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JP2008051655

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DESCRIPTION JP2008051655
An object of the present invention is to provide a position detection system that is easy to install,
can increase the utilization efficiency of ultrasonic waves, and can improve the accuracy of
position detection. SOLUTION: A transmitter 1 having an ultrasonic wave transmission unit 11
mounted on a moving object A to be detected and transmitting an ultrasonic wave, and ultrasonic
waves transmitted from the ultrasonic wave transmission unit 11 are received. And an ultrasonic
wave receiving apparatus 2 having an ultrasonic wave receiving unit 21 formed of an array
sensor in which a plurality of wave receiving elements for converting an ultrasonic wave received
together with an electric wave into an electric wave receiving signal are arranged on the same
substrate; Based on the time difference of the time when the ultrasonic wave was received by
each wave receiving element of the wave receiving section 21 and the arrangement position of
each wave receiving element, the direction in which the transmitting apparatus 1 exists is
determined for the receiving apparatus 2 2 calculating the distance between the transmitter 2
and the transmitter 1, and calculating the relative position of the transmitter 1 with respect to
the receiver 2. The directivity for adjusting the directivity of the ultrasonic wave transmitted
from the ultrasonic wave transmitter 11. And an adjusting unit 18. [Selected figure] Figure 1
Position detection system
[0001]
The present invention relates to a position detection system that detects the position information
of an object to be detected using ultrasonic waves.
[0002]
05-05-2019
1
Conventionally, transmitting devices (ultrasonic transmitters) provided for each of a plurality of
moving objects to be position detected, and at least three receiving devices (ultrasonic receivers)
installed for each predetermined area of a ceiling surface in a building Position detection system
has been proposed (e.g., for example), and arithmetic processing means for obtaining position
information of a moving object based on the time until ultrasonic waves transmitted from the
transmission apparatus are received by the reception apparatus (e.g. , Patent Documents 1 and
2).
In the position detection system disclosed in Patent Document 1, each receiving apparatus is
connected to a junction box by a two-wire signal line, and a computer forming part of the
arithmetic processing means and the junction box are separately provided. It is connected via a
signal line.
[0003]
In the position detection system disclosed in Patent Document 1 described above, the reception
device transmits a permission signal using infrared light as a medium to the transmission device,
and the transmission device transmits ultrasonic waves when the permission signal is received.
Therefore, in the above-mentioned position detection system, the distance to the transmitting
device can be calculated by measuring the time from the transmission of the permission signal to
the reception of the ultrasonic wave in the receiving device, and three receptions Since the device
calculates the distance to the transmitting device, the position of the transmitting device can be
determined based on the known positions of the three receiving devices.
[0004]
In addition, as a position detection system for detecting the position of a mobile object present in
a building, a first transmission device (ultrasound transmission device) and a second transmission
device (ultrasound transmission device), which are disposed apart from each other An ultrasonic
pulse signal intermittently transmitted from the first transmission device and an ultrasonic pulse
signal intermittently transmitted from the second transmission device; There has been proposed
a position detection system in which the position of a mobile object is determined by receiving
the signal by the reception device (for example, Patent Document 2). JP-A 2003-279640
(paragraphs [0012] to [0024], FIGS. 1 to 4) JP-A 7-140241 (paragraphs [0009] to [0022], FIGS.
1 to 6)
05-05-2019
2
[0005]
The position detection system disclosed in Patent Document 1 needs to install one reception
device for each predetermined area of the ceiling surface of the building, and the position
information of the object (moving object) whose position is to be detected by the arithmetic
processing means In order to obtain the above, it is necessary to install the receiving device in at
least three places, and the construction takes time. Moreover, in the above-mentioned position
detection system, only position information of an object present in the overlapping area of
detection areas of the three reception devices can be obtained, so the layout design of the
reception device is difficult, and the problem is that construction takes time. there were.
[0006]
Further, in the position detection system disclosed in Patent Document 1, it is necessary to lower
the directivity of the ultrasonic wave so that the ultrasonic wave transmitted from the transmitter
is received by each of the three receivers. However, it is necessary to widen the area of the
ultrasonic wave transmission wavefront of the transmitter, and the energy consumption in the
transmitter becomes high.
