JP2007147654A - Flow line measuring system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flow line measuring system which can facilitate installation execution of fixing a transmitter device at a predetermined position, and can accurately carry out specifying of the coordinate position of a receiving device, in tracking the position of an object to be detected. <P>SOLUTION: The transmitter device 1 has a compression wave transmitter part 11 transmitting a compression wave intermittently, and is fixed to the predetermined position. The receiver device 2 has a compression wave receiver part 21 which receives the compression wave. A position operation part 24 finds the coordinate position of the transmitter device 1 at a local coordinate by using the compression wave which is received by the compression wave receiver part 21; then, the coordinate position is associated with the time of day, and the object to be detected is tracked. In calibration mode, the receiver device 2 is located at a reference position, whose coordinate position in a global coordinate is known. In the position operation part 24, the position of the transmitter device 1 in the global coordinate is computed. In an operation mode, using the position coordinate of the transmitter device 1 in the global coordinate and the local coordinate, the position of the receiver device 2 in the global coordinate is computed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a flow line measurement system that tracks the position of a detection target using an ultrasonic wave that periodically repeats a pressure change of a medium or a so-called pressure wave in which the pressure change of the medium is single. It is.

Conventionally, an ultrasonic pulse signal is transmitted from two transmitters (ultrasonic transmitters) fixed at a fixed position, and the ultrasonic pulse signal is received by a receiver (ultrasonic receiver) attached to a moving body. Therefore, a position detection system has been proposed in which the coordinate position of a moving body in a two-dimensional plane is obtained based on the propagation time of ultrasonic waves (see, for example, Patent Document 1).
JP-A-7-140241

  By the way, in order to specify the coordinate position of the receiving device, the coordinate position of the transmitting device must be specified. Therefore, it is necessary to accurately measure the coordinate position of the installation place when installing the transmission device, and there is a problem that it takes time to install the transmission device. In particular, the transmission device is often arranged at a high place such as a ceiling in order to take a wide detection area, and it is difficult to accurately measure and install the coordinate position in the high place work.

  The present invention has been made in view of the above-described reasons, and its purpose is to enable the accurate specification of the coordinate position of the transmission device while tracking the position of the detection target while facilitating the installation and installation of the transmission device. Is to provide a flow line measurement system.

  According to the first aspect of the present invention, there is provided a transmission device having a dense wave transmission unit that is arranged at a fixed position and intermittently transmits a dense wave, and a dense wave that is mounted on a position detection target and transmitted from the transmission device. The receiver detects the relative position of the detection target with respect to the transmission device by receiving the signal, and the flow line by tracking the path the detection target has moved by associating the relative position of the detection target detected by the reception device with the time. A receiving device that receives a sparse wave transmitted from the sparse / dense wave transmission unit and converts the received sparse / dense wave into a received signal that is an electrical signal. Transmission to the receiving device based on the time difference between the reception times of the dense / sparse waves by the receiving / receiving elements of the dense / sound receiving unit and the receiving / receiving units of the dense / sound receiving unit and the arrangement positions of the receiving elements. The relative position of the device is set to the receiving device. The local position calculation unit obtained in the local coordinates and the transmission in the local coordinates obtained by the local position calculation unit when the detection target is located at the reference position where the coordinate position in the global coordinate specifying the coordinate position of the receiving device is known The transmission position calculation unit that calculates the coordinate position of the transmission device in the global coordinates using the relative position of the device, the coordinate position of the reception device in the local coordinates obtained by the local position calculation unit, and the global coordinate obtained by the transmission position calculation unit And a global position calculation unit that calculates the coordinate position of the receiving apparatus in the global coordinates using the coordinate position of the transmitting apparatus.

  According to this configuration, in a state where the detection target is positioned at the reference position, by using the known coordinate position of the reference position in the global coordinates and the coordinate position of the transmission device in the local coordinates set in the reception device, The coordinate position of the transmission device in the global coordinates can be obtained. After obtaining the coordinate position of the transmission device in the global coordinates, the coordinate position of the transmission device in the local coordinates and the local coordinate position of the transmission device in the global coordinates are obtained by obtaining the coordinate position of the transmission device in the local coordinates. Using the coordinate position of the transmission device obtained in the coordinates, the coordinate position of the reception device in the global coordinates can be obtained.

  Further, since it is not necessary to know the global coordinates of the transmission device in advance, it is possible to obtain the coordinate position of the transmission device in the global coordinates simply by determining the reference position and positioning the detection target at the reference position. It is not necessary to measure the position of the transmission device at the time of installation construction, and the installation construction becomes easy. Furthermore, instead of obtaining the position of the receiving device using the distance of the receiving device to the two transmitting devices as in the conventional configuration, the receiving device uses an array sensor, so reception is performed using only one transmitting device. The position of the device can be specified, and as a result, the entire spatial area where the sparse and dense waves from the transmitter arrive can be used for detecting the position of the detection target, and the detection of the position of the detection target is realized in a wide spatial area can do.

  According to a second aspect of the present invention, in the first aspect of the invention, the transmission device includes a trigger transmission unit that transmits a trigger signal using electromagnetic waves simultaneously with the transmission of the dense wave from the dense wave transmission unit, and the reception device Is provided with a trigger receiving unit that receives a trigger signal transmitted from the trigger transmitting unit, and the local position calculating unit until the sparse wave receiving unit receives a sparse wave after the trigger receiving unit receives the trigger signal. Is converted into a distance to the detection target.

