JPH05203743A - Ultrasonic distance measuring apparatus - Google Patents

Abstract

(57) [Summary] (Correction) [Purpose] The moving object is the object to be measured, such as when an ultrasonic distance measuring device is installed in a vehicle that moves at high speed to measure the distance to a running road surface. There is provided an ultrasonic distance measuring device capable of measuring the distance between the ultrasonic transducer mounted on the moving body and the object to be measured even when moving at a high speed substantially parallel to. In an ultrasonic distance measuring device that transmits and receives ultrasonic waves and performs distance measurement based on a time difference between a transmission timing and a reception timing, one end side 14 arranged linearly close to each other is provided. For sending, other plural, 16,
A plurality of ultrasonic transducers 18, 20, 22 were used for reception.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic distance measuring device for measuring a distance using ultrasonic waves, and is particularly suitable for measuring a distance between two objects moving relatively at high speed. The present invention relates to an ultrasonic distance measuring device.

[0002]

2. Description of the Related Art Ultrasonic waves are transmitted from an ultrasonic transducer, reflected by the reflecting surface of the object to be measured, again received by the ultrasonic transducer, and the timing of transmission is received. A technique for measuring the distance between the ultrasonic transducer and the reflection surface of the object to be measured based on the time difference from the timing has been conventionally known.

In this case, one ultrasonic transducer may transmit and receive ultrasonic waves, and two ultrasonic transducers may be used for transmission and reception, respectively.

[0004]

By the way, since the speed of sound in air is about 340 m / sec, when the ultrasonic distance measuring device moves at a high speed substantially parallel to the object to be measured, When performing transmission and reception of ultrasonic waves with the ultrasonic transducer, even if the ultrasonic waves reflected by the measured object reach the position of the ultrasonic transducer during transmission, the reflected ultrasonic waves are received. The reflected wave cannot be received because the ultrasonic transducer to be moved has not moved to the original position. Even when the two ultrasonic transducers are used for transmission and reception, respectively, if they move at a speed different from the originally planned speed, the ultrasonic waves reflected by the DUT should be received. The ultrasonic transducer may move to a position different from the expected position, and the reflected ultrasonic wave may not be received. That is, since there is a time lag between the reflected wave returning after the ultrasonic wave is transmitted, the ultrasonic distance measuring device moves at a high speed in a direction different from the ultrasonic wave transmitting / receiving direction with respect to the measured object. In some cases, the reflected wave may not be received, and in this case, there is a problem that the distance between the ultrasonic transducer and the measured object cannot be measured.

The reason why distance measurement is impossible is as follows.
For example, there is a case where an ultrasonic distance measuring device is mounted on a moving body such as an automobile moving at high speed to measure the distance between the automobile and the road surface. In view of the above circumstances, the present invention is
For example, when the ultrasonic distance measuring device is mounted on a vehicle that moves at high speed, even when the ultrasonic distance measuring device moves at high speed with respect to the measured object, the ultrasonic transducer and the measured object are It is an object of the present invention to provide an ultrasonic distance measuring device capable of measuring the distance between the two.

[0006]

An ultrasonic distance measuring apparatus of the present invention for achieving the above object transmits and receives ultrasonic waves and measures distances based on a time difference between transmission timing and reception timing. The distance measuring device is provided with a plurality of ultrasonic transducers linearly arranged close to each other, one of which is used for transmission and the other of which is used for reception. ..

Further, a plurality of ultrasonic transducers linearly arranged close to each other and one ultrasonic transducer on one end side or the other end side of the plurality of ultrasonic transducers are switched and transmitted. It is preferable that the ultrasonic distance measuring device is provided with switching means for use as a credit and for using a plurality of other ultrasonic transducers for receiving. Furthermore, a detection and addition circuit that detects each reception signal received by each of the plurality of ultrasonic transducers for reception and adds the detection signals to each other, and the reception timing is detected based on the output signal of the detection and addition circuit, and the transmission is performed. It is preferable that the above ultrasonic distance measuring apparatus is provided with a time difference calculation circuit that obtains a time difference between the above timing and the reception timing.

