JP2009168693A - Ultrasonic displacement sensor apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic sensor for reliably avoiding an effect of an obstacle other than a measurement object to be detected, stably detecting an interval or a distance between the measurement object to be detected, and improving a detecting and/or ranging performance. <P>SOLUTION: An ultrasonic displacement sensor apparatus includes an ultrasonic oscillator, and a signal processor. The signal processor captures all reflection signals generated for one period, extracts the last reflection signal within the period (i), determines the last reflection signal as the reflection signal from the measurement object (ii), and detects a time based on the determined last reflection signal until a reflection sound returns after a sound is emitted (iii). A constitution is provided so as to detect or measure the interval or the distance from a sensor body to the measurement object. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention detects ultrasonic waves that detect or measure the distance or distance from the sensor body to the measurement object by detecting the time from when the sound is projected to the measurement object to when the reflected sound returns to the sensor body. The present invention relates to a displacement sensor device.

  As for a sensor for detecting or measuring a distance or distance to a specific measurement object (hereinafter referred to as a “displacement sensor” in this specification), an ultrasonic wave is used in addition to an optical type using laser light or infrared light. Many systems have been developed and provided to the market depending on the application, such as the system used.

  As an example, in a grain drying apparatus or the like as shown in FIG. 8 or Patent Document 1, a grain level detection device that detects or measures a sediment level (amount or height) in a storage tank (mainly a large tank or silo). As described above, the displacement sensor is provided.

From the viewpoint of a displacement sensor suitable for this grain drying device, in the case of an optical type using laser light or infrared rays,
i) The problem that dust or dust fluctuates frequently in the storage tank, and errors or errors are likely to occur in the detection or measurement results of the sensor, especially when the object to be measured is fine grained or powdered grains. There is. other than this,
ii) In principle, since the area of the measurement object that can be monitored or covered by the sensor is narrow (near the operating point of the sensor), when the upper surface of the measurement object serving as the detection surface of the sensor has a large area, FIG. In view of the fact that the height of the upper surface of the measurement object may vary at each position in the storage tank as illustrated in Fig. 2, it is still likely that errors or errors occur in the sensor detection or measurement results. There is a problem.
In addition, considering the possibility that the height of the upper surface of the measurement object may vary at each position in the storage tank, there are cases in which multiple sensors are installed and averaged. Also in this case, there is a problem that the configuration of the signal processing device tends to be complicated.

  On the other hand, since the above-mentioned problems do not occur if the method uses ultrasonic waves, the method using ultrasonic waves is commonly used as a grain level detection device in current grain drying apparatuses and the like.

As previously known, the configuration of the ultrasonic sensor is: i) a transmission function capable of projecting an ultrasonic signal toward a measurement object according to a transmission signal pulse, and that the ultrasonic signal is reflected from the surface of the measurement object An ultrasonic transducer having a receiving function capable of performing electro-acoustic conversion on the reflected sound that has entered through and outputting as a corresponding electrical signal, and ii) appropriately receiving a signal output from the ultrasonic transducer It consists of a signal processing device capable of electrical signal processing.
As is apparent from FIG. 8, the basic operation principle is that the time from the sound projecting time to the time when the reflected sound returns to the ultrasonic transducer is detected, from the sensor body to the measurement object. The interval or distance is detected or measured.

  Examples of the measurement target include sediments such as grains (rice, soybeans, etc.) accumulated in the storage tank and liquid. In addition, the upper surface of the measurement object is, for example, a deposition surface (upper surface) of the grain or the like when the measurement object is a grain or the like accumulated in the storage tank, and the measurement object is in the storage tank or the like. When the liquid is stored, it becomes the liquid level.

The ultrasonic transducer is composed of an electro-acoustic conversion element, and functions as a transmitter that transmits an ultrasonic signal toward a measurement object (hereinafter referred to as “sound projection” in the present specification). In addition,
The reflected sound from the measurement object is received and subjected to electro-acoustic conversion, and an electric signal corresponding to the reflected sound (hereinafter referred to as “reflected signal” in the present specification) can be output to the signal processing device. Functions as a receiver.

The signal processing device appropriately processes the output signal from the ultrasonic transducer, and detects the time from the sound projection time to the time when the reflected sound returns to the ultrasonic transducer, thereby measuring the measurement from the sensor body. Detect or measure the distance or distance to the object.
In the grain drying apparatus or the like, the grain level can be detected by using the measurement result of the distance from the sensor main body to the upper surface of the object to be measured by the ultrasonic sensor.

  Here, in the conventionally known ultrasonic sensor, the measurement is performed from the sensor body based on the reflected sound (or the reflected signal converted into an electric signal) first returned to the ultrasonic transducer after sound projection. It is the structure which detects or measures the space | interval or distance to a target object.