  According to this configuration, the reception device knows the time required for the sparse / dense wave to reach the reception device from the transmission device by measuring the time from reception of the trigger signal to reception of the sparse / dense wave. The distance to the transmitter can be determined using the known propagation velocity of the dense wave and the measured time. That is, the distance between the detection target equipped with the receiving device and the transmitting device can be obtained. As a result, the three-dimensional position of the transmission device (that is, the detection target) can be obtained from the arrival direction of the dense wave and the distance to the transmission device.

  In the invention of claim 3, in the invention of claim 1 or claim 2, the receiving device includes a direction sensor that detects a rotation angle of the coordinate axis of the local coordinate with respect to the coordinate axis of the global coordinate, and the global position calculation unit includes: The coordinate position of the receiving device in global coordinates is calculated in consideration of the rotation angle of the coordinate axis detected by the direction sensor.

  According to this configuration, the rotation angle of the local coordinate relative to the global coordinate can be obtained by providing a plurality of reference positions. In other words, even when the coordinate axis of the local coordinate set in the receiving device is rotated with respect to the coordinate axis of the global coordinate when the detection target is positioned at the reference position, the position of the receiving device is converted to the coordinate position of the global coordinate. be able to.

  According to a fourth aspect of the present invention, there is provided a flow line measurement system according to any one of the first to third aspects, wherein a plurality of the transmission devices are provided, and the dense wave from two or more transmission devices is received by the reception device. When there is a spatial region where signals can be received simultaneously, the reference position is set in the spatial region.

  According to this configuration, it is possible to obtain the coordinate position in the global coordinates for a plurality of transmission apparatuses only by positioning the detection target at one reference position, thereby reducing the burden of calibration work. In addition, the continuity of the coordinate position is maintained even when the transmission device that receives the dense wave is switched with the movement of the detection target.

  According to the configuration of the present invention, there is no need to know the global coordinates of the transmission device in advance, the reference position is determined, and the coordinate position of the transmission device in the global coordinates is obtained simply by positioning the detection target at the reference position. Therefore, there is no need to measure the position of the transmission device when the transmission device is installed, and there is an advantage that the installation operation becomes easy. Furthermore, since an array sensor is used for the receiving device, the position of the receiving device can be specified by using only one transmitting device, and the entire space area where the dense waves from the transmitting device reach can be detected. This has the advantage that it can be used for detection, and position detection of the detection target can be realized in a wide spatial region.

  In this embodiment, as shown in FIGS. 2 and 3, a moving body (for example, a shopping cart) that moves on the floor FL in a building is set as a detection target Ob for position detection, and the position where the detection target Ob has moved is set. The flow line measuring system to track is illustrated. In order to track the position of the detection target Ob, the transmitting device 1 that transmits a sparse / dense wave is installed at a fixed position of the ceiling surface CL above the floor surface FL, and the sparse wave is received on the upper surface of the detection target Ob. A wave receiving device 2 is mounted. In the present embodiment, a pressure wave in which a pressure change of the medium (air) occurs once as a dense wave is used.

  As shown in FIG. 1, the transmission device 1 includes a dense wave transmission unit 11 that transmits a dense wave, a trigger transmission unit 12 that transmits a wireless signal using electromagnetic waves (infrared rays or radio waves) as a transmission medium, and identification information transmission. Unit 13. The sparse / dense wave transmission unit 11, the trigger transmission unit 12, and the identification information transmission unit 13 operate in response to instructions from the control unit 10 via the drivers 14 to 16, respectively. The control unit 10 includes a one-chip microcomputer and includes a CPU, RAM, ROM, and serial communication interface. The sparse / dense wave transmission unit 11 intermittently transmits the sparse / dense wave, and the trigger transmission unit 12 simultaneously transmits the sparse / dense wave (actually, there is a time difference in instruction processing of the microcomputer) as a wireless signal as a trigger signal. (Hereinafter simply referred to as “trigger signal”). Further, the identification information transmitting unit 13 transmits a wireless signal including identification data (hereinafter referred to as “identification information signal”) following the trigger signal. The identification data is set in the control unit 10, and unique identification data is set for each receiving device 2. The control unit 10 controls the transmission timing of the density wave, the transmission timing of the trigger signal, and the transmission timing of the identification information signal. The density wave, the trigger signal, and the identification information signal are intermittently output at predetermined time intervals. The function of the receiving device 2 described above is realized by mounting an appropriate program on the one-chip microcomputer constituting the control unit 10.

  The receiver 2 includes a sparse wave receiver 21 that receives the sparse wave transmitted from the sparse wave transmitter 11 provided in the transmitter 1, and the sparse wave receiver 21 receives the sparse wave. A received signal that is an electrical signal is output. That is, the dense wave receiving unit 21 converts the dense wave into a received signal. In addition, the reception device 2 receives a trigger signal transmitted from the trigger transmission unit 12 provided in the transmission device 1 and an identification information reception that receives an identification information signal transmitted from the identification information transmission unit 13. Part 23. The trigger receiving unit 22 shapes the waveform of the trigger signal, and the identification information receiving unit 23 removes the carrier from the identification information signal. The output of the trigger receiving unit 22 instructs the timing for starting the operation of the receiving device, and activates the position calculating unit 24 and the timer unit 25 provided in the transmitting device 1. In addition, identification data including a pulse train output from the identification information receiving unit 23 is stored in the memory 26. The timer unit 25 also has a clock function for measuring the current time, and the time when the trigger signal is received by the trigger receiving unit 22 is stored in the memory 26.