Here, the above "one end side" and "other end side" mean
The ultrasonic transducers may be arranged at the end of the plurality of ultrasonic transducers arranged in a straight line, but the present invention is not limited to this, and is a concept that also refers to an ultrasonic transducer arranged at a position near the end.

[0009]

The ultrasonic distance measuring apparatus according to the present invention has a structure in which one end side of a plurality of ultrasonic transducers linearly arranged close to each other is provided.
One of them is used for transmission and the other is used for reception. Therefore, by mounting these ultrasonic transducers on the moving body with the one end side forward in the movement direction, the ultrasonic vibrations for transmission are transmitted. While the ultrasonic wave is transmitted from the child toward the object to be measured and the reflected ultrasonic wave reaches the ultrasonic transducer for reception, the moving body moves at a high speed substantially parallel to the object to be measured, Even if the moving speed changes from one to another, the reflected wave is received by any one or more of the plurality of ultrasonic transducers for reception, and the distance between the moving body and the object to be measured is thereby detected. It will be possible to measure.

Further, the ultrasonic distance measuring device includes a plurality of ultrasonic transducers linearly arranged close to each other, and one ultrasonic transducer on one end side or the other end side of the plurality of ultrasonic transducers. When a switching means for switching the sonic wave oscillators to be used for transmission and using a plurality of other ultrasonic wave oscillators for reception is provided, the moving body equipped with this ultrasonic distance measuring device is No matter which of the linearly arranged oscillators is moved at high speed, the switching means causes one of the ultrasonic transducers for transmission and the other ultrasonic vibrations on one side in the traveling direction of the moving body. Since the child can be used for reception, the distance between the measured object and the moving object can be measured.

When any one or more of the plurality of ultrasonic transducers are received, for example, the ultrasonic transducer having the largest received signal may be selected and the calculation may be performed based on the received signal. However, in this case, one signal is discarded when it is received by a plurality of transducers. In contrast,
A detection and addition circuit that detects each reception signal received by each of the plurality of ultrasonic transducers for reception and adds the detection signals to each other, and the reception timing is detected based on the output signal of the detection and addition circuit, and the transmission timing is detected. When the above ultrasonic distance measuring apparatus is provided with a time difference calculation circuit that obtains a time difference between the reception timing and the reception timing, it is not necessary to determine which receiving transducer is used for receiving, and multiple ultrasonic transducers are used for receiving. If so, all of those received signals can be utilized, and therefore, a good S / N ratio can be measured.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a perspective view showing an array state of ultrasonic transducers provided in an ultrasonic distance measuring apparatus according to a first embodiment of the present invention, and FIG. 2 is a distance when the ultrasonic transducers shown in FIG. 1 are moved. It is explanatory drawing which shows the principle of measurement.

The probe 10 of the ultrasonic distance measuring apparatus shown in FIG. 1 includes five ultrasonic transducers 14 and 1 in a case 12.
6, 18, 20, 22 are linearly arranged in close proximity to each other, and each of the vibrators 14, 16, 18, 20,
Each signal line passing through the signal cable 24 is connected to the signal cable 22, and the rear end side of each signal line is electrically connected to an internal circuit provided inside the main body (not shown). The ultrasonic transducer 14 is for transmission, and the other ultrasonic transducers 16, 1
8, 20, and 22 are for receiving, and the ultrasonic wave transmitted from the transmitting ultrasonic transducer 14 is reflected by the object to be measured, and any one of the receiving ultrasonic transducers 16, 18, 20, 22 is used.
One or more of these will be received.

Next, referring to FIG. 2, the principle of distance measurement when the ultrasonic distance measuring apparatus equipped with the probe 10 shown in FIG. 1 is moving at a high speed substantially parallel to the object to be measured. explain. FIG. 2 shows only the moving probe and the ultrasonic transducer. The ultrasonic wave 26 is transmitted at the position of the probe 10 (shown by the solid line) and reflected by the measured object 28 at the position of the probe 10A (shown by the broken line). The case where the ultrasonic wave 26 received is described.

