JPH05208636A - Warning sound generating device - Google Patents

Abstract

PURPOSE:To reduce in-car transmission of a warning sound by providing an adaptive type controller in which a reverse transmission characteristic relating to a transmission characteristic of an in-car space transmission system is identified by a reference signal and an input of a microphone to control an output sound of an in-car speaker through an amplifier so as to minimize an input of the microphone. CONSTITUTION:Since a warning sound generated from an out-car speaker 7 is transmitted also in a car room, in order to reduce this transmission, an adaptive type controller 3, based on a reference signal synchronized with rotation of a drive motor 4 from a tachometer 5 and an input of a microphone 9, identifies a reverse transmission characteristic relating to a transmission characteristic of an in-car space transmission system to control an amplifier 10. In this way, an output sound of an in-car speaker 11 is controlled. As a result, transmission of the warning sound to the inside of a car can be reduced by minimizing the input of the microphone 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a warning sound generator,
In particular, the present invention relates to a warning sound generating device such as a carrier vehicle or an electric vehicle that uses a motor as a drive source.

[0002]

2. Description of the Related Art In a transportation vehicle or an electric vehicle using a motor as a drive source, the driving noise during running is smaller than that in an engine-driven vehicle, so that pedestrians in the vicinity may not notice it and may cause an unexpected accident. It is necessary to generate some warning sound while driving.

FIG. 9 shows a conventionally used warning sound generator, 1 is a power battery, 2 is a potentiometer mechanically interlocked with, for example, an accelerator (see FIG. 10) of an automobile, 3 Is a controller, 4 is a drive motor, 5 is a tachometer of the drive motor 4, 6 is an amplifier, 7 is a speaker connected to the controller 3 via the amplifier 6,
Then, 8 turns on / off the connection between the power supply 1 and the controller 3.
It is a switch that turns off.

As shown in FIG. 10, such a warning sound generating device is provided with a power source 1, a controller 3, a drive motor 4, a tachometer 5 and an amplifier 6 at the bottom of the vehicle, and a speaker 7 is provided outside the vehicle. Connected to the amplifier 6, the potentiometer 2 is provided in combination with the accelerator. The switch 8 is provided near the driver's cab.

In operation, when the driver turns on the switch 8 and depresses the accelerator, the resistance value of the potentiometer 2 changes according to the amount of depression, and the controller 3 reads this resistance value to determine the rotation speed of the drive motor 4. Control.

At this time, the tachometer 5 detects the number of revolutions of the drive motor 4 and gives it to the controller 3. Therefore, the controller 3 outputs a warning sound of sound quality and volume corresponding to (synchronized) the detected number of revolutions from the speaker 7. The gain of the amplifier 6 is controlled so that it is generated.

Therefore, the sound volume and sound quality of the warning sound generated from the speaker 7 outside the vehicle changes as the rotation speed of the drive motor 4 increases (speed increase), for example, to inform nearby pedestrians that the danger is approaching. it can.

[0008]

However, there is a problem in that a warning sound generated in a vehicle driven by such a motor is transmitted to the inside of the vehicle to give an unpleasant noise to an occupant.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to reduce a warning sound transmitted to the inside of a vehicle in a warning sound generating device for a vehicle using a motor as a driving source.

[0010]

With reference to FIG. 1, the structure of an alarm sound generating apparatus according to the present invention for achieving the above-mentioned object will be described with reference to FIG. Tachometer 5), speaker 7 outside the vehicle, speaker 11 inside the vehicle, and microphone 9 provided at the position in the vehicle where sound reduction is desired
And the outside speaker 7 via the amplifier 6 according to the reference signal.
A warning sound is generated from the speaker, and an inverse transfer characteristic with respect to the transfer characteristic of the vehicle interior space transfer system is identified by the reference signal and the input of the microphone 9, and the in-vehicle speaker 11 via the amplifier 10 so that the input of the microphone 9 is minimized. And an adaptive controller 3 for controlling the output sound of.