  However, even when the above ultrasonic sensor is applied to a grain level detection device such as a grain dryer, there are the following problems.

  That is, when the storage tank A of the grain drying apparatus 100 illustrated in FIG. 8 is particularly large, the storage tank A itself is stored in order to prevent the storage tank A from expanding or deforming due to the weight of the deposit. It is necessary to provide reinforcing members 11 and 12 such as reinforcing bars and stretched wires between the inner walls of the tank A.

  However, a conventionally known ultrasonic sensor detects or measures the distance or distance from the sensor body to the measurement object based on the reflected sound or reflected signal first returned to the ultrasonic transducer after sound projection. Therefore, the reinforcing members 11 and 12 described above are obstacles other than the measurement target that should be detected from the viewpoint of the sensor.

  When such an obstacle is present in the detection area of the sensor, there is a case where the conventional ultrasonic sensor detects the reinforcing member 11 or 12 in error instead of the measurement object W due to the basic operation principle. As a result, there is a problem that the distance or distance to the measurement object that should be detected cannot be detected stably. Further, when the influence of an obstacle is strengthened, there is a problem that a measurement object to be detected cannot be detected, and an interval or distance to the measurement object cannot be detected.

Based on this problem,
i) A method for avoiding the reinforcing member 11 or 12 that becomes an obstacle by narrowing down the ultrasonic detection area,
ii) a technique for avoiding the influence of an obstacle by storing the position of the reinforcing member 11 or 12 in advance in the signal processing device of the sensor;
Etc. have been devised and attempts have been made to improve the sensor in order to stably detect the distance or distance to the measurement object, but none of them has been able to achieve a sufficient effect.
JP 2006-017329 A

  Therefore, according to the present invention, it is possible to more reliably avoid the influence of obstacles other than the measurement object to be originally detected, and to stably detect the interval or distance to the measurement object to be originally detected. An object of the present invention is to provide an ultrasonic displacement sensor device excellent in detection and / or ranging performance.

  As a result of various studies to solve the above problems, the present inventor has found that the above problems can be solved by using an ultrasonic displacement sensor device having the following configuration, and has completed the present invention.

That is, the inventor of the present application changed the idea including i), ii) and the like related to the improvement of the sensor that has been conventionally devised to avoid the influence of the obstacle,
(A) Based on a reflected sound (or a reflected signal obtained by converting this into an electrical signal) first returned to the ultrasonic transducer after sound projection, which is a signal processing method employed in an old-known ultrasonic sensor, Instead of using a method of detecting or measuring the distance or distance from the sensor body to the measurement object,
(B) Rather, positively detect the reinforcing member that becomes an obstacle, and then,
(C) Detection range when viewed on the time axis (for example, in the case where the ultrasonic signal is emitted toward the measurement object in accordance with the transmission signal pulse periodically transmitted) The farthest reflected signal as seen from the end or sounding point in the inside is determined as the reflected signal from the measurement object,
(D) Only the reflected signal from the determined measurement object is handled as necessary detection data, and based on this, the time from when the sound is projected until when the reflected sound returns to the ultrasonic transducer is detected. Through the process of detecting or measuring the distance or distance from the sensor body to the measurement object,
As a result, it was found that the influence of the obstacle can be canceled reliably, and the present invention has been completed.

The ultrasonic displacement sensor device of the present invention capable of solving the above-described problems includes: (1) a transmission function capable of projecting an ultrasonic signal toward a measurement object in accordance with a periodically transmitted transmission signal pulse; An ultrasonic transducer having a receiving function capable of performing electro-acoustic conversion on a reflected sound that is input when a sound wave signal is reflected from the surface of the measurement object and outputting the reflected sound as a corresponding electric signal;
The reflected signal output from the ultrasonic transducer comprises a signal processing device capable of appropriately performing electrical signal processing,
An ultrasonic displacement sensor device that detects or measures an interval or distance from a sensor main body to the measurement object by detecting a time from a sound projection time to a time when a reflected sound returns to the ultrasonic transducer. There,
The signal processing device includes:
i) After capturing all the reflected signals generated within one period, extract the last reflected signal within the period;
ii) determining the last reflected signal as the reflected signal from the measurement object;
iii) Based on the determined reflection signal at the tail end, the time from the sound projection time to the time when the reflected sound returns to the ultrasonic transducer is detected, and thereby the sensor main body It has a configuration for detecting or measuring an interval or a distance to a measurement object.

  In this specification, “sound” is used as a broad concept including so-called ultrasonic waves exceeding the audible band in acoustic engineering.

  Note that the function of avoiding the influence of obstacles other than the measurement target that should be detected may be abbreviated as an Obstructor cancel function.