When the ultrasonic distance measuring apparatus equipped with the probe 10 moves at a high speed from the right side to the left side in FIG. 2 substantially parallel to the object 28 to be measured, at the position of the probe 10 shown by the solid line. The ultrasonic wave transmitted from the transmitting ultrasonic transducer 14 is reflected by the object 28 to be measured, and when returning through the almost same path 26 as when transmitting, the probe 10 has already moved to the position of 10A shown by the broken line. Therefore, the transmitting ultrasonic transducer 14 is at the position of 14A shown by the broken line, and the receiving ultrasonic transducers 16 and 18 are already 16
Since they have moved to the positions A and 18A, the two receiving ultrasonic transducers 16 and 18 cannot receive the reflected wave. However, since the receiving ultrasonic transducer 20 has moved to the position of 20 A (the position of the transmitting ultrasonic transducer 14 before the movement), the ultrasonic transducer 20 at the position of 20 A is moved.
The reflected wave is received by.

In this embodiment, four ultrasonic transducers for reception are used.
Although two transducers are arranged, when the probe 10 moves at a higher speed, one ultrasonic pulse may not be able to be received by the two ultrasonic transducers for reception 20 and 22 at this time. One ultrasonic pulse can be received by arranging more receiving ultrasonic vibrators near the ultrasonic vibrator 22.

Next, a specific example of the relationship between the length and the moving speed of the receiving ultrasonic transducers when a plurality of receiving ultrasonic transducers are arranged will be shown. When the length of the plurality of ultrasonic transducers for reception is L (cm), the maximum moving speed is V (km / h), and the maximum measurement range is D (cm), L = 1.6 × V × D ×
It becomes 10 ⁻³ (cm). For example, the moving speed is 100 per hour
If the maximum measurement range is 50 cm, the length of the ultrasonic transducer for reception is 8 cm.

As described above, the ultrasonic distance measuring apparatus according to the present embodiment is for receiving even if the ultrasonic transducer for transmitting and receiving ultrasonic waves moves at a high speed substantially in parallel with the object to be measured. By appropriately determining the number of ultrasonic transducers, the reflected wave can be received when moving at a speed within the maximum moving speed V, and based on the received reflected wave, the measured object and the ultrasonic transducer are The distance can be measured.

In this embodiment, one of the plurality of ultrasonic transducers linearly arranged at the end is the ultrasonic transducer for transmission, and the other ultrasonic transducers are the ultrasonic transducers. Although the ultrasonic transducer for reception is used, by using one of the ultrasonic transducers on one end side, for example, the second ultrasonic transducer from one end as the ultrasonic transducer for transmission, The reflected wave reflected from the front surface in the moving direction of the ultrasonic distance measuring device rather than the transmitting ultrasonic transducer can be received. Therefore, the moving body equipped with the ultrasonic distance measuring device is inclined due to the unevenness of the surface of the measured object,
Even when the ultrasonic wave transmitted from the ultrasonic transducer for transmission is reflected from the surface of the measured object toward the front in the moving direction of the ultrasonic distance measuring device with respect to the ultrasonic transducer for transmission, It is possible to measure the distance between the measuring body and the ultrasonic transducer.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 3 is a circuit block diagram of the ultrasonic distance measuring apparatus according to the second embodiment. The probe 32 of the ultrasonic distance measuring apparatus 30 according to the second embodiment is the same as the probe 10 of the first embodiment in that a plurality of ultrasonic transducers are linearly arranged close to each other. However, one ultrasonic transducer on one end side or the other end side of the plurality of linearly arranged ultrasonic transducers is switched for transmission and the other plural ultrasonic transducers are used for reception. It is different from the ultrasonic distance measuring apparatus of the first embodiment in that a switching circuit 34 capable of performing the above is provided. With this switching circuit 34, any one of the ultrasonic transducers on the one end side or the other end side of the plurality of ultrasonic transducers can be selectively used as the transmitting ultrasonic transducer. It is possible to measure the distance between the moving body equipped with the ultrasonic distance measuring device and the object to be measured no matter which direction the linear shape in which the ultrasonic transducers are arranged moves at high speed. .

Since the reflected ultrasonic waves are diffused and spread depending on the state of the reflecting surface, they may be simultaneously received by a plurality of transducers, and the ultrasonic transducers are moving during reception. It is in. In order to deal with this, the ultrasonic distance measuring apparatus 30 of the present embodiment includes a detection and addition circuit 36 that detects each reception signal received by each of a plurality of ultrasonic transducers for reception and adds the detection signals to each other. The reception timing is detected based on the output signal of the detection addition circuit 36,
A time difference calculation circuit 38 for calculating the time difference between the transmission timing and the reception timing is provided.

