JP2010071746A - Distance measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform stable measuring of a distance by suppressing influence of a reflective object even when the object exists around a sensor unit for performing measuring of a distance between two points by using an ultrasonic wave. <P>SOLUTION: The sensor unit includes an omnidirectional ultrasonic wave oscillator 100 for generating an ultrasonic wave signal in all the directions in a horizontal plane and ultrasonic wave receivers 101-106 for receiving the ultrasonic wave signal arriving from a specific direction in the horizontal plane. In a reflective object detection mode, the omnidirectional ultrasonic wave oscillator 100 is allowed to generate the ultrasonic wave signal. When the ultrasonic wave signal is received by one or more of the ultrasonic wave receivers 101-106 within a predetermined time period, a direction in which a reflective object exists is obtained on the basis of levels of signals received by the ultrasonic wave receivers. A reception sensitivity of a part of the ultrasonic wave receivers corresponding to the direction is controlled and is made to be lower than those of any other ultrasonic wave receivers. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a distance measuring apparatus that performs distance measurement using airborne ultrasonic waves.

  A device for distance measurement is installed at two points where the distance is to be measured, and the ultrasonic signal transmitted from one device is received by the other device, and the propagation time of the ultrasonic signal between the devices is A distance measuring method for obtaining a distance is known (for example, see Patent Documents 1 and 2). In such a distance measurement method, a technique is often employed in which transmission / reception timing of an ultrasonic signal is used between apparatuses using radio waves or infrared rays having a faster propagation speed in the air than ultrasonic waves (for example, Patent Documents). 1 and 2).

JP 2006-194707 A JP-A-1-88174

  In a distance measurement method that measures the propagation time of an ultrasonic signal between devices equipped with at least an ultrasonic signal receiver and transmitter, if there is a wall or the like in the vicinity of each device, the ultrasonic wave reflected by the wall or the like Stable measurement may not be possible due to the influence of In particular, in the case of an apparatus that transmits an ultrasonic signal in all directions on a predetermined plane, there is a high frequency of the presence of walls or the like around the apparatus, and the frequency of adverse effects of reflection by the walls or the like is also high.

  Therefore, an object of the present invention is to enable stable distance measurement even in the distance measurement apparatus for distance measurement using ultrasonic waves even if a wall or the like that reflects the ultrasonic waves is present in the vicinity thereof.

A distance measuring device according to the invention of claim 1
An omnidirectional ultrasonic transmitter for transmitting an ultrasonic signal in all directions in a predetermined plane, and a plurality of ultrasonic receivers for receiving an ultrasonic signal arriving from a specific direction in the predetermined plane And equipped with
When the ultrasonic signal is transmitted from the omnidirectional ultrasonic transmitter and the ultrasonic signal is received by one or more of the plurality of ultrasonic receivers within a predetermined time, the plurality of ultrasonic receivers Based on the received signal level, the direction in which the reflector exists is obtained, and the reception sensitivity of some of the plurality of ultrasonic receivers corresponding to the direction is set to the reception sensitivity of the other ultrasonic receivers. It is characterized by having an operation mode for performing control lower than the reception sensitivity.

A distance measuring device according to the invention of claim 2
An omnidirectional ultrasonic receiver for receiving ultrasonic signals coming from all directions in a predetermined plane, and a plurality of ultrasonic transmissions for transmitting ultrasonic signals in a specific direction on the predetermined plane And equipped with
By transmitting ultrasonic signals sequentially from the plurality of ultrasonic transmitters and checking whether or not the ultrasonic signals are received by the omnidirectional ultrasonic receiver within a predetermined time, the direction in which the reflector exists is determined. And having an operation mode for controlling the transmission power of some of the plurality of ultrasonic transmitters corresponding to the direction to be lower than the transmission power of the other ultrasonic transmitters. It is a feature.

A distance measuring device according to the invention of claim 3 is:
A plurality of ultrasonic transmitters for transmitting an ultrasonic signal toward a specific direction in a predetermined plane, and a plurality of ultrasonic receptions for receiving an ultrasonic signal arriving from a specific direction in the predetermined plane And equipped with
When the ultrasonic signals are simultaneously transmitted from all of the plurality of ultrasonic transmitters and the ultrasonic signals are received by one or more of the plurality of ultrasonic receivers within a predetermined time, the plurality of ultrasonic waves The direction in which the reflector exists is obtained based on the received signal level by the receiver, and the reception sensitivity of some of the plurality of ultrasonic receivers corresponding to the direction is set to the other ultrasonic wave. In addition to having an operation mode that performs control lower than the reception sensitivity of the receiver,
Presence of reflector by transmitting ultrasonic signals sequentially from the plurality of ultrasonic transmitters and checking whether the ultrasonic signals are received by any of the plurality of ultrasonic receivers within a predetermined time An operation mode for controlling to lower the transmission power of some of the plurality of ultrasonic transmitters corresponding to the direction from the transmission power of the other ultrasonic transmitters It is characterized by having.

