KR102261686B1 - Ultrasonic Wave Distance Meter - Google Patents

Abstract

An ultrasonic rangefinder is disclosed. The ultrasonic rangefinder of the present invention includes: a transmission unit for transmitting a coded ultrasonic signal; a reception unit for receiving the coded ultrasonic signal after the transmission unit transmits the coded ultrasonic signal; and an operation unit for determining whether the coded ultrasonic signal received by the reception unit is a valid signal corresponding to the coded ultrasonic signal transmitted by the transmission unit, and operating a distance based on a time required for the reception unit to receive a valid ultrasonic signal after the transmission unit transmits the coded ultrasonic signal. According to the present invention, accurate distance measurement is possible by maximally preventing cross-talk even when ultrasonic measuring devices of the same type coexist within a distance which affects each other by using the coded ultrasonic signal.

Description

Ultrasonic Wave Distance Meter

The present invention relates to an ultrasonic range finder, and more particularly, to an ultrasonic range finder that can measure a precise distance by using a coded ultrasonic signal to prevent cross-talk as much as possible even when the ultrasonic measuring devices of the same type coexist within a distance that affects each other. it's about

Ultrasonic sensors are used for various purposes as industrial distance measuring tools. Specifically, the ultrasonic sensor is used as a means for recognizing and giving attention to surrounding objects, a means for determining whether an appropriate distance is maintained, and a means for determining the spatial location of an object, etc. The sensor of about 42 [KHz]) is mainly used.

The basic operating principle of the ultrasonic sensor is to measure the time of flight between transmission and reception by paying attention to the fact that the ultrasonic wave has a relatively constant speed when it travels through space, and to calculate the distance by reflecting this.

When the transmission time is measured with an accuracy of 0.2 [msec], the distance precision is about 6.8 [cm], which is suitable for measuring the spatial distance around an object moving at low speed. There is a limit in that it is difficult to use for the purpose of

On the other hand, conventional ultrasonic sensors transmit an ultrasonic signal of a certain length (8 cycles of signal frequency, about 200uSec) having a frequency of around 42 [KHz] (40 to 48 [KHz]) and directly receive it (unidirectional transmission and reception), When the reflected signal is received (two-way transmission and reception) and a signal of an appropriate size and length (time) is received, it operates in a manner that determines the distance from the target.

On the other hand, if an ultrasonic transceiver having the same characteristics is present in the vicinity, crosstalk may occur, which causes a malfunction such as a shortened measurement distance.

In particular, when an ultrasonic sensor is used as a distance recognition device for a target-following type robot such as a smart cart, multiple robots exist at a close distance where they can affect each other, which can cause confusion, and this can cause confusion. It has a huge impact on the , so a means to avoid it is needed.

1 is a diagram illustrating an example of a malfunction that occurs when an ultrasonic signal having the same length as a conventional ultrasonic sensor is used. As shown in FIG. 1 , when an ultrasonic signal having the same length (l) as that of an ultrasonic signal in a conventional ultrasonic sensor is used, the original time information to be measured is T1, but the time information T2, which is incorrect due to the recognition of an unwanted ultrasonic signal, is There is a problem in that it is measured and has a distance measurement error.

Accordingly, it is an object of the present invention to provide an ultrasonic rangefinder capable of precise distance measurement by maximally preventing crosstalk even when ultrasonic measuring instruments of the same type coexist within a distance that affects each other by using a coded ultrasonic signal.

Ultrasonic range finder according to the present invention for achieving the above object, a transmitter for transmitting a coded ultrasonic signal; a receiver configured to receive the coded ultrasonic signal after the transmitter transmits the coded ultrasonic signal; and determining whether the coded ultrasonic signal received by the receiver is a valid signal corresponding to the coded ultrasonic signal transmitted by the transmitter, and after the transmitter transmits the coded ultrasonic signal, the receiver transmits the effective ultrasonic signal and a calculating unit that calculates a distance based on the time required to receive .

Preferably, the coded ultrasound signal transmitted by the transmitter includes a main code, the first code and the last code in the main code are '1', and the remaining codes except for the first code and the last code have the same number of codes. It is characterized in that it consists of '0' and '1'.

In addition, when the sub-code, which is a code obtained by converting all or part of '0' included in the remaining codes in the main code into '1', is included in the coded ultrasound signal received by the receiver It is characterized in that the coded ultrasound signal received by the receiver is determined as a valid signal.

According to the present invention, accurate distance measurement is possible by maximally preventing cross-talk even when ultrasonic measuring instruments of the same type coexist within a distance that affects each other by using a coded ultrasonic signal.