As shown in FIG. 2, such a warning sound generating device of the present invention is provided with an in-vehicle speaker 11 in the driver's cab as compared to the conventional example shown in FIG. The difference is that 9 is provided.

[0012] In this case, the microphones 9 may be arranged at a place where a muffled sound in the vehicle is loud and a place where a transmitted sound of the warning sound is loud, respectively, and a plurality of in-vehicle speakers may be provided in accordance with these microphones.

Further, the adaptive controller 3 may identify the inverse transfer characteristic by using the spatial transfer characteristic between the speaker 11 and the microphone 9 measured in advance by white noise.

Further, it is preferable to provide a confirmation light which is turned on when the adaptive controller 3 is operating.

[0015]

In the warning sound generator shown in FIGS. 1 and 2,
As described in the conventional example, the driver operates the switch 8
When is turned on and the accelerator is depressed, the resistance value of the potentiometer 2 changes according to the depression amount, and the adaptive controller 3 reads this and controls the rotation speed of the drive motor 4.

At this time, the tachometer 5 as a means for detecting the reference signal synchronized with the rotation of the drive motor 4 detects the rotation speed of the drive motor 4 and supplies it to the adaptive controller 3, so that the adaptive controller 3 The gain of the amplifier 6 is controlled so that a warning sound corresponding to (synchronized with) the detected rotation speed is generated from the vehicle exterior speaker 7. As a result, the volume and sound quality change as the rotation of the drive motor 4 increases (speed increases).

On the other hand, the warning sound generated from the exterior speaker 7 is also transmitted to the interior of the vehicle. Therefore, in order to reduce the sound, the adaptive controller 3 receives the reference signal from the tachometer 5 and the input of the microphone 9. Based on the above, the reverse transfer characteristic to the transfer characteristic of the vehicle interior space transmission system is identified, and the amplifier 10 is controlled to control the output sound of the vehicle interior speaker 11 to minimize the input of the microphone 9 and The transmitted sound of the warning sound can be reduced.

That is, there is generally a correlation (large coherence) between the noise source and the sound at the place where noise reduction is desired. As above, active noise
By generating the opposite phase signal of the warning sound by the control (ANC), a sufficient sound reduction effect can be obtained at the microphone position.

In this case, it is possible to reduce the muffled sound (standing wave) simultaneously generated by the transmitted sound of the warning sound.

If the warning sound transmitted through the vehicle is reduced as described above, the warning sound becomes difficult for the driver to hear. Therefore, the confirmation light can be turned on when the adaptive controller 3 is operating. it can.

[0021]

FIG. 3 shows an embodiment of the adaptive controller 3 shown in FIGS. 1 and 2, and the same parts as those in FIGS. 1 and 2 are designated by the same reference numerals.
Is a controller that is installed in the vehicle 12 and identifies the reverse transfer characteristic of the transfer characteristic of the vehicle interior space transfer system by the outputs of the tachometer 5 and the microphone 9, and is an A / D converter that converts the analog output of the tachometer 5 into a digital output. Device 21, a filter 22 for giving a spatial transfer characteristic GD between the speaker 11 and the microphone 9 which is measured and stored in advance for the digital output signal of the A / D converter 21, and the output signal of the filter 22 is used as a reference signal. As an input signal, a D / A converter 24 that converts the output signal of the adaptive filter 23 into an analog signal, and a power amplifier 25 that amplifies the analog signal from the D / A converter 24 and supplies it to the speaker 11. And an A / D converter 26 which converts the analog output of the microphone 9 into a digital signal and gives it to the adaptive filter 23 as a control signal.
It consists of and.

The filter 22 of the controller 3 as described above
The initial identification mode for measuring the space transfer characteristic GD stored in FIG. 4 is shown in FIG. 4, and it will be explained that, depending on the vehicle, the distance between the speaker and the microphone in the vehicle and the pressure / temperature / temperature of the vehicle environment. Humidity and the like are different, and unless the transmission delay between each speaker and microphone is taken into consideration, the operation becomes unstable, the convergence time is delayed, and the effect of reducing residual noise deteriorates.