  According to a fourth aspect of the present invention, a means for transmitting a radio signal and a means for receiving a radio signal are added to the distance measuring device according to any one of the first to third aspects.

  By installing the distance measuring device of the present invention at two points where the distance is to be measured, distance measurement using ultrasonic waves can be performed. Then, by operating the distance measuring device installed at one or both of the two points in the above operation mode prior to the distance measuring operation, there is a reflector such as a wall within a predetermined distance around the distance measuring device. However, since the reception sensitivity or the transmission power can be controlled so as to reduce the influence of the ultrasonic signal reflected by the reflector, stable distance measurement is possible.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the distance measuring device according to the present invention is referred to as a sensor unit.

[First embodiment]
As shown in FIG. 1 (plan view) and FIG. 2 (front view), the sensor unit according to the first embodiment of the present invention transmits an omnidirectional ultrasonic wave that transmits an ultrasonic signal in all directions on a horizontal plane. The six ultrasonic receivers (1) 101 to (6) 106 are provided in the horizontal plane and receive ultrasonic signals propagating from different directions in a horizontal plane within a predetermined directivity angle range. The sound wave transmitters 100 are arranged at equal angular intervals around the sound wave transmitter 100. The ultrasonic receivers 101 to 106 are arranged at a position lower than the omnidirectional ultrasonic transmitter 100 so as not to interfere with transmission of ultrasonic signals from the omnidirectional ultrasonic transmitter 100.

  FIG. 5 shows the directivity angle dependence (directivity characteristics) of the attenuation of the detection signals of the ultrasonic receivers 101 to 106. Since each of the ultrasonic receivers 101 to 106 has a diameter direction of a circle centering on the ultrasonic omnidirectional transmitter 100 and the center of the directivity angle is 60 °, there are six ultrasonic receivers 101 to 106. The entire ultrasonic receivers 101 to 106 can receive an omnidirectional ultrasonic signal with an attenuation of about several decibels in the horizontal plane. The omnidirectional ultrasonic transmitter 100 has a directivity characteristic as shown in FIG. 3 with respect to a horizontal plane, and has a directivity characteristic as shown in FIG. 4 with respect to a vertical plane.

  As shown in FIG. 2, the sensor unit includes a signal processing circuit unit 108 and an interface unit 109 under the printed circuit board 107 on which the omnidirectional ultrasonic oscillator 100 and the ultrasonic receivers 101 to 106 are mounted. (The interface unit 109 is omitted in FIG. 1). The sensor unit and an external personal computer (PC) are connected via the interface unit 109.

  The internal configuration of the signal processing circuit unit 108 is shown in FIG. In FIG. 6, 300 is a microcomputer, 301 is a transmission circuit for transmitting an ultrasonic signal from the omnidirectional ultrasonic oscillator 100 (electrical / ultrasonic transducer), and includes an FM modulation circuit. Reference numeral 302 denotes a reception circuit that amplifies and detects output signals (reception signals) of the ultrasonic receivers (ultrasound / electrical converters) 101 to 106. Including an FM detection circuit for detecting received signals. The input of the transmission circuit 301 is connected to the digital I / O interface of the microcomputer 300. The output of the receiving circuit 302 (both the output of the amplifier circuit and the output of the FM detection circuit) is connected to the A / D conversion interface of the microcomputer 300. A PC or the like connected to the interface unit 109 is connected to the communication interface of the microcomputer 300. The microcomputer 300 incorporates a program for operation as described later.

  This sensor unit has a transmission mode and a reception mode for distance measurement as its operation mode, but separately has a reflector detection mode. The operation of the sensor unit in the reflection object detection mode will be described with reference to the flowchart shown in FIG.

  A command is sent to the microcomputer 300 from a PC or the like connected to the sensor unit, and the sensor unit shifts to the reflector detection mode (step 400). The microcomputer 300 drives the transmission circuit 301 through the digital I / O interface, and transmits an ultrasonic signal from the omnidirectional ultrasonic transmitter 100 (step 401). This ultrasonic signal may be an unmodulated signal. The microcomputer 300 starts checking the reception signals (output signals of the amplification circuits inside the reception circuit) corresponding to the ultrasonic receivers 101 to 106 through the A / D conversion interface immediately after transmitting the ultrasonic signals. Then, it is monitored whether or not the ultrasonic signal transmitted in step 401 is received within a predetermined time (steps 402 and 403). Reflector that reflects an ultrasonic signal within a predetermined distance from the sensor unit when it is confirmed that an ultrasonic signal is received by any one or more ultrasonic receivers within a predetermined time (step 402, Y). And an ultrasonic signal reflected by the reflector and returned is received. In this case, the direction in which the reflector is present is calculated based on the reception signal level of the one or more ultrasonic receivers (step 404). Then, an ultrasonic receiver corresponding to the direction (in the case of distance measurement, an ultrasonic signal transmitted from another sensor unit is reflected by the reflecting object, and is highly likely to receive the reflected ultrasonic signal. The value of the reception sensitivity control parameter (reception coefficient) is determined and stored so that the reception sensitivity of the ultrasonic wave receiver is lower than the reception sensitivity of the other ultrasonic wave receivers (step 405). This completes the reflector detection mode.