In the detection addition circuit 36, when the plurality of reception waveforms received by the plurality of reception ultrasonic transducers in the probe 32 are added, the reception waveforms may cancel each other, so that the reception waveforms are added. Before the conversion, the conversion is performed so as to take the envelope, and then the reception waveforms having the envelope are added. As a result, it is possible to obtain a reception signal in which all of them are summed regardless of which transducer received, one transducer received, or multiple transducers received. The time difference calculation circuit 38 detects the reception timing based on the output signal from the detection addition circuit 36, and calculates the time difference between the transmission timing from the transmission circuit 40 and this reception timing. The calculation result of this time difference is displayed as a distance from the measured object on the display unit 4
It is displayed in 2. Further, a DC signal indicating the distance is output from the display unit 42, and the distance information can be transmitted to an external device such as a computer.

Next, referring to FIG. 4, an embodiment in which the ultrasonic distance measuring device 30 shown in FIG. 3 can be mounted on an automobile will be described. The ultrasonic distance measuring device 50 accommodates a probe 62 including five ultrasonic transducers 52, 54, 56, 58 and 60, a switching circuit 34 and a detection addition circuit 36 shown in FIG. The main body 64 is provided.
Ultrasonic transducers 52, 54, 56, 58, 60 and main body 6
The circuit inside 4 is electrically connected by a cable 66. Electric power is supplied from the car battery 68 to the circuit in the main body 64.

By mounting the ultrasonic distance measuring device 50 on an automobile and mounting the probe 62 on the underbody of the automobile, the vehicle height, which is the distance from the road surface when the automobile is driven at high speed, is measured. Records can be made. Further, whether the vehicle runs in the front or rear direction, the vehicle height can be measured by appropriately switching the transmitting ultrasonic transducer by the switching circuit.

[0025]

As described above, the ultrasonic distance measuring apparatus of the present invention is provided with a plurality of ultrasonic transducers linearly arranged in close proximity to each other, one of which is on one end side for transmitting, and the other one. Since it is used for reception, even if this ultrasonic distance measuring device moves at a high speed substantially parallel to the object to be measured, it is possible to measure the distance to the object to be measured. Becomes

[Brief description of drawings]

FIG. 1 is a perspective view showing an array state of ultrasonic transducers included in an ultrasonic distance measuring apparatus according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing the principle of distance measurement when the ultrasonic transducer shown in FIG. 1 moves.

FIG. 3 is a block diagram showing a circuit of an ultrasonic distance measuring apparatus according to a second embodiment of the present invention.

FIG. 4 is a plan view showing an embodiment in which the ultrasonic distance measuring device shown in FIG. 3 can be mounted on an automobile.

[Explanation of symbols]

 14 ultrasonic transducer for transmission 16, 18, 20, 22 ultrasonic transducer for reception 30, 50 ultrasonic distance measuring device 34 switching circuit 36 detection addition circuit 38 time difference calculation circuit

Claims (3)

[Claims] 1. An ultrasonic distance measuring device that transmits and receives ultrasonic waves and measures a distance based on a time difference between a transmission timing and a reception timing, wherein one of the one ends arranged linearly close to each other is provided. An ultrasonic distance measuring device comprising a plurality of ultrasonic transducers used for transmission and a plurality of others used for reception. 2. An ultrasonic distance measuring device that transmits and receives ultrasonic waves and measures distances based on the time difference between the transmission timing and the reception timing, wherein a plurality of ultrasonic transducers linearly arranged close to each other. And a switching means for switching one ultrasonic transducer on one end side or the other end side of the plurality of ultrasonic transducers for use for transmission and using another plurality of ultrasonic transducers for reception. An ultrasonic distance measuring device comprising: 3. A detection adder circuit that detects each reception signal received by each of the plurality of ultrasonic transducers for reception and adds the detection signals to each other, and a reception timing based on an output signal of the detection addition circuit. 3. The ultrasonic distance measuring device according to claim 1, further comprising a time difference calculation circuit that detects the time difference between the transmission timing and the reception timing.