JPH09230874A - Active noise/vibration control system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable rear-time monitoring by comprehensively managing plurality of control means and also to enable the timing adjustment of data transmission between the control means. SOLUTION: A sensor S1 detects noise/vibration produced from a noise/ vibration source 1, and a control means 5a having a filter 5a simulating feedback transfer system 4 eliminates influence of sound/vibration fed back from the feedback transfer system 5 from the noise/vibration detected by the sensor 1, and gives the result to a control means 6. The control means 6 is provided with a filter 6a simulating a transfer characteristic of a unknown transfer system 3, and produces an output canceling the noise/vibration based on the output of the control means 5, and gives it to a sound/vibration producing means 2 to eliminate the noise/vibration. Further, the coefficient of the filter 6a of the control means 5 is adjusted according to an output of a sensor 2. A control means 7 supervises and manages the control means 5 and 6, and displays on a monitor 9 in rear time the filter coefficient stored in a shared memory 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active noise / vibration control system for reducing noise or vibration by generating an output for canceling noise / vibration from a speaker / vibration generator or the like. Active noise / vibration control applicable to various measurement / control systems such as active noise control system, seismic isolation control system in building field, vibration control system, echo canceller for telephones, and image processing as ghost countermeasures It is about the system.

[0002]

2. Description of the Related Art The prior art will be described below by taking an active noise control system as an example. FIG. 12 is a diagram showing the configuration of the active noise control system. In the figure, D is an air duct, and a fan F is provided at one end of the air duct D, and the fan F rotates to cool devices and the like (not shown). When the fan F rotates, noise is generated, and this noise propagates through the air duct D in the direction of the arrow in the figure. SP
Is a speaker, and cancels the noise by generating an erasing sound from the speaker SP. Further, the erasing sound or the like generated by the speaker SP propagates through the air duct D in the direction of the arrow in the figure (the direction opposite to the noise) (this is called echo sound).

M1 is a sensor microphone, and the noise generated by the fan F is detected by the sensor microphone M1. Also,
M2 is an error microphone. With the error microphone M2,
A noise (error amount) that cannot be canceled is detected by the erasing sound generated by the speaker SP. The sensor microphone M
1. The sound detected by the error microphone M2 is amplified by the microphone amplifiers MA1 and MA2 and sent to the active noise control device Cnt including, for example, a digital signal processor (hereinafter referred to as DSP).

In the active noise control device Cnt, F1 is a noise control filter (NCF: Noise Control Filter), and the sound transmission of the noise of the fan F detected by the sensor microphone M1 until it propagates through the air duct D and reaches the error microphone M1. Simulate system {H} (noise control filter F
The characteristic of 1 is written as {h}). F2 is an acoustic feedback filter (AFF: Acoustic Feedback Filter), which simulates an acoustic transmission system {Hf} until the elimination sound generated by the speaker SP propagates through the air duct D and reaches the sensor microphone M1 (acoustic feedback filter). The characteristic of F2 is expressed as {hf}).

F3 is an error scattering filter (EP
F: Error Path Filter) and simulates an acoustic transmission system from the speaker SP to the error microphone M2 (hereinafter referred to as an error scattering system {Hpf}) (characteristic of the error scattering filter F3 is {hpf. })). AL
Is an adaptive algorithm, which adjusts the coefficient of the noise control filter F1 based on the error detected by the error microphone M2 and the output of the error scattering system filter F3 so that the transfer characteristic {hf} of the noise control filter F1 is the air duct D. The transfer characteristic {H} is controlled so as to approach.

FIG. 13 is a block diagram showing the active noise control system. In the figure, the same components as those shown in FIG. 13 are designated by the same reference numerals.
As shown in the figure, the air duct D includes an unknown transmission system {H} indicating a transmission characteristic from the fan F1 which is a noise source to the error microphone M2, and the erase speaker SP to the sensor microphone M.
It can be represented by an acoustic system Df including an acoustic feedback system {Hf} showing transfer characteristics up to 1. The error scattering system {Hp
f} is omitted.

Further, as shown in the figure, the sensor microphone M1
The sound detected at is the sum of the echo sound Xf fed back through the acoustic feedback system {Hf} and the noise Xj generated from the noise source. Further, the sound detected by the error microphone M2 becomes a difference Ej between the noise transmitted through the unknown transmission system {H} and the erased sound sent from the noise control filter F1 to the speaker SP. In the figure, the disturbance signal Nj is added to the output of the unknown transmission system {H}, and the noise source is sampled by the sampling signal fs.

In FIGS. 12 and 13, active noise control is performed as follows. The sensor microphone M1 detects the sum Xj + Xf of the noise Xj generated by the fan F and the echo sound Xf fed back via the acoustic feedback system {Hf}. Xj + Xf detected by the sensor microphone M1 is
Xf output from the acoustic feedback filter F2 is subtracted from Xj + Xf sent to the active noise control device Cnt (here, the transfer characteristic {hf} of the acoustic feedback filter F2 matches the acoustic feedback system {Hf} of the air duct D. Be assumed).