  For example, it is assumed that the reception signal levels (levels converted by the A / D conversion interface) by the ultrasonic reception signals (1) 101 to (6) 106 are values as shown in FIG. In this case, it can be estimated that the direction in which the reflector is present is the direction facing the ultrasonic receiver (2) 102. In this case, considering the directivity of each ultrasonic receiver, the ultrasonic receivers (1), (2), and (3) are highly likely to receive the ultrasonic signal reflected by the reflector during distance measurement. Therefore, the value of the reception coefficient is determined and stored so that the reception sensitivity of these ultrasonic receivers is relatively lowered by the other ultrasonic receivers (4), (5), and (6). The reception coefficient value determined here is applied in the reception mode for distance measurement, and the default reception coefficient value is applied in the reflector detection mode.

  If no ultrasonic signal is received within a predetermined time (step 403, Y), this means that there is no reflector within a predetermined distance from the sensor unit. In this case, the reception coefficient of each ultrasonic receiver remains the default value.

[Second Embodiment]
The sensor unit according to the second embodiment of the present invention is configured as shown in FIG. 8 in addition to the configuration (FIGS. 1, 2 and 6) related to transmission / reception of ultrasonic signals similar to that of the first embodiment. In addition, an antenna 304 and a transmission circuit 305 for transmitting a radio signal, and an antenna 306 and a reception circuit 307 for receiving a radio signal are provided. The transmission circuit 305 includes an FM modulation circuit, and the reception circuit 307 includes an FM detection circuit. The output of the reception circuit 307 is connected to the A / D conversion interface of the microcomputer 300, and the input of the transmission circuit 301 is connected to the digital I / O interface of the microcomputer 300.

  The sensor unit of the present embodiment also has a transmission mode and a reception mode for distance measurement and a reflector detection mode as its operation mode. Since the operation in the reflector detection mode is the same as that in the first embodiment, the description will not be repeated.

[Third embodiment]
As shown in FIG. 9, the sensor unit according to the third embodiment of the present invention includes an omnidirectional ultrasonic generator 200 and six directional ultrasonic waves arranged at equal angular intervals so as to surround it. Transmitters (1) 201 to (6) 206 are provided. The ultrasonic transmitters 201 to 206 are located below the omnidirectional ultrasonic receiver 200. As described above, the relationship between the ultrasonic transmitter and the ultrasonic receiver is exactly reversed between the present embodiment and the first embodiment. The ultrasonic transmitters 201 to 206 have directivity characteristics as shown in FIG. The omnidirectional ultrasonic receiver 200 has directivity characteristics similar to those of the omnidirectional ultrasonic transmitter shown in FIGS.

  FIG. 11 shows the configuration of the signal processing circuit section of this sensor unit. The transmission circuit 301 and the reception circuit 302 are the same circuits as the corresponding circuits in FIGS.

  This sensor unit has a transmission mode and a reception mode for distance measurement, and a reflector detection mode as its operation mode. The operation of the sensor unit in the reflection object detection mode will be described with reference to the flowchart shown in FIG.

  A command is sent to the microcomputer 300 from a PC or the like connected to the sensor unit, and the sensor unit shifts to the reflector detection mode (step 410). The microcomputer 300 drives the transmission circuit 301 through the digital I / O interface and transmits an ultrasonic signal from one selected ultrasonic transmitter (initially, for example, the ultrasonic transmitter (1) 201) (step 411). . This ultrasonic signal may be an unmodulated signal. The microcomputer 300 starts checking the reception signal of the omnidirectional ultrasonic receiver 200 (the output signal of the amplification circuit inside the reception circuit 302) through the A / D conversion interface immediately after transmitting the ultrasonic signal, It is monitored whether or not the ultrasonic signal transmitted in step 411 is received within a predetermined time (steps 412 and 413). When it is confirmed that the ultrasonic signal has been received by the ultrasonic receiver within a predetermined time (step 412, Y), the ultrasonic signal that has been reflected and reflected by the reflector within a predetermined distance from the sensor unit is received. That is. The presence or absence of reception is temporarily stored in association with the transmitted ultrasonic transmitter. When reception of the ultrasonic signal is confirmed (step 412, Y), or when a predetermined time elapses without confirming reception of the ultrasonic signal (step 413, Y), another ultrasonic transmitter ( For example, the ultrasonic transmitter (2) 202) is selected (step 414). Then, the selected ultrasonic transmitter is transmitted (step 411), and whether or not an ultrasonic signal is received by the omnidirectional ultrasonic receiver 200 within a predetermined time immediately after that is monitored (steps 412 and 413). . The same operation is repeated while switching the ultrasonic transmitter.

