JP2003028956A - Distance-measuring apparatus and position-measuring apparatus using ultrasonic waves, and program for them - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain high temporal resolution in distance measurement between transmitters and receivers, without making the signal processing system of ultrasonic distance measurement complex. SOLUTION: The approximate distance between a transmitter and a receiver is obtained by detecting the threshold of reception ultrasonic waves, and then correction processing corresponding to the size is executed. Since ultrasonic waves are attenuated by propagation and the reception waveform increases gradually, a case or the like for detecting threshold, only after the second wave by the receiver for example within a distance of A-B from the transmitter is generated. Then, for example, when for example the smaller out of the first and second approximate distances (propagation time * speed), based on the positive and negative threshold detection of reception ultrasonic waves is due to a threshold and is equal to or less than a reference distance D (in the case of the detection of the second wave), a correction amount 'λ/2' of the second wave is subtracted from the approximate distance. Using the next zero-cross point, after detecting the threshold of ultrasonic waves as the end of ultrasonic wave propagation time, is also disclosed. Additionally, the distance measurement method in the above is utilized, to measure the transmitter position on a display screen.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distance measuring device and a position measuring device using ultrasonic waves, and in particular, to the transmitter and the receiver by using the propagation time of the ultrasonic wave from the transmitter to the receiver. A device for measuring a distance between

In addition, one of the transmitter and the receiver is arranged at each of the first and second positions of known coordinates, and the other is arranged at an arbitrary position, from the transmitter to the receiver. The first and second propagation times of the ultrasonic wave, and the position measuring device that specifies the other position coordinate by using the known coordinate.

As the propagation time for distance measurement and position measurement, the elapsed time from the time of transmitting an ultrasonic wave until the receiver detects the specific waveform portion (for example, the first wave portion) should be used. is there.

However, since ultrasonic waves are generally attenuated as the propagation distance thereof increases, when the distance from the transmitter to the receiver is long, the receiver causes the rising waveform portion () of the ultrasonic wave sent from the transmitter. First wave, second
Wave, the third wave, etc.), the leading wave (first wave) whose amplitude value is smaller than the subsequent received waveform portion cannot be detected as a waveform portion that exceeds the threshold value by being distinguished from the noise component. There is. The ultrasonic wave output by the transmitter has a waveform in which the amplitude gradually increases and then gradually attenuates due to the mechanical impedance of the transmitter. The same applies to the received waveform.

At this time, the waveform portion detected by the receiver is
Not the original first wave, but the following second and third waves ...
The waveform part that exceeds the threshold value becomes the first in the above, and the propagation time of the ultrasonic wave also becomes a value up to the detection timing of this subsequent wave.

This value is, of course, longer than the true propagation time from the transmission to the detection of the first wave.

Therefore, the distance measurement value obtained by multiplying this value (the ultrasonic wave propagation time until the detection timing of the subsequent wave) by the sound velocity is also the first wave to be detected and the actual detected waveform portion (for example, the third wave). The value includes an error corresponding to the deviation from.

The present invention responds to the demand to correct this error amount and to improve the accuracy of measuring the distance between the transmitter and the receiver.

[0009]

2. Description of the Related Art FIG. 16 is an explanatory diagram showing the configuration of a general transmitter-side device and receiver-side device for distance measurement using ultrasonic waves.

Here, 51 is a switch for setting ON / OFF of ultrasonic wave transmission, 52 is a drive circuit for ultrasonic wave transmission,
53 is a timer for transmitting ultrasonic waves periodically in the ON state of the switch, 54 is an LED drive circuit, 55
Is an ultrasonic drive circuit, and 56 is an infrared LE that outputs an optical pulse for notifying the receiver side of the ultrasonic transmission timing.
D and 57 are ultrasonic oscillators, respectively. The above are the constituent elements of the transmitter.

Reference numeral 61 is a photodiode (infrared PD) for receiving infrared pulsed light from a transmitter, 62 is a receiver for receiving ultrasonic waves from the transmitter, and 63 is an input amplifier for amplifying the received ultrasonic waves (amplitude). Reference numeral 64 is a comparator for comparing the output value of the input amplifier (amplitude of the received ultrasonic wave) with a predetermined threshold value, and 65 is the output of the infrared detection section to start the time counting operation and the output of the comparator to stop it. The timer 66 is a microcontroller that has a function of calculating the distance from the transmitter to the receiver using the operating time of the timer (time from infrared pulse reception to ultrasonic threshold detection) and ultrasonic velocity. Shows. The above are the components of the receiver-side device.

FIG. 17 is an explanatory view showing a general ultrasonic wave reception waveform and reception detection pulse. The vertical axis shows the amplitude of the transmission / reception wave and the horizontal axis shows the passage of time.

Here, 71 is a transmission pulse (optical pulse) optically transmitted from a transmitter for specifying the time of ultrasonic transmission, 72 is an ultrasonic reception waveform, and 73 is this reception waveform as a threshold value. Each of the received detection pulses is generated at a timing that exceeds.

The propagation time trcv of the ultrasonic wave from the transmitter to the receiver is calculated by the transmission pulse 71 and the reception detection pulse 73.
It is calculated as the time difference between the respective rising timings. Then, the distance from the transmitter to the receiver is calculated by multiplying the time difference and the sound velocity.

FIG. 18 is an explanatory diagram showing the time shift of the reception detection pulse with the distance of the receiver with respect to the transmitter. (A) shows the receiver in the position close to the transmitter, and (b) shows
The receiver is located farther from the transmitter than in (a).
The circled numbers indicate the respective waveform portions of the first wave, the second wave, and the third wave of the received ultrasonic wave.

When the position of the receiver is close to the transmitter as shown in (a), the received waveform 72 of the ultrasonic wave transmitted from the transmitter
Is also small, and the receiver outputs the reception detection pulse 73 at the timing of the threshold detection of the first wave of the reception waveform.

On the other hand, when the position of the receiver is far from the transmitter as shown in (b), the amplitude of the received waveform 72 'of the ultrasonic wave sent from the transmitter is attenuated and the amplitude of the first wave is It is less than or equal to the threshold.