[0007]
Further, in the position detection system disclosed in Patent Document 2 described above, in
order to obtain position information of a moving object to be position detected, at least two
transmission devices of a first transmission device and a second transmission device are installed.
In order to synchronize the ultrasonic pulse signal intermittently transmitted from the first
transmitter and the ultrasonic pulse signal intermittently transmitted from the second
transmitter, a separate control means is required. The cost is high.
[0008]
Further, in the position detection system disclosed in Patent Document 2 above, it is necessary to
receive ultrasonic waves transmitted from two transmitting devices in one receiving device, and
the directivity of the ultrasonic waves is lowered. As a result, it is necessary to widen the area of
the ultrasonic wave transmission surface of the transmission apparatus, and the energy
consumption in the transmission apparatus becomes high.
[0009]
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3
Further, in the position detection systems disclosed in Patent Documents 1 and 2 above, even
when the moving space of the moving body is determined to a certain extent, the area from the
transmitting device to the unnecessary area is irrelevant to the moving space of the moving body.
Since the sound waves are transmitted, the utilization efficiency of the ultrasonic waves is
lowered.
Also, in the case where the moving space of the moving object is limited to a relatively narrow
space such as a passage separated by a wall, for example, the accuracy of position detection may
be degraded due to the influence of the reflected wave. was there.
[0010]
The present invention has been made in view of the above, and an object of the present invention
is position detection that is easy to install, can improve the utilization efficiency of ultrasonic
waves, and can improve the accuracy of position detection. To provide a system.
[0011]
According to the first aspect of the present invention, there is provided a transmitting device
having an ultrasonic wave transmitting unit mounted on a moving object to be position detected
and capable of generating ultrasonic waves, and receiving ultrasonic waves transmitted from the
ultrasonic wave transmitting unit. Receiving apparatus having an ultrasonic wave receiving unit
comprising an array sensor in which a plurality of wave receiving elements for converting
received ultrasonic waves into electric wave received signals are arranged on the same substrate,
ultrasonic wave receiving unit The direction in which the transmitting device exists is determined
for the receiving device based on the time difference of the time when the ultrasonic wave was
received by each of the receiving elements and the arrangement position of each receiving
element, and the distance between the receiving device and the transmitting device And a
directivity adjustment unit for adjusting the directivity of the ultrasonic wave transmitted from
the ultrasonic wave transmission unit.
[0012]
According to the present invention, the plurality of wave receiving elements for receiving the
ultrasonic waves transmitted from the ultrasonic wave transmitting unit and converting the
received ultrasonic waves into the electric wave receiving signals are received by the receiving
apparatus. It has an ultrasonic wave receiving part which consists of an array sensor arranged on
the same substrate, and the position operation part is the time difference of the time when the
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ultrasonic wave was received by each wave receiving element of the ultrasonic wave receiving
part and each wave receiving element Since the direction in which the transmitting device exists
is determined with respect to the receiving device based on the arrangement position of, the
distance between the receiving device and the transmitting device is determined, and the relative
position of the transmitting device with respect to the receiving device is determined. Since the
relative position of the transmitting device to the receiving device can be determined based on
the output of one receiving device, installation becomes easy, and the directivity of the ultrasonic
wave transmitted from the ultrasonic wave transmitting unit Because it has a directivity
adjustment unit to adjust the It is possible to enhance the utilization efficiency of the acoustic
waves, it is possible to increase the accuracy of position detection.
[0013]
According to the second aspect of the present invention, there is provided a transmitting
apparatus having an ultrasonic wave transmitting unit arranged at a fixed position and capable of
transmitting ultrasonic waves into the moving space of a moving object to be position detected;
Receiving an ultrasonic wave consisting of an array sensor in which a plurality of receiving
elements for receiving the ultrasonic waves transmitted from the unit and converting the
received ultrasonic waves into electric wave receiving signals are arranged on the same substrate
The time difference between the time when the ultrasonic wave was received by each of the
receiving elements of the ultrasonic wave receiving unit and the direction detecting means for
detecting the direction of the movable body in the plane parallel to the substrate, and the
receiving device having the wave portion Based on the arrangement position of the wave
receiving element and the direction of the moving body detected by the direction detecting
means, the direction in which the transmitting device exists is determined for the receiving
device, and the distance between the receiving device and the transmitting device is determined.