The signal Xj is sent to the noise control filter F1, which produces an erasing signal having substantially the same magnitude and opposite phase as the noise generated by the fan F.
This erasing signal is sent to the speaker SP, and the erasing sound is generated from the speaker SP to cancel the noise. Further, the cancellation signal sent by the noise control filter F1 is given to the acoustic feedback filter F2, and the acoustic feedback filter F2 outputs a signal corresponding to the echo sound reaching the sensor microphone M1.

On the other hand, an error Ej is generated by the error microphone M2.
Is detected and sent to the adaptive algorithm AL,
The signal Xj is sent to the error scattering filter F3 (here, the transfer characteristic of the error scattering filter F3 is {hp
f} is assumed to match the transfer characteristic {Hpf} of the error scattering system). The adaptive algorithm AL uses the normalized least squares method (NLMS) or the least squares method (LMS) based on the output of the error scattering filter F3 and the error Ej detected by the error microphone M2 to reduce the noise Ej. The coefficient of the control filter F1 is calculated, and control is performed so that the transfer characteristic of the noise control filter F1 matches the transfer characteristic {H} of the air duct D.

In the above noise control system, since the coefficient of the noise control filter F1 is constantly adjusted during the operation of the system, the transfer characteristic should be close to that of the acoustic transfer system {H} of the air duct D. But you can
Regarding the acoustic feedback filter F2 and the error scattering system filter F3, the coefficients are not adjusted during the operation of the system.

Therefore, the acoustic feedback filter F2,
The error scattering system filter F3 needs to be pre-learned to match the transfer characteristic of the acoustic feedback system {Hf} of the air duct D with the transfer characteristic {Hpf} of the error scattering system.
Therefore, as shown in FIG. 13, at the time of pre-learning, a calibration generator CG is provided, and an M-sequence signal or white noise is applied from the calibration generator CG, and the acoustic feedback filter F2 and the error scattering filter F3 are applied. Pre-learn.

FIG. 14 is a diagram showing the configuration of the acoustic feedback filter F2 at the time of learning. In FIG. 14, Df 'is the transfer characteristic {Hf} of the acoustic feedback system of the air duct D, SP is the speaker, and F2 is the acoustic feedback. A filter, R1 is a coefficient adjusting means, and the coefficient adjusting means R1 is a normalized least square method (NLM).
S) or the least squares method (LMS) is used to adjust the coefficient of the acoustic feedback filter F2 so that the transmission characteristic of the acoustic feedback filter F2 substantially matches the transmission characteristic of the acoustic feedback system {Hf}. The coefficient adjusting means R1 does not operate while the active noise control system is in operation, and operates only during pre-learning (for this reason, it is not shown in FIGS. 12 and 13).

In order to perform the pre-learning of the acoustic feedback filter F2, as shown in the figure, a calibration generator CG for generating an M-sequence signal or a white noise signal is provided, and the M-sequence generated by the calibration generator CG is provided. The signal or white noise signal is given to the speaker SP and the acoustic feedback filter F2. The sound generated from the speaker SP due to the M-sequence signal or the white noise signal is detected by the sensor microphone M1 through the acoustic feedback system {Hf} of the air duct D.

On the other hand, the M-sequence signal or the white noise signal is transmitted through the acoustic feedback filter F2 to the acoustic feedback filter F.
2 is output, is compared with the sound detected by the sensor microphone M1, and the difference is given to the coefficient adjusting means R1. The coefficient adjusting means R1 adjusts the coefficient of the acoustic feedback filter F2 so that the difference becomes zero. By performing the pre-learning as described above, the acoustic feedback system {Hf} and the transfer characteristic {hf} of the acoustic feedback filter F2 can be substantially matched.

[0016]

The above-mentioned prior art has the following problems. (1) The control is performed using only one DSP, and there is no hardware that integrates the DSPs by using a plurality of DSPs and performs supervisory processing. Also,
Since the DSP specialized in digital signal processing, it was impossible to perform a supervisory operation.

(2) When two DSPs are used, they do not have a function of transmitting and receiving data between them. (3) Since the output signal of the DSP depends on the output of the firmware, when two DSPs are used, it is difficult to adjust the timing of data exchange between them.

(4) Real-time OS (operating system) that enables the above (1), (2) and (3)
Did not exist. (5) The conventional microphone amplifier that detects noise and the like is expensive because it has a dual power source system having a microphone power source and an amplifier power source.

The present invention has been made in view of the above-mentioned problems of the prior art, and the first object of the present invention is to use a plurality of DSPs and to integrate them into a supervisory processing hardware. The purpose of the present invention is to provide an active noise / vibration control system that can perform high-speed processing in real time by providing software and an OS. A second object of the present invention is to provide an active noise / vibration control system capable of adjusting the timing of data transfer between DSPs independently of the number of steps of firmware.