  When the above operations are completed for all the ultrasonic transmitters (step 415, Y), the direction in which the reflecting object is present is calculated based on the reception presence / absence data stored in step 412 (step 416). Then, the transmission power of the ultrasonic transmitter corresponding to the calculated direction of the reflecting object (the transmitted ultrasonic signal is highly likely to be reflected by the reflecting object) is made relatively lower than other ultrasonic transmitters. Thus, the value of the transmission power control parameter (transmission coefficient) is determined and stored (step 417), and the reflector detection mode is terminated. In addition, when an ultrasonic signal is not received within a predetermined time when it is transmitted from any ultrasonic transmitter, it means that there is no reflector within a predetermined distance of the sensor unit. In this case, the transmission coefficient of each ultrasonic transmitter remains the default value.

  The transmission coefficient value determined here is applied in the transmission mode for distance measurement, and the default transmission coefficient value is applied in the reflector detection mode.

  As an example, consider a case where there is a reflector in the direction facing the ultrasonic transmitter (2). In this case, the reception signal level when the ultrasonic signal is transmitted from the ultrasonic transmitters (1) to (6) is the highest when the ultrasonic signal (2) is transmitted, The reception signal level when transmitting from the ultrasonic transmitter (1) or (3) is lower than that, but it is considered to have been received. However, when transmitted from the ultrasonic transmitter (4), (5) or (6), the received signal level is extremely low and is regarded as non-reception. Based on the relationship between the received signal levels, it can be easily estimated that the direction in which the reflecting object is present is the direction facing the ultrasonic transmitter (2). And since it is a case where it transmits from ultrasonic transmitter (1) (2) (3) that it is easy to receive to the influence of reflection by this reflector, the transmission power of these ultrasonic transmitters is transmitted to other ultrasonic transmitters. (4) The value of the transmission coefficient is determined and stored so as to be relatively lower than (5) and (6).

  In addition, it is also possible to add the transmission / reception means of the radio wave signal similar to the second embodiment to the sensor unit according to the present embodiment. Such a sensor unit is also included in the present invention.

[Fourth embodiment]
The sensor unit according to the fourth embodiment of the present invention includes an omnidirectional ultrasonic transmitter 100 according to the first embodiment and six ultrasonic transmitters (1) 201 to (6) according to the third embodiment. ) 206, and the side shape is shown in FIG. The six ultrasonic receivers (1) 101 to (6) 106 are mounted on the printed circuit board 107 side by side at equal angular intervals as shown in FIG. 1, and the six ultrasonic transmitters (1) 201 are mounted. To (6) 206 are mounted side by side at equal angular intervals as shown in FIG. 9 on another printed circuit board 110.

  FIG. 14 shows the configuration of the signal processing circuit unit 108 of this sensor unit. The transmission circuit 301 and the reception circuit 302 are the same circuits as the corresponding circuits in FIGS.

  This sensor unit has a transmission mode and a reception mode for distance measurement, and two reflector detection modes.

  The reflector detection mode of this sensor unit will be briefly described. The first reflector detection mode is the same as the reflector detection mode in the first embodiment shown in FIG. 7, and the values of the reception coefficients of the six ultrasonic receivers are determined and stored (however, By simultaneously transmitting ultrasonic signals from the six ultrasonic transmitters, the six ultrasonic transmitters are substantially operated as one omnidirectional ultrasonic transmitter). The second reflector detection mode is the same as the reflector detection mode in the third embodiment shown in FIG. 12, and the values of the transmission coefficients of the six ultrasonic transmitters are determined and stored ( However, the six ultrasonic receivers as a whole are treated as one omnidirectional ultrasonic receiver).

  In addition, it is also possible to add the transmission / reception means of the radio wave signal similar to the second embodiment to the sensor unit according to the present embodiment. Such a sensor unit is also included in the present invention.

[Distance measurement operation]
Next, distance measurement using the sensor unit of the present invention will be described. A sensor unit is installed at each of two points where the distance is to be measured. A PC is connected to each sensor unit.

[Distance measurement operation using only ultrasonic waves]
First, a case will be described in which two sensor units according to the first embodiment are installed at two points where the distance is to be measured, and the distance is measured using only ultrasonic waves. In this case, since each sensor unit operates in the reception mode when measuring the distance, each sensor unit is set to the reflecting object detection mode by a command from the PC prior to the distance measurement, and will be described with reference to FIG. The reflected object detection operation is executed.