A position calculation unit for determining the relative position of the transmitter relative to
Characterized in that it comprises a directivity adjustment unit for adjusting the ultrasonic wave
directivity that is transmitting the sound wave transmitting unit.
[0014]
According to the present invention, the plurality of wave receiving elements for receiving the
ultrasonic waves transmitted from the ultrasonic wave transmitting unit and converting the
received ultrasonic waves into the electric wave receiving signals are received by the receiving
apparatus. It has an ultrasonic wave receiving part which consists of an array sensor arranged on
the same substrate, and the position operation part is the time difference of the time when the
ultrasonic wave was received by each wave receiving element of the ultrasonic wave receiving
part and each wave receiving element Since the direction in which the transmitting device exists
is determined with respect to the receiving device based on the arrangement position of, the
distance between the receiving device and the transmitting device is determined, and the relative
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position of the transmitting device with respect to the receiving device is determined. Since the
relative position of the transmitting device to the receiving device can be determined based on
the output of one receiving device, installation becomes easy, and the directivity of the ultrasonic
wave transmitted from the ultrasonic wave transmitting unit Because it has a directivity
adjustment unit to adjust the It is possible to enhance the utilization efficiency of the acoustic
waves, it is possible to increase the accuracy of position detection.
[0015]
The invention according to claim 3 is the invention according to claim 1 or 2, wherein the
transmission device has a trigger signal transmission unit for transmitting a trigger signal, and
the reception device receives a trigger signal. And the position calculating unit determines the
distance between the receiving device and the transmitting device from the relationship between
the time when the trigger signal is received by the trigger signal receiving unit and the time
when the ultrasonic wave is received by the wave receiving element. It is characterized by
[0016]
According to the present invention, the ultrasonic wave propagates from the transmitter to the
receiver by measuring the time from the reception of the trigger signal by the trigger signal
receiver to the reception of the ultrasonic wave by the wave receiving element. The required
propagation time can be known, and the distance between the receiver and the transmitter can
be determined using the propagation time and the known velocity of the ultrasonic wave.
[0017]
According to a fourth aspect of the present invention, in the first to third aspects, the directivity
adjusting section adjusts the directivity of the ultrasonic wave by changing the wavelength of the
ultrasonic wave generated by the ultrasonic wave transmitting section. It comprises the
wavelength adjustment means which
[0018]
According to this invention, the directivity of the ultrasonic wave can be adjusted by the
wavelength adjusting means for changing the wavelength of the ultrasonic wave generated by
the ultrasonic wave transmitting unit.
[0019]
According to the invention of claim 5, according to the invention of claims 1 to 3, the directivity
adjusting unit adjusts the directivity of the ultrasonic wave by changing the area of the ultrasonic
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wave transmitting wavefront of the ultrasonic wave transmitting unit. It is characterized by
comprising area adjustment means.
[0020]
According to this invention, the directivity of the ultrasonic wave can be adjusted by the area
adjusting means for changing the area of the ultrasonic wave transmitting wavefront of the
ultrasonic wave transmitting unit.
[0021]
According to the inventions of claims 1 and 2, there is an effect that the construction becomes
easy, the utilization efficiency of ultrasonic waves can be enhanced, and the accuracy of position
detection can be enhanced.
[0022]
Embodiment 1 In this embodiment, as a position detection system, as shown in FIG. 1A, a
movable body (for example, a shopping cart) in which an object whose position is to be detected
moves on a floor 100 in a building. A, the transmitter 1 having the ultrasonic wave transmission
unit 11 capable of intermittently transmitting ultrasonic waves is mounted on the upper surface
of the mobile unit A, while the ultrasonic wave transmission unit 11 intermittently transmits
waves. The receiving device 2 having the ultrasonic wave receiving unit 21 for receiving the
ultrasonic waves is installed at a fixed position on the ceiling surface 200, which is a construction
surface, and tracking the movement situation of the moving body A Flow line measurement
system.
