JP2782396B2 - Automotive obstacle sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an obstacle sensor for an automobile, which can accurately measure an obstacle even at a short distance.

[0002]

2. Description of the Related Art Conventionally, as an obstacle sensor installed in an automobile to detect an obstacle in front and behind, an integrated ultrasonic sensor in which a transmitting unit and a receiving unit are integrated is often used. The obstacle sensor is configured to measure the distance to the obstacle by receiving the ultrasonic wave transmitted by the transmission unit reflected by the obstacle by the reception unit,
When there is an obstacle at a short distance, signals S1 and S2 as shown in FIG. 1 are input to the receiving unit.

That is, the ultrasonic wave transmitted from the transmitting unit and reflected by the obstacle is input to the receiving unit as a signal S1, and at this time, a part of the reflected wave is reflected from the sensor surface and reaches the obstacle again. The ultrasonic wave re-reflected by the obstacle is input to the receiving unit as a signal S2.

After that, when the vehicle further approaches the obstacle, the initially input signal S1 is hidden by the reverberation wave S of the sensor as shown in FIG. 2, and only the double reflection signal S2 is detected.

[0005]

In the above-mentioned conventional obstacle sensor, when an obstacle at a short distance is detected, the signal S1 actually detecting the obstacle is hidden by the reverberant wave S.
The distance to the obstacle may be calculated using the double reflection signal S2 as the obstacle detection signal. As a result, the distance to the obstacle may not be accurately measured. SUMMARY OF THE INVENTION The present invention has been made for the purpose of improving the above disadvantages, and an object of the present invention is to provide an automobile obstacle sensor capable of accurately detecting a distance even at a close distance.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention is directed to an ultrasonic wave installed on an automobile and directed toward an obstacle.
Transmitting and receiving reflected waves from obstacles.
An ultrasonic sensor for detecting the more obstacles, the arithmetic processing unit for calculating the distance to the obstacle by a signal detected by the ultrasonic sensor, automobile disorders with an alarm to alert the distance to the obstacle In the object sensor, from the ultrasonic sensor
The time to receive the first ultrasonic signal transmitted and reflected by an obstacle is below a certain set value and
The ultrasonic signal reflected from the front of the ultrasonic sensor or from the car
Signal is reflected by the obstacle again and received by the ultrasonic sensor
The time until the double reflection signal arrives is the first ultrasonic wave
When the signal is twice as large, the processing unit
Recognize and when the double reflection signal arrival time is less than,
An object of the present invention is to provide an automobile obstacle sensor characterized in that a distance to an obstacle is calculated based on the time of arrival of the double reflection signal , thereby solving the above problem.

[0007]

With the above arrangement, even if an obstacle is at a close distance and the actual obstacle detection signal is hidden by the ultrasonic reverberation wave, the distance to the obstacle can be measured accurately.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described in detail with reference to FIGS. FIG. 3 is a block diagram of the vehicle obstacle sensor, and FIG. In FIG. 3, reference numeral 1 denotes an ultrasonic sensor integrated with a transmission / reception unit mounted on the front part of the automobile 10; 2, an arithmetic processing unit (CPU); 3, an alarm;

The transmission signal generated by the transmission signal generator 4 in accordance with the command from the arithmetic processing unit 2 is amplified by the amplifier 5 and transmitted from the transmission unit of the ultrasonic sensor 1 as ultrasonic waves to the front of the automobile. Further, the reflected wave reflected by the obstacle or the like is
The signal is sent to the comparator 8 via the detector 7 and is compared with the mask signal generated by the mask signal generator 9 in the comparator 8.

Now, as shown in FIG.
Has reached a distance d ₁ from an obstacle 11 such as a wall. The ultrasonic wave transmitted from the ultrasonic sensor 1 attached to the front of the automobile 10 is reflected by the obstacle 11 and reaches the ultrasonic sensor 1 after t ₁ time, and the signal S1 is received. Further t
₁ 'later reached is reflected to the ultrasonic again obstacle 11 that is reflected by the front surface of the front or vehicle 10 of the ultrasonic sensor to the ultrasonic sensor 1, the signal S _1' is received. These signals S ₁ and S ₁ ′ are detected by the detector 7 and become the waveform signals shown in FIG.