1 is a view showing an example of a malfunction that occurs when using an ultrasonic signal having the same length as a conventional ultrasonic sensor;
2 is a view showing an example in which a malfunction can be avoided when using an ultrasonic signal having a length (L) longer than the length (l) of the ultrasonic signal in a conventional ultrasonic sensor;
3 is a view showing the maximum error occurrence situation that can occur when using an ultrasonic signal having a length (L) longer than the length (l) of the ultrasonic signal in a conventional ultrasonic sensor;
4 is a diagram illustrating a case in which two signals do not overlap each other as an example of a method of avoiding crosstalk with a normal ultrasound signal (1 bit) using an ultrasound signal (6 bits) coded into 6 bits according to an embodiment of the present invention; ,
5 is a diagram illustrating a case where two signals overlap as an example of a method of avoiding crosstalk with a normal ultrasound signal (1 bit) using a coded ultrasound signal (6 bits) according to an embodiment of the present invention;
6 is a view showing an example of a method of avoiding crosstalk with other coded ultrasound signals (6 bits) using a coded ultrasound signal (6 bits) according to an embodiment of the present invention;
7 is a table diagram showing a crosstalk state when the main code is '100111';
8 is a table diagram showing a state of confusion when the main code is '101011';
9 is a table diagram showing a crosstalk state when the main code is '101101';
10 is a table diagram showing a state of confusion when the main code is '110011';
11 is a table diagram showing a crosstalk state when the main code is '110101';
12 is a table diagram showing a crosstalk state when the main code is '111001';
13 is a table diagram showing an 8-bit main code and sub-code;
14 is a table diagram showing a case in which the main code is lagged while the 8-bit main code '10001111' is mixed with the code '11010101' causing the confusion;
15 is a table diagram showing a case in which the main code is leading among the crosstalk of the 8-bit main code '10001111'; and
16 is a functional block diagram illustrating the structure of an ultrasonic rangefinder according to an embodiment of the present invention.

Hereinafter, the present invention will be described in more detail with reference to the drawings. It should be noted that the same components in the drawings are denoted by the same reference numerals wherever possible. In addition, detailed descriptions of well-known functions and configurations that may unnecessarily obscure the gist of the present invention will be omitted.

FIG. 2 is a diagram illustrating an example in which a malfunction can be avoided when an ultrasonic signal having a length L longer than a length l of an ultrasonic signal in a conventional ultrasonic sensor is used.

Referring to FIG. 2, when an ultrasonic signal having a longer length (L) than that of a conventional ultrasonic sensor is used in carrying out the present invention, when receiving an ultrasonic signal of a shorter length (l) as in a conventional ultrasonic sensor Ultrasonic rangefinder 100 does not recognize this as reception of an effective signal, and determines that a valid signal is received only when a sufficiently long length (L) signal is received as in FIG. It is possible to prevent erroneous measurement that may be caused by an ultrasonic rangefinder installed nearby using the

However, even in this case, when an ultrasonic rangefinder installed adjacently also uses an ultrasonic signal having a long length (L), the problem of erroneous measurement still remains.

FIG. 3 is a diagram illustrating a maximum error occurrence situation that may occur when an ultrasonic signal having a length L longer than a length l of an ultrasonic signal in a conventional ultrasonic sensor is used.

As an ultrasound signal causing erroneous measurement as shown in FIG. 3 , when the measurement time interval L of the receiving target ultrasound signal starts at the end point of the measurement time interval l of the unwanted ultrasound signal, based on the initial signal detection time When the distance is calculated, as a result, the distance is calculated based on T2 instead of T1, so that a measurement error corresponding to the ultrasonic signal length l in a typical ultrasonic sensor may occur.

Accordingly, the present invention proposes a distance measurer 100 and a distance measuring method using a coded ultrasonic signal in order to more completely prevent crosstalk by adjacent ultrasonic distance measurers.

16 is a functional block diagram showing the structure of the ultrasonic range finder 100 according to an embodiment of the present invention. Referring to FIG. 16 , the ultrasonic range finder 100 according to an embodiment of the present invention includes a transmitter 110 , a receiver 130 , and a calculator 150 .

The transmitter 110 transmits the coded ultrasonic signal, the receiver 130 receives the coded ultrasonic signal after the transmitter 110 transmits the coded ultrasonic signal, and the calculator 150 receives the receiver 130 . It is determined whether one coded ultrasound signal is a valid signal corresponding to the coded ultrasound signal transmitted by the transmitter 110, and after the transmitter 110 transmits the coded ultrasound signal, the receiver 130 receives the effective ultrasound signal. The distance is calculated based on the time required to receive.

In addition, the coded ultrasound signal according to the present invention is defined as follows.

In each code constituting the time section of the coded ultrasound signal, '0' means a time section without an ultrasound signal, and '1' means a time section with an ultrasound signal.