  After finishing the reflector detection operation of both sensor units, the distance measurement operation is executed. In the distance measurement operation, when each sensor unit operates in the reception mode, the reception coefficient determined and stored in the reflector detection operation is applied, so that the reception sensitivity for the ultrasonic signal directly reaching from the other sensor unit is high. Since the reception sensitivity with respect to the ultrasonic signal that is reflected by the reflecting object in the vicinity is low, it is hardly affected by the presence of the reflecting object.

  Next, the distance measurement operation will be described with reference to the flowchart shown in FIG. One sensor unit (1) is set to the transmission mode by a command from the PC connected thereto (step 500), and the other sensor unit (2) is set to the reception mode by a command from the PC connected thereto. (Step 501).

  The microcomputer 300 of the sensor unit (1) set to the transmission mode encodes the ID of its own device (step 502) and applies the code to the transmission circuit 301 of the omnidirectional ultrasonic transmitter 100. (Step 503). The microcomputer of the sensor unit (1) starts the elapsed time by starting an internal timer (step 504), and applies the converted voltage pattern to the transmission circuit 301 of the omnidirectional ultrasonic transmitter 100. Then, an ultrasonic signal that is FM-modulated by the voltage pattern is transmitted from the omnidirectional ultrasonic transmitter 100 (step 506). After the transmission, the sensor unit (1) transitions to the reception mode (step 506).

  The microcomputer 300 of the sensor unit (2) set to the reception mode takes in the detection signals of the reception signals from the ultrasonic receivers (1) to (6) via the A / D conversion interface, and the sensor unit (1). Monitor the reception of ultrasonic signals from. That is, if a detection signal corresponding to a start bit (start signal) is detected within a predetermined time after the reception mode is set, it is determined that a signal is received (step 507, Y). The microcomputer 300 also takes in the reception signals from the ultrasonic receivers (1) to (6) via the A / D conversion interface, and applies the corresponding reception coefficient value to the level of the reception signals. The level after the reception sensitivity correction is performed is checked, one ultrasonic receiver having the highest level is selected, and only the detection signal of the reception signal by this ultrasonic receiver is subjected to reception monitoring. By doing in this way, it becomes difficult to receive the influence of the signal reflected by the reflector.

  If the start bit cannot be detected within the predetermined time (step 508, Y), the sensor unit (2) returns an error (1) to the connected PC (step 509) and ends the operation (distance measurement has failed). )

  When the start bit is detected (step 507, Y), the reception of the stop bit (end signal) is monitored (step 510). When the detection signal corresponding to the stop bit is detected within a predetermined time after detecting the start bit, it is determined that the signal reception is completed (step 510, Y). When the stop bit is not detected within the predetermined time (step 511, Y), an error (2) is returned to the PC (step 512), and the operation is terminated (distance measurement has failed).

  When the microcomputer of the sensor unit (2) determines that the signal reception is completed, it restores the received code from the start bit to the stop bit (step 513) and transitions to the transmission mode (step 514). Then, the restored code is converted into a voltage pattern to be applied to the transmission circuit 301 of the omnidirectional ultrasonic transmitter 100 (step 515), and this voltage pattern is applied to the transmission circuit 301, thereby omnidirectional ultrasonic transmission. The ultrasonic signal which is FM-modulated with the voltage pattern is transmitted from the device 100 (step 516), and the series of operations is completed.

  In the sensor unit (1) that has transitioned to the reception mode, the microcomputer 300 takes in the detection signals of the reception signals from the ultrasonic receivers (1) to (6) via the A / D conversion interface, and from the sensor unit (2). Monitor the reception of ultrasound signals. That is, if a detection signal corresponding to a start bit (start signal) is detected within a predetermined time after transition to the reception mode, it is determined that a signal is received (step 517, Y). The microcomputer 300 also receives reception signals from the ultrasonic receivers (1) to (6) via the A / D conversion interface, and applies reception coefficient values corresponding to the levels of the reception signals to correct reception sensitivity. The level after applying is checked, one ultrasonic receiver having the highest level is selected, and only the detection signal of the received signal by this ultrasonic receiver is the object of reception monitoring. By doing in this way, it becomes difficult to receive the influence of the signal reflected by the reflector.

  When the start bit cannot be detected within the predetermined time (step 518, Y), the sensor unit (1) returns an error (3) to the connected PC (step 501) and ends the operation (distance measurement has failed). )

  When a start bit is detected (Y in step 517), reception of a stop bit (end signal) is monitored (step 520). When the detection signal corresponding to the stop bit is detected within a predetermined time after the start bit is detected, it is determined that the signal reception is completed (step 520, Y). When the stop bit is not detected within the predetermined time (step 521, Y), the timer started in step 504 is stopped (step 522), an error (4) is returned to the PC (step 523), and the operation is terminated. (Distance measurement failed).