  The position calculation unit 24 shifts from the standby state to the reception state when the output of the trigger reception unit 22 is generated, and uses the output of the dense wave reception unit 21 obtained in the reception state to transmit the transmission device 1 and the reception device 2. The position of is calculated. The reception state continues for a predetermined time.

The position of the transmission device 1 obtained by using the output of the sparse / dense wave reception unit 21 is a relative position of the transmission device 1 with respect to the reception device 2, and local coordinates X _L set in the reception device 2 as shown in FIG. -Y It is calculated | required as a coordinate position of _L. Here, in the present embodiment, the height from the floor surface FL to the ceiling surface CL is considered to be constant. Accordingly, since the height position of the receiving device 2 does not change in the space in which the detection target Ob moves, the local coordinates X _L -Y _L are handled as two-dimensional coordinates on the floor surface FL. As will be described later, the reception device 2 stores the coordinate position of the transmission device 1 in the global coordinates X _G -Y _{G, and} the transmission in the local coordinates X _L -Y _L using the output of the sparse wave reception unit 21. by determining the coordinate position of the device 1, it is to be able to determine the coordinate position of the receiving apparatus 2 in the global coordinate X _G -Y _G. The global coordinates X _G -Y _G are also considered as two-dimensional coordinates on the floor surface FL without considering the height.

In the present embodiment, the receiver 2 needs to be calibrated. At the time of calibration, the position calculator 24 uses the output of the sparse / dense wave receiver 21 in the local coordinates X _L -Y _L. obtains the coordinate position of the transmitting apparatus 1, the receiving apparatus 2 are positioned in the known coordinate positions in the global coordinate X _G -Y _G, the transmission apparatus 1 in the global coordinate X _G -Y _G using both coordinate position Find the coordinate position. Further, after obtaining the coordinate position of the transmitting device 1 in the global coordinate _X G -Y _G, by using the coordinate position of the transmitting device 1 of the local coordinate _X L -Y _L, global coordinates _X G -Y _G The coordinate position of the receiving device 2 can be obtained.

In other words, the receiving device 2 uses the coordinate position of the transmitting device 1 at the local coordinates X _L -Y _L to obtain the operation mode (calibration mode) for obtaining the coordinate position of the transmitting device 1 at the global coordinates X _G -Y _G. And an operation mode (operation mode) for obtaining the coordinate position of the receiving device 2 in the global coordinates X _G -Y _G. The position calculation unit 24 has a function of a local position calculation unit that obtains the coordinate position of the transmission device 1 in the local coordinates X _L -Y _L in both operation modes. Further, when in the operation mode, it functions as a global position calculation unit. Operations of the global position calculation unit and the local position calculation unit will be described later.

In the memory 26, the coordinate position of the receiving device 2 in the global coordinates X _G -Y _G obtained by the position calculation unit 24 and the time when the reception device 2 is located at the coordinate position (the trigger signal is received by the trigger reception unit 22). Time) and the identification data of the receiving device 2 are associated with each other and stored as one record. The data stored in the memory 26 is read as necessary by the control unit 20 and output to an external management device through the output unit 27. The control unit 20 includes a microcomputer as a main component, and includes a CPU, a RAM, a ROM, and a serial communication interface. The output unit 27 is an output interface, and adopts a serial interface such as TIA / EIA-232-E and USB, and a parallel interface such as SCSI. The detection result taken out from the output unit 27 is used in a separate management device. In this embodiment, the flow line is measured by tracking the path along which the detection target Ob has moved. Here, since the receiving device 2 is mounted on the detection target Ob, it is desirable to transmit the detection result extracted from the output unit 27 to the management device wirelessly.

  The configuration of each unit of the receiving device 2 will be described in more detail. The sparse / dense wave receiving unit 21 is an array sensor in which a plurality of receiving elements are arranged. In the position calculation unit 24, the time difference between the receiving times of the sparse and received waves by each receiving element and the arrangement position of the receiving elements are obtained. Based on this, the arrival direction of the density wave, that is, the direction in which the detection target Ob exists is obtained.

  In order to obtain the direction of arrival of the sparse / dense wave, information including the time difference between the reception times of the reception elements that have received the sparse / dense wave is required. After the / D converter 24a converts the received data that is a digital signal, the output corresponding to each receiving element is stored in the data storage unit 24b that temporarily stores the output. The sparse / dense wave receiving unit 21 always receives incoming sparse / dense waves, but the processing in the position calculation unit 24 is limited to a reception gate period that is a fixed time after the output of the trigger receiving unit 22 is obtained. The

  The reception data stored in the data storage unit 24b is read into the processing unit 24c after the reception gate period ends, and adjacent reception signals are obtained in order to obtain a time corresponding to the time difference between reception times at each reception element. The received data corresponding to the element is shifted by a predetermined time in the time axis direction and added. The processing unit 24c has a microcomputer as a main component.