According to the present invention, even if there are obstacles other than the measurement object to be detected, such as bars, bars, or wire meshes, between the sensor and the measurement object, these obstacles are viewed from the sensor. It is possible to reliably detect or measure the distance or distance to the measurement object located on the opposite side beyond the distance.
Therefore, according to the present invention, it is possible to more reliably avoid the influence of obstacles other than the measurement object that should be originally detected, and to stably detect the interval or distance to the measurement object that should be detected. It is possible to provide an ultrasonic displacement sensor device that is excellent in detection and / or ranging performance.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a typical arrangement of various received signals received on the sensor side, and an example showing the correspondence between each received signal and a transmitted signal pulse on the time axis, and FIG. 2 shows an object to be measured. A diagram showing a typical arrangement of various received signals received on the sensor side on the time axis when the upper surface is at a level between the first reinforcing rod assembly and the second reinforcing rod assembly. FIG. 3 is a diagram showing a typical arrangement of received signals received on the sensor side on the time axis when the upper surface of the measurement object is at a level higher than the first reinforcing rod assembly. is there.
FIG. 5 is a block diagram showing a configuration of an embodiment of the ultrasonic displacement sensor according to the present invention, and FIGS. 6 and 7 are flowcharts showing a flow in which a received signal is subjected to signal processing in a distance measurement processing unit. .

[First embodiment]
First, the ultrasonic displacement sensor device according to the first embodiment of the present invention will be described in order.
In the present embodiment, a case where the ultrasonic displacement sensor device according to the present invention is applied as a grain level detection device of a conventionally known grain drying apparatus will be described as an example.
Therefore, the general installation mode when the ultrasonic displacement sensor device is applied to the grain drying device, for example, the positional relationship between the measurement object and the ultrasonic displacement sensor device is as shown in FIG.

Note that, as is well known, the ultrasonic sensor detects the interval or distance from the sensor body to the measurement object by detecting the time from when the sound is projected until when the reflected sound returns to the ultrasonic transducer. Measuring is the basic principle of operation.
As for the configuration, as shown in FIG. 5, i) a transmission function capable of projecting an ultrasonic signal toward a measurement object according to a transmission signal pulse, and that the ultrasonic signal is reflected by the surface of the measurement object An ultrasonic transducer 2 having a wave receiving function capable of electro-acoustic converting the reflected sound that enters and outputting as a corresponding electrical signal; and ii) a received signal output from the ultrasonic transducer 2 And a signal processing device 3 capable of appropriately performing electrical signal processing.

[Constitution]
The configuration of the present embodiment will be described based on FIGS. 5 and 8. In the present embodiment, the measurement target W is grains (rice, soybeans, etc.) accumulated in the storage tank A. In addition, the upper surface F of the measurement object W corresponding to the grain level (height) in the storage tank A of the grain drying apparatus 100 is a deposition surface of grains or the like accumulated in the storage tank A in this embodiment. Become.

  Here, a part of the inner wall surface of the storage tank A of the grain drying apparatus 100 is provided with a plurality of reinforcing members in order to prevent the storage tank A itself from expanding or deforming due to the weight of the deposit. Yes. In the example shown in FIG. 8, a first reinforcing rod assembly 11 and a second reinforcing rod assembly 12 that are formed by combining reinforcing bars fixed between inner walls of the storage tank A are provided as reinforcing members.

  The first reinforcing rod assembly 11 and the second reinforcing rod assembly 12 are composed of a plurality of reinforcing rods each having one end and the other end fixed to the inner wall surface of the storage tank A in a cross-beam shape, and the reinforcing rods crossing each other. It is an assembly constructed by knotting.

  In addition, the further detailed configuration, operation method, and the like of the grain drying apparatus 100 itself excluding the installation mode of the ultrasonic displacement sensor apparatus 1 are already known, and the description thereof is described in Patent Document 1 and other known documents. To give.

  The ultrasonic transducer 2 is composed of an electro-acoustic conversion element and functions as a transmitter for projecting an ultrasonic signal toward the measurement target W, and receives a reflected sound from the measurement target W. It functions as a receiver (receiver) that can perform electro-acoustic conversion and output a reflected signal, which is an electrical signal corresponding to the reflected sound, to the signal processing device 3.

The signal processing device 3 appropriately processes the output signal from the ultrasonic transducer 2 and measures from the sensor body by detecting the time from when the sound is projected until when the reflected sound returns to the ultrasonic transducer 2. The interval or distance to the object W is detected or measured.
In the grain drying apparatus 100 shown in FIG. 8, the grain level is obtained by using the measurement result of the distance from the sensor main body to the upper surface F of the measurement object W by the ultrasonic displacement sensor apparatus 1 according to the present embodiment. Can be detected.