A third object of the present invention is to enable transmission / reception of data between the DSP for processing the supervisory process and the DSP, and real-time monitoring of the filter coefficient of the active noise / vibration control system. It is to provide an active noise / vibration control system. A fourth object of the present invention is to provide an active noise / vibration control system in which a microphone and a microphone amplifier for detecting noise and the like can operate with one type of power supply.

[0021]

FIG. 1 is a basic configuration diagram of the present invention. In the figure, 1 is a noise / vibration source, 2
Is an acoustic / vibration generating means for generating an output for canceling the noise / vibration, 3 is an unknown transmission system having a transfer characteristic from the source 1 to the acoustic / vibration generating means 2, 4 is a feedback transmission system, and S1 is a first transmission system. The first sensor and S2 are the second sensors.
Further, SA1 and SA2 are amplification means, 5 is first control means, 5a is first filter, 6 is second control means, and 6a.
Is a second filter, 7 is a third control means for controlling and managing the first and second control means, 8 is a shared memory shared by the first, second and third control means, and 9 is It is a monitor.

In FIG. 1, the present invention solves the above problems as follows. (1) A noise / vibration generation source, and an acoustic / vibration generation unit that is provided at a location where the noise / vibration is transmitted through an unknown transmission system and that generates an output that cancels the noise / vibration.
The first sensor is provided near the noise / vibration source and detects the noise / vibration generated by the source, and is provided near the sound / vibration generating means and can be canceled by the output of the sound / vibration generating means. A second sensor for detecting an error that has not occurred and an output signal to the sound / vibration generating means, and a first sensor for simulating a feedback transmission system from the sound / vibration generating means to the noise / vibration generation source. Noise of the noise detected by the first sensor by calculating the difference between the first filter output and the first sensor output.
First control means for generating an output for eliminating the influence of sound / vibration returned from the vibration by the feedback transmission system, and output of the first control means are provided, and the sound / vibration generating means is generated from the source. A second filter simulating the transfer characteristics of the unknown transfer system up to, the output of the second filter is output to the sound / vibration generating means, and the output of the second sensor causes the second filter to operate. A noise / vibration control system comprising: a second control unit that adjusts a coefficient of the second filter so as to match the transfer characteristic of the unknown transfer system; and the first control unit and the second control unit. A third control means for integrating and managing the means is provided, and the third control means is connected to the first and second control means via a common bus.

(2) A shared memory shared by the first, second and third control means is provided, and the third control means receives a data output request from the first or second control means. The output data of the first or second control means is written in the shared memory and transferred to the other control means. (3) A timer unit having an adjustable delay time is provided, and the output request output from the first or second control unit at the time of data transfer is delayed by the timer unit and sent to the third control unit. (4) The third control means has a function of reading at least the data stored in the shared memory and outputting the data to the monitor.
It has a function of writing data to the shared memory, reads the data stored in the shared memory according to an instruction from the operator, and displays the coefficients of the first and second filters on a monitor in real time.

(5) A noise generating source, a sound generating means which is provided at a position where the noise is transmitted through an unknown transmission system, and which generates an output for canceling the noise, and a sound generating means which is provided in the vicinity of the noise generating source. A first microphone that detects noise emitted from the source, a first amplification means that amplifies the output of the first microphone, and a sound generator that is provided in the vicinity of the sound generation means. A second microphone that detects an error that cannot be canceled, a second amplification unit that amplifies the output of the first microphone, and an output signal to the sound generation unit are given, and the sound generation unit generates noise. From the noise detected by the first sensor by providing a first filter simulating a feedback transmission system up to the source of the noise, and obtaining the difference between the output of the first filter and the output of the first sensor. By the above feedback transmission system The transfer characteristic of the unknown transfer system from the source to the sound generating means is simulated by the first control means for generating an output for removing the influence of the returned sound and the output of the first control means. A second filter is provided, the output of the second filter is output to the sound generating means, and the output of the second sensor causes the second filter to match the transfer characteristic of the unknown transfer system. Second above
And a second control means for adjusting the coefficient of the filter, the power supply circuit supplies power to the respective amplification means from the power supply circuits of the first and second amplification means, and the first microphone and The first and second microphones are connected via a line that transmits a detection signal from the second microphone to each amplifier.
Supply power to the microphone.

In the invention of claim 1 of the present invention, since it is configured as in the above (1), even if the first control means and the second control means are constituted by independent processing means, the third control means These can be integrated and managed by the control means, and high-speed processing can be realized in real time. In the invention of claim 2 of the present invention, since it is configured as in the above (2), it is possible to perform data transfer between the first and second control means via the shared memory, and also the shared memory. It is possible to read and write data via the.