  On the other hand, when it is determined that the signal reception is completed (step 520, Y), the sign from the received start bit to the stop bit is restored (step 525), the timer started in step 504 is stopped, and the timer value, that is, the start The elapsed time is recorded (step 525), and the restored code is compared with the ID code encoded in step 502 (step 526). If the two codes match (step 526, Y), the sign and the elapsed time are output to the PC connected to the sensor unit (1) (step 528), and a series of operations are completed (distance measurement succeeded). That's what it means). If the codes do not match (step 526, N), an error (5) is returned to the PC (step 527), and the series of operations is terminated (distance measurement fails).

  In the example of distance measurement described so far, an ultrasonic signal as a cue is transmitted from the sensor unit (1), and an ultrasonic wave transmitted from the sensor unit (2) in response to the ultrasonic signal from this transmission point. A method of measuring the elapsed time until the signal is received by the sensor unit (1) is adopted. This method has an advantage that signals other than ultrasonic waves (signals such as radio waves and infrared rays) for timing are unnecessary. It has been described that the elapsed time is output from the sensor unit (1) to the PC. In this case, calculation for conversion from elapsed time to distance is performed on the PC side. However, this calculation can be performed by the sensor unit (1).

  Note that the same distance measurement can be performed using the sensor unit according to the fourth embodiment. In this case, at step 605, the ultrasonic signals are simultaneously transmitted from the six ultrasonic transmitters (the six ultrasonic transmitters are operated as one omnidirectional ultrasonic transmitter). Further, prior to the distance measurement, it is necessary to perform the reflector detection operation described with reference to FIG.

  It is also possible to use the sensor unit according to the third embodiment. In this case, prior to the distance detection operation, each sensor unit needs to execute the reflector detection operation described with reference to FIG. In the distance detection operation, in each sensor unit, in the transmission mode, ultrasonic signals are transmitted at intervals from the six ultrasonic transmitters in order. At this time, the transmission power is controlled by applying a transmission coefficient for each ultrasonic transmitter. Further, the ID for each ultrasonic detector is superimposed on the ultrasonic signal. In each sensor unit, the reception signal level of the ultrasonic signal is checked in the reception mode, one reception signal having the highest level is treated as valid, and the code is restored.

[Distance measurement operation using both ultrasonic waves and radio waves]
Next, in the case where two sensor units according to the second embodiment are installed at two points where the distance is to be measured, and the distance is measured using both ultrasonic waves and radio waves, the flowchart shown in FIG. Refer to and explain. In this case, only one sensor unit (1) that operates in the reception mode during distance measurement is set to the reflector detection mode by a command from the PC prior to the distance measurement operation, and has been described with reference to FIG. The reflector detection operation is executed.

  In the distance measurement operation, the sensor unit (1) installed at one point is set to the reception mode by a command from the PC connected to it (step 600), and the sensor unit (2) installed at the other point is connected to it. The transmission mode is set by a command from the PC (step 601).

  In the microcomputer 300 of the sensor unit (2) set in the transmission mode, the ID of the own device is encoded (step 602), and the code is converted into a voltage pattern to be applied to the transmission circuits 301 and 305 (step 603). ) By applying this voltage pattern to the transmission circuits 301 and 305, an ultrasonic signal and a radio wave signal that are FM-modulated by the voltage pattern are transmitted from the omnidirectional ultrasonic transmitter 100 and the transmitting antenna 304 (step 604). ). When this transmission is finished, the operation of the sensor unit (2) is finished.

  The microcomputer 300 of the sensor unit (1) set in the reception mode takes in the reception signal of the radio signal and its detection signal, the reception signal of the ultrasonic signal and its detection signal via the A / D conversion interface, and the sensor unit It can be checked whether or not the radio wave signal or ultrasonic signal transmitted from (2) has been received, and the code superimposed on the radio wave signal or ultrasonic signal can be restored from the detection signal.

  First, the microcomputer 300 of the sensor unit (1) monitors reception of radio wave signals (steps 605 and 606). When reception of a radio wave signal is detected (step 605, Y), a timer inside the microcomputer is started (step 607), and reception of an ultrasonic signal is monitored (steps 608 and 609). When reception of an ultrasonic signal is detected within a predetermined time (step 608, Y), the timer is stopped and the elapsed time from the timer start is recorded (step 611). And the code | symbol of a radio wave signal and the code | symbol of an ultrasonic signal are decompress | restored (step 612), these codes | symbols and elapsed time are output to PC (step 613), and operation | movement is complete | finished. The microcomputer checks the level after the reception sensitivity correction is performed by applying the corresponding reception coefficient value to the level of the received signal from each of the ultrasonic receivers (1) to (6). One ultrasonic receiver having the highest is selected, only the detection signal of the reception signal by this ultrasonic receiver is treated as effective, and the code is restored. By doing in this way, it becomes difficult to receive the influence of the long cold wave signal reflected by the reflector.