  The signal processing device 3 normally receives an output signal from the ultrasonic transducer 2, and i) a peak value (mainly indicating a voltage level), ii) a width (which indicates a so-called signal duration), and iii) a waveform of the signal. From the rise and fall, etc., the reflected signal, which is an electrical signal corresponding to the reflected sound received by the ultrasonic transducer 2 when the ultrasonic signal is reflected by the surface of the measurement object W, is recognized. At this time, in this embodiment, the waveform shaping unit 32 provided in the signal processing device 3 is used (see FIG. 5). Here, in the present embodiment, the waveform shaping unit 32 includes a comparator.

  The configuration of the signal processing device 3 will be described in more detail with reference to FIG. 5. The signal processing device 3 includes an amplifier circuit 31, a waveform shaping unit 32, a distance measurement processing unit D, and an output circuit 36. ing. These are connected in order, and the output signal from the ultrasonic transducer 2 can be appropriately processed to finally detect the grain level.

In the present embodiment, the distance measurement processing unit D includes a data capture processing unit 33, a time measurement processing unit 34, and a data determination / extraction processing unit 35. These are connected in order, and the reflected signal output from the waveform shaping unit 32 made of a comparator is appropriately processed to finally obtain the measurement result of the distance from the sensor body to the upper surface F of the measurement object W. It is possible.
In the present embodiment, the distance measurement processing unit D includes a one-chip microcomputer, and the processing units 33 to 35 included in the distance measurement processing unit D are stored in the one-chip microcomputer.
The signal processing performed by the distance measurement processing unit D will be described in detail later.

  The amplification circuit 31 and the waveform shaping unit 32 receive the signal output from the ultrasonic transducer 2 so that the distance measurement processing unit D can process the received signal output from the ultrasonic transducer 2 as easily as possible. In other words, the preprocessing, i.e., amplification and waveform shaping are performed to obtain a pulsed reflected signal.

  The output circuit 36 performs processing for obtaining a grain level (height or amount) by using the measurement result of the distance from the sensor main body to the upper surface of the measurement object, which is output from the distance measurement processing unit D, The result is output to the outside.

[Operation]
Next, with respect to the operation of the ultrasonic displacement sensor device 1 according to the present embodiment, each diagram (FIGS. 1 to 3) necessary for explaining a series of flows in which the reflected signal received by the signal processing device 3 is processed. The signal waveform diagram according to FIG. 5, the block diagram shown in FIG. 5, and the flowcharts shown in FIGS.

FIG. 1 is an example of a typical arrangement of various received signals received on the sensor side and a correspondence relationship between each received signal and a transmitted signal pulse on a time axis. 1A shows a transmission signal pulse on the time axis, FIG. 1B shows a reception signal received on the sensor side on the time axis, and FIG. 1C shows FIG. It is a partial enlarged view of (b), and is a figure which expands and shows the received signal received by the sensor side in one cycle.
Here, FIG. 1 corresponds to FIG. 8 showing the installation mode when the ultrasonic displacement sensor device is applied to the grain drying device and the distance measurement principle of the measurement object by the ultrasonic displacement sensor device.
That is, FIG. 1 shows the sensor side when the upper surface of the measurement object is at a level below the first reinforcing rod assembly and the second reinforcing rod assembly, as shown in FIG. The correspondence relationship between various received signals received and transmission signal pulses is shown.
For the sake of simplicity, in the following description regarding FIGS. 1 to 3, the signal before waveform shaping shown in FIGS. 1 to 3 is treated as a reflected signal. 1 to 3, the vertical axis corresponds to the voltage level, and the horizontal axis represents the time axis.

FIG. 2 shows typical examples of various received signals received on the sensor side when the upper surface F of the measurement object W is at a level between the first reinforcing rod assembly 11 and the second reinforcing rod assembly 12. This is a time series.
In FIG. 2, R 12 ′ is from the second reinforcing rod assembly 12 that is not received by the sensor side because the level of the second reinforcing rod assembly 12 is below the upper surface F of the measurement object W. This is a virtual representation of the form of the received signal corresponding to the reflected sound.

FIG. 3 shows a typical arrangement of received signals received on the sensor side on the time axis when the upper surface F of the measurement object W is at a level higher than the first reinforcing rod assembly 11. It is a thing.
In FIG. 3, R 11 ′ is from the first reinforcing rod assembly 11 that is not received by the sensor side because the level of the first reinforcing rod assembly 11 is below the upper surface F of the measurement object W. This is a virtual representation of the form of the received signal corresponding to the reflected sound. R12 ′ is as described in relation to FIG.

In the ultrasonic displacement sensor device 1 according to the present embodiment,
i) After taking in all the reflected signals R11, R12, RW generated within one period Tc, the last reflected signal RW within the period Tc is extracted;
ii) Determine the last reflected signal RW as a reflected signal from the measurement object W;
iii) Based on the determined last reflected signal RW, the time from the time of sound projection to the time when the reflected sound returns to the ultrasonic transducer 2 is detected, whereby the measurement object from the sensor body is detected. It is configured to detect or measure an interval or distance up to W.
A specific configuration example that can extract the last reflected signal RW within one cycle Tc will be described later in detail with reference to the flowchart shown in FIG. 6 or FIG.

