JPH03186784A - Ultrasonic type distance measuring device - Google Patents

Abstract

PURPOSE:To prevent an erroneous distance to an object caused by a noise from being derived, and also, to measure the distance with excellent responsiveness by outputting the shortest distance in all calculated distances stored in a storage part as a result of measurement. CONSTITUTION:A transmission limiting part 2a outputs a transmitting timing signal for transmitting simultaneously ultrasonic pulses from transmitting means of detecting blocks 11 - 1n. Subsequently, a distance calculating part 2b derives a distance to an object from the time required for the receiving time point of a reflected wave from a transmitting time point of the ultrasonic pulses of the respective detecting blocks 11 - 1n, respectively. Next, a discriminating part 2c compares the respective distances derived by the distance calculating part 2b with a specific calculated distance and discriminates it to be a result of calculation in an allowable distance error. Thereafter, in the case it is discriminated by the discriminating part 2c that a storage part 2d is within the allowable distance error, the distance calculated by the distance calculating part 2b is stored, and also, in the case of being outside of the allowable distance error, the previous calculated distance is stored as it is, and the shortest distance in all the calculated distances stored in the storage part 2d is outputted as a result of measurement by an output part 2e.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an ultrasonic distance measuring device that measures the distance to an object using ultrasonic pulses.

[Prior art 1] An ultrasonic distance measuring device transmits an ultrasonic pulse consisting of a pulse train, receives the reflected wave of this ultrasonic pulse from an object, and determines whether there is a reflected wave or not and the ultrasonic pulse is transmitted. Some devices detect the presence of an object and measure the distance to the object based on the time required from the time of the wave to the time of reception of the reflected wave.

As shown in Fig. 3, this type of ultrasonic distance measuring device includes an ultrasonic transducer 1a for both transmitting and receiving waves, and a transmitting control device that outputs a transmitting timing signal of a constant period for transmitting ultrasonic pulses. part 2a, and a transmission signal creation part 1b that creates a transmission signal based on the transmission timing signal from the transmission control part 2a;
Ultrasonic transducer 1 according to the output of this transmission signal generation section 1b
A wave reception date is set in which the output of the ultrasonic transducer 1a is passed during the period (wave reception date 1jAl?11) indicating the detection distance range based on the wave transmission timing signal of the wave transmission control unit 2a. 1d, a wave receiving section 1e that detects and amplifies the output of the wave receiving gate section 1d, and a distance calculation section 2b that calculates the distance to the object from the output of the wave receiving section 1e. Here, the ultrasonic transducer 1a, the transmitting signal generator I & part i
b, drive@lc, wave reception date section] d and wave reception section 1e constitute a detection block 1, and a transmission control section m section 2a and distance calculation section 2b constitute a signal processing block 2'.

In this ultrasonic distance measuring device, as shown in Fig. 4,
When the reflected wave (b) is received within the wave reception date period (c) indicating the detection path #l range, the distance to the object is determined.

However, in the above-mentioned ultrasonic distance measurement system, if noise (d) is received within the reception date period (c), it is difficult to determine whether the received signal is noise or a reflected wave from an object. Since it is not possible to identify the noise (d), the reflected wave (
If the wave is received before (b), the distance will be determined based on the noise (d), resulting in an incorrect distance.

Therefore, in order to solve the above problem, the patent application No. 59-228
According to No. 763 or Japanese Patent Application No. 59-228764, when a wave reflected from an object is received continuously more than a preset number of times, it is determined that the wave is reflected from an object.
2. Description of the Related Art An ultrasonic distance measuring device that uses a so-called continuous multiple detection method to determine the distance to an object has been proposed. With this ultrasonic distance measuring device, it is no longer possible to obtain an erroneous distance due to a single noise.

[Problem to be Solved by the Invention 1] However, the above-mentioned ultrasonic distance measuring device also has the following problems. In other words, with this method, the distance cannot be determined until the reflected wave is received a set number of times in succession (Figure 5 shows the case where the influence of noise is ignored for the nth time), so the response time is slow. It is.

The present invention has been made in view of the above points, and its purpose is to provide an ultrasonic distance measurement method that eliminates the need to determine the wrong distance to an object due to noise and has excellent responsiveness. The goal is to provide equipment.

[Means for Solving the Problems J In order to achieve the above object, the present invention provides a plurality of wave transmitting means for respectively transmitting ultrasonic pulses of different frequencies, and a wave transmitting means that is paired with each of these wave transmitting means. a plurality of wave receiving means for selectively receiving reflected waves of the ultrasonic pulse by the object;
A wave transmission control unit that outputs a wave timing signal that causes all of the above-mentioned wave transmitting means to simultaneously transmit ultrasonic pulses, and a reflected wave of the wave receiving means from the point of transmission of the ultrasonic pulse of each pair of wave transmitting means. A distance paw output unit calculates the distance to the object from the time required to receive the wave, and each distance calculated by this distance calculation unit is compared with a specific calculated distance to obtain a calculation result within the allowable distance error. A discriminating unit that determines whether the distance is within the allowable distance error, and a distance calculated by the distance calculating unit when the discriminating unit determines that the distance is within the allowable distance error, are stored, and the allowable pressure is 1lJl.
It includes a storage section that stores the previously calculated distance as is if it is outside the error, and an output section that outputs the shortest distance among all the calculated distances stored in this storage section as a measurement result.