This process will be briefly described. Now, it is assumed that the receiving elements 40 are arranged one-dimensionally at equal intervals on the same plane as shown in FIG. 4 (in practice, they are arranged two-dimensionally). ). When the angle of the wavefront of the ultrasonic wave with respect to the surface on which the wave receiving elements 40 are arranged is θ ₀ , the arrival direction of the dense wave is also θ ₀ . If the speed of sound is c and the arrangement pitch (intermediate distance) of the receiving elements 40 is L, the time difference ΔT ₀ when the wavefront of the dense wave whose arrival direction is θ ₀ reaches the adjacent receiving element 40 is , ΔT ₀ = L · sin θ ₀ / c. That is, θ ₀ = sin ⁻¹ (ΔT ₀ · c / L), and the arrival direction θ ₀ can be obtained by obtaining the time difference ΔT ₀ .

Based on the above relationship, if the received signal corresponding to the sparse / dense wave received by each receiving element 40 is delayed by the time difference ΔT ₀ corresponding to the arrival direction θ ₀ , the position of the received signal matches in the time axis direction. You can see that For example, received signals as shown in FIGS. 5A to 5C are output from three adjacent receiving elements 40, and the received signals output from adjacent receiving elements 40 have a time difference ΔT ₀ . Suppose you are. In this case, the reception signals obtained from the adjacent reception elements 40 are delayed by ΔT _{0 from} each other by appropriate delay means. That is, when the received signal in FIG. 5C is delayed by 2ΔT ₀ and the received signal in FIG. 5B is delayed by ΔT ₀ , both received signals are shown in FIG. 5A in the time axis direction. It matches the position of the received signal. If the received signals that are the outputs of the receiving elements 40 have the same position in the time axis direction, when these received signals are added, the addition result has a large amplitude. In other words, if the amplitude of the addition result is large, it can be said that the arrival direction θ ₀ of the density wave corresponds to the delay time ΔT ₀ .

In the present embodiment, the received signal is not shifted in the time axis direction, but the received data is shifted in the time axis direction. However, for the purpose of calculating the arrival direction θ ₀ , the difference is Absent. Therefore, the processing unit 24c adds the delay time to the received data stored in the data storage unit 24b after applying a plurality of preset delay times and adding the delay time, and the delay when the addition result is maximized. Ask for time. Since this delay time corresponds to the time difference ΔT ₀ , the arrival direction of the dense wave can be immediately obtained by associating the arrival direction θ ₀ with the delay time in advance. The delay time is set so that, for example, the arrival direction can be detected in increments of 5 degrees. As described above, the process of adding the received data after shifting the received data in the time axis direction is called a delay addition process. The delay addition process is realized by a program set in the processing unit 24c.

  Here, the trigger signal and the density wave are output almost simultaneously, and the trigger signal transmission from the trigger transmission unit 12 and the reception of the wireless signal at the trigger reception unit 22 can be regarded as substantially simultaneous. The time difference between the reception time of the trigger signal at the unit 22 and the reception time of the dense wave at the dense wave receiving unit 21 can be regarded as the time during which the dense wave propagates through the medium. Therefore, it is possible to know the relative distance of the transmission device 1 with respect to the reception device 2 based on the time from reception of the wireless signal to reception of the dense wave. That is, since the direction and distance of the transmission device 1 can be known, the reception device 2 can obtain the three-dimensional position of the transmission device 1. However, as described above, in this embodiment, the coordinate position in two-dimensional coordinates on the floor surface FL is obtained. That is, the two-dimensional coordinates on the floor surface FL can be obtained by using a known height dimension for the three-dimensional position. This calculation is performed in the processing unit 24c.

As described above, when the receiving device 2 receives the trigger signal from the transmitting device 1, the receiving device 2 waits for the received signal within the limit of the receiving gate period, and uses only the dense wave received within the receiving gate period. The arrival direction of the sparse / dense wave and the distance to the transmission device 1 are calculated, and the coordinate position in two-dimensional coordinates (local coordinates X _L −Y _L ) on the floor surface FL of the detection target Ob is obtained. The time at which the trigger signal is received and identification data corresponding to the trigger signal are stored in the memory 26.

  The capacity of the data storage unit 24b depends on the number of receiving elements 40, the receiving gate period, and the sampling period of the A / D converter 24a. For example, the receiving element 40 is eight elements, the sampling period of the A / D converter 24a is 1 μs, the receiving gate period is 30 ms (the distance to the receiving device 2 is within a range of about 10 m), and one data is one word. Therefore, if the resolution of the A / D converter 24a is 8 bits, a capacity of 30k words × 8 elements = 240k words is required. An SRAM having a capacity of 256 kbytes can be used with such a capacity.

The coordinate position of the transmission apparatus 1 at the local coordinates X _L -Y _L can be obtained by the processing described above. That is, a local position calculation unit for obtaining the coordinate position of the receiving device 2 at the local coordinates X _L -Y _L is configured by the data storage unit 24 b and the processing unit 24 c in the position calculation unit 24. On the other hand, in this embodiment, it is necessary to obtain the coordinate position of the transmission device 1 at the global coordinates X _G -Y _G , and therefore, the reference position where the coordinate position of the global coordinates X _G -Y _G is known as the detection target Ob. To be located.

