JPH0321501Y2 - - Google Patents

Description

[Detailed description of the invention] "Industrial application field" This invention relates to a scanning sonar for a vehicle that detects obstacles around the vehicle by rotating an ultrasonic unit mounted on the vehicle with a motor to perform scanning. .

"Prior art and its problems" As a conventional obstacle detection device for a vehicle, there is a device disclosed in, for example, Japanese Patent Laid-Open No. 84377/1983. This uses ultrasonic waves to detect the location and presence of obstacles around the vehicle. However, there are problems in that the configuration is complicated, such as switching and controlling a plurality of ultrasonic units in a time-sharing manner, and the ultrasonic units are fixed, which limits the detection range of obstacles.

Therefore, a so-called scanning sonar has been proposed in which scanning is performed by rotating an ultrasonic unit using a motor.

An example of such scanning sonar is
For example, as shown in FIGS. 2 and 3, there is an automobile A in which a rotating ultrasonic unit 5 is provided at the upper left of the rear bumper B.

However, since the rear fender F, for example, protrudes from the body of the car A, when the ultrasonic unit 5 comes to the search position close to the car body, as shown in FIG. F, etc. enter, and its reflected wave may be included in the received signal.

When there is no reflection from the body of car A and there are no obstacles, the received signal immediately after the ultrasonic wave is emitted will only capture the so-called wraparound peak α, as shown in Figure 4d. When there is such a reflection from the body of car A, the sum α+β of the peak α and the peak β of the reflected wave from the body of car A is captured as shown in FIG. 4b.

If there is only the peak α, it is not determined that there is an obstacle, but if the sum of the waveforms α+β is received, there is a peak β of the reflected wave from the body of car A, so there is an obstacle at a close distance. There is a risk of misperceiving the object as if it were there.

One method for preventing this misidentification is to ignore the portion connected to the peak α. According to this, since there is a peak β of the reflected wave from the body of the car A, there is no possibility that it will be mistaken that there is an obstacle.

However, if there is an obstacle I near the body of car A, the obstacle I
Therefore, the peak τ is captured in the received wave, but since it is connected to the peaks α and β and becomes the sum of the waveforms α + β + τ, if we ignore the part connected to the peak α as mentioned above, then Therefore, it becomes impossible to detect a true obstacle I.

``Purpose of the invention'' The present invention was developed in view of the above circumstances, and it is possible to separate the reflected waves from the vehicle body itself and the reflected waves from the real obstacle to determine the presence or absence of an obstacle. It provides scanning sonar for vehicles that can be used.

``Composition of the invention'' The vehicle scanning sonar of the present invention performs scanning by rotating an ultrasonic unit mounted on the vehicle with a motor to detect obstacles around the vehicle. Reference signal storage means for storing as a reference signal waveform data of a received signal received when there is no obstacle at a search position of the ultrasonic unit such that the received signal includes a reflected wave from the ultrasonic unit; The configuration further comprises a subtraction means for subtracting the stored waveform data as the reference signal from the waveform data of the signal, and a determination means for determining the presence or absence of an obstacle at the search position based on the subtraction result. This is a characteristic feature.

"Example" The present invention will be described in more detail below based on the example shown in the drawings. Here, FIG. 1 is a block diagram of the configuration of an automobile scanning sonar according to an embodiment of the present invention, and FIG. 2 is a perspective view of an automobile scanning sonar according to an embodiment of the present invention attached to the rear bumper of an automobile. Figure 3 is a plan view of Figure 2, showing the detection area of the ultrasonic unit, Figure 4 is a signal waveform diagram, a is a received signal diagram in the state shown in Figure 3, and b is the same as in Figure 3. c is a signal diagram of the result when the received signal of b is subtracted from the received signal of a, and d is a diagram of the received signal due to so-called wraparound. Note that the present invention is not limited to the embodiment shown in this figure.

As shown in FIG. 1, the scanning sonar 1 of this automobile is operated by a computer 2 to
The stepping motor 4 is driven through the motor to rotate the ultrasonic unit 5.

The ultrasonic unit 5 is provided with a transmitting sensor 5a and a receiving sensor 5b adjacent to each other.

The 40KHz carrier wave generated by the fundamental wave generation circuit 6 becomes a pulse wave by the computer 2 opening the AND gate 7 in a 300μs pulse shape, and is input to the transmission sensor 5a via the amplifier circuit 8 and the output circuit 9. . As a result, ultrasonic waves are transmitted in a pulsed manner from the transmitting sensor 5a.

The reflected waves of the ultrasonic waves emitted in a pulsed manner are reflected from the outside and returned to the receiver sensor 5b, and are detected by the receiving sensor 5b, and sent to the amplifier circuit 10, the filter 11, and the detection circuit 1.
2. The signal is input as a digital value to the computer 2 via the programmable gain amplifier 13, the programmable peak hold circuit 14, and the A/D converter 15.

The reason why the programmable gain amplifier 13 is used is that the further away an obstacle is, the greater the attenuation of the ultrasonic waves, making it difficult to detect, so to compensate for this, the gain is increased as time passes. .

The computer 2 determines that if a reflected wave is detected within a predetermined time from when the AND gate 7 is opened and pulsed ultrasonic waves are emitted, there is an obstacle at a distance proportional to the elapsed time until the reflected wave is detected. If no obstacle is detected even after a period of time, it is basically determined that there is no obstacle.