In this case, the receiver first detects the threshold value of, for example, the third wave of the reception waveform of the ultrasonic wave, and outputs the reception detection pulse 73 'at that timing. This output is sent for one wavelength longer than the reception detection pulse 73 in (a).

As described above, since the waveform (amplitude) of the ultrasonic wave used for distance measurement becomes longer as it propagates longer, it is inconvenient that the first wave portion, which is the original detection target of the reception timing, cannot be detected. As a distance measuring method that solves the above problem, there is a method disclosed in the following patent publications and the like. 1. JP-A-5-215850. JP-A-8-254454

In the distance measuring method using ultrasonic waves disclosed in Japanese Patent Laid-Open No. 5-215850, the propagation time of ultrasonic waves, that is, from the time of transmission to the time when the received wave first exceeds the threshold, with the envelope of the received ultrasonic waveform as a threshold. Seeking time.

In the ultrasonic distance measuring method disclosed in Japanese Unexamined Patent Publication No. 8-254454, each level of a plurality of peaks of a received ultrasonic waveform is held and a virtual zero-cross point of the received waveform is obtained from the hold value. The time when the predetermined offset time (the time peculiar to the receiver) is added to the zero-cross point is the reception time of the first wave.

[0022]

These conventional distance measuring methods using ultrasonic waves have the following problems.

In the case of the distance measuring method disclosed in Japanese Unexamined Patent Publication No. 5-215850, since a threshold value for determining the timing of ultrasonic wave reception is interlocked with the received waveform itself, ultrasonic wave propagation is performed as compared with the method of fixing the threshold value. Time detection error is reduced.

However, since the threshold value in which the received waveform is blunted is used, the detection time resolution cannot be increased, and the measurement distance resolution is inevitably difficult to obtain.

Further, in the case of the distance measuring method disclosed in Japanese Unexamined Patent Publication No. 8-254454, complicated signal processing such as level holding of a plurality of peaks of a received waveform and calculation of a virtual zero cross point of the received waveform based on the hold value. Is required.

Therefore, in the present invention, once the approximate information (ultrasonic wave propagation time and the approximate distance corresponding thereto) from the transmitter to the receiver is once obtained by the ordinary method of detecting the fixed threshold value of the received ultrasonic wave, To obtain high time resolution of the distance measurement without complicating the signal processing system of ultrasonic distance measurement by executing the preset correction processing according to the size of the approximate distance. With the goal.

It is another object of the present invention to measure the position of an arbitrary point on the display screen by using this distance measuring method.

[0028]

The present invention solves this problem as follows. (1) In a distance measuring device that calculates the distance between the transmitter and the receiver by using the propagation time of the ultrasonic wave from the transmitter to the receiver: Means for obtaining approximate information, which comprises a propagation time based on a timing exceeding a threshold value or an approximate distance corresponding to the propagation time, and a reference propagation time for specifying what part of the received waveform the timing is. Or, a means for holding reference information, which is composed of a reference distance corresponding to the reference propagation time, and, based on the size relationship between the approximate information and the held reference information, corrects the approximate information, and And means for calculating the distance. (2) In the above (1), the means for obtaining the approximate information uses the zero crossing point next to the timing of the received waveform as the end of the propagation time. (3) In the above (1) and (2), the means for calculating the distance, when correcting the approximate information, has the timing of one of the positive polarity portion and the negative polarity portion of the received waveform. And the difference information from the timing of the other part following this is used. (4) With one of the transmitter and the receiver placed at the first and second positions of the known coordinates and the other placed at an arbitrary position, the distance from the transmitter to the receiver is increased. In a position measuring device that specifies the other position coordinate by using the first and second propagation times of the sound wave and the known coordinate, the method is based on the timing at which the size of the received waveform of the ultrasonic wave exceeds a threshold value. A means for obtaining approximate information, which comprises first and second propagation times, or first and second approximate distances corresponding to the propagation times; and-specifying what wave portion of the received waveform the timing is. Means for holding the reference information, which comprises a reference propagation time for performing, or a reference distance corresponding to the reference propagation time, and-based on the magnitude relation between the approximate information and the held reference information. Means for correcting the information to calculate the first and second distances; specifying the other position coordinate by using the known coordinate and each of the calculated first and second distances And means for doing so.

According to the present invention, as described in (1) above, approximate information regarding the distance from the transmitter to the receiver (the ultrasonic wave propagation time between the transmitter and the receiver and the approximate distance corresponding thereto) can be obtained by a usual method. After the calculation, the correction information based on the magnitude relation with the known reference information regarding the reception timing of the ultrasonic wave is executed for the rough estimation information, and thereby the transmission / reception is performed without complicating the distance measurement signal processing system. Improves the accuracy of instrument distance measurement.

The ultrasonic wave propagation time between the transmitter and the receiver and the corresponding approximate distance are uniquely converted via the ultrasonic wave velocity. Therefore, in the distance measurement processing of the present invention, either the ultrasonic wave propagation time or the approximate distance may be used. The same is true for the reference propagation times and reference distances mentioned above.

In the present specification, it is assumed that the approximate distance and the reference distance are used for convenience of explanation, but instead of the distance information, the ultrasonic wave propagation time (= approximate distance ÷
Of course, the ultrasonic velocity) and the reference propagation time (= reference distance / ultrasonic velocity) may be used.

Further, as described in (2) above, as the end of the ultrasonic wave propagation time (approximate information) between the transmitter and the receiver, the zero crossing time point next to the threshold value detection timing of the ultrasonic wave reception waveform is used. The ultrasonic wave propagation time is calculated accurately when the amplitude of the received waveform is different, and the measurement accuracy of the distance between the transmitter and the receiver is improved.

As in (3) above, the actual difference information between the threshold detection timing of the n-wave portion and the threshold detection timing of the (n + 1) -wave portion of the ultrasonic reception waveform is used as the correction amount for the rough estimation information. By using this, the accuracy of the approximate information correction when the actual wavelength of each waveform portion deviates from “λ / 2” and becomes a variable value is improved, and the measurement accuracy of the distance between the transmitter and the receiver is improved.