Note that the output unit outputs as a measurement result the shortest distance among all calculated distances that are within the allowable distance error, excluding the calculated distance of the storage unit that is determined by the discriminator to be outside the allowable distance error. You can do it like this.

[Operation 1] As described above, in the present invention, the discrimination unit compares each distance obtained by the distance calculation unit with a specific calculated distance and determines that the calculation result is within the allowable pressure a error, and the storage unit If the discrimination unit determines that the pressure is within the allowable pressure #I error, the distance calculated by the distance calculation unit is stored, and if it is outside the allowable chamber III vaporization range, the previous ml of Masao Ide is stored as is. Then, the output unit outputs the shortest distance among all calculated distances stored in the storage unit as a measurement result, so that the allowable distance lll! based on a specific calculated distance! Calculated distances outside of the error are not used for distance determination, so that the distance calculated due to noise is less likely to be used as a basis for determining the measurement result, and multiple pairs of transmitting means and receiving means are used to simultaneously By transmitting and receiving sound wave pulses to determine the distance to the object, object detection is not repeated and there is no response delay that occurs with ultrasonic distance measuring devices that detect multiple times continuously. This is what I did.

F example] An embodiment of the present invention is shown in FIGS. 1 and 2. FIG.

The ultrasonic distance measuring device of this embodiment includes a conventional ultrasonic transducer 1a that transmits ultrasonic pulses, and a transmission signal control section 1b.
A conventional ultrasonic transducer 1a1 receives a wave reflected by an object from an ultrasonic pulse transmitted from the wave transmitting means, and a wave receiving unit 1d and a receiver a.
A plurality of detection blocks 1. consisting of a wave receiving means consisting of a section 1e; ~1n and these detection blocks 1. In addition to controlling the transmission of ultrasonic pulses by the transmitting means of 1 to 10, each detection block 1. The signal processing block 2 calculates the distance to the object from the received wave outputs of ~1n, and determines the distance to the object from each calculated distance. The frequencies of the ultrasonic pulses transmitted from the wave transmitting means of detection blocks II to 10 are different from each other, and the wave receiving means selectively receives only the waves reflected by the ultrasonic pulses from the corresponding wave transmitting means. That's what I do. Note that the ultrasonic transducer 1a may be provided separately for transmitting and receiving waves. The signal processing block 2 includes a wave transmission control section 2a that outputs a wave timing signal that causes the wave transmission means of all the detection blocks 11 to 1n to simultaneously transmit ultrasonic pulses, and a wave transmission means of each of the detection blocks 1 to 1n. A distance calculation unit 2h calculates the distance to the object from the time required from the time of transmitting the ultrasonic pulse to the time of receiving the reflected wave of the wave receiving means, and this distance sur and the distance calculated by the output unit 2b are specified. Discrimination unit 2 that compares the calculation result with the distance calculated by the distance calculation unit and determines that the calculation result is within the allowable distance error.
c, and when the determining unit 2c determines that the distance calculated by the distance calculating unit 2b is within the allowable distance error, the distance calculating unit 2
A storage unit 2d that stores the distance determined in step b, and this storage unit 2
and an output section 2e that outputs the shortest distance among all calculated distances stored in d as a measurement result. Here, in the storage unit 2d, when the determination unit 2c determines that the distance calculated by the distance calculation unit 2b is a calculation result outside the allowable distance error when compared with the distance calculated by the specific distance calculation g2b, The distance calculated by the distance calculation unit 2b is not stored in the storage unit 2d, and the distance calculated by the previous distance calculation unit 2b''c is recorded as is.

First, the operation when there is no influence of noise (there is no noise indicated by 2 in FIG. 2) and an object exists within the detection distance range will be described. When ultrasonic pulses are simultaneously transmitted from the wave transmitting means of the detection blocks 1 to 1n based on the wave transmission timing signal of the signal processing block 2 as shown in FIG. The received signal (b) is output from the detection blocks 11 to 1n, and at this time, the signal processing block 2 detects the object based on the time required from the time of transmitting the ultrasonic pulse (a) to the time of receiving the received signal (b). The distance to is calculated for each detection block II to 10. Then, the shortest one among these calculated distances is output as the measurement result.