When the vehicle 10 further approaches the obstacle 11 as shown in FIG. 4B, the output of the detector 7 becomes waveform signals S ₂ and S ₂ ′ shown in FIG. Approach S. The output of the position to the detector 7 car 10 approaches the obstacle 11 shown in (c) of FIG. 4, the signal S ₃ of the reflected wave becomes a waveform was about to overlap partially the reverberation wave S, the reverberation wave S determination of the signal S ₃ of the reflected wave becomes difficult.
At this time, the signal S ₃ is within a preset time period T (time of the reverberation waves), the distance d ₃ at this time, because although the d ₃ ≦ Ct _3/2 can not be measured the time t _3, the obstacle Distance cannot be measured accurately. Here, C represents the speed of sound.

[0012] Therefore, in this way the reflected wave signal _{S 3} of the time t
₃ takes a predetermined time T, and the next signal S
_When it is confirmed that the time t ₃ ′ up to ₃ ′ is t ₃ = t ₃ ′ / 2, this fact is stored in the memory of the arithmetic processing unit 2. Then, the signal t ₃ ′ becomes t ₃ ′ ≦ 2 × T.
₃ processing unit 2 from _'the distance d ₃ to the obstacle double reflected signals S ₃ within the ≧ _T' is calculated by the following equation. d ₃ = ct ₃ ′ / 4

Thereafter, as shown in FIG.
When 0 is further approaches the obstacle 11 up to a distance d _4, the reflected signal S ₄ is made to completely hide the reverberation wave S, the detector 7 outputs only the signal S _{4 'as} shown in (d) in FIG. 4 Becomes More time t ₄ the state of the case 4 (c)
Becomes smaller, so that the distance d from d ₄ = ct ₄ ′ / 4 to the obstacle 11 can be accurately calculated as in (c) of FIG. By notifying the driver with the alarm 3 when the distance to the obstacle 11 becomes a preset distance, the vehicle can be stopped without colliding with the obstacle 11.

[0014]

According to the present invention, as described in detail above, the distance to an obstacle at a short distance is calculated by using a double reflected wave. Even if the detection signal is hidden by the reverberation wave of the ultrasonic sensor, the distance to the obstacle can be accurately measured. As a result, even if the obstacle is a short-distance obstacle, the distance to the obstacle is not erroneously notified to the driver, so that the vehicle can be safely stopped.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the operation of a conventional vehicle obstacle sensor.

FIG. 2 is a diagram illustrating the operation of a conventional automobile obstacle sensor.

FIG. 3 is a block diagram of an obstacle sensor for a vehicle according to an embodiment of the present invention.

FIGS. 4A to 4D are explanatory diagrams of the operation of the vehicle obstacle sensor according to one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ultrasonic sensor 2 Processing unit 3 Alarm 11 Obstacle

Claims (2)

(57) [Claims] 1. An ultrasonic wave installed at an automobile for an obstacle
By transmitting and receiving reflected waves from obstacles,
Ri and ultrasonic sensor for detecting an obstacle, the arithmetic processing unit for calculating the distance to the obstacle by a signal detected by the ultrasonic sensor, automobile disorders with an alarm to alert the distance to the obstacle in the object sensor, transmission from the ultrasonic sensor
Shin by and yet below a certain set value the time to receive the first ultrasonic signal reflected by an obstacle super
Ultrasonic signal reflected from the front of the acoustic sensor or from the car
Is reflected by the obstacle again and received by the ultrasonic sensor.
The time until the double reflection signal arrives is the first ultrasonic signal.
When the number is twice the number, the arithmetic processing unit recognizes that.
When the arrival time of the double reflected signal is less than
An obstacle sensor for an automobile, wherein the distance to the obstacle is calculated based on the arrival time of the double reflected signal . 2. After confirming that the time until reception of the first reflected wave from the obstacle and the next reflected wave is doubled, the time until the first reflected wave is received is set to be equal to or less than a set value. 2. The obstacle according to claim 1, wherein the distance to the obstacle is calculated by determining the next reflected signal and determining the value obtained by dividing the time until the reception by two minutes as the time required for the round trip to the obstacle. Sensor.