Further, the computer 2 determines the rotation position of the ultrasonic unit 5, that is, the search position, from the rotation angle of the stepping motor 4.

In this way, the computer 2 can determine the presence or absence of an obstacle and its position (direction, distance).

The determination result is displayed on the LED matrix 20 via decoders 16, 17 and drivers 18, 19.

Further, the computer 2 determines the type of obstacle based on the magnitude of the detection level of the reflected wave, and outputs this as an onomatopoeic sound from the speaker 22 via the onomatopoeia generating circuit 21.

For example, when it is determined that an obstacle is behind the car, if the detection level of the reflected wave is higher than a predetermined value, it is determined that it is a wall-like obstacle and an onomatopoeic sound that sounds like "knocking on a wall" is generated. , when the value is less than a predetermined value, it is determined that it is a bicycle or a person, and an onomatopoeic sound "similar to a human voice" is generated. Additionally, if it determines that an obstacle is to the side of the car, it will make an onomatopoeic sound that sounds like a motorcycle.

Therefore, the driver can determine the presence or absence of an obstacle and its location based on the blinking state of the LED matrix 20, and can also get an idea of what the obstacle is based on the onomatopoeia generated from the speaker 22.

Next, the processing of the computer 2 when the received signal includes a reflected wave from the body of the automobile A will be explained.

The computer 2 uses an ultrasonic unit 5 whose reception signal includes a reflected wave from the body of the automobile A.
The search positions are taught in advance, and the received signal waveforms obtained when there is no obstacle I at these search positions are stored as reference signals.

To give a specific example, if the search position is as shown in FIG. 3 and there is no obstacle I, the received signal obtained is the waveform α+β in FIG. 4b, then this waveform α
At each sampling time for +β t ₀ , t ₁ , t ₂ ……
The output value of the A/D converter 15 is stored.

When the search position of the ultrasonic unit 5 becomes as shown in FIG. 3 during actual obstacle detection, the computer 2 subtracts the stored waveform α+β of FIG. 4b from the waveform of the received signal at that time.

Specifically, for example, for a waveform α+β+τ as shown in FIG. 4a, at each sampling time t ₀ , t ₁ , t ₂ ,
When reading the values of the A/D converter 15 at ..., the same sampling time t ₀ , t ₁ ,
The stored reference values corresponding to t ₂ , . . . are respectively subtracted.

Then, as a result of the subtraction, Figure 4 c
A signal as shown in is obtained, which is the peak γ of the reflected wave from the obstacle I. Of course, if there are no obstacles, the peak will not appear.

Thus, this car's scanning sonar 1
Now, even if the received signal includes a reflected wave from the body of the automobile A, it can be suitably removed and only the peak γ of the reflected wave from the real obstacle I can be extracted.

``Effects of the invention'' According to the invention, in the scanning sonar of a vehicle, which detects obstacles around the vehicle by rotating an ultrasonic unit mounted on the vehicle with a motor to perform scanning, reflected waves from the vehicle body itself can be detected. a reference signal storage means for storing as a reference signal waveform data of a received signal received when there is no obstacle at a search position of the ultrasonic unit such that the waveform data of the received signal at the search position is included in the received signal; A scanning sonar for a vehicle, comprising: a subtraction means for subtracting the stored waveform data as the reference signal from the subtraction result; and a determination means for determining the presence or absence of an obstacle at the search position based on the subtraction result. This makes it possible to separate the reflected waves from the vehicle body itself and the reflected waves from real obstacles, and eliminate the influence of the reflected waves from the vehicle body itself, making it possible to detect obstacles very close to the vehicle body. can also be performed with extremely high precision.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a scanning sonar for an automobile according to an embodiment of the present invention, FIG. 2 is a perspective view of a scanning sonar for an automobile according to an embodiment of the present invention attached to the rear bumper of an automobile, and FIG. The figure is a plan view of Fig. 2 and shows the detection area of the ultrasonic unit, Fig. 4 is a signal waveform diagram, a is a received signal diagram in the state shown in Fig. 3, and b is a diagram of the received signal in the state shown in Fig. 3. A received signal diagram when there is no obstacle I, c is a signal diagram resulting from subtracting the received signal b from the received signal a, and d is a received signal diagram due to so-called wraparound. Explanation of symbols: 1...Automobile scanning sonar, 2...Computer, 4...Stepping motor, 5...Ultrasonic unit, A...Automobile, F
...Rear fender, B...Rear bumper, I...Obstacle, α...Peak due to wraparound, β...Peak of reflected waves from the vehicle body itself, γ...Peak due to obstacles near the vehicle body.

Claims (1)

[Scope of Claim for Utility Model Registration] In a vehicle scanning sonar that detects obstacles around the vehicle by rotating an ultrasonic unit mounted on the vehicle to perform scanning, the received signal is the reflected wave from the vehicle itself. a reference signal storage means for storing waveform data of a received signal received when there is no obstacle at a search position of the ultrasonic unit as a reference signal; 1. A scanning sonar for a vehicle, comprising: a subtraction means for subtracting waveform data as a reference signal, and a determination means for determining the presence or absence of an obstacle at the search position based on the subtraction result.