Since the local position calculation unit of the receiving apparatus 2 can obtain the coordinate position of the transmitting apparatus 1 in the local coordinates X _L -Y _L , this coordinate position is assumed to be (X _L1 , Y _L1 ). Here, if the constraint condition that the directions of the coordinate axes of the global coordinates X _G -Y _G and the local coordinates X _L -Y _L coincide with each other is set, as shown in FIG. 6, the global coordinates X _G of the transmitting apparatus 1 are set. The coordinate position (X _G1 , Y _G1 ) in −Y _G, the coordinate position (X _L1 , Y _L1 ) in the local coordinates X _L -Y _L of the transmission apparatus 1, and the reception apparatus 2 in the global coordinates X _G -Y _G The relationship of X _G1 = X _R + X _L1 and Y _G1 = Y _R + Y _L1 is established between the coordinate positions (X _R , Y _R ). That is, when the receiving device 2 is located at the coordinate position (X _R , Y _R ), the global coordinate X _G is used by using the coordinate position (X _L1 , Y _L1 ) in the local coordinates X _L -Y _L of the transmission device 1. The coordinate position (X _G1 , Y _G1 ) of the transmission device 1 at −Y _G can be obtained. Conversely, if the coordinate position (X _G1 , Y _G1 ) in the global coordinates X _G -Y _G is known for the transmission device 1, the coordinate position (X _L1 , Y _L1 ) in the local coordinates X _L -Y _L is measured. Thus, the coordinate position (X _R , Y _R ) of the receiving device 2 in the global coordinates X _G -Y _G can be obtained.

  Here, since the position of the receiving device 2 with respect to the detection target Ob does not change, the following description will be made assuming that the position of the detection target Ob represents the position of the receiving device 2.

In order to obtain the coordinate position (X _R , Y _R ) of the receiving device 2 in the global coordinates X _G -Y _G , the position calculation unit 24 is set in the calibration mode, and the coordinate position of the transmitting device 1 in the global coordinates X _G -Y _G It is necessary to obtain (X _G1 , Y _G1 ). That is, the coordinate position of the global coordinates X _G -Y _G on the floor surface FL sets the reference position is known, while setting the position calculating unit 24 in the calibration mode, located at the reference position detection object Ob Let When the detection object Ob is positioned at the reference position, the coordinate position (X _R , Y _R ) of the receiving device 2 in the global coordinates X _G -Y _G is known, and the coordinates of the transmitting device 1 in the local coordinates X _L -Y _L Since the position (X _L1 , Y _L1 ) can be measured, the coordinate position (X _G1 , Y _G1 ) of the transmission device 1 in the global coordinates X _G -Y _G can be obtained.

The coordinate position (X _G1 , Y _G1 ) of the transmission device 1 in the global coordinates X _G -Y _G is stored in the coordinate conversion processing unit 24d and used for subsequent processing in the processing unit 24c. Further, the coordinate conversion processing unit 24d also is stored coordinate position of the reference position in the global coordinate X _G -Y _G. Therefore, the processing unit 24c and the coordinate conversion processing unit 24d function as a transmission position calculation unit in the calibration mode. Since the data stored in the coordinate conversion processing unit 24d is rarely changed, it is desirable to use a nonvolatile memory such as an EEPROM for the coordinate conversion processing unit 24d. The coordinate position of the reference position in the global coordinates X _G -Y _G is set by actual measurement. Since the measurement of the reference position is performed on the floor surface FL, the operation is easy.

Coordinate position of the transmitting device 1 in the global coordinate _{X G -Y G (X G1,} Y G1) after obtaining the the global coordinates _X G -Y receiving apparatus 2 coordinates at _G the position calculating unit 24 as the operation mode The position (X _R , Y _R ) can be determined. In the operation mode, the coordinate position (X _R , Y _R ) of the receiving device 2 is calculated by using the coordinate position (X _G1 , Y _G1 ) of the transmitting device 1 stored in the coordinate conversion processing unit 24d. That is, the processing unit 24c and the coordinate conversion processing unit 24d function as a global position calculation unit in the operation mode.

By the way, in the above description, the constraint condition that the orientation of the coordinate axes of the global coordinate X _G -Y _G and the local coordinate X _L -Y _L is the same is set. There are also restrictions on the movement of Therefore, in order to remove the above-described constraint conditions, in the present embodiment, a direction sensor 28 such as a gyro sensor is provided on the detection target Ob. The output of the direction sensor 28 is input to the processing unit 24c via the A / D converter 24e.

In the above-described operation, since the rotation angle of the local coordinates X _L -Y _L with respect to the global coordinates X _G -Y _G , that is, the direction of the detection target Ob is not taken into consideration, the unknown is 2, and as described above, one reference If two formulas are set for the position, the unknown can be obtained. On the other hand, when the rotation angle of the coordinate axes is taken into account, the rotation angle θ _R of the coordinate axes of the local coordinates X _L -Y _L with respect to the coordinate axes of the global coordinates X _G -Y _G must be obtained, so three unknowns (X _R , Y _R , θ _R ). That is, the unknown cannot be obtained by only two formulas obtained from one reference position Ps. Accordingly, there is provided a direction sensor 28 to determine the rotation angle theta _R.

Considering the rotation angle θ _{R of the} coordinate axis, as shown in FIG. 7, the coordinate position (X _G1 , Y _G1 ) in the global coordinates X _G -Y _G of the transmission apparatus 1 and the local coordinates X _L -Y of the transmission apparatus 1 coordinates in _L and _{(X L1, Y L1),} the coordinate position of the receiving apparatus 2 in the global coordinate _{X G -Y G (X R,} Y R) between the number 1 relationship is established.