Note that the distance calculated by the distance calculating section 2b described above is temporarily stored in the storage section 2d so that the shortest distance to the exit section 2e can be determined. Upon storage, the following signal processing is performed by the discriminator 2c. In other words, in the determination unit 2c, the received signal of the detection block 11 (
Based on the result of calculating the distance to the object according to (b), the distance l calculated for each of the other detection blocks 12 to 1n.
1l (distance fi based on the time T1 required until the received signal (b) shown in Fig. 2 is received) is the allowable distance a error (±ε)
Determine whether it is within. Expressed mathematically, T+ ・C/ 2- E'= Tx ・C/ 2≦T
I-C/2,000! However, TX: vP required until the time of receiving the reception signal (b) of the detection blocks 12 to 1n; C: the speed of sound.

Here, for example, as shown in Fig. 2, if the noise (d) is received by the detection block 1□ before the received signal (b), the distance from this noise (d) to the object (noise ( (d) is calculated based on the time T2 required until the wave is received, so the distance calculated based on the output of the detection block 12 at this time does not fall within the above-mentioned allowable distance error. In this case, the calculated distance corresponding to this detection block 1□ is stored @2
Not stored in d. That is, in this case, the calculated distance stored in the storage unit 2d is the calculated distance at the time of transmitting the previous ultrasonic pulse. In this way, the calculated distance due to the noise (d) shown in FIG.
It is not used as a material for determining the measurement result of e, and is considered noise (d).
It is possible to reduce the occurrence of incorrect distance measurement results due to Then, the output section 2e outputs the shortest distance among the distances stored in the storage section 2d as the measured distance.

By the way, in the above case, the reference detection block 1.
In such a case, most of the distances calculated for each of the other detection blocks 12 to 1n will not fall within the above-mentioned allowable distance error. Therefore, at this time, the determination unit 2c changes the detection block 1□ to be used as a reference and performs the same determination as described above again. Furthermore, if the distance does not fall within the allowable distance error, the criterion is changed to detection block 1, . . . and the above determination is repeated.

Here, detection block 1. If the distance of the detection block 1 is considered to be a valid standard when the majority of ~1n is within the allowable distance error, some detection blocks 1
Even if noise (d) is received, the overall majority decision is taken, and the M reliability of the measured data is therefore improved.

Note that in the above case, if the distance calculation result is not within the allowable distance error due to noise (d) etc., the previously calculated distance is used, but if it is not within the allowable distance error, the distance is It may not be used to determine the shortest distance.

F Effect of the Invention 1 As described above, in the present invention, the determination unit compares each distance obtained by the distance calculation unit with a specific calculated distance, determines that the calculation result is within the allowable distance error, and records the If the discrimination section determines that the distance is within the allowable distance error, the distance calculated by the distance calculation section is stored, and if it is outside the allowable distance error, the previously calculated distance is stored as is, and the output section stores the distance calculated by the distance calculation section. Since the shortest distance among all calculated distances stored in the storage unit is output as the measurement result, calculated distances outside the allowable distance error based on a specific calculated distance (± are not used for distance judgment, and r )
W-The distance obtained is less likely to be used as a basis for determining the measurement result, and the output result is less likely to be an incorrect distance due to noise. In addition, since the distance to the object is determined by transmitting and receiving ultrasonic pulses at the same time using multiple pairs of transmitting means and receiving means, there is no need to repeat object detection to obtain one measurement result. Unlike continuous detection ultrasonic distance measuring devices, there is no response delay.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, FIG. 2 is an explanatory diagram of the same operation, FIG. 3 is a block diagram showing the configuration of a conventional example, and FIG. 4 is an explanation of the problems in the same example. FIG. 5 is an explanatory diagram of problems in other conventional examples. II to 1n are detection blocks, 2 is a signal processing block, 2
a is a wave transmission control section, 2b is a distance calculation section, 2c is a discrimination section, 2
d is a storage section, and 2e is an output section.

Claims (2)

[Claims] (1) A plurality of transmitting means each transmitting ultrasonic pulses of different frequencies, and a plurality of transmitting means paired with these transmitting means selectively receiving reflected waves of the ultrasonic pulses from an object. a wave receiving means, a wave transmitting control section that outputs a wave transmitting timing signal that simultaneously transmits ultrasonic pulses from all the above-mentioned wave transmitting means, and a wave transmitting means from the time of transmitting the ultrasonic pulse of the corresponding wave transmitting means. A distance calculation unit that calculates the distance to the object from the time required to receive the reflected wave of the wave receiving means, and compares each distance calculated by this distance calculation unit with a specific calculated distance and calculates the distance within the allowable distance error. A discriminating unit that determines whether the calculated result is within the allowable distance error, and a distance calculating unit that stores the distance calculated by the distance calculating unit if the discriminating unit determines that the distance is within the allowable distance error, and if it is outside the allowable distance error, the distance calculated by the distance calculating unit is stored. An ultrasonic distance measuring device comprising: a storage section that stores the calculated distance as it is; and an output section that outputs the shortest distance among all the calculated distances stored in the storage section as a measurement result. (2) The output unit outputs as a measurement result the shortest distance among all calculated distances that are within the allowable distance error, excluding the calculated distance of the storage unit that was determined by the discriminator to be outside the allowable distance error. The ultrasonic distance measuring device according to claim 1.