JPH0246910B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an obstacle detection device for a vehicle that is mounted on a vehicle such as an automobile and uses sound waves to detect objects that impede the vehicle's travel.

“Prior Art” Conventional sonic obstacle detection devices generally detect obstacles by emitting ultrasonic waves from a vehicle and capturing the sound pressure of the ultrasonic waves reflected by the obstacle. An example of this is disclosed in Japanese Patent Application Laid-open No. 84377/1983.

"Problems with the Prior Art" The conventional device described above requires an ultrasonic oscillator, its drive circuit, etc. as a means for emitting ultrasonic waves from a vehicle, and there is a problem in that the configuration becomes complicated accordingly.

OBJECT OF THE INVENTION An object of the present invention is to provide an obstacle detection device for a vehicle that can detect obstacles without specifically providing an ultrasonic oscillator or the like for obstacle detection.

"Structure of the Invention" The obstacle detection device for a vehicle of the present invention is a vehicle obstacle detection device mounted on a vehicle and installed inside the vehicle or facing the vehicle so as to mainly detect sounds generated due to the functions of the vehicle. a second microphone mounted on the vehicle in an attitude facing the outside of the vehicle so as to mainly detect reflected sound generated by the generated sound being reflected by an obstacle located outside the vehicle;
The structure is characterized in that it includes a detection control means for determining the presence or absence of an obstacle based on a comparison between the sound pressure of the first microphone and the sound pressure of the second microphone and outputting a notification signal. It is something.

In the above configuration, "sound generated due to the functions of a vehicle" means, for example, engine sound and exhaust sound in a car.

"Example" The present invention will be described in more detail below based on the example shown in the drawings. FIG. 1 is a schematic diagram of an obstacle detection device according to an embodiment of the present invention and a vehicle equipped with the same, and FIG. 2 is a block diagram of the structure of an obstacle detection device for a vehicle according to an embodiment of the present invention. . Note that the present invention is not limited thereby.

As shown in FIG. 1, a vehicle obstacle detection device 1 according to the present invention is composed of a first microphone 2, a second microphone 3, and a detection control means 4, which are installed in a vehicle A. has been done.

The first microphone 2 is provided in the engine room and mainly detects noise generated by the engine E. External sounds are blocked by the body of car A and suppressed to a low level.

The second microphone 3 is attached to the front end of the body of the automobile A, and has directivity, so it mainly detects sounds coming from the front.
In other words, if there is an obstacle W in front of the vehicle, the engine sound reflected by the obstacle W will be detected.

The detection control means 4 includes the first microphone 2
The sound pressure detected by the second microphone 3 is compared with the sound pressure detected by the second microphone 3 to determine whether or not there is an obstacle W ahead, and to notify the driver. The principle is that the closer the obstacle W is to the automobile A, the more engine sound is reflected, and the sound pressure of the reflected sound detected by the second microphone 3 becomes higher. However, if the sound itself generated by the engine E becomes louder, the reflected sound will naturally also become louder, so in order to cancel this, the sound itself generated by the engine E is detected by the first microphone 2.

FIG. 2 shows a block diagram of the vehicle obstacle detection device 1 in more detail.

First microphone 2, second microphone 3
Amplifiers 5 and 6, variable frequency bandpass filters 7 and 8, and AD converters 9 and 1 correspond to
0 is provided, and AD converters 9 and 10 are connected to a microcomputer 11. Further, the microcomputer 11 uses the frequency variable bandpass filters 7 and 8 to control the frequency band.
It is further connected to a display 12 to output a display signal.

Next, to explain the operation, the microcomputer 11 controls the frequency bands of the variable frequency bandpass filters 7 and 8, and digitalizes the sound pressure component at a predetermined frequency for the first microphone 2 and the second microphone 3. Read by value. As the predetermined frequencies, it is preferable to select several frequencies such that, if the generated sound is the sound of the engine E, a spectrum pattern characteristic of the engine sound can be obtained. Therefore, if the type of generated sound differs (that is, if the sound source differs), it is preferable to change the frequency setting accordingly.

The microcomputer 11 calculates the spectral pattern of the generated sound and the average sound pressure level from the sound pressure component data related to the first microphone 2.

Further, based on the spectral pattern of the generated sound, components related to the generated sound are extracted from the sound pressure spectrum data related to the second microphone 3, and the average sound pressure level is obtained. As a method for extracting components related to generated sound from sound pressure component data, for example, a correlation coefficient calculation method can be adopted.

Next, the average sound pressure level of the second microphone 3 is divided by the average sound pressure level of the first microphone 2 to obtain the quotient.

Next, the quotient is compared with a predetermined value, and if it is large, it is judged that there is an obstacle, and if it is small, it is judged that there is no obstacle, and the judgment result is displayed on the display 12. The predetermined value used for this determination can be determined empirically.

As can be understood from the above, this obstacle detection device 1 can detect the obstacle W without particularly having a sound wave generating means.

Another example is one in which the first microphone 2 is installed near the exhaust pipe at the rear of the vehicle A, and the second microphone 3 is installed at the rear end of the vehicle A facing rearward. In this case, obstacles behind the vehicle can be detected.

Another example is a rear-engine bus or the like in which, like the obstacle detection device 1, the engine sound is used as a generated sound to detect obstacles behind the vehicle.

Another example is a simple one in which the obstacle is detected based on the ratio of the sound pressure level of the first microphone to the sound pressure level of the second microphone without determining the spectrum pattern of the generated sound. can be mentioned. In this case, it must be used under the condition that there are no external noises, but it can be used in a place such as a private garage without any problems.

"Effects of the Invention" According to the present invention, a first microphone mounted on a vehicle in a manner such that it mainly detects sounds generated due to the functions of the vehicle or in a position facing the vehicle; a second microphone mounted on the vehicle in an attitude facing the outside of the vehicle so as to mainly detect the reflected sound generated by the generated sound being reflected by an obstacle outside the vehicle; and a sound pressure of the first microphone. and detection control means for determining the presence or absence of an obstacle based on a comparison of the sound pressure of the second microphone and outputting a notification signal. This makes it possible to suitably detect obstacles without providing a special sound source for detecting obstacles such as an ultrasonic oscillator. Therefore, there is an advantage that the device configuration can be simplified.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an obstacle detection device according to an embodiment of the present invention and a vehicle equipped with the same, and FIG. 2 is a block diagram of the structure of an obstacle detection device for a vehicle according to an embodiment of the present invention. (Explanation of symbols), 1...Vehicle obstacle detection device,
2... First microphone, 3... Second microphone, 4... Detection control means, 5, 6... Amplifier, 7, 8... Frequency variable band pass filter,
11...Microcomputer, 12...Display device.

Claims (1)

[Claims] 1. A first microphone installed inside the vehicle or mounted on the vehicle in a position facing the vehicle so as to mainly detect sounds generated due to the functions of the vehicle, and a first microphone mounted on the vehicle in a position facing the vehicle to mainly detect sounds generated due to the functions of the vehicle; A second microphone is installed on the vehicle in a posture facing the outside of the vehicle so as to mainly detect the reflected sound, and the sound pressure of the first microphone and the sound pressure of the second microphone are detected. What is claimed is: 1. An obstacle detection device for a vehicle, comprising: detection control means for determining the presence or absence of an obstacle based on comparison and outputting a notification signal.