According to the invention of claim 3 of the present invention, since it is configured as in the above (3), the setting of the timer means can be adjusted even if the number of steps of the firmware in the first control means changes. As a result, it is possible to easily deal with a change in the number of steps, and it is possible to keep the entire processing within one sampling period. According to the invention of claim 4 of the present invention, since it is configured as in the above (4), the operator can set the data in the shared memory and read the filter coefficient from the shared memory in real time. According to the invention of claim 5 of the present invention, since it is configured as in the above (5), it is not necessary to provide a separate power source for the microphone, the configuration of the device can be simplified, and the cost can be reduced. it can.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of the present invention will be described with reference to FIG.
The active noise control system shown in will be described. It should be noted that in the following embodiments, the propagation 1 is performed via an air duct or the like.
A description will be given of an active noise control system that eliminates three-dimensional noise. The application of the present invention is not limited to a one-dimensional active noise control system, but for example, three-dimensional active noise control that eliminates noise emitted in a three-dimensional space. System, or
It can be applied to various measurement and control systems such as seismic control systems and vibration control systems.

FIG. 2 is a diagram showing the hardware configuration of the embodiment of the present invention. In the figure, D is an air duct, and one end of the air duct D has a fan F as in FIG.
Is provided and the fan F rotates to cool devices and the like not shown. When the fan F rotates, noise is generated, and this noise propagates through the air duct D in the direction of the arrow in the figure. SP denotes a speaker, which generates an erasing sound from the speaker SP to cancel the noise. Further, the erasing sound or the like generated by the speaker SP propagates through the air duct D in the direction of the arrow in the figure (the direction opposite to the noise) (this is called echo sound).

M1 is a sensor microphone, and the noise generated by the fan F is detected by the sensor microphone M1. Also,
M2 is an error microphone. With the error microphone M2,
A noise (error amount) that cannot be canceled is detected by the erasing sound generated by the speaker SP.

The sensor microphone M1 and the error microphone M2
The sound detected by is amplified by the microphone amplifiers MA1 and MA2, and passed through the low-pass filters FL1 and FL2 to the analog / digital converters AD1 and AD2 (hereinafter, AD).
1, AD2) and converted into a digital signal. C-DSP and L-DSP are digital signal processors (hereinafter referred to as C-DSP DSP and L-DSP)
C-DSP is a noise control filter (NCF),
Error scattering filter (EPF), adaptive algorithm AL
The L-DSP also has a function as an acoustic feedback filter (AFF).

Then, the analog / digital converter A described above is used.
The digital signals output from D1 and AD2 are CD
Sent to SP, L-DSP, and as described above, C-DS
P outputs a noise elimination signal. The output of the C-DSP is converted into an analog signal by a digital / analog converter DA1 (hereinafter referred to as DA1), is sent to an audio amplifier AU1 via a low pass filter F3, is amplified, and is given to a speaker SP that generates a deleted sound. To be

Reference numeral 11 is a system bus, 12 is a processor, and 13 is a ROM that integrates the C-DSP and L-DSP and stores an OS for supervisory processing. 14 is a C-DSP. A shared RAM shared between the L-DSP and the processor 12, 15 is an interface controller, 16 is a monitor, and the shared RAM 14
The noise control filter (NCF), acoustic feedback filter (AFF) and other filter coefficients are stored in the C-DS.
Data transmission / reception between the P and L-DSP is performed via the shared RAM 14. Further, the processor 12 reads the filter coefficient from the shared RAM 14 and displays it on the monitor 16 in real time under the control of the OS.

FIG. 3 is a block diagram showing the active noise control system. In the figure, the same components as those shown in FIG. 2 are designated by the same reference numerals. As shown in the figure, the L-DSP is an acoustic feedback filter (AF
F) Functioning as F2, C-DSP is noise control filter F1, error scattering system (EPF) F3, adaptive algorithm A
Functions as L.

Further, as described above, the air duct D is
It can be represented by an acoustic system Df including an unknown transfer system {H} showing a transfer characteristic from the fan F1 to the error microphone M2 and an acoustic feedback system {Hf} showing a transfer characteristic from the erasing speaker SP to the sensor microphone M1. The sound detected by the sensor microphone M1 is the sum of the echo sound Xf fed back via the acoustic feedback system {Hf} and the noise Xj generated from the noise source. Further, the sound detected by the error microphone M2 becomes a difference Ej between the noise transmitted through the unknown transmission system {H} and the erased sound sent from the noise control filter F1 to the speaker SP.

FIG. 4 is a diagram showing the basic structure of a digital filter used as the noise control filter F1, the acoustic feedback filter F2, and the error scattering system F3. The digital filter of this embodiment is as shown in FIG. Further, a non-recursive digital filter (FIR) composed of multipliers Mx0 to Mxm of filter coefficients a0 to aM and delay means TD0 to TDm of time T can be used. The output yk of the non-recursive digital filter is generally represented by the formula shown in FIG. 4, and when a unit impulse is given, it shows an impulse response having a peak value corresponding to the coefficient value thereof.

