operating amplifier can input the amplified driving voltage according to the driving signal to the exciter of the noise control system. Accordingly, the exciter can vibrate according to the driving voltage, and thus the vibration of the exciter inside the case or the case can be offset, so that the noise can be reduced.

The embodiments described in this specification and the configurations illustrated in the drawings are merely preferred examples of the disclosed invention, and there may be various modified examples that can replace the embodiments and drawings of this specification at the time of filing of the present application.

In addition, the terminology used herein is for the purpose of describing embodiments, and is not intended to limit and/or restrict the disclosed invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this specification, the terms "comprises" or "has" and the like are intended to specify that a feature, number, step, operation, component, part, or combination thereof described in the specification is present, but do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

Additionally, terms including ordinal numbers such as “first”, “second”, etc., used herein may be used to describe various components, but the components are not limited by the terms, and the terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component. The term “and/or” includes any combination of a plurality of related described items or any item among a plurality of related described items.

In addition, the terms "unit", "device", "block", "member", "module", etc. used throughout this specification can mean a unit that processes at least one function or operation. For example, it can mean software, hardware such as an FPGA or an ASIC. However, the terms "unit", "device", "block", "member", "module", etc. are not limited to software or hardware, and the terms "unit", "device", "block", "member", "module", etc. can be a configuration stored in an accessible storage medium and executed by one or more processors.

200: Gajingi

Claims (20)

delete delete delete delete delete A memory storing information about the frequency of noise signals due to vibration of a previously measured excitation source, the frequency of noise signals measured inside a factory, and the natural frequency of the excitation source;
A reference signal generation unit that compares the frequency of the noise signal according to the vibration of the above-mentioned source, the frequency of the noise signal within the factory, and the natural frequency of the above-mentioned source to determine at least one target frequency among a plurality of problem frequencies, and generates a reference signal based on the determined at least one target frequency; and
A control unit that calculates an adaptive filter value by inputting the above-mentioned generated reference signal as an argument in the adaptive control logic, and generates a driving signal based on the calculated filter value to control the exciter;
Including,
The above reference signal generation unit,
A noise control device that determines, if there is a frequency within a preset frequency range that is close to the preset frequency range, the frequency within the preset frequency range that is close to the preset frequency range as a first-priority problem frequency, determines the frequency of the noise signal within the factory as a second-priority problem frequency among the frequencies outside the preset frequency range, determines the natural frequency of the excitation source as a third-priority problem frequency, and determines a preset number of problem frequencies as a target frequency according to priority among the plurality of problem frequencies. In Article 6,
The above control unit transmits the driving signal to the operating amplifier,
The above operating amplifier is a noise control device that applies a driving voltage to the exciter based on the driving signal. delete In Article 6,
On one side of the case including the above-mentioned member, a plurality of candidate attachment locations are provided,
The above control unit,
A noise control device that generates a noise transfer function on an exciter attached to each of the plurality of candidate attachment locations, and determines at least one location among the plurality of attachment location candidates as an attachment location based on the noise transfer function. In Article 6,
The above multiple problem frequencies are,
A noise control device that determines the level within a preset problem frequency band. delete delete delete delete delete A step of comparing the frequency of a noise signal according to the vibration of a previously measured excitation source, the frequency of a previously measured noise signal in a factory, and the natural frequency of the excitation source to determine at least one target frequency among a plurality of problem frequencies;
A step of generating a reference signal based on at least one target frequency determined above; and
A step of calculating an adaptive filter value by inputting the above-mentioned generated reference signal as an argument in the adaptive control logic, and generating a driving signal based on the calculated filter value to control the exciter;
Including,
The above decision-making steps are:
If there is a frequency within the preset frequency range, the frequency within the preset frequency range is determined as the first-priority problem frequency.
Among the frequencies outside the above preset frequency range, the frequency of the noise signal within the factory is determined as the second-priority problem frequency,
The natural frequency of the above-mentioned source is determined as the third-order problem frequency,
A control method for a noise control device, comprising determining a preset number of problem frequencies as target frequencies according to priority from among the above-mentioned plurality of problem frequencies. In Article 16,
The above controlling step is,
A step of controlling the operating amplifier to apply a driving voltage to the exciter through the driving signal;
A method for controlling a noise control device further comprising: delete In Article 16,
On one side of the case including the above-mentioned member, a plurality of candidate attachment locations are provided,
The above controlling step is,
A step of generating a noise transfer function on an exciter attached to each of the plurality of candidate attachment locations, and determining at least one location among the plurality of attachment location candidates as an attachment location based on the noise transfer function;
A method for controlling a noise control device further comprising: In Article 16,
The above multiple problem frequencies are,
A control method of a noise control device determined within a preset problem frequency band.

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