[0023]
The transmission device 1 includes the ultrasonic wave transmission unit 11 described above, a
driver 12 for driving the ultrasonic wave transmission unit 11, a trigger signal transmission unit
13 for transmitting a trigger signal consisting of light or radio waves, and a trigger signal
transmission unit A driver 14 for driving 13, an identification information signal transmission
unit 15 for transmitting a unique identification information signal, a driver 16 for driving the
identification information signal transmission unit 15, and a control unit 17 for controlling the
respective drivers 12, 14 and 16 And have.
Here, the transmission start timing of the ultrasonic wave transmission from ultrasonic
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transmission unit 11, the transmission start timing of the trigger signal from trigger signal
transmission unit 13, and the transmission timing of the identification information signal from
identification information signal transmission unit 15 are controlled. It is controlled by the unit
17.
The control unit 17 mainly includes a microcomputer, and the functions of the control unit 17
described above are realized by installing an appropriate program in the microcomputer.
[0024]
On the other hand, the receiving device 2 receives the above-mentioned ultrasonic wave
receiving unit 21, the trigger signal receiving unit 23 that outputs a trigger reception signal
when the trigger signal transmitted from the trigger signal transmission unit 13 is received, and
identification information signal transmission Using the identification information signal
receiving unit 25 for receiving the identification information signal transmitted from the unit 15,
the received wave signal output from the ultrasonic wave receiving unit 21, and the trigger
received signal output from the trigger signal receiving unit 23 The position reception unit 22
for obtaining the position of the transmission device 1 in global coordinates consisting of
orthogonal coordinates set in the space in which the mobile unit A moves, and the clock function
to clock the current time, trigger reception signal from the trigger signal reception unit 23 When
the timer 26 for outputting the time when it receives (hereinafter referred to as the trigger
reception time), the position of the transmission device 1 determined by the position calculation
unit 22 and the transmission device 1 at that position Time (the trigger receiving time output
from the timer 26), and a memory 24 for time series stored in association with identification data
of the identification information signal of the transmitter 1.
[0025]
Here, the position of the transmitter 1 determined by using the output from the ultrasonic wave
receiver 21 and the output of the trigger signal receiver 23 in the position calculator 22 is a
relative position with respect to the receiver 2, as shown in FIG. As shown, it is determined as the
coordinate position of the orthogonal coordinates (local coordinates XL-YL) set in the receiving
device 2.
Here, in the present embodiment, the height from the floor surface 100 to the ceiling surface
200 is considered to be constant.
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8
Therefore, since the height position of the transmitter 1 does not change in the moving space of
the mobile A, the local coordinate XL-YL set in the receiver 2 is treated as a two-dimensional
coordinate on the floor 100, and the mobile A The global coordinates XG-YG set in the space to
move are also considered as two-dimensional coordinates on the floor surface 100 without
considering the height.
To explain further, the position calculation unit 22 uses the output from the ultrasonic wave
reception unit 21 and the output of the trigger signal reception unit 23 to transmit at the local
coordinates XL-YL composed of orthogonal coordinates set in the reception device 2 The
coordinate position of the device 1 is determined, and the coordinate position of the transmitting
device 1 at the global coordinate XG-YG is based on the coordinate position of the receiving
device 2 at the global coordinate XG-YG and the coordinate position of the transmitting device 1
at the local coordinate XL-YL. It is configured to ask for.
This configuration will be described later.
[0026]
In the position detection system of the present embodiment, calibration of the receiving device 2
is necessary, and at the time of calibration, the position calculating unit 22 outputs the output of
the ultrasonic wave receiving unit 21 and the output of the trigger signal receiving unit 23. The
coordinate position of the transmitter 1 at the local coordinate XL-YL is determined using the
two coordinate positions when the transmitter 1 is located at a known coordinate position
(reference position) at the global coordinate XG-YG The coordinate position of the receiver 2 in
XG-YG is determined.