Further, as described in (4) above, for example, the receivers are arranged at the first and second positions of known coordinates, and one transmitter is arranged at an arbitrary position. After the approximate information on the first and second distances of 1 is obtained by a normal method, the approximate information is subjected to correction processing based on the magnitude relationship with known reference information on the reception timing of ultrasonic waves. , The known coordinates of the first and second positions and the corrected first and second distances are used to identify the position coordinates of the transmitter, thereby complicating the distance measurement signal processing system. Instead, the measurement accuracy of the position where the transmitter is placed is increased.

Furthermore, by using a piezoelectric film sensor having a small Q as the receiver,
The threshold is detected by distinguishing the wave from the noise.

The present invention is directed to a distance measuring device and a position measuring device having such characteristics, and further to a distance measuring program and a position measuring program executed by the device.

[0037]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to FIGS.

In these figures, 11 is a photodiode (infrared PD) that receives an infrared pulse from the transmitter,
Reference numeral 12 is an ultrasonic wave reception unit for receiving ultrasonic waves from a transmitter, 13
Is an input amplifier that amplifies received ultrasonic waves (amplitude), 14, 1
Reference numeral 4'is a first comparator for obtaining the magnitude relation between the output value of the input amplifier 13 and the "positive" threshold value, and 15 and 15 'is a first comparator for obtaining the magnitude relation between the output value of the input amplifier 13 and the "negative" threshold value. Two comparators, 141 and 151, are zero-cross comparators that determine the zero-crossing point immediately after the threshold detection timing in the received ultrasonic wave, and 142 and 152 are flip-flops, which are inverted by the outputs of the comparators 14 and 15 and output "H" level, 143. , 153 is an AND circuit using the outputs of the zero-cross comparators 141 and 151 and the flip-flops 142 and 152 as input signals,
Reference numerals 16 and 16 'are first timers that start the timing operation with the output of the infrared photodiode 11 and stop it with the output of the comparator 14, and 17 and 17' start the timing operation with the output of the infrared photodiode 11. Comparator 15
Second timer to stop this with the output of, 18 is timer 1
After calculating the approximate distances L1 and L2 from the transmitter to the receiver using the measurement time (ultrasonic wave propagation time) 6 and 17 and the sound velocity value, the correction processing described later for the approximate distance (FIG. 3, FIG. 5, see FIG. 15), a microcontroller having a function of outputting the original distance L,
Reference numeral 19 is an external memory, 20 is a reference distance information table that holds reference distances corresponding to respective waveform portions (first wave, second wave, third wave, ...) In half-wavelength units of ultrasonic waves, and 31 is displayed. Screen, 32 is an ultrasonic transmitter movably arranged on the display screen 31, 33 is a first ultrasonic receiver arranged at the upper left corner of the display screen 31, and 34 is an upper right corner of the display screen 31. The arranged second ultrasonic wave receivers 41 calculate and correct the distances between the ultrasonic wave transmitters 32 and the ultrasonic wave receivers 33 and 34 based on the ultrasonic wave transit time, and use the distance data to calculate the ultrasonic wave. The microcontroller 42 having a function of obtaining the position coordinates on the display screen 31 of the transmitter 32 displays reference distance information (distances A, B, C, D, E, etc.) and coordinate data of the ultrasonic receivers 33, 34. Show each external memory you have That.

FIG. 1 shows the relationship between the detectable distance of each waveform portion of the received ultrasonic wave, the utilized waveform portion and the correction amount (No. 1).
FIG. The circled numbers indicate the respective waveform portions of the received ultrasonic wave (first wave, second wave, third wave, fourth wave, ...).

FIG. 2 is an explanatory diagram showing the relationship between the ultrasonic wave reception waveform and the positive and negative threshold values. This received waveform shows the time change itself of the output of the receiver placed at a certain point. Circled numbers are waveform portions of the received ultrasonic waves, as in FIG.

The origin (distance 0) in FIG. 1 indicates the position of the ultrasonic oscillator. Further, although only the threshold value detection up to the fifth wave of the received ultrasonic wave is shown in the figure, it goes without saying that this is followed by the propagation time (distance) corresponding to the threshold value detection of each waveform portion after the sixth wave. .

Here, the distance A is the limit distance at which the first wave (positive polarity) of the received ultrasonic wave can be threshold-detected, and the distance B is the limit distance at which the second wave (negative polarity) of the received ultrasonic wave can be threshold detected. The distance C indicates the limit distance at which the third wave (positive polarity) of the received ultrasonic wave can be threshold-value detected.

Also, the distance D is the second threshold value of the received ultrasonic wave (negative polarity).
The reference distance / distance E for determining a wave is the threshold value detection portion of the received ultrasonic wave (positive polarity)
The reference distances for determining waves are shown.

Note that the distance A <the distance D <the distance B <the distance E <
It is the distance C, and these distance data are held in the reference distance information table 20 in advance.

The receiver located at the distance D from the transmitter can detect the waveform portion of the received ultrasonic wave after the second wave (negative polarity) by the threshold value, but for the first wave (positive polarity). Threshold cannot be detected.

The receiver located at a distance E from the transmitter can detect the waveform portion of the received ultrasonic wave after the third wave (positive polarity) by the threshold value, but the first wave (positive polarity). The threshold value cannot be detected for the second wave (negative polarity).

In the case shown in the figure, the wave used (for distance measurement) of the ultrasonic receiver located in the range from the origin to the distance D is the second wave, and located in the range from the distance D to the distance E. The used wave of the ultrasonic receiver is the third wave, and the used wave of the ultrasonic receiver located in the range from the distance E to the next reference distance is the fourth wave.

When the used waveform portion for distance measurement of the ultrasonic receiver is (1) the second wave, "λ / 2" is used as the correction amount for detecting the first wave, and (2) the third wave. If, first
“Λ” is used as the correction amount for wave detection, and (3) In the case of the fourth wave, “3λ / 2” is used as the correction amount for the first wave detection.
To use.