First, the operation of the ultrasonic displacement sensor device 1 according to the present embodiment will be described with reference to FIG.
With reference to FIGS. 1A and 1B, when looking at the correspondence on the time axis between the received signal and the transmitted signal pulse received on the sensor side, in the present embodiment, every sound projection cycle The transmission signal pulses ts1, ts2,... Tsn are transmitted from the ultrasonic transducer 2.
Looking at the received signal, in the present embodiment, the reflected signal R11 from the first reinforcing rod assembly 11, the reflected signal R12 from the second reinforcing rod assembly 12, and the measurement object W are measured every sounding cycle. The reflected signal RW from the upper surface F is received.
FIG. 1B shows that the signal Rts is received almost simultaneously with the time of sound projection. This received signal Rts corresponds to the reverberation that occurs during sound projection. In a specific example of the configuration in which the last reflected signal RW within one cycle Tc, which will be described later with reference to FIG. 6 or FIG. 7, can be extracted, the signal Rts received almost simultaneously with the time of sound projection. Are specifically excluded from consideration.

  Referring to FIG. 1 (c), when the received signal is examined in more detail, in one cycle Tc, the time from receiving the reflected signal R11 from the first reinforcing rod assembly 11 to receiving the reflected signal R11 is T1. The time from when the sound is received until the reflected signal R12 from the second reinforcing rod assembly 12 is received is T2, and the time from when the sound is projected until the reflected signal RW from the upper surface F of the measurement object W is received is T3. It is said.

  In the present embodiment, i) the farthest reflection signal, that is, the last reflected signal from the time of sound projection within one cycle Tc, is determined as the reflected signal (RW) from the measurement object W, and ii) the determined measurement object Only the reflected signal RW from the object W is treated as necessary detection data, and based on this, the time from the sound projection time to the time when the reflected sound returns to the ultrasonic transducer 2 is detected and measured from the sensor body. It is configured to perform processing for detecting or measuring an interval or distance to the object.

Accordingly, in the example shown in FIG. 1, i) the farthest reflected signal as viewed from the time of sound projection within one period Tc exceeds the first reinforcing rod assembly 11 and the second reinforcing rod assembly 12 as viewed from the sensor body. The reflection signal RW from the measurement object W in the back is ii) Time T3 from when the sound is projected until the reflection signal RW from the upper surface F of the measurement object W is received is necessary detection data ( = Time Tx). And in this embodiment, the process of detecting or measuring the space | interval or distance from a sensor main body to the measuring object W is performed by using the value of this time Tx.
In the grain drying apparatus 100 shown in FIG. 8, the grain level is obtained by using the measurement result of the distance from the sensor main body to the upper surface F of the measurement object W by the ultrasonic displacement sensor apparatus 1 according to the present embodiment. Can be detected.

  When the received signal in the example shown in FIG. 2 is examined in detail, i) the farthest reflected signal from the point of time of sound projection within one period Tc is the first reinforcement on the upper surface F viewed from the sensor body. The reflection signal RW from the measurement object W is at a level between the rod assembly 11 and the second reinforcing rod assembly 12, and ii) the reflection signal RW from the upper surface F of the measurement object W is received from the time of sound projection. The time T2 until this is handled as the necessary detection data (= time Tx). In the case shown in FIG. 2, the time Tx value (= T2) is used to detect or measure the distance or distance from the sensor body to the measurement object W.

  Further, when the received signal of the example shown in FIG. 3 is examined in detail, since the upper surface F of the measurement object W is at a level higher than the first reinforcing rod assembly 11 in FIG. The farthest reflected signal viewed from the time of sound projection within the period Tc is such that the upper surface F serving as the reflective surface is closer to the level than the first reinforcing rod assembly 11 and the second reinforcing rod assembly 12 when viewed from the sensor body. A reflection signal RW from a certain measurement object W is obtained, and ii) a time T1 from when the sound is projected until the reflection signal RW from the upper surface F of the measurement object W is received is necessary detection data (= time Tx). Will be handled. In the case shown in FIG. 3, the time Tx value (= T1) is used to detect or measure the distance or distance from the sensor body to the measurement object W.

[Example of specific processing flow that can extract tail data]
Next, an example of a specific processing flow capable of extracting the above-mentioned tail data will be described with reference to FIGS.
FIG. 6 is an example of a flowchart roughly showing a flow of processing a received signal in the distance measurement processing unit D, and FIG. 7 is an example of a processing flow relating to the last data extraction in the data determination / extraction processing unit 35. It is a figure explaining. 6 and 7 correspond to the block diagram related to FIG. 5 described above, and will be described below with reference to FIG.
Note that the determination flow shown in FIG. 6 has one cycle as a unit, that is, makes a round in one cycle Tc.