FIG. 5 shows microphone amplifiers MA1 and MA2 (hereinafter referred to as microphone amplifier MA) used in this embodiment.
FIG. 3 is a diagram showing a configuration of a sensor microphone / error microphone (hereinafter referred to as a microphone M), and C / M2 in FIG.
b1 is a coaxial cable, PW is a power source, C1 to C5 are capacitors, R1 to R5 are resistors, and LA1 and LA2 are amplifiers.

The microphone amplifier MA has a power supply PW of + 15V and -15V, and the power supplies of + 15V and -15V are
It is supplied to the amplifiers LA1 and LA2, and + of them
The 15V power supply line is connected to the input terminal A of the output signal of the microphone M, and is supplied to the microphone M via the coaxial cable Cb1. With the above configuration, the microphone M
It is possible to supply power to the microphone M by the power supply provided in the microphone amplifier MA without providing a power supply on the side.

In the figure, the signal detected by the microphone M is transmitted through the coaxial cable Cb1 to the microphone amplifier MA.
Is transmitted to The capacitors C1 and C2 and the resistor R2 are circuit elements that function as an equalizer, and the microphone amplifier MA can have flat characteristics by selecting appropriate values for the capacitors C1 and C2 and the resistor R2. Capacitors C1 and C2 that constitute the equalizer,
The output of the resistor R2 is given to an amplifier LA1 having a feedback circuit composed of a condensate C3 and a resistor R3, amplified to a predetermined level (for example, gain 10), and an amplifier having a 1: 1 feedback circuit functioning as a buffer amplifier. It is input to LA2 (gain 1), and its output is output to the low-pass filters FL1 and FL2 shown in FIG. 2 as a microphone amplifier output.

Next, the operation of this embodiment will be described. (1) Operation at System Power-on / System Power-off FIG. 6A and FIG. 6B are diagrams showing the operation at system power-on and system power-off in the present embodiment. In FIG. 5A, when the power is turned on, the hardware is first reset and then the C-DSP outputs a digital signal to DA1 to calibrate DA1.

Next, a learning signal is generated from the calibration generator CG shown in FIG.
The coefficient of the acoustic feedback filter (AFF) F2 of the DSP is identified. When the identification of the AFF is completed, the filter coefficient of the L-DSP becomes constant, the C-DSP extracts only the sensor microphone information, and the filter coefficient of the noise control filter of the C-DSP is identified. And
When the identification of the C-DSP is completed, the erase operation is started.

On the other hand, when the power is turned off, if the power is turned off, as shown in FIG.
Noise control filter (NCF) F1 of DSP, acoustic feedback filter (AFF) F2, error scattering system (EPF) F3
After the filter coefficient data (shown as LDSP tap data and CDSP tap data in the figure) of each of the taps is stored in the floppy disk or hard disk, the power is turned off.

(2) Pre-learning of Acoustic Feedback Filter (AFF) FIG. 7 is a diagram showing an operation at the time of pre-learning for identifying the coefficient of the acoustic feedback filter (AFF) F2 of the L-DSP. The identification of the filter coefficient is performed in synchronization with the sampling pulse, and in the present embodiment, the sampling frequency fs is 8k.
Hz or 4 kHz (sampling cycle 1 / fs is 12
5 μs or 250 μs).

As shown in FIG. 14, the calibration generator CG generates an output, and the speaker S
When the output is generated from P (FIG. 7), the speaker SP output is detected by the sensor microphone M1 and the difference between the acoustic feedback filter (AFF) F2 and the acoustic feedback system {Hf} is obtained (FIG. 7). Acoustic feedback filter (AF
F) The coefficient of F2 is updated (FIG. 7) The above process is repeated until the difference becomes small, and when the difference becomes small, the identification of the filter coefficient is ended and the learning completion signal is notified to the C-DSP.

(3) Noise Elimination Operation in C-DSP and L-DSP FIG. 8 is a time chart of the noise elimination operation in the C-DSP and L-DSP, with reference to FIG. 2 and FIG. The noise elimination operation in this embodiment will be described with reference to FIG. The figure shows an acoustic feedback filter (AF
The operation after the end of the identification of F) is shown. The noise elimination operation is performed in each sampling cycle (in the figure, the sampling cycle 1
/ Fs is performed every 250 μs, and may be 125 μs as described above), and all processing is completed within each sampling ring cycle.

In FIG. 8, after the weight is waited in the L-DSP, Xj + Xf detected by the sensor microphone M1 and converted into a digital signal in AD1 is read (in FIG. 8), and Xf (acoustic feedback) saved in the previous processing is read. The output of the filter F2) is subtracted to obtain Xj (in FIG. 8). Then, as will be described later, the subtraction result is set in the output buffer (FIG. 8), a data output request is output to the processor 12, and then wait is performed.