FIG. 3 is an explanatory diagram showing the configuration of the receiver side device.

Main differences from the receiver-side device of FIG. 16 are as follows: First and second comparators 14 and 15 for comparing the amplitude of received ultrasonic waves with positive and negative thresholds are provided. The microcontroller 18 executes the correction processing of the approximate distance LA obtained from the propagation time of the ultrasonic wave between the transmitter and the receiver, and creates the reference distance information table 20 in the external memory 19 to ensure the correction processing. Is.

FIG. 4 is an explanatory view showing a distance measurement processing procedure corresponding to FIG. 1, and the contents thereof are as follows.
The execution subject is the microcontroller 18. (s11) The measurement time T1 of the timer 16 and the measurement time T2 of the timer 17 are fetched, and the process proceeds to the next step. This measurement time indicates the ultrasonic wave propagation time. (s12) By multiplying each of T1 and T2 by the sound velocity value, an approximate distance L1 based on the threshold detection of the "positive polarity portion" of the received ultrasonic wave and an approximate distance L2 based on the threshold detection of the "negative polarity portion" of the received ultrasonic wave. And are calculated, and the process proceeds to the next step. (s13) It is determined whether or not "L2> distance D (see FIG. 1)" is established. If "Yes", the process proceeds to step (s15), and if "No", the process proceeds to the next step. Where "N
In the case of “o”, the second wave first exceeds the threshold value in the negative polarity portion of the received ultrasonic wave. (s14) The corrected distance L is obtained by "L = L2- [lambda] / 2". (s15) It is determined whether or not "L1> distance E (see FIG. 1)" is established. If "Yes", the process proceeds to step (s17), and if "No", the process proceeds to the next step. Where "N
In the case of “o”, the third wave first exceeds the threshold in the positive polarity portion of the received ultrasonic wave. (s16) The corrected distance L is obtained by "L = L1-λ". (s17) It is determined whether or not "L2> next reference distance" is established, and if "Yes", proceed to the corresponding step for L1. If "No", proceed to the next step. here,
In the case of “No”, the fourth wave first exceeds the threshold value in the negative polarity portion of the received ultrasonic wave. (s18) The corrected distance L is obtained by "L = L2-3? / 2".

In the case of "Yes" in step (s17), the contents of the processing thereafter are as follows: for L1 and L2, the magnitude relationship with the next reference distance is alternately compared, and steps (s16) and (s1)
It is to execute the same new correction as in 8). If this comparison process does not result in "No" even if it has been performed a predetermined number of times, it will be forced to end.

FIG. 5 shows the relationship between the detectable distance of each waveform portion of the received ultrasonic wave, the utilized waveform portion and the correction amount (part 2).
FIG.

The meanings of the distance A, the distance B, and the distance C as the threshold-detectable limit distances, the omission of the propagation time (distance) corresponding to the threshold detection of each waveform portion after the sixth wave, etc. , As in FIG.

On the other hand, the main differences from the case of FIG. 1 are as follows: Criteria for judging the distance A, the distance B, and the distance C for the used wave (for distance measurement) of the ultrasonic receiver It is also used as a distance.-The correction amount when the calculated approximate distance is less than the distance A is "0" .- The correction amount when the calculated approximate distance is the distance A or more and less than the distance B is "λ / 2", For example, the correction amount when the calculated approximate distance is greater than or equal to the distance B and less than the distance C is set to “λ”.

FIG. 6 is an explanatory diagram showing a distance measurement processing procedure corresponding to FIG. 5, and the contents thereof are as follows.
The execution subject is the microcontroller 18. (s21) The measurement time T1 of the timer 16 and the measurement time T2 of the timer 17 are fetched, and the process proceeds to the next step. (s22) By multiplying each of T1 and T2 by a sound velocity value, an approximate distance L1 based on the threshold detection of the "positive polarity portion" of the received ultrasonic wave and an approximate distance L2 based on the threshold detection of the "negative polarity portion" of the received ultrasonic wave. And are calculated, and the process proceeds to the next step. (s23) Judging whether "L1>L2" is established,
If "Yes", proceed to step (s25). If "No", proceed to next step. Here, "Yes" means
It is when the negative polarity portion of the received ultrasonic wave first exceeds the threshold value. (s24) Set "L = L1" and proceed to step (s26). (s25) Set "L = L2" and proceed to the next step. (s26) Judging whether or not “L> distance A” holds,
If "Yes", the process proceeds to step (s27), and if "NO", the series of processes ends. Here, "No" means
This is when the receiver detects the first wave of the ultrasonic wave with a threshold value, and the correction for the distance L (= L1) based on the first wave is not necessary (see FIG. 4). (s27) Judging whether “L> distance B” is established,
If "Yes", proceed to step (s29). If "No", proceed to next step. Here, “No” is when the receiver threshold-detects the second wave of the ultrasonic wave (the first wave cannot be threshold-detected) (see FIG. 4). (s28) The corrected distance L is obtained by "L = L-λ / 2". (s29) Judging whether “L> distance C” is established,
In the case of "Yes", the process shifts to a comparison process (not shown) between the L and the next reference distance, and in the case of "No", the process proceeds to the next step. Here, “No” is when the receiver threshold-detects the third wave of the ultrasonic wave (the first wave and the second wave cannot be detected by the threshold) (see FIG. 4). (s30) The corrected distance L is obtained by "L = L-λ".

In the case of "Yes" in step (s29), the subsequent processing contents are the same as those in steps (s28) and (s30) by alternately comparing L with the next reference distance. Correct correction. If this comparison process does not become "NO" even if it is performed a predetermined number of times, it will be forcibly terminated.

FIG. 7 is an explanatory view showing the outline of an ultrasonic wave transmitting / receiving unit for obtaining the position coordinates of an arbitrary point on the display screen.

This unit has at least the display screen 3
It is composed of one ultrasonic transmitter 32 and two ultrasonic receivers 33, 34 arranged in one, and has a function of obtaining the distance between the ultrasonic transmitter and each of the ultrasonic receivers.