  Further, the following description is made on the assumption that the accumulation level of the measurement object W in the storage tank A is as shown in FIGS. 1 and 8. Needless to say, even if the accumulation level of the measurement object W in the storage tank A is as shown in FIG. 2 or FIG.

[Step 1 (preprocessing: S1)]
Each processing stage of amplification and waveform shaping of the received signal output from the ultrasonic transducer 2 after the sound projection corresponds to a preprocessing stage in performing the final determination of the reflected signal in the flowchart shown in FIG. Handled in bulk.
Therefore, the amplification circuit 31 and the waveform shaping unit 32 in FIG. 5 that perform the process of amplifying the received signal output from the ultrasonic transducer 2 and shaping the waveform to obtain a pulsed reflected signal are in the preprocessing stage. You can think of it as being included.

[Step 2 (data capture processing: S2)]
The signal processing according to this step is performed by the data capture processing unit 33 included in the distance measurement processing unit D in FIG.
In this step, whether or not a reflected signal has been received is monitored throughout the period of one cycle Tc. When it is determined that a reflected signal has been received, processing for capturing the reflected signal data is performed. It is carried out.

In the present embodiment, the reflected signal data to be captured is time data related to the time from when the sound is projected until each reflected signal is received. As shown in FIG.
i) When it is determined that the reflected signal R11 from the first reinforcing rod assembly 11 has been received, a process of taking in the value of time T1 as data [1] is performed,
ii) When it is determined that the reflection signal R12 from the second reinforcing rod assembly 12 has been received, a process of taking in the value of time T2 as data [2] is performed,
iii) When it is determined that the reflection signal RW from the upper surface F of the measurement object W has been received, a process of taking in the value of the time T3 as data [3] is performed.

  The determination block for determining whether or not the measurement time has ended, which is the first determination block in this step, stores the value of the time Tc in one cycle in advance, and the reflection signal capturing process has been completed. When the time Tc has elapsed, a process of proceeding to the next step is performed.

In this step, time data T1, T2,... Ti are captured as data [1], data [2]... Data [i] until a numerical value “i” described next reaches a final value.
Here, “i” starts from 1 in correspondence with the number of reflection signal data to be subjected to the determination of the tail of the reflection signal, and the reflection signal data to be subjected to the determination of the tail of the reflection signal. The maximum number of values that can be stored is the final value. It should be noted that the maximum number of values that can store the reflected signal data to be subjected to the final determination of the reflected signal that is the final value of i can be arbitrarily determined when actually carrying out the present invention.

  In this embodiment when the accumulation level of the measuring object W in the storage tank A is set to the extent shown in FIGS. 1 and 8, when the final value of i is 8, for example, data [1] until i = 3. , Data [2]... Data [i] store actual time data. On the other hand, the side that is physically farther from the upper surface F of the measurement object W when viewed from the sensor body (if the time axis in FIG. 1 describes, the region that is temporally advanced from the last reflected signal RW). In this embodiment, data [4], data [5]... Data [] are used when i = 4 to 8. 8] is stored for convenience.

  In the example shown in FIG. 2, “0” is stored for convenience as data [3], data [4]... Data [8] after i = 3. In the example shown in FIG. 3, “0” is stored for convenience as data [2], data [3]... Data [8] after i = 2.

[Step 3 (time measurement process: S3)]
The signal processing according to this step is performed by the time measurement processing unit 34 included in the distance measurement processing unit D of FIG.
In this step, the values of the data data [1], data [2]... Data [i] fetched in step S2 are changed to times T1, T2,. A process of measuring each time is performed on the assumption that the time data is related to Ti.

[Step 4 (data determination / extraction process: S4)]
The signal processing according to this step is performed by the data determination / extraction processing unit 35 included in the distance measurement processing unit D of FIG.
In this step, based on the data data [1], data [2]... Data [i] fetched in step S2, the tail of the reflected signal is determined, and the reflected signal data determined as the tail is extracted. Processing is performed.

Next, an example of a processing flow related to the tail data extraction in this step will be described with reference to FIG.
In the final determination loop of this step shown in FIG.
i) Based on the result of determining whether or not the value of the data data [1], data [2]... data [i] fetched in step S2 is “0”,
ii) For those that are not “0”, the process of forcibly replacing the values of data [1], data [2]... data [i] with “0” is sequentially performed.
iii) As a result, the only data finally remaining as data having a value other than “0” in the captured data data [1], data [2]. And the value (time value) is extracted as the last data.
The extracted tail data is handled as necessary detection data (= time Tx) corresponding to the time from when the sound is projected until the reflection signal RW from the upper surface F of the measurement object W is received.