The request output by the L-DSP is given to the processor 12 after being delayed by a predetermined time by a hardware timer which can be set later. On the other hand, in the C-DSP, after waiting, Ej detected by the error microphone M2 and converted into a digital signal by AD2.
Read ((1) in Fig. 8) and wait. Further, the processor 12 is always performing a monitoring process described later, and when a request is issued from the L-DSP, the subtraction result (X
j) is written in the common RAM 14. When Xj is written in the shared RAM 14, the C-DSP reads Xj ((2) in FIG. 8) and performs convolution calculation to obtain the output Gj of the noise control filter F1 ((3) in FIG. 8).

Next, the output Gj obtained by the convolution operation is set in the output buffer ((4) in FIG. 8) and a request is issued ((4) in FIG. 8). As a result, the output Gj
Is converted into an analog signal by DA1 and is given to the speaker SP via the low-pass filter FL3 and the audio amplifier AU1, and an erasing sound is emitted from the speaker SP.

Then, the C-DSP updates the coefficient of the noise control filter F1 based on Ej (the detection result of the error microphone M2) read in (1) ((5) in FIG. 8) and waits. On the other hand, in the L-DSP, after waiting,
Read Gj output by C-DSP ('in FIG. 8),
A convolution operation is performed to find Xf from Gj (in FIG. 8), and the found Xf is saved for the next operation cycle (in FIG. 8). In the pre-learning, the coefficient of the acoustic feedback filter F2 is updated at the next timing ((in FIG. 8)).

FIG. 9 is a diagram showing the operation of the hardware timer for delaying the request signal output by the L-DSP. As described above, when the subtraction result Xj is obtained by the L-DSP, a request is issued to the hardware timer TM. The hardware timer TM is a timer whose delay time can be set by the dip switch DP, and outputs a request to the processor 12 after the time set by the dip switch DP.

When the processor 12 receives the request, it returns a response to the L-DSP, the L-DSP transfers the subtraction result Xj written in the output buffer to the processor 12, and the processor 12 shares the subtraction result Xj with the shared RA.
Write to M14. As described above, by providing the hardware timer TM whose delay time can be set and delaying the request signal by the set time, L
-Even if the number of steps of the DSP or the like changes, the entire processing can be put within one sampling period by adjusting the setting of the hardware timer.

That is, the sampling frequency fs needs to be set so that fs ≧ 2f with respect to the frequency f of the acoustic signal to be controlled, and the sampling cycle 1 /
There is an upper limit on fs. Therefore, for example, in FIG. 8, when the number of steps from the input reading to the request output in the L-DSP becomes long, the subsequent processing is delayed, and in some cases, the entire processing time is the sampling cycle 1 / There are cases where it exceeds fs. Therefore, in consideration of the fluctuation of the processing time, the entire processing is set within the sampling cycle 1 / fs, and the hardware timer TM capable of setting the delay time is used to adjust the number of steps of the L-DSP or the like. By adjusting the delay time accordingly, it becomes possible to easily cope with the variation in the number of steps.

(4) Real-time monitoring process by the processor 12 As described above, the processor 12 operates under the OS for performing the real-time monitoring process and the like, and the filter written in the shared RAM 14 is requested by the operator. The coefficient and the like are displayed on the monitor 16. Hereinafter, the processing in the processor 12 will be described.

In the present embodiment, when the monitor is activated, the processor 12 performs the following processing in response to the command input by the operator. (A) Reset By inputting a reset command from the monitor 16, the hardware of the L-DSP, C-DSP and processor 12 is reset. (B) Acquisition of status The status of the system is displayed on the screen of the monitor 16.

(C) Setting of offset address The start address of the shared RAM 14 at the time of READ / WRITE / Fill is set. The offset address is set to address 0 when the monitor is activated, and is updated each time the commands (d), (e), and (g) below are input. (D) Memory read The setting length data is read from the setting address of the shared RAM 14 and displayed on the screen of the monitor 16. (E) Memory write Write the specified data to the set address of the shared RAM 14 for the specified length. (F) Memory fill From the set address of the shared RAM 14, the specified length,
Fill with specified data.

FIG. 10 is a diagram showing the processing in the processor 12. In the figure, the OS (AN of this embodiment is
When COS: Active Noise Control Operating System) is activated, the processor waits until there is a write request to the shared RAM 14, and when there is a write request to the shared RAM 14, data transfer from the L-DSP to the shared RAM 14 is performed.

Further, the command issued by the command SHELL is analyzed, and the processing (reset, offset address setting, memory write) is executed according to the command. On the other hand, at the time of data transfer, if the status is not normally terminated, the process of displaying an error is terminated, and if the status is normally terminated, the data of the DSP calculation result (filter coefficient etc.) is read from the shared RAM 14. Also, the command S
The command issued by HELL is analyzed and executed (offset address setting, memory read).