An ultrasonic wave receiver may be used instead of the ultrasonic wave transmitter 32, and the ultrasonic wave transmitters may be provided at the respective positions of the ultrasonic wave receivers 33 and 34. In this case, the first transmitted ultrasonic wave and the second transmitted ultrasonic wave are frequency-divided or time-divided, for example, so that the ultrasonic wave receiver can discriminate the ultrasonic wave from each of the transmitters.

FIG. 8 is an explanatory view showing a receiver side device corresponding to FIG.

This position measuring device has two sets for individually obtaining the propagation times "T1, T2", "T3, T4" of ultrasonic waves from the ultrasonic transmitter 32 to the ultrasonic receivers 33, 34. Propagation time calculation means (see FIG. 2) -The distance between the ultrasonic transmitter 32 and the ultrasonic receivers 33 and 34 is calculated based on the ultrasonic propagation time (see FIGS. 4 and 6), and this distance data is calculated. Microcontroller 41 having a function of obtaining position coordinates on the display screen 31 of the ultrasonic transmitter 32 by using the reference distance information (distances A, B, C, D, E, etc.) and coordinate data described later (see FIG. 9). (Refer to FIG. 4) and the like.

Each set of timers 16 of the ultrasonic receiving unit,
Reference numerals 17 (16 ', 17') denote infrared detection diodes 11 and comparators 14, 15 (14 ', 1), respectively.
Based on the output of 5 '), the ultrasonic wave propagation times T1, T2 from the ultrasonic wave transmitter 32 to the own ultrasonic wave receivers 33, 34,
Time T3 and T4.

The micro controller 41 uses the time information T1, T2, T3, T4, etc. First of all, the distance measuring process of FIG. 3 and FIG. Distance r to 33, 34
1, r2 is calculated, and then the two-dimensional position coordinates of the ultrasonic transmitter 32 are obtained by the procedure (triangulation method) described later using the r1 and r2.

FIG. 9 is an explanatory view showing the positional relationship between the receiver and the transmitter on the display screen of FIG.

On the display screen 31, the origin is the lower left corner, the size is (m × n), the position coordinates of the receiver 33 fixed at the upper left corner of the display screen are (0, n), and the upper right corner of the display screen. The position coordinates of the receiver 34 fixed to the section are (m, n).

FIG. 10 is an explanatory diagram showing a procedure for calculating the position coordinates of the transmitter shown in FIG. 9, the contents of which are as follows. The execution subject is the microcontroller 41. (s41) The measurement times T1, T2, T3, T4 of the timers 16, 17, 16 ', 17' and the position coordinates of the receivers 33, 34 are fetched, and the process proceeds to the next step. (s42) Distance r from transmitter 32 to each receiver 33, 34
1, r2 are calculated by the same processing as the step (s12) in FIG. 3, and the process proceeds to the next step. (s43) An equation representing the first circle with radius r1 centered on the position coordinate (0, n) of the receiver 33 is obtained, and the process proceeds to the next step. (s44) An equation showing the second circle having a radius r2 centered on the position coordinate (m, n) of the receiver 34 is obtained, and the process proceeds to the next step. (s45) The solution between the equation indicating the first circle and the equation indicating the second circle is obtained and used as the position coordinate of the transmitter 32.

The formula of the circle in steps (s43) and (s44) may be expressed in a format such as xy coordinates or polar coordinates. For example, expression of a first circle is ^{"x 2 + (y-n)} 2 = r1 2 " or "x = r1 * cosθ, y = n + r1 * sinθ ".

In the process of step (s45), two solutions are usually obtained, and "0≤x≤a, 0≤y≤b" in them is obtained.
The one that satisfies the above is adopted as the position coordinate of the transmitter 32.

FIG. 11 is an explanatory diagram showing the rising time of the ultrasonic wave reception waveform.

Generally, the Q of the piezoelectric ceramic receiver is "20" or more, and the Q of the piezoelectric film receiver is around "3". Therefore, the rise time of the piezoelectric ceramic receiver is longer than that of the piezoelectric film receiver.

By using the ultrasonic wave receiver having a low Q in this way, the first wave of the ultrasonic wave can be discriminated from the noise to detect the threshold value.

FIG. 12 is an explanatory view showing a propagation time determining method using the zero cross points of the received ultrasonic waves.

Here, S1 is the first ultrasonic waveform, S2 is the second ultrasonic waveform whose amplitude is smaller than S1, and t1 is the first ultrasonic waveform.
Of the ultrasonic waveform S1 of the first exceeds the threshold, t2 is the time of the second ultrasonic waveform S2 of the first exceeds the threshold, and t3 is the next after the first and second ultrasonic waveforms exceed the threshold. The respective zero crossing points are shown.

As shown in the figure, the ultrasonic waveform S having different amplitudes
For 1 and S2, "t1-t"
2 ”deviation occurs.

Therefore, for the same transmission timing,
With the same threshold value, there is a difference in the ultrasonic wave propagation time between the time when the ultrasonic wave waveform S1 is received and the time when the ultrasonic wave waveform S2 is received, by the above-mentioned deviation. This difference inevitably means that the measured distance from the ultrasonic transmitter to the receiver (=
It causes an error of ultrasonic wave propagation time * sound velocity).

The method of determining the propagation time in FIG. 12 is for eliminating the error in the measurement distance. Ultrasonic wave S1
Paying attention to the fact that the zero crossing time t3 of S2 becomes the same regardless of the magnitude of each amplitude.
The next zero-crossing time point t3 that exceeds the predetermined threshold value is used to determine the timing when obtaining the ultrasonic wave propagation time.

That is, the time from the detection of the optical pulse indicating the start of ultrasonic wave transmission to the zero crossing time t3 is the ultrasonic wave propagation time (measurement time of the timer) T1,
As T2, the distance calculation process of FIGS. 3 and 5 is executed.

However, steps (s14), (s16), (s18), (s2)
8), (s30) In each distance correction process, the offset of only half wavelength is further reduced. In addition, the step (s
Even if "No" is returned in step 26), the offset is reduced.