Therefore, in order to obtain the spatial transfer characteristic (acoustic characteristic) GD between the speaker 11 and the microphone 9, in the system shown in FIG. 4, the noise component from the motor 4 is not used, but instead, in the controller 3 separately. White noise of a digital signal generated from the provided white noise (random number sequence) source 31 is converted into an analog signal by the D / A converter 34 and the amplifier 35 and output from the speaker 11, and the white noise signal is output to the passenger compartment. The signal is picked up by the microphone 9 via 13 and converted into a digital signal by the A / D converter 36 to control the adaptive filter 33 receiving white noise.

FIG. 5 shows an example of the configuration of the adaptive filter 33. The adaptive algorithm in this case includes the known steepest descent method, learning identification method, LMS method, etc. The method is as follows.

That is, Z ^-1 represents a delay element for delaying the input signal X (n) for each sample, and h (0) to h (n-
1) is a filter (tap) coefficient for multiplying the output signal of each delay element Z ⁻¹ , and each filter coefficient is L
Updated sample by sample according to the MS algorithm: h (n + 1) = h (n) +2 μe (n) X (n). However, n = 0 ... i,
μ is the above-described step size, and by selecting the step size μ in this case, the output to the speaker 11 is performed by performing a convolution operation of multiplying and adding the filter coefficient to the input signal X (n) of each sample. Signal y
(n) is required.

Then, the speaker output y (n) is transmitted to the microphone 9 via the passenger compartment 13 to make the microphone 9
Generates an error component e (n) = Y (n) -y (n) which is reduced by the component Y (n) attenuated by the passenger compartment 13, and minimizes the microphone output e (n) by the LMS algorithm. If the filter coefficient is updated for each sample so that the value converges, the characteristic GD of the vehicle interior space transfer system can be identified.

In this way, the characteristic GD of the vehicle interior space transmission system
In the adaptive control of the normal identification mode shown in FIG. 3, the spatial transfer characteristic GD from the speaker 11 to the microphone 9 and the transfer characteristic GC of the transfer system from the motor mount to the speaker 11 are obtained. The transfer characteristic GP from the motor mount to the microphone 9 is GP = GD + GC. Therefore, after the elapse of a certain time set by the timer 35, only the remaining transfer characteristic GC is identified by the adaptive filter 23 in FIG. Become.

In the case of the adaptive control shown in FIG. 3, the input signal is the motor warning sound component X (n) from the tachometer 5,
The component Y (n) corresponds to the noise around the ears of the passenger in the seat.

In this way, the speaker measured in advance is
The filter 22 of the spatial transfer characteristic GD between the microphones becomes a memory having a filter configuration as shown in FIG. 6 by being provided with the filter coefficients h1 ... hn obtained by the adaptive filter 33, and this should be inserted before the adaptive filter 23. This makes it possible to perform adaptive control from the beginning in consideration of the transmission delay between the speaker and microphone, follow the frequency change due to the change in the motor rotation speed, and transmit the warning sound to the interior noise of the vibration transmission system. It follows the characteristic change and further follows the transfer characteristic that changes depending on the number of passengers, so that the degree of convergence is improved and the residual noise reducing effect is also improved.

If the warning sound transmitted through the vehicle is reduced as in the above-described embodiment, the driver cannot hear the warning sound easily. Therefore, the terminal voltage of the in-vehicle speaker 11 or the warning from the controller 3 to the amplifier 10 is given. It is preferable to provide a confirmation light that is turned on when a sound signal is detected.

When it is desired to reduce the muffled sound generated in the vehicle together with the above-mentioned transmission warning sound, the microphone 9
It is preferable to provide the former both in a place where the coherence between the transparent warning sound and the warning sound signal is high and in a place where the sound pressure of the muffled sound is high (for example, near the head) (one place if both places are the same) Correspondingly, it is preferable to provide a plurality of speakers 11. Regarding these installation locations, locations with large noise reduction effects will be experimentally obtained.

FIG. 7 shows a case in which two microphones and two speakers are used for adaptive control. In this case, four combined transmission channels of the microphones 9a and 9b and the speakers 11a and 11b are formed. , And the respective spatial transfer characteristics are GD ₁₁ to GD ₂₂ .