  When reception of an ultrasonic signal is not detected within a predetermined time (step 609, Y), an error is returned to the PC (step 610), and the process is terminated. When the reception mode is canceled by a command from the PC before the reception of the radio signal is detected (step 606, Y), the operation ends at that stage.

  In the sensor unit (1), both the sign of the radio signal and the sign of the ultrasonic signal are restored and output to the PC. On the PC side, both codes are compared, and if they do not match, it can be determined that there is a possibility that radio signal interference or erroneous reception of noise radio waves may have occurred. However, if there is no such concern, the code of the radio signal may not be restored, and in this case, an unmodulated radio signal may be transmitted on the sensor unit (2) side. Moreover, although calculation which converts elapsed time into distance is performed by PC side, it is also possible to make this calculation perform with a sensor unit (1).

[Example of distance measurement in the presence of reflective objects]
The embodiment of the present invention will be further described with reference to FIGS.

  FIG. 17 schematically shows a state in which the sensor units (1) and (2) are installed at two points where the distance is to be measured, as viewed from above. In this example, a wall exists as a reflector. As the sensor unit (1) (2), the sensor unit according to the second embodiment capable of transmitting / receiving ultrasonic signals and radio wave signals is used. Although not shown, a PC is connected to each sensor unit.

  Before the distance measurement, the sensor unit (1) is set to the reflecting object detection mode and executes the reflecting object detection operation shown in FIG. An ultrasonic signal is transmitted in all directions from the omnidirectional transmitter of the sensor unit (1), a part of the ultrasonic signal (T1_1) is directed to the wall, and a part (R1_1) is reflected on the wall and the sensor unit ( Return to 1).

  When the sensor unit (1) is placed so that the ultrasonic receiver (2) faces the wall, the reception signal levels of the reflected ultrasonic signals of the ultrasonic receivers (1) to (6) are For example, as shown in FIG. 18, the reception signal level of the ultrasonic receiver (2) is the highest, and the reception signal levels of the ultrasonic receivers (1) and (3) are smaller than that. The reception signal levels of the devices (4) to (6) are extremely small. From such a relationship of the received signal level, it can be seen that there is a reflector such as a wall in the direction of the ultrasonic receiver (2) within a predetermined distance of the sensor unit (1). Therefore, each ultrasonic reception is performed so that the reception sensitivity of the ultrasonic receivers (1) to (3) of the sensor unit (1) is relatively lower than the reception sensitivity of the ultrasonic receivers (4) to (6). The value of the reception coefficient of the device is determined and stored.

  In the sensor unit (1), the ultrasonic wave signal (T2_0) transmitted from the omnidirectional transmitter of the sensor unit (2) and reflected by the wall is applied by using the reception coefficient value determined in this way at the time of distance measurement. The reception sensitivity is lowered, and an ultrasonic signal (T2_1) transmitted from the omnidirectional transmitter of the sensor unit (2) and directly reaching the sensor unit (1) can be received with high sensitivity.

  Thereafter, the distance measurement operation of FIG. 16 is performed. As shown in FIG. 19A, the ultrasonic signal (T2_1) and the radio signal (E2_1) on which the encoded ID pattern is superimposed are simultaneously transmitted from the sensor unit (2). The sensor unit (1) measures the elapsed time (t) from the reception of the radio wave signal (E2_) to the reception of the ultrasonic signal (T2_1) as shown in FIG. 19 (b). This elapsed time can be converted into a distance between two points using the speed of sound.

  In addition, when a reflected object is detected, in the sensor unit (2), as shown in FIG. 20, by executing a process of receiving only the time Δt from the start of reception of the ultrasonic signal (T2_1), It is possible to reduce the influence of the reflected ultrasonic signal that arrives later than the directly arrived ultrasonic signal.

  Further, when a reflection is detected, the sensor unit (2) calculates the cross-correlation between the reception signal of the radio wave signal (E2_1) and the reception signal of the ultrasonic signal (T2_1) as shown in FIG. Thus, for example, the influence of noise such as a reflected wave superimposed on the ultrasonic signal can be reduced.