The reason for this is that the zero-cross time point t3 is later than the ultrasonic wave detection time points t1 and t2 by an amount corresponding to about half a wavelength. When the ultrasonic wave detection time points t1 and t2 are the nth wave portion (n is a positive integer), the zero-crossing time point t3 is nothing but the start of reception of the next (n + 1) th wave.
A time difference of about half a wavelength occurs between t2 and t3.

FIG. 13 is an explanatory view showing the configuration of the receiver-side device having the ultrasonic wave propagation time determining function of FIG.

Compared to the receiver side device of FIG. 3, the newly added components are: a zero cross comparator which detects the zero level of the received ultrasonic waveform (the output of the input amplifier 3) and outputs the “H” level. 141, 151 ・ Inverted by the outputs of the comparators 14 and 15, "H"
Flip-flops 142, 152 that output a level A that uses the outputs of the zero-cross comparators 141, 151 and the flip-flops 142, 152 as input signals
ND circuits 143, 153, etc.

Here, the timers 16 and 17 start the time counting operation by detecting the optical pulse (time counting start signal) sent from the ultrasonic transmitter by the infrared PD 1.

At each point in time when the output waveform of the ultrasonic wave receiver 12 (input amplifier 13) exceeds the threshold value of each of the comparators 14 and 15, the comparator outputs a threshold value detection signal and the subsequent flip-flops 142 and 152, respectively.
Apply to.

The flip-flops 142 and 152 invert by the threshold detection signal and output "H" level. This "H" level is the AND circuit 143, 15
3 is applied.

When the AND circuits 143 and 153 are in the "H" level state, the zero cross comparator 1
The stop signals of the timers 16 and 17 are output at the timing when the outputs of 41 and 151 are applied, that is, at the next zero-cross timing when the received ultrasonic waveform exceeds the threshold value.

The timers 16 and 17 respectively hold the ultrasonic wave propagation times T1 and T2 from the time when the above-mentioned optical pulse (time measurement start signal) is detected to the time when the stop signal is output.

FIG. 14 is an explanatory diagram showing variations in the wavelength of the received ultrasonic waves. Since the amplitude of the ultrasonic wave on the leading side of the waveform gradually increases in the positive and negative directions as described above, the actual wavelength of each continuous waveform is generally "λ".
The values deviate from "/ 2" and vary from each other.

The actual wavelength (actual correction amount) of each portion of the first wave and the second wave shown in FIG. 9 (b) is deviated from "λ / 2". Of course, the actual correction amount b (= λ / 2 + β) of the second wave is longer than the actual correction amount a (= λ / 2 + α) of the first wave.

In the correction processing of FIGS. 3 and 5, "λ / 2,
By using the actual correction amounts a and b instead of λ ..., It is possible to measure the ultrasonic distance in consideration of such a wavelength shift.

FIG. 15 is an explanatory diagram showing the procedure for calculating the actual correction amount shown in FIG. 14, and the contents thereof are as follows.
Here, for convenience of explanation, the actual correction amount b when measuring the distance between the transmitter 32 and the receiver 33 of FIG. 7 is targeted.
The execution subject on the device side is a microcontroller or a timer. (s51) The specific position P is displayed on the display screen 31 of FIG.
The true distance LP between the receiver 33 and the position P is stored in the external memory 42 in advance. Also, the position P
Is a point in a range in which the second wave portion (negative polarity) and the third wave portion (positive polarity) of the received ultrasonic wave can be threshold-detected (the first wave portion cannot be threshold-detected). (s52) The user sets the transmitter 32 to the position P on the display screen 31 and performs an ultrasonic wave transmission operation. (s53) Time t21 at which the negative polarity portion of the received ultrasonic wave first exceeds the threshold value (time point for detecting the second wave threshold value) and time point at which the positive polarity portion of the ultrasonic wave first exceeds the threshold value (third wave threshold value detection) Time point) t31 is calculated. (s54) The actual correction amount (actual wavelength) b is calculated by calculating "b = (t31-t21) * v". v is the ultrasonic velocity. (s55) The second wave propagation distance LP 'of the received ultrasonic wave is calculated by calculating "(t21-t0) * v". t0 is the transmitter 32
It is the time of receiving the optical pulse sent from. (s56) The actual correction amount a is obtained by calculating "a = LP'-LP".

In this way, the nth wave of the received ultrasonic wave and the (n +) th wave are received.
1) If the receiver is placed at a position where both of the waves and the threshold value can be detected and the detection times of these waves are obtained, the actual wavelength (actual correction amount) between the two waves can be calculated.

Then, by using this actual correction amount, FIG.
By performing the distance correction processing in (1), it is possible to improve the accuracy of the measured distance between the ultrasonic transmitter and receiver.