A is an arithmetic expression even when considering the rotation angle theta _R are different only be similar to the above-described processing process. That is, the coordinate position (X _G1 , Y _G1 ) of the transmission device 1 at the global coordinates X _G -Y _G is obtained in the calibration mode and stored in the coordinate conversion processing unit 24d, and the global coordinates X _G -Y _G are obtained in the operation mode. When the coordinate position (X _R , Y _R ) of the receiving device 2 is obtained, the coordinate position (X _G1 , Y _G1 ) of the transmitting device 1 stored in the coordinate conversion processing unit 24d is used.

  By the way, as described above, the position of the transmission device 1 can be obtained by positioning the detection target Ob at the reference position. However, when a plurality of transmission devices 1 are provided, the reference position is determined for each transmission device 1. If each is set separately, it takes time to measure the reference position. Therefore, as shown in FIG. 8, when there is a spatial region in which dense waves from a plurality of transmission apparatuses 1 can be received simultaneously, it is desirable to set a reference position in the spatial region.

In this case, since one reference position can be shared by a plurality of transmitters 1, the coordinate position (in the global coordinates X _G -Y _G) of the plurality of transmitters 1 can be obtained without moving the receiver 2. X _G1 , Y _G1 ) can be obtained. That is, the coordinate positions (X _G1 , Y _G1 ) of the plurality of transmission apparatuses 1 can be obtained in a short time. Here, identification data is individually set for each transmission device 1, and the reception device 2 identifies each transmission device 1 by an identification information signal.

  By the way, although the ultrasonic transducer which consists of a piezoelectric element may be used for the transmission element which comprises the dense wave transmission part 11 in the transmitter 1, a piezoelectric element generally has a sharpness (Q value). Since it exceeds 100, the reverberation time is relatively long, and considering the reverberation time, the time interval for transmitting the dense wave becomes long. That is, when the detection target on which the receiving device 2 is mounted is a moving body, the position of the moving body cannot be measured finely.

  Therefore, it is desirable to use the transmission element 30 having the structure shown in FIG. In this transmission element 30, a heat insulating layer 32 made of a porous silicon layer is formed on one surface (upper surface in FIG. 9) side of a support substrate 31 made of a single crystal p-type silicon substrate. A heating element layer 33 made of a metal thin film (for example, a tungsten thin film) is formed, and a pair of electrode pads 34 electrically connected to the heating element layer 33 is formed on the one surface side of the support substrate 31. Yes. The planar shape of the support substrate 31 is rectangular, and the planar shape of the heat insulating layer 32 and the heating element layer 33 is also rectangular.

  The wave transmitting element 30 is of a thermal excitation type, and the heating element layer 33 is energized so that a temperature change occurs in the heating element layer 33 and the medium in contact with the heating element layer 33 is encouraged to expand and contract. Generate a wave. That is, by energizing between the electrode pads 34 at both ends of the heating element layer 33 to cause a temperature change in the heating element layer 33, a temperature change is caused in the air that is in contact with the heating element layer 33. The air in contact with the heating element layer 33 expands when the temperature of the heating element layer 33 rises and contracts when the temperature of the heating element layer 33 decreases. It is possible to generate a dense wave.

  Since a wave transmitting element made of a piezoelectric element has a high sharpness (Q value), even when a sparse wave is generated instantaneously, the piezoelectric element is also shown in FIG. 10B even after driving of the piezoelectric element is stopped. Thus, reverberation continues due to resonance. On the other hand, the thermally excited wave transmitting element 30 shown in FIG. 9 has a small sharpness and substantially does not have a resonance frequency. In the thermal excitation type wave transmitting element 30, as described above, a sparse wave is generated in accordance with a temperature change of the heating element layer 33 accompanying energization to the heating element layer 33 via the pair of electrode pads 34.

  That is, when the waveform of the drive voltage or drive current applied to the heating element layer 33 has a sine wave shape, a dense wave having a frequency twice that of the sine waveform can be generated. Therefore, if the waveform of the drive voltage applied to the electrode pad 34 is an isolated wave corresponding to a half cycle of a sine wave, a dense wave corresponding to one cycle of the sine waveform as shown in FIG. Can do. In addition, the reverberation time is very short because the thermal excitation type transmitting element 30 does not substantially have a resonance frequency. In addition, since the piezoelectric element has a specific resonance frequency, the frequency range of the density wave that can be generated is narrow. However, since the thermal excitation type transmission element 30 does not substantially have the resonance frequency, the frequency range of the density wave that can be generated. Becomes widespread. In addition, if the waveform of the drive voltage or drive current is an isolated wave, a sparse / dense wave of about one cycle can be generated as shown in FIG.

  In the thermal excitation type wave transmitting element 30 described above, a p-type silicon substrate is used as the support substrate 31, and the thermal insulating layer 32 is constituted by a porous silicon layer having a porosity of approximately 70%. The thermal insulating layer 32 can be formed by anodizing a part of a silicon substrate used as the support substrate 31 in an electrolytic solution made of a mixed solution of hydrogen fluoride aqueous solution and ethanol. Here, by appropriately setting conditions for anodizing treatment (for example, current density, energization time, etc.), the porosity and thickness of the porous silicon layer to be the heat insulating layer 32 can be set to desired values, respectively. .