Specifically, this tail determination loop is configured to process two data in association sequentially, and after determining whether data [i + 1] is “0”,
i) If it is “0” (in the determination block of FIG. 7, it applies to “No” pointing to the right), no processing is performed on the data [i].
ii) If it is not “0” (in the judgment block of FIG. 7, this is true for “Yes” pointing downward), the value of data [i] immediately before that data [i + 1] is forcibly set to “ A process of replacing with 0 ″ is performed.

  This loop is repeated sequentially, and at the point when [i-1] iterations (the reason will be described later) is completed, only one data finally remains as having a value other than “0”. Data having a value other than “0” is determined as the last data, and the value (time value) is extracted as the last data.

  This tail determination loop will be further explained with an example. When the accumulation level of the measurement object W in the storage tank A is as shown in FIGS. 1 and 8 and the final value of i is 8, Specific processing performed in the determination loop is as follows.

  First, in this last determination loop, two data are sequentially related and processed. When the final value of i is 8, the processing form is as follows.

[Two numbers of data to be processed in relation to the number of loops in sequence]
Number of loops: 2 data to be processed in sequence
(Data [i], data [i + 1])
1: data [1], data [2]
2: data [2], data [3]
・ 3: data [3], data [4]
・ 4: data [4], data [5]
5: data [5], data [6]
6: data [6], data [7]
7: data [7], data [8]
As is clear from the above, since the two data are sequentially related and processed, the number of loops is i−1.

[Changes in data before and after processing]
Data (data [i]): Data value before processing: Data value after processing data [1]: 1000: 0
Data [2]: 2000: 0
Data [3]: 3000: 3000
Data [4]: 0: 0
Data [5]: 0: 0
Data [6]: 0: 0
Data [7]: 0: 0
Data [8]: 0: 0

Here, the values 1000, 2000, and 3000 of data [1], data [2], and data [3] relatively indicate the time from when the sound is projected until the reflected signal is received.
As for the above-described data change, it can be seen that such a result can be obtained by applying the tail determination loop while actually relating the two data sequentially.

According to the above example, the value of data [3], which is the only data finally remaining after the processing in the tail determination loop, is determined as the tail data, and the value (relative value corresponding to the time value) is determined. "3000") is extracted as the last data.
The extracted tail data is handled as necessary detection data (time Tx = T3) corresponding to the time from when the sound is projected until the reflection signal RW from the upper surface F of the measurement object W is received.

If the necessary detection data = time Tx is obtained, the process of detecting or measuring the interval or distance from the sensor body to the measurement object W in the output circuit 36 using the value of the time Tx in the present embodiment thereafter ( Distance data conversion).
In the grain drying apparatus 100 shown in FIG. 8, the grain level is detected by using the obtained measurement result of the distance from the sensor main body to the upper surface F of the measurement object W.

  According to the present embodiment described above for the configuration and operation, the influence of obstacles other than the measurement object that should be detected can be canceled reliably, and the interval or distance to the measurement object that should be detected can be stabilized. It is possible to provide an ultrasonic displacement sensor device that can be detected by this method and has excellent detection and / or ranging performance.

[Second Embodiment]
Hereinafter, a second embodiment of the ultrasonic displacement sensor device according to the present invention will be described. FIG. 4 is a diagram showing a second embodiment of the present invention.

  As shown in FIGS. 1, 2, and 4 (a), when the plurality of reflected signals exist in a state of being separated from each other on the time axis, the signal processing device 3 has no particular problem, and the plurality of reflected signals are displayed. Each can be recognized separately from different signals.

  However, as shown in FIG. 4B, when a plurality of reflected signals are present in a state where at least a part of them is overlapped with each other or very close to each other on the time axis, the signal processing device 3 is a part of this. There are cases where it is difficult to recognize and process a plurality of reflected signals in a state where they are overlapped or in a very close state.

  In the present embodiment, in such a case, as shown in FIG. 4C, a composite having a width from the rising point to the falling point of a plurality of reflected signals partially overlapped or very close to each other. The signal RC is obtained by the waveform shaping circuit 32 in FIG. 5 and the value of the center RCc of the time width is observed, so that even under such circumstances, the reflected signal RW from the upper surface F of the measurement object W is not particularly problematic from the time of sound projection. Is calculated so as to detect or measure the distance or distance from the sensor body to the measuring object W.

[Modification]
As mentioned above, although the detail of this invention was demonstrated centering on one Embodiment, this invention is not limited to the above at all, Various deformation | transformation are possible.