(Supplementary Note 1) In the distance measuring device for calculating the distance between the transmitter and the receiver by using the propagation time of the ultrasonic wave from the transmitter to the receiver, the received waveform of the ultrasonic wave Of the propagation time based on the timing at which the magnitude of the threshold value exceeds the threshold value, or an approximate distance corresponding to the propagation time, and means for determining what part of the received waveform the timing is. Means for holding the reference information, which is composed of the reference propagation time of, or a reference distance corresponding to the reference propagation time, and the approximate information based on the size relation between the approximate information and the held reference information. A means for correcting and calculating the distance, the distance measuring apparatus using ultrasonic waves. (Supplementary Note 2) The means for obtaining the approximate information uses the zero crossing point next to the timing of the received waveform as the end of the propagation time, the distance measuring apparatus using ultrasonic waves according to Supplementary Note 1. . (Supplementary Note 3) The means for calculating the distance is configured to correct the approximate information, the timing of one portion of the positive polarity portion and the negative polarity portion of the received waveform and the timing of the other portion subsequent thereto. A distance measuring device using ultrasonic waves according to appendix 1 or 2, characterized in that difference information from timing is used. (Supplementary Note 4) The distance measuring device using ultrasonic waves according to Supplementary Notes 1 to 3, wherein a piezoelectric film sensor is used as the receiver. (Supplementary Note 5) One of the transmitter and the receiver is arranged at each of the first and second positions of known coordinates, and the other one is arranged at an arbitrary position. A position measuring device that specifies the other position coordinates by using the first and second propagation times of the ultrasonic wave and the known coordinates, based on the timing at which the size of the received waveform of the ultrasonic waves exceeds a threshold value. A means for obtaining rough estimation information comprising the first and second propagation times, or first and second rough distances corresponding to the propagation times; and what wave portion of the received waveform the timing is. A means for holding reference information, which comprises a reference propagation time for specifying, or a reference distance corresponding to the reference propagation time; and-based on the magnitude relation between the approximate information and the held reference information, Means for correcting the calculation information to calculate the first and second distances; -using the known coordinates and each of the calculated first and second distances, the other position coordinates are calculated. A position measuring device using ultrasonic waves, comprising: a means for specifying. (Supplementary Note 6) In a program for calculating a distance from a transmitter of an ultrasonic wave to a receiver, the program has a propagation time based on a timing at which the size of the received waveform of the ultrasonic wave exceeds a threshold value, or this propagation time. And an approximate information consisting of an approximate distance and a reference propagation time for specifying what part of the received waveform the timing is, or reference information consisting of a reference distance corresponding to the reference propagation time, and A distance measuring program for causing a computer to realize a function of correcting the approximate information and calculating the distance based on the magnitude relation of. (Supplementary Note 7) One of the transmitter and the receiver is arranged at each of the first and second positions of known coordinates, and the other position coordinate is specified while the other is arranged at an arbitrary position. In the program for
Approximate information consisting of the first and second propagation times based on the timing when the size of the received waveform of the ultrasonic wave exceeds a threshold value, or the first and second approximate distances corresponding to the propagation times, and the timing. Is composed of a reference propagation time for specifying what part of the received waveform is, or a reference distance corresponding to this reference propagation time, based on the magnitude relationship with the reference information, the approximate information is corrected to The first and second distances are calculated, and the known coordinates and the calculated first and second distances are calculated.
A position measuring program for causing a computer to realize a function of specifying the other position coordinate by using each of the second distances.

[0095]

As described above, according to the present invention, the approximate information regarding the distance from the transmitter to the receiver (the ultrasonic wave propagation time between the transmitter and the receiver and the approximate distance corresponding thereto) is obtained by the usual method. Since the correction processing based on the magnitude relation with the known reference information regarding the reception timing of the ultrasonic wave is executed for the rough estimation information, the measurement accuracy of the distance between the transmitter and the receiver can be achieved without complicating the distance measurement signal processing system. Can be increased.

Further, since the zero crossing point next to the threshold detection timing of the ultrasonic wave reception waveform is used as the end of the ultrasonic wave propagation time (approximate information) between the transmitter and the receiver, the ultrasonic wave when the amplitude of the ultrasonic wave reception waveform is different. It is possible to improve the accuracy of the propagation time calculation and improve the measurement accuracy of the distance between the transmitter and the receiver.

As the correction amount for the rough estimation information, the threshold value detection timing of the n-wave portion of the ultrasonic wave reception waveform and (n
+1) Since the actual difference information from the threshold detection timing of the wave portion is used, the accuracy of the approximate information correction when the actual wavelength of each waveform portion deviates from "λ / 2" and becomes a scattered value, It is possible to improve the measurement accuracy of the distance between the transmitter and the receiver.

In addition, for example, with the receiver placed at the first and second positions of known coordinates and the transmitter placed at an arbitrary position, the first and second distances between the transmitter and the receiver are set. After the approximate information on the first and second positions is calculated by a normal method, the approximate information is subjected to correction processing based on the magnitude relationship with known reference information regarding the reception timing of the ultrasonic waves. Since the position coordinates of the transmitter are specified by using the known coordinates of and the corrected first and second distances, for example, the transmitter is placed without complicating the distance measurement signal processing system. The position measurement accuracy can be improved.

Furthermore, since a piezoelectric film sensor having a low Q is used as the receiver, the first wave of the received ultrasonic wave can be threshold-detected in a form that is distinct from noise.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a relationship (part 1) between a detectable distance of each waveform portion of a received ultrasonic wave, a utilized waveform portion, and a correction amount according to the present invention.

FIG. 2 is an explanatory diagram showing a relationship between an ultrasonic wave reception waveform and positive and negative threshold values according to the present invention.

FIG. 3 is an explanatory diagram showing a configuration of a receiver-side device of the present invention.

FIG. 4 is an explanatory diagram showing a distance measurement processing procedure corresponding to FIG. 1 of the present invention.

FIG. 5 is an explanatory diagram showing a relationship (part 2) between a detectable distance of each waveform portion of a received ultrasonic wave, a utilized waveform portion, and a correction amount according to the present invention.

FIG. 6 is an explanatory diagram showing a distance measurement processing procedure corresponding to FIG. 5 of the present invention.

FIG. 7 is an explanatory diagram showing an outline of an ultrasonic transmission / reception unit for obtaining position coordinates of an arbitrary point on a display screen according to the present invention.

FIG. 8 is an explanatory diagram showing a receiver-side device corresponding to FIG. 7 of the present invention.

9 is an explanatory diagram showing a positional relationship between a receiver and a transmitter on the display screen of FIG. 7 according to the present invention.

10 is an explanatory diagram showing a procedure of calculating position coordinates of the transmitter of FIG. 9 according to the present invention.

FIG. 11 is an explanatory diagram showing the rising time of the ultrasonic reception waveform of the present invention.

FIG. 12 is an explanatory diagram showing a propagation time determination method using a zero-cross point of a received ultrasonic wave according to the present invention.

13 is an explanatory diagram showing the configuration of a receiver-side device having the ultrasonic propagation time determination function of FIG. 12 of the present invention.

FIG. 14 is an explanatory diagram showing variations in wavelength of received ultrasonic waves according to the present invention.

FIG. 15 is an explanatory diagram showing a procedure for calculating the actual correction amount of FIG. 14 according to the present invention.