'1' is used to indicate the start and end of the coded ultrasound signal. That is, a code having a value of '1' is used at the beginning and the end of the coded ultrasound signal.

In the coded ultrasound signal according to the present invention, a code excluding the first code (1) and the last code (1) is called a body code, and the number of '1' and '0' in this code is the same. The coded ultrasound signal in this case is called a main code.

On the other hand, codes in which '0' included in the main code is converted to '1' are referred to as sub codes (sub codes) of the corresponding main code.

For example, since the number of '1' and '0' in this code, which is a code except for the first code (1) and the last code (1) in the coded ultrasound signal '110011', is the same, the coded ultrasound signal '110011' becomes a main code, and this main code '110011' has '111011', '110111' and '111111' as sub codes.

On the other hand, the main code 110011 is a code generated by the transmitting unit 110, and the calculating unit 150 is not only when the receiving unit 130 receives the main code 110011, but also a sub code of the corresponding main code 110011 ( 111011, 110111, 111111), it is determined that a valid code such as the main code has been received.

Meanwhile, in the case of a main code having a total length of 6 bits, sub codes for each main code are arranged as shown in Table 1 below.

main code sub code 1 sub code 2 sub code 3 100111 110111 101111 111111 101011 111011 101111 111111 101101 111101 101111 111111 110011 111011 110111 111111 110101 111101 110111 111111 111001 111101 111011 111111

As shown in Table 1, although each main code is different from each other, even if the main codes are different from each other, the sub-codes for each main code partially overlap. In addition, as shown in Table 1 above, '111111' is included as a sub-code of all 6-bit main codes.

4 is a diagram illustrating a case in which two signals do not overlap each other as an example of a method of avoiding crosstalk with a normal ultrasound signal (1 bit) using an ultrasound signal (6 bits) coded into 6 bits according to an embodiment of the present invention; to be. Meanwhile, in the case of FIG. 4 , crosstalk with a normal ultrasound signal can be avoided in the same manner as in FIG. 2 .

5 is a diagram illustrating a case in which two signals overlap as an example of a method of avoiding crosstalk with a normal ultrasound signal (1 bit) using a coded ultrasound signal (6 bits) according to an embodiment of the present invention.

Referring to FIG. 5 , because of the normal ultrasound signal superimposed on the coded ultrasound signal (6 bits), the operation unit 150 reads the code originally to be read as '110011' as '111011'.

However, since '111011', which is the code read by the operation unit 150, is converted from '0' in the main code 110011 to '1' and corresponds to one of the sub codes of the corresponding main code 110011, the operation unit By processing this as that the valid code was received in the same way as the main code 110011 was received, 150 can obtain accurate reception time information without error.

6 is a diagram illustrating an example of a method of avoiding crosstalk with other coded ultrasound signals (6 bits) using a coded ultrasound signal (6 bits) according to an embodiment of the present invention.

In the case of FIG. 6, the entire code received through the receiver 130 becomes '10011110011',

In this case, the operation unit 150 receives the entire code in which the code matching '110011' [main code], which is the reception target ultrasound signal, '111011', '110111' or '111111' corresponding to the sub-code of the corresponding main code is received. It is determined whether '10011110011' is included, and as a result, it is confirmed that the 6-digit code (110011) at the back of the entire code '10011 110011' matches.

Accordingly, the operation unit 150 determines the start time of the corresponding 6-digit code 110011 as the reception time of the valid code, thereby making it possible to measure the distance without an error.

7 is a table diagram illustrating a crosstalk state when the main code is '100111'. In the table of FIG. 7, the subcode of the main code '100111' is listed in the first line, the code '101011' causing confusion with the main code '100111' is displayed in the third line, and the main code '100111' in the sixth line In the case of leading ', codes from the case where 1 bit overlapped to the case where all bits were overlapped are respectively indicated.

According to the present invention, in principle, even if the main code is worst affected by the code causing confusion, since '1' in the main code is not converted to '0', the main code is the leading code. In this case, the operation unit 150 can recognize the main code affected by the crosstalk code as a valid code.

On the other hand, in the tenth line of the table of FIG. 7, a case in which the main code, which is the detection target code, is lagged is indicated. In the case of overlapping 3 bits indicated in blue, the sub-code '101111' is recognized first. , has a time error of 3 bits compared to the original position of the main code.

In addition, in the 37th line of the table of FIG. 7, the case where the main code '100111' is delayed by 2 bits compared to the code '110101' causing confusion is indicated, and in this case, the main code '100111' is delayed by 4 bits compared to the original position of the main code. It can be seen that there is an error.

According to the above review, according to the present invention, it can be confirmed that, in most cases, when there is crosstalk between two ultrasonic rangefinders, distance measurement is possible without a relatively large error, and even if some error occurs in a specific case, it is within an acceptable range. .