On the other hand, at the time of reading data, if the status is not normally terminated, the error display processing is terminated, and if the status is normally terminated, the impulse response graph or the like is displayed on the screen of the monitor 16. . FIG. 11 is an example of a graph of the above-mentioned impulse response.
A graph of the impulse response as shown in the figure is displayed on the screen of, and the operator can know the filter coefficient in real time from the graph.

[0058]

As described above, in the present invention,
The following effects can be obtained. (1) A noise / vibration generation source, and an acoustic / vibration generation unit that is provided at a location where the noise / vibration is transmitted through an unknown transmission system and that generates an output that cancels the noise / vibration.
The first sensor is provided near the noise / vibration source and detects the noise / vibration generated by the source, and is provided near the sound / vibration generating means and can be canceled by the output of the sound / vibration generating means. A second sensor for detecting an error that has not occurred and an output signal to the sound / vibration generating means, and a first sensor for simulating a feedback transmission system from the sound / vibration generating means to the noise / vibration generation source. Noise of the noise detected by the first sensor by calculating the difference between the first filter output and the first sensor output.
First control means for generating an output for eliminating the influence of sound / vibration returned from the vibration by the feedback transmission system, and output of the first control means are provided, and the sound / vibration generating means is generated from the source. A second filter simulating the transfer characteristics of the unknown transfer system up to, the output of the second filter is output to the sound / vibration generating means, and the output of the second sensor causes the second filter to operate. A noise / vibration control system comprising: a second control unit that adjusts the coefficient of the second filter so as to match the transfer characteristic of the unknown transfer system; and the first control unit and the second control unit. A third control means for integrating and managing the means is provided, and the third control means is connected to the first and second control means via a common bus, so that the first control means and the second control means are connected. Control means from independent processing means Also forms a third can be comprehensively and manage them with control means, it is possible to realize high-speed processing in real time.

(2) A shared memory shared by the first, second and third control means is provided, and the third control means receives a data output request from the first or second control means. Since the output data of the first or second control means is written in the shared memory and transferred to the other control means, the data transfer between the first and second control means is performed via the shared memory. Along with being able to do
Further, it becomes possible to read and write data through the shared memory.

(3) A timer means having an adjustable delay time is provided, and the output request output from the first or second control means at the time of data transfer is delayed by the timer means and sent to the third control means. With this configuration, even if the number of steps of the firmware in the first control unit or the like changes, the setting of the timer unit can be adjusted to easily cope with the change in the number of steps, and the entire process can be performed in one sampling cycle. It can be housed inside.

(4) Since the third control means has the function of reading the data stored in the shared memory and outputting it to the monitor, and the function of writing the data in the shared memory, it is possible to write to the shared memory. It is possible to set data and read the filter coefficient from the shared memory in real time.

(5) A noise generating source, a sound generating means which is provided at a position where the noise is transmitted through an unknown transmission system, and which generates an output for canceling the noise, and a sound generating means which is provided in the vicinity of the noise generating source. A first microphone that detects noise emitted from the source, a first amplification means that amplifies the output of the first microphone, and a sound generator that is provided in the vicinity of the sound generation means. A second microphone that detects an error that cannot be canceled, a second amplification unit that amplifies the output of the first microphone, and an output signal to the sound generation unit are given, and the sound generation unit generates noise. From the noise detected by the first sensor by providing a first filter simulating a feedback transmission system up to the source of the noise, and obtaining the difference between the output of the first filter and the output of the first sensor. By the above feedback transmission system The transfer characteristic of the unknown transfer system from the source to the sound generating means is simulated by the first control means for generating an output for removing the influence of the returned sound and the output of the first control means. A second filter is provided, the output of the second filter is output to the sound generating means, and the output of the second sensor causes the second filter to match the transfer characteristic of the unknown transfer system. Second above
And a second control means for adjusting the coefficient of the filter, the power supply circuit supplies power to the respective amplification means from the power supply circuits of the first and second amplification means, and the first microphone and The first and second microphones are connected via a line that transmits a detection signal from the second microphone to each amplifier.
Since it is configured to supply power to the microphone, it is not necessary to provide a separate power source for the microphone, the configuration of the device can be simplified, and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram of the present invention.

FIG. 2 is a diagram illustrating a hardware configuration of an embodiment of the present invention.

FIG. 3 is a block diagram showing an active noise control system according to an embodiment of the present invention.

FIG. 4 is a diagram showing a basic structure of a digital filter used in an embodiment of the present invention.

FIG. 5 is a diagram showing a configuration of a microphone amplifier used in an embodiment of the present invention.

FIG. 6 is a diagram showing an operation when the system power is turned on / off according to the embodiment of this invention.

FIG. 7 is a diagram showing an operation during pre-learning of the acoustic feedback filter according to the embodiment of the present invention.

FIG. 8 is a time chart showing the noise elimination operation according to the embodiment of the present invention.