FIG. 16 is an explanatory diagram showing a configuration of a general transmitter and receiver side device for distance measurement using ultrasonic waves.

FIG. 17 is an explanatory diagram showing a general ultrasonic reception waveform and reception detection pulse, in which the vertical axis represents the amplitude of the transmission / reception wave and the horizontal axis represents the passage of time.

FIG. 18 is an explanatory diagram showing a general time shift of a reception detection pulse depending on the distance between a transmitter and a receiver.

[Explanation of symbols]

11: Photodiode (infrared PD) 12: Ultrasonic wave receiver 13: Input amplifiers 14, 14 ': First comparators 15 and 15': "Positive" thresholds, Second comparators having "negative" thresholds 141, 151: Zero-cross comparators 142, 152: Flip-flops 143, 153: AND circuits 16, 16 ': First timer 17, 17': Second timer 18: Microcontroller 19 having distance calculation / correction function: External Memory 20: Reference distance information table 31: Display screen 32: Ultrasonic transmitter 33: Ultrasonic receiver 34: Ultrasonic receiver 41: Microcontroller 42 having distance calculation / correction function and position calculation function: External memory T1, T2, T3, T4: Ultrasonic propagation time between transmitter and receiver (timer operating time) L1, L2: Between transmitter and receiver based on T1, T2 Estimated distance L: Distance between transmitter and receiver after correction m, n: Size of display screen 31 r1: Distance between ultrasonic transmitter 32 and ultrasonic receiver 33 r2: Ultrasonic transmitter 32 and ultrasonic reception Distance from the device 34: first ultrasonic waveform S2: second ultrasonic waveform t1 whose amplitude is smaller than S1: time point at which the ultrasonic waveform S1 first exceeds the threshold value t2: ultrasonic waveform S2 reaches the threshold value first Time point t3: next zero-cross time point after the ultrasonic waveforms S1 and S2 exceed the threshold value a, b: actual distance correction amount t0: light pulse reception time point (timer operation start time point) t21: received ultrasonic wave (Second wave) threshold detection time t31: Reception ultrasonic wave (third wave) threshold detection time P: Specific point LP on display screen 31: True distance LP 'between receiver 33 and specific point P: Super reception Sound wave propagation distance 51: switch for ultrasonic wave transmission 52: drive for ultrasonic wave transmission Path 53: Ultrasonic wave transmission timer 54: LED drive circuit 55: Ultrasonic wave drive circuit 56: Infrared LED 57: Ultrasonic oscillator 61: Photodiode 62: Ultrasonic wave receiver 63: Input amplifier 64: Comparator 65: Ultrasonic wave Propagation time measuring timer 66: Microcontroller 71 with distance calculation function: Transmission pulse (optical reception pulse) 72, 72 ': Ultrasonic wave reception waveform 73, 73': Reception detection pulse

Continued front page    (72) Inventor Soichi Hama             4-1, Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa             No. 1 within Fujitsu Limited F term (reference) 5J083 AA04 AC07 AC28 AD01 AD04                       AE07 BA01 BE13 BE21 CB01

Claims (5)

[Claims] 1. A distance measuring device for calculating the distance between the transmitter and the receiver by using the propagation time of the ultrasonic wave from the transmitter to the receiver, the magnitude of the received waveform of the ultrasonic wave. Is a propagation time based on the timing of exceeding a threshold value, or means for obtaining approximate information, which is composed of an approximate distance corresponding to the propagation time, and a reference propagation time for specifying what part of the received waveform the timing is. , Or a means for holding reference information, which is composed of a reference distance corresponding to the reference propagation time, and the approximate information is corrected based on the size relationship between the approximate information and the held reference information. And a means for calculating the distance. 2. The means for obtaining the approximate information uses the zero crossing point next to the timing of the received waveform as the end of the propagation time.
A distance measuring device using the described ultrasonic waves. 3. From the transmitter to the receiver in a state where one of the transmitter and the receiver is arranged at the first and second positions of known coordinates and the other is arranged at an arbitrary position. In the position measuring device that specifies the other position coordinate by using the first and second propagation times of the ultrasonic wave and the known coordinate, based on the timing when the size of the received waveform of the ultrasonic wave exceeds the threshold value. A means for obtaining rough estimation information composed of the first and second propagation times or first and second rough distances corresponding to the propagation times; and specifying what wave portion of the received waveform the timing is. A reference propagation time for performing, or a means for holding reference information, which is composed of a reference distance corresponding to the reference propagation time, the rough estimate information, and the rough approximation based on the magnitude relation between the held reference information. The first and second information is corrected by correcting the information.
And means for calculating the distance, and means for specifying the other position coordinate by using the known coordinate and each of the calculated first and second distances. Position measuring device using ultrasonic waves. 4. A program for calculating the distance from a transmitter of an ultrasonic wave to a receiver, wherein the program is a propagation time based on a timing at which the magnitude of the received waveform of the ultrasonic wave exceeds a threshold value, or this propagation time. Approximate information consisting of an approximate distance corresponding to time, reference propagation time for specifying what wave portion of the received waveform the timing is, or reference information consisting of a reference distance corresponding to the reference propagation time A distance measuring program for causing a computer to realize a function of correcting the approximate information and calculating the distance based on the magnitude relationship with 5. A position coordinate of the other is specified in a state where one of the transmitter and the receiver is arranged at each of first and second positions of known coordinates and the other is arranged at an arbitrary position. In the program for performing the above, the program includes the first and second propagation times based on the timing at which the magnitude of the received waveform of the ultrasonic wave exceeds a threshold value, or the first and second approximate calculations corresponding to the propagation times. Approximate information consisting of a distance, and a reference propagation time for specifying what wave portion of the received waveform the timing is, or consisting of a reference distance corresponding to the reference propagation time, in relation to the reference information, Based on this, the approximate information is corrected to calculate the first and second distances, and the other position coordinates are calculated by using the known coordinates and the calculated first and second distances, respectively. specific A position measuring program for causing a computer to realize the function to perform.