Meanwhile, FIG. 8 is a table diagram illustrating a crosstalk state when the main code is '101011', FIG. 9 is a table diagram illustrating a crosstalk state when the main code is '101101', and FIG. ' is a table diagram showing a crosstalk state in the case of ', FIG. 11 is a table diagram illustrating a crosstalk state when the main code is '110101', and FIG. 12 is a table diagram illustrating a crosstalk state when the main code is '111001'. to be.

8 to 12 , it is confirmed that the maximum error is 4 bits, which is an acceptable degree, even when the main codes are cross-talked.

13 is a table diagram showing an 8-bit main code and a sub code. Referring to FIG. 13 , except for the '1's at the beginning and the end of the 8-bit main code, the main code in the 8-bit main code consists of three '0's and three '1's.

All main codes in the 8-bit main code are different from each other by 2 bits or more, and the sub codes in the 8-bit main code are a sub code having two '0's, a sub code having one '0' and a sub code having all '1's. separated by code.

On the other hand, of course, since the subcode having two '0's is closer to the main code than the subcode having one '0', it has higher reliability.

On the other hand, in the case of an 8-bit main code, when the operation unit 150 searches for a detection target code in the received code string, the main code is primarily the main code, the second sub code having two '0's, and the third '0' If one individual sub-code is searched in the order of the sub-codes that are all '1', the occurrence of measurement error can be reduced as much as possible.

Partially analyzing the case where the 8-bit main code '10001111' is lagging during the confusion with the code '11010101' causing the confusion, 3 bits, 4 bits, 5 bits, and 6 bits overlap It is confirmed that the error can be further reduced when the case calculating unit 150 detects a subcode having two '0's than when detecting a subcode having one '0' (blue).

On the other hand, when 3 bits overlap, when the operation unit 150 detects a subcode having one '0', an error of 5 bits occurs, and when detecting a subcode having two '0's, an error does not occur. can

As shown in FIG. 15 , as a result of partially analyzing a case in which the main code is leading among the crosstalk of the 8-bit main code '10001111', it can be confirmed that a meaningful error does not occur even in this case.

As described above, according to the present invention, by using the coded ultrasonic signal, even when ultrasonic measuring devices of the same type coexist within a distance that affects each other, cross-talk is prevented as much as possible, so that precise distance measurement is possible.

In addition, it can be seen that through this, it is possible to configure and operate a group of position trackers in which cross-talk between measuring instruments using a generalized low-cost ultrasonic sensor is suppressed to the maximum.

In addition, although the case of 8 bits is presented as an example in this specification, it should be said that it is within the scope of the present invention in the same context even when a code of more bits (10 bits or more) is used.

Terms used in the present invention are only used to describe specific embodiments and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present application, terms such as “comprise” or “have” are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, but one or more other features It should be understood that this does not preclude the existence or addition of numbers, steps, operations, components, parts, or combinations thereof.

In the above, preferred embodiments and applications of the present invention have been shown and described, but the present invention is not limited to the specific embodiments and applications described above, and the present invention is not limited to the scope of the present invention as claimed in the claims. Various modifications may be made by those skilled in the art to which this belongs, of course, and these modifications should not be individually understood from the technical spirit or prospect of the present invention.

100: ultrasonic range finder, 110: transmitter,
130: receiving unit, 150: calculating unit.

Claims (3)

In the ultrasonic rangefinder,
a transmitter for transmitting the coded ultrasound signal;
After the transmitter transmits the coded ultrasonic signal, the ultrasonic range finder and the receiver receive an ultrasonic signal in which the coded ultrasonic signal is superimposed with another coded ultrasonic signal from an ultrasonic range finder of the same type within a mutually influencing distance ; and
To prevent crosstalk caused by the ultrasonic rangefinder of the same kind, It is determined whether the superimposed ultrasound signal includes a valid code corresponding to the coded ultrasound signal, and the time required for the receiving unit to receive the valid code after the transmitting unit transmits the coded ultrasound signal Calculator that calculates distance based on
includes,
The first code and the last code in the coded ultrasound signal are '1', and the valid code is all or part of '0' included in the remaining codes except for the first code and the last code in the coded ultrasound signal. 1' is the converted code,
In each code constituting the time section of the coded ultrasound signal, '0' means a time section without an ultrasound signal and '1' means a time section with an ultrasound signal.
According to claim 1,
In the coded ultrasound signal, except for the first code and the last code, the remaining codes are composed of the same number of '0' and '1' ultrasonic rangefinder.
According to claim 1,
from the coded ultrasound signal and the homogeneous ultrasound rangefinder. When other coded ultrasound signals overlap, all or part of '0' included in the remaining codes except for the first code and the last code in the coded ultrasound signal is converted to '1'.

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