FIG. 9 is a diagram showing an operation of a hardware timer that delays a request signal.

FIG. 10 is a diagram showing processing in the processor 12 according to the embodiment of this invention.

FIG. 11 is a diagram showing an example of a graph of an impulse response.

FIG. 12 is a diagram showing a configuration of an active noise control system to which the present invention is applied.

13 is a block diagram showing the active noise control system of FIG.

FIG. 14 is a diagram showing a configuration of an acoustic feedback filter of the active noise control system during learning.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Noise / vibration generation source 2 Acoustic / vibration generation means 3 Unknown transmission system 4 Feedback transmission system 5 1st control means 5a 1st filter 6 2nd control means 6a 2nd filter 7 3rd control means 8 Shared memory 9 Monitor S1, S2 Sensor SA1, SA2 Amplifying means 11 System bus 12 Processor 13 ROM 14 Shared RAM 15 Interface controller 16 Monitor D Air duct F Fan SP Speaker M1 Sensor microphone M2 Error microphone MA1, MA2 Microphone amplifier F1, F2 Low-pass filter AD1, AD2 Analog / digital converter DA1 Digital / analog converter AU Audio amplifier C-DSP Digital signal processor L-DSP Digital signal processor F1 Noise control filter F2 Acoustic feedback filter F3 error scattering system AL adaptive algorithm Cb1 coaxial cable PW power C1~C5 capacitor R1~R5 resistor LA1, LA2 amplifier TM hardware timer

Claims (5)

[Claims] 1. A noise / vibration generation source, and an acoustic / vibration generation unit that is provided at a location where the noise / vibration is transmitted through an unknown transmission system and that generates an output that cancels the noise / vibration. The first sensor is provided near the noise / vibration source and detects the noise / vibration generated by the source, and is provided near the acoustic / vibration generating means and can be canceled by the output of the acoustic / vibration generating means. A second sensor for detecting an error that has not occurred and an output signal to the sound / vibration generation means, and a first feedback simulation system from the sound / vibration generation means to the noise / vibration generation source The sound / vibration which is fed back by the feedback transmission system from the noise / vibration detected by the first sensor by determining the difference between the output of the first filter and the output of the first sensor. Excluding the effect of A first control means for generating an output to be removed and a second filter to which the output of the first control means is applied and which simulates the transfer characteristic of the unknown transfer system from the source to the sound / vibration generating means. The output of the second filter is output to the sound / vibration generating means, and the second filter is provided.
A noise / vibration control system comprising: second control means for adjusting the coefficient of the second filter so that the second filter matches the transfer characteristic of the unknown transfer system by the output of the sensor. A third control means for integrating and managing the first control means and the second control means, wherein the third control means is connected to the first and second control means via a common bus. A noise / vibration control system that is characterized by: 2. A shared memory shared by the first, second and third control means is provided, and the third control means, when there is a data output request from the first or second control means, 2. The noise / vibration control system according to claim 1, wherein the output data of the first or second control means is written in the shared memory and transferred to the other control means. 3. A timer means having an adjustable delay time is provided, and an output request output from the first or second control means at the time of data transfer is delayed by the timer means and sent to the third control means. The noise according to claim 2 /
Vibration control system. 4. The third control means has at least a function of reading data stored in the shared memory and outputting the data to a monitor, and a function of writing data in the shared memory, and according to an instruction from an operator. 4. The data stored in the shared memory is read out and the coefficients of the first and second filters are displayed on the monitor in real time.
Noise / vibration control system. 5. A noise generation source, a sound generation unit which is provided at a position where the noise is transmitted through an unknown transmission system, and which generates an output for canceling the noise, and a sound generation unit which is provided near the noise generation source. A first microphone that detects noise generated by the source, a first amplification unit that amplifies the output of the first microphone, and a first microphone that is provided near the sound generation unit and that is canceled by the output of the sound generation unit. A second microphone that detects an error that could not be generated, a second amplification means that amplifies the output of the first microphone, and an output signal to the sound generation means are given, and the sound generation means generates noise. A first filter simulating a feedback transmission system to the generation source is provided, and the difference between the output of the first filter and the output of the first sensor is calculated to obtain the above from noise detected by the first sensor. Return by feedback transmission system A first control means for generating an output for removing the influence of the generated sound, and a first control means for simulating the transfer characteristic of the unknown transfer system from the generation source to the sound generating means given the output of the first control means. Two
The output of the second filter is output to the sound generating means, and the output of the second sensor causes the second filter to match the transfer characteristic of the unknown transfer system. A noise control system comprising: second control means for adjusting the coefficient of the second filter, wherein the first and second amplifying means include a power supply circuit, and the power supply circuit supplies power to each amplifying means. And a power source for supplying power to the first and second microphones through a line for transmitting a detection signal from the first microphone and the second microphone to each amplifier.