Also, after determining the coordinate position of the receiving device 2 at the global coordinates
XG-YG, using the coordinate position of the transmitting device 1 at the local coordinates XL-YL,
the coordinate position of the transmitting device 1 at the global coordinates XG-YG You can ask
for
That is, the operation mode (calibration mode) for obtaining the coordinate position of the
reception device 2 at the global coordinates XG-YG using the coordinate position of the
transmission device 1 at the local coordinates XL-YL in the reception device 2 and the global
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coordinates There is an operation mode (operation mode) for obtaining the coordinate position of
the transmitter 1 in XG-YG.
The operation of the position calculation unit 22 will be described later.
[0027]
The trigger reception time stored in the memory 24 and the coordinate position of the
transmitter 1 at the global coordinates XG-YG for each trigger reception time are converted by
the control unit 27 into a data train of the data transfer format of the output unit 28 through the
output unit 28 It is output to a management device such as an external computer.
As the output unit 28, for example, an interface of a serial transfer method such as TIA / EIA232-E or USB, or an interface of a parallel transfer method such as SCSI can be adopted.
The data extracted from the output unit 28 is used in the management device, and it is possible
to measure the flow line by tracking the path traveled by the mobile body A.
The function of the control unit 27 is realized by installing an appropriate program in a
microcomputer.
[0028]
As shown in FIG. 4, the ultrasonic wave transmitting unit 11 of the transmitting apparatus 1 is
formed of a porous silicon layer on one surface (upper surface in FIG. 4) side of a supporting
substrate 31 made of a single crystal p-type silicon substrate. A heat insulating layer (heat
insulating layer) 32 is formed, a heat generating layer 33 made of a metal thin film (for example,
a tungsten thin film) is formed on the heat insulating layer 32, and the heat generating layer 33
is formed on the one surface side of the support substrate 31. It is desirable to use a thermally
excited ultrasonic wave generating element 11a in which a pair of electrically connected pads 34,
34 are formed.
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The planar shape of the support substrate 31 is rectangular, and the planar shape of the heat
generating layer 33 is also rectangular.
In addition, an insulating film (not shown) made of a silicon oxide film is formed on the surface of
the portion where the heat insulating layer 32 is not formed on the one surface side of the
support substrate 31.
[0029]
In the thermally excited ultrasonic wave generating element 11 a, when the temperature change
is caused in the heating element layer 33 by supplying electricity between the pads 34 and 34 at
both ends of the heating element layer 33, the air in contact with the heating element layer 33 is
Temperature change occurs.
Since the air in contact with the heat generating layer 33 expands when the temperature of the
heat generating layer 33 rises and shrinks when the temperature of the heat generating layer 33
decreases, it is possible to control the current flow to the heat generating layer 33 appropriately.
Can be generated.
[0030]
On the other hand, in the case of a piezoelectric ultrasonic wave generating element which has
been widely used as an ultrasonic wave generating element conventionally, since the Q value of
the resonance characteristic is high, the reverberation time becomes long as in the ultrasonic
waveform shown in FIG. In the above-described heat-excitation-type ultrasonic wave generating
element 11a, an ultrasonic wave is generated in accordance with the temperature change of the
heat generating body layer 33 accompanying the energization of the heat generating body layer
33 through the pair of pads 34, 34. If the waveform of the drive voltage or drive current applied
to the heat generating body layer 33 is, for example, a sine wave having a frequency of f1,
ultrasonic waves having a frequency substantially twice that of the frequency f1 can be
generated. By applying a solitary wave of a half cycle of a sinusoidal waveform as a drive voltage
from the driver 12 to a pair of pads 34, 34, the reverberation time as shown in FIG. 5A is short
and the generation period is approximately one cycle. Emits ultrasound It can be.
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11
In short, the piezoelectric ultrasonic generating element has a narrow frequency band since it has
a unique resonance frequency, but the thermally excited ultrasonic generating element 11a can
widely change the frequency of the generated ultrasonic wave, If the waveform of the drive
voltage or drive current is an isolated wave, it is possible to generate an ultrasonic wave of
approximately one cycle as shown in FIG. 5A.