It is known that the porous silicon layer has a lower thermal conductivity and heat capacity as the porosity increases. For example, a single crystal silicon substrate having a thermal conductivity of 148 W / (m · K) and a heat capacity of 1.63 × 106 J / (m ³ · K) is anodized to form a porous silicon layer having a porosity of 60%. When formed, this porous silicon layer has a thermal conductivity of 1 W / (m · K) and a heat capacity of 0.7 × 10 6 J / (m ³ · K). In the present embodiment, as described above, the heat insulating layer 32 is formed of a porous silicon layer having a porosity of approximately 70%, and the heat conductivity of the heat insulating layer 32 is 0.12 W / (m · K), The heat capacity is 0.5 × 10 6 J / (m ³ · K).

  The thermal insulation layer 32 is made smaller than the support substrate 31 in terms of thermal conductivity and heat capacity, and the product of thermal conductivity and thermal capacity is also made sufficiently smaller than the support substrate 31 in terms of the product of thermal conductivity and thermal capacity. The temperature change of the heat generating body layer 33 can be efficiently transmitted to the air, and heat can be efficiently exchanged between the heat generating body layer 33 and the air. In addition, since the support substrate 31 efficiently receives the heat from the heat insulating layer 32, the heat of the heat insulating layer 32 can be released and the heat from the heating element layer 33 is prevented from being accumulated in the heat insulating layer 32. Can do.

The heating element layer 33 is made of tungsten, which is a kind of refractory metal, and has a thermal conductivity of 174 W / (m · K) and a heat capacity of 2.5 × 10 6 J / (m ³ · K). . The material of the heating element layer 33 is not limited to tungsten, and for example, tantalum, molybdenum, iridium, or the like may be employed.

  In the thermal excitation type wave transmitting element 30 described above, the thickness of the support substrate 31 is 525 μm, the thickness of the thermal insulating layer 32 is 10 μm, the thickness of the heating element layer 33 is 50 nm, and the thickness of each electrode pad 34 is 0. .5 μm. However, these thicknesses are only examples, and are not intended to be particularly limited. Further, Si is adopted as the material of the support substrate 31, but the material of the support substrate 31 is not limited to Si, and for example, it can be made porous by anodizing treatment of Ge, SiC, GaP, GaAs, InP or the like. Other semiconductor materials may be used.

  By the way, the wave receiving element 40 used for the dense wave receiving unit 21 of the receiving device 2 receives the dense wave and converts the received dense wave into a received signal that is an electric signal. The wave section 21 is configured by arranging a plurality of receiving elements 40 on a single substrate (not shown). Here, it is assumed that an array sensor in which the wave receiving elements 40 are two-dimensionally arranged is configured. In the array sensor, the center-to-center distance (arrangement pitch) of the wave receiving elements 40 is set to about the wavelength of the density wave generated from the density wave transmission unit 11 (for example, about 0.5 to 5 times the wavelength of the density wave). It is desirable. This is because if the wavelength is smaller than 0.5 times the wavelength of the dense wave, the time difference between the times when the wave front of the dense wave reaches each of the adjacent receiving elements 40 becomes small, making it difficult to detect the time difference. Although a piezoelectric element can be used as the wave receiving element 40, a configuration with less reverberation is desirable as in the case of the dense wave transmission unit 11. Therefore, it is desirable to use a capacitive wave receiving element 40 that converts the pressure (sound pressure) of the density wave into a change in capacitance.

  This type of receiving element 40 has a configuration shown in FIG. A wave receiving element 40 shown in the figure is formed by a micromachining technique and has a rectangular frame-shaped frame 41 formed by providing a silicon substrate with a window hole 41a penetrating in the thickness direction, and a window hole on one surface side of the frame 41. And a cantilever type pressure receiving plate 42 which is fixed to one of the four sides surrounding 41a and is arranged to cover the window hole 41a. A silicon oxide film 46 is laminated on the one surface of the frame 41 via a thermal oxide film 45, and the surface of the silicon oxide film 46 is covered with a silicon nitride film 47. One end of the pressure receiving plate 42 is fixed to the frame 41 via the thermal oxide film 45, and the other end of the pressure receiving plate 42 faces the silicon oxide film 46 in the thickness direction of the silicon substrate. A fixed electrode 43a made of a metal thin film (for example, a chromium film) is formed on a surface of the silicon oxide film 46 facing the other end of the pressure receiving plate 42, and the other end of the pressure receiving plate 42 faces the fixed electrode 43a. A movable electrode 43b made of a metal thin film (for example, a chromium film) is formed on the back side of the surface facing the fixed electrode 43a. A silicon nitride film 48 is formed on the other surface of the frame 41. Here, the pressure receiving plate 42 is formed of a silicon nitride film formed in a separate process from the silicon nitride films 47 and 48.

  In the capacitive wave receiving element 40 shown in FIG. 11, when the pressure (sound pressure) of the dense wave acts on the pressure receiving plate 42, the distance between the fixed electrode 43a and the movable electrode 43b changes according to the pressure of the dense wave. Therefore, the pressure of the dense wave can be detected by detecting the capacitance between the fixed electrode 43a and the movable electrode 43b. Therefore, if a DC bias voltage is applied between the fixed electrode 43a and the movable electrode 43b, a voltage change corresponding to the pressure of the dense wave occurs between the fixed electrode 43a and the movable electrode 43b. Sound pressure can be converted into an electrical signal. Since this type of capacitive wave receiving element 40 has a sharpness smaller than that of the piezoelectric element, it is possible to widen the frequency bandwidth of the dense wave that can be received compared to the case where the piezoelectric element is used.