For example, in the above embodiment, the configuration and operation of the ultrasonic displacement sensor device according to the present invention have been described by taking as an example the case where it is applied as a grain level detection device of a conventionally known grain drying apparatus. However, the present invention can be applied to various apparatuses and can be used alone.
Further, in the above embodiment, the measurement object is described as a grain deposited in the storage tank, but the measurement object is not particularly limited thereto. For example, the measurement object may be a liquid stored in a storage tank. In this case, the upper surface of the measurement object is the liquid level of the liquid that is the measurement object.
In addition, it is of course possible to use the ultrasonic displacement sensor device according to the present invention as a liquid level detection device for a river or the like in the same usage manner as a conventional ultrasonic sensor.

  In the above-described embodiment, the transmission and reception are performed by one ultrasonic transducer. However, the transmission and reception may be performed by separate ultrasonic transducers.

  In the said embodiment, although the storage tank A of the grain drying apparatus 100 demonstrated the case where it provided with two sets of reinforcement members 11 and 12 in the inner wall at intervals in the height direction, The number is not limited to this, and more reinforcing members may be provided on the inner wall of the storage tank A over the height direction as necessary.

In the above embodiment, the configuration of the ultrasonic displacement sensor device 1 according to the present invention is modeled on a case in which two sets of reinforcing members 11 and 12 serving as obstacles are fixed to the inner wall of the storage tank A of the grain drying device 100. Although the operation has been described, the present invention is not limited to the case where the obstacle is fixed, and can be applied even when the obstacle is moving. As an example when the obstacle is moving,
i) When there is an object to be detected originally at a position facing the sensor body, but an obstacle other than the object to be measured (for example, a robot arm) crosses between the sensor body and the object to be measured, Besides,
ii) In the case where the sensor is installed in the installation mode as shown in FIG. 8 with respect to the storage tank, a case where a wire mesh or a monkey placed in the storage tank is moving in the vertical direction,
Etc.

  As described above, the present invention can more reliably avoid the influence of obstacles other than the object to be detected, and stably detect the distance or distance to the object to be detected. It is clear that this is a new and useful object of providing an ultrasonic displacement sensor device that can perform and has excellent detection and / or ranging performance.

This is an example in which a typical arrangement of various reception signals received on the sensor side and a correspondence relationship between each reception signal and transmission signal pulse are shown on the time axis. When the upper surface of the measurement object is at a level between the first reinforcing rod assembly and the second reinforcing rod assembly, a typical arrangement of various received signals received on the sensor side is shown on the time axis. It's what you see. This shows a typical arrangement of received signals received on the sensor side on the time axis when the upper surface of the measurement object is at a level higher than the first reinforcing rod assembly. It is a figure shown about 2nd embodiment of this invention. It is a block diagram which shows the structure of one Embodiment of the ultrasonic displacement sensor which concerns on this invention. It is an example of the flowchart which shows roughly the flow in which a received signal is signal-processed in a ranging process part. It is a figure explaining an example of the processing flow which concerns on the tail data extraction in a data determination / extraction process part. It is a figure which shows the distance measurement principle of the measuring object by the installation aspect at the time of applying an ultrasonic displacement sensor apparatus to a grain drying apparatus, and an ultrasonic displacement sensor apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ultrasonic displacement sensor apparatus 2 Ultrasonic transducer 3 Signal processing apparatus 11, 12 1st reinforcement rod assembly, 2nd reinforcement rod assembly 21 Pulse generator 100 Grain drying apparatus A Storage tank D Ranging processing part F Measurement object Top surface of object ts1, ts2, tsn Transmission signal pulse Tc One period of transmission signal pulse R11, R12 Received signal corresponding to reflected sound from first reinforcing rod assembly and second reinforcing rod assembly Rts At substantially the same time as sounding Received signal corresponding to reverberation generated RW Received signal corresponding to reflected sound from measurement object W Measurement object

Claims (1)

A transmission function capable of projecting an ultrasonic signal toward a measurement object in accordance with a periodically transmitted transmission signal pulse, and a reflected sound that has entered due to reflection of the ultrasonic signal on the surface of the measurement object An ultrasonic transducer having a receiving function capable of performing electro-acoustic conversion and outputting a corresponding reflected signal as an electric signal;
The reflected signal output from the ultrasonic transducer comprises a signal processing device capable of appropriately performing electrical signal processing,
An ultrasonic displacement sensor device that detects or measures an interval or distance from a sensor main body to the measurement object by detecting a time from a sound projection time to a time when a reflected sound returns to the ultrasonic transducer. There,
The signal processing device includes:
i) After capturing all the reflected signals generated within one period, extract the last reflected signal within the period;
ii) determining the last reflected signal as the reflected signal from the measurement object;
iii) Based on the determined reflection signal at the tail end, the time from the sound projection time to the time when the reflected sound returns to the ultrasonic transducer is detected, and thereby the sensor main body It is equipped with a configuration for detecting or measuring the distance or distance to the measurement object.
An ultrasonic displacement sensor device.

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