Then, such four spatial transfer characteristics G
D₁₁~ GD_{twenty two}Figure 8 shows the adaptive control system when using
In the calculation units 41 to 44, the above space transfer characteristics are
GD ₁₁~ GD_{twenty two}Rotation from the matrix and the tachometer 5
The convolution operation with the minute X (n) is performed and its value R₁₁~ R_{twenty two}=
X (n) * GD₁₁~ X (n) * GD_{twenty two}Multi-channel arithmetic
Give to part 50. This calculation unit 50 performs matrix calculation
Due to tap coefficient H_1,H₂Is required and updated
Speakers 11a, 11b and two microphones 9a, 9b
Input level of each speaker is performed by combined adaptive control.
Will be minimized.

[0034]

As described above, in the warning sound generating device according to the present invention, the warning sound is generated from the speaker outside the vehicle by the reference signal synchronized with the rotation of the drive motor, and the reference signal and the position in the vehicle where noise reduction is desired. Since the reverse transfer characteristic with respect to the transfer characteristic of the vehicle interior space transmission system is identified by the input of the provided microphone and the output sound of the in-vehicle speaker is controlled via the amplifier so that the input of the microphone is minimized, It is possible to realize a vehicle of high quality by reducing the sound transmitted through the vehicle in the warning sound of an automobile or the like.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a warning sound generating device according to the present invention.

FIG. 2 is a diagram showing a configuration when the warning sound generating device according to the present invention is attached to a vehicle.

FIG. 3 is a block diagram showing a configuration for measuring an inverse transfer characteristic with respect to a transfer characteristic of an in-vehicle space transfer system in a normal identification mode, which is an embodiment of an adaptive controller in the warning sound generating device according to the present invention. ..

FIG. 4 is a block diagram showing a configuration for measuring a spatial transfer characteristic between a speaker and a microphone in an initial identification mode of the adaptive controller used in the present invention.

FIG. 5 is a block diagram showing a configuration of an adaptive filter used in the warning sound generation device according to the present invention.

FIG. 6 is a block diagram showing a configuration of a filter (memory) having filter coefficients obtained by initial identification.

FIG. 7 is a diagram showing paths of space transfer characteristics by a plurality of combinations of a microphone and a speaker.

FIG. 8 is a diagram showing an example of adaptive control using the spatial transfer characteristics obtained in FIG.

FIG. 9 is a block diagram showing a configuration of a conventional warning sound generation device.

FIG. 10 is a diagram showing a configuration when a conventional warning sound generating device is attached to a vehicle.

[Explanation of symbols]

 2 Potentiometer 3 Adaptive controller 4 Drive motor 5 Tachometer 6,10 Amplifier 7 Outside speaker 9 Microphone 11 Inside speaker 23,33 Adaptive filter 31 White noise source

Claims (4)

[Claims] 1. A means for detecting a reference signal in synchronization with the rotation of a drive motor, a speaker outside the vehicle and a speaker inside the vehicle, a microphone provided at a position in the vehicle where noise reduction is desired, and a speaker from the vehicle outside via the amplifier via the reference signal. A warning sound is generated and an inverse transfer characteristic with respect to the transfer characteristic of the vehicle interior space transfer system is identified by the reference signal and the input of the microphone, and the output sound of the speaker in the vehicle is output through an amplifier so that the input of the microphone is minimized. An alarm sound generating device, comprising: an adaptive controller for controlling. 2. The microphone is arranged at a place where a muffled sound in the vehicle is large and a place where a transmitted sound of the warning sound is large, and a plurality of in-vehicle speakers are arranged according to the positions of these microphones. The warning sound generating device according to claim 1. 3. The warning sound according to claim 1, wherein the adaptive controller identifies the reverse transfer characteristic by using a spatial transfer characteristic between a speaker and a microphone which is previously measured by white noise. Generator. 4. The warning sound generating device according to claim 1, further comprising a confirmation light which is turned on when the adaptive controller is operating.