  The wave receiving element 40 is not limited to the structure shown in FIG. 11. For example, a movable electrode formed by processing a silicon substrate or the like by a micromachining technique or the like and including a diaphragm portion that receives the pressure of a dense wave, and a diaphragm You may employ | adopt the structure which detects the electrostatic capacitance between the fixed electrodes which consist of a backplate part which opposes a part. In this configuration, a spacer portion made of an insulating film that defines the gap length between the diaphragm portion and the back plate portion when the pressure of the dense wave is not applied is provided, and a plurality of exhaust holes are provided in the back plate portion. To do.

  The sharpness (Q value) of the thermal excitation type transmitting element 30 shown in FIG. 9 is about 1, and the sharpness of the capacitive type receiving element 40 shown in FIG. 11 is about 3-4. However, the sharpness is significantly smaller than that of the piezoelectric element. Therefore, as compared with the case where piezoelectric elements are used for the transmitting and receiving elements, the ratio of the reverberation component included in the dense wave transmitted from the dense wave transmitting unit 11 is reduced, and the density of the dense wave receiving unit 21 is reduced. The ratio of the reverberation component contained in the output received signal is reduced. In other words, the transmission interval of the sparse / dense wave can be shortened during transmission, and the received signal corresponding to the sparse / dense wave can be separated so as not to overlap even when the sparse / dense wave is received at a short time interval during reception. it can. As a result, it is possible to receive the dense waves from a plurality of transmitters 1 one after another, and even if a relatively large number of transmitters 1 exist in the detection area of the receiver 2, they are separated separately. Position. Note that the sharpness (Q value) of each of the transmitting element 30 and the receiving element 40 is desirably 10 or less, and desirably 5 or less.

It is a block diagram which shows embodiment. It is a schematic block diagram which shows the usage example same as the above. It is a schematic perspective view which shows the usage example same as the above. It is operation | movement explanatory drawing same as the above. It is operation | movement explanatory drawing same as the above. It is principle explanatory drawing same as the above. It is principle explanatory drawing in other operation | movement same as the above. It is a schematic block diagram which shows the usage example same as the above. It is sectional drawing which shows an example of the wave transmission element used for the same as the above. It is operation | movement explanatory drawing same as the above. An example of the wave receiving element used for the above is shown, (a) is a partially broken perspective view, and (b) is a sectional view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transmission apparatus 2 Reception apparatus 10 Control part 11 Density wave transmission part 12 Trigger transmission part 13 Identification information transmission part 20 Control part 21 Density wave reception part 22 Trigger reception part 23 Identification information reception part 24 Position calculation part 24a A / D Converter 24b Data storage unit (local position calculation unit)
24c processing unit (local position calculation unit, transmission position calculation unit, global position calculation unit)
24d Coordinate conversion processing unit (transmission position calculation unit, global position calculation unit)
24e A / D converter 28 Direction sensor 40 Receiving element

Claims (4)

  Transmitting by receiving a sparse wave transmitted from a transmitter mounted on a position detection target and a transmitter having a sparse wave transmitter that is arranged at a fixed position and intermittently transmits the sparse wave A receiving device that detects a relative position of the detection target with respect to the device, and a management device that measures a flow line by tracking a path along which the detection target moves by associating the relative position of the detection target detected by the receiving device with time The receiving device includes an array sensor in which a plurality of receiving elements that receive the dense wave transmitted from the dense wave transmission unit and convert the received dense wave into a received signal that is an electric signal are arranged. The relative position of the transmission device with respect to the reception device based on the time difference between the reception times of the dense waves by the reception devices of the dense wave reception unit and the reception devices of the dense wave reception unit and the arrangement positions of the reception devices At the local coordinates set to The relative position of the transmission device in the local coordinates obtained by the local position calculation unit when the detection target is located at a reference position where the coordinate position in the global coordinates specifying the coordinate position of the receiving device is known. The transmission position calculation unit that calculates the coordinate position of the transmission device in the global coordinates using the position, the coordinate position of the reception device in the local coordinates obtained by the local position calculation unit, and the transmission device in the global coordinates obtained by the transmission position calculation unit A flow line measurement system comprising: a global position calculation unit that calculates a coordinate position of a receiving device in global coordinates using a coordinate position.   The transmission device includes a trigger transmission unit that transmits a trigger signal using electromagnetic waves simultaneously with the transmission of the dense wave from the dense wave transmission unit, and the reception device receives the trigger signal transmitted from the trigger transmission unit. A trigger receiver, wherein the local position calculator converts a time from when the trigger receiver receives the trigger signal until the sparse wave receiver receives the sparse wave into a distance to the detection target. 2. The flow line measuring system according to claim 1, wherein   The reception device includes a direction sensor that detects a rotation angle of a coordinate axis of a local coordinate with respect to a coordinate axis of a global coordinate, and the global position calculation unit takes the rotation angle of the coordinate axis detected by the direction sensor into account for the reception in the global coordinate The flow line measurement system according to claim 1, wherein the coordinate position of the apparatus is calculated.   A flow line measurement system including a plurality of the transmission devices, wherein when there is a spatial region in which a dense wave from two or more transmission devices can be received simultaneously by the reception device, the reference in the spatial region The flow line measurement system according to claim 1, wherein a position is set.

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