It is a schematic plan view of the sensor unit according to the first embodiment. It is a schematic front view of the sensor unit which concerns on a 1st Example. It is a figure which shows the directional characteristic in the horizontal surface of the omnidirectional ultrasonic transmitter in the sensor unit which concerns on a 1st Example. It is a figure which shows the directional characteristic in the vertical surface of the omnidirectional ultrasonic wave transmitter in the sensor unit which concerns on a 1st Example. It is a figure which shows the directional characteristic in the horizontal surface of the ultrasonic receiver in the sensor unit which concerns on a 1st Example. It is a block diagram which shows the structure of the signal processing circuit part of the sensor unit which concerns on a 1st Example. It is a flowchart for demonstrating the reflector detection operation | movement of the sensor unit which concerns on a 1st Example. It is a block diagram for demonstrating structures, such as a signal processing circuit part of the sensor unit which concerns on a 2nd Example. It is a schematic plan view of the sensor unit which concerns on a 3rd Example. It is a figure which shows the directional characteristic in the horizontal surface of the ultrasonic transmitter in the sensor unit which concerns on a 3rd Example. It is a block diagram which shows the structure of the signal processing circuit part of the sensor unit which concerns on a 3rd Example. It is a flowchart for demonstrating the reflector detection operation | movement of the sensor unit which concerns on a 3rd Example. It is a schematic front view of the sensor unit which concerns on a 4th Example. It is a block diagram which shows the structure of the signal processing circuit part of the sensor unit which concerns on a 4th Example. It is a flowchart for demonstrating the distance measurement operation | movement which uses only an ultrasonic signal. It is a flowchart for demonstrating the distance measurement operation | movement which uses an ultrasonic signal and an electromagnetic wave signal together. It is a schematic diagram for demonstrating distance measurement in case a reflector exists. It is a figure which shows the example of the received signal level by six ultrasonic receivers in a reflector detection operation | movement. It is a signal waveform diagram which shows the time relationship of the radio wave signal and ultrasonic signal which are transmitted from one sensor unit, and the radio wave signal and ultrasonic signal which are received by the other sensor unit. It is a signal waveform diagram for demonstrating the method to restrict | limit the reception period of an ultrasonic signal in order to eliminate the influence of a reflected signal. It is a signal waveform diagram for explaining a method of reducing a noise signal such as a reflected wave superimposed on an ultrasonic signal by taking a cross-correlation between the ultrasonic signal and a radio wave signal.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Omnidirectional ultrasonic transmitter 101-106 Ultrasonic receiver 200 Omnidirectional ultrasonic receiver 201-206 Ultrasonic transmitter 300 Microcomputer 301 Ultrasonic signal transmitting circuit 302 Ultrasonic signal receiving circuit 304 Radio wave signal Transmission antenna 305 Radio signal transmission circuit 306 Radio signal reception antenna 307 Radio signal reception circuit

Claims (4)

An omnidirectional ultrasonic transmitter for transmitting an ultrasonic signal in all directions in a predetermined plane, and a plurality of ultrasonic receivers for receiving an ultrasonic signal arriving from a specific direction in the predetermined plane And equipped with
When the ultrasonic signal is transmitted from the omnidirectional ultrasonic transmitter and the ultrasonic signal is received by one or more of the plurality of ultrasonic receivers within a predetermined time, the plurality of ultrasonic receivers Based on the received signal level, the direction in which the reflector exists is obtained, and the reception sensitivity of some of the plurality of ultrasonic receivers corresponding to the direction is set to the reception sensitivity of the other ultrasonic receivers. A distance measuring device having an operation mode in which control is performed to lower the receiving sensitivity. An omnidirectional ultrasonic receiver for receiving ultrasonic signals coming from all directions in a predetermined plane, and a plurality of ultrasonic transmissions for transmitting ultrasonic signals in a specific direction on the predetermined plane And equipped with
By transmitting ultrasonic signals sequentially from the plurality of ultrasonic transmitters and checking whether or not the ultrasonic signals are received by the omnidirectional ultrasonic receiver within a predetermined time, the direction in which the reflector exists is determined. And having an operation mode for controlling the transmission power of some of the plurality of ultrasonic transmitters corresponding to the direction to be lower than the transmission power of the other ultrasonic transmitters. Characteristic distance measuring device. A plurality of ultrasonic transmitters for transmitting an ultrasonic signal toward a specific direction in a predetermined plane, and a plurality of ultrasonic receptions for receiving an ultrasonic signal arriving from a specific direction in the predetermined plane And equipped with
When the ultrasonic signals are simultaneously transmitted from all of the plurality of ultrasonic transmitters and the ultrasonic signals are received by one or more of the plurality of ultrasonic receivers within a predetermined time, the plurality of ultrasonic waves The direction in which the reflector exists is obtained based on the received signal level by the receiver, and the reception sensitivity of some of the plurality of ultrasonic receivers corresponding to the direction is set to the other ultrasonic wave. In addition to having an operation mode that performs control lower than the reception sensitivity of the receiver,
Presence of reflector by transmitting ultrasonic signals sequentially from the plurality of ultrasonic transmitters and checking whether the ultrasonic signals are received by any of the plurality of ultrasonic receivers within a predetermined time An operation mode for controlling to lower the transmission power of some of the plurality of ultrasonic transmitters corresponding to the direction from the transmission power of the other ultrasonic transmitters A distance measuring device comprising:   4. The distance measuring device according to claim 1, further comprising means for transmitting a radio signal and means for receiving the radio signal.

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