[0031]
The above-described heat-excitation-type ultrasonic wave generating element 11 a uses a p-type
silicon substrate as the support substrate 31, and the heat insulating layer 32 is formed of a
porous silicon layer having a porosity of approximately 70%. A porous silicon layer to be the heat
insulating layer 32 can be formed by anodizing a part of the silicon substrate used as the support
substrate 31 in an electrolytic solution composed of a mixture of hydrogen fluoride aqueous
solution and ethanol. Here, the porosity and thickness of the porous silicon layer to be the heat
insulating layer 32 can be set to desired values by appropriately setting the conditions of the
anodizing treatment (for example, current density, current passing time, etc.). . In the porous
silicon layer, the thermal conductivity and the thermal capacity decrease as the porosity
increases. For example, the thermal conductivity is 148 W / (m · K) and the thermal capacity is
1.63 × 10 <6> J / (m < The porous silicon layer having a porosity of 60% formed by anodizing a
single crystal silicon substrate of 3> · K) has a thermal conductivity of 1 W / (m · K) and a heat
capacity of 0.7 × 10 It is known that <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 conductivity and the thermal
capacity of the thermal insulating layer 32 are made smaller than the thermal conductivity and
the thermal capacity of the supporting substrate 31, and the product of the thermal conductivity
of the thermal insulating layer 32 and the thermal capacity is the thermal conductivity of the
supporting substrate 31 By sufficiently reducing the product of heat capacity, the temperature
change of heat generating body layer 33 can be efficiently transmitted to the air, and efficient
heat exchange occurs between heat generating body layer 33 and air, and The support substrate
31 can efficiently receive the heat from the heat insulating layer 32 to dissipate the heat of the
heat insulating layer 32 and prevent the heat from the heat generating layer 33 from being
accumulated in the heat insulating layer 32. Can.
[0032]
The heat generating layer 33 is formed of tungsten, which is a kind of high melting point metal,
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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 may be
tantalum, molybdenum, iridium, or the like, for example.
[0033]
In the heat-excitation type ultrasonic wave generating element 11a described above, the
thickness of the support substrate 31 is 525 μm, the thickness of the heat insulating layer 32 is
10 μm, the thickness of the heat generating layer 33 is 50 nm, and the thickness of each pad 34
Is 0.5 μm, but these thicknesses are an example and not particularly limited. In addition,
although Si is employed as the material of the support substrate 31, the material of the support
substrate 31 is not limited to Si, and for example, it is possible to make porous by anodic
oxidation treatment of Ge, SiC, GaP, GaAs, InP, etc. Other semiconductor materials may be used.
[0034]
The trigger signal transmission unit 13 may use, for example, a light emitting diode when
adopting light as a trigger signal, and may use, for example, a radio wave transmission unit when
employing a radio wave as a trigger signal. Here, since light and radio waves are sufficiently fast
for sound waves, in the range of arrival time of ultrasonic waves from the transmitter 1 to the
receiver 2, the arrival time of light and radio waves can be regarded as zero.
[0035]
When light is used as the identification information signal, for example, a light emitting diode
may be used as the identification information signal transmission unit 15, and when a radio wave
is used as the identification information signal, for example, the radio wave transmission unit
may be used. In the case of using a sound wave as the identification information signal, for
example, a heat excitation-type sound wave generating element may be used.
[0036]
The ultrasonic wave receiving unit 21 of the receiving device 2 receives an ultrasonic wave
transmitted from the ultrasonic wave transmitting unit 11 and receives an ultrasonic wave
received as an electric signal, as shown in FIG. 2B. A plurality of wave receiving elements 21a for
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converting into wave receiving signals are constituted by an array sensor two-dimensionally
arranged on the same substrate 21b.
Here, the center-to-center distance (arrangement pitch) L of the wave receiving elements 21a is
set to about the wavelength of the ultrasonic wave generated from the ultrasonic wave
transmitting unit 11 (for example, about 0.5 to 5 times the wavelength of the ultrasonic wave) If
the wavelength is smaller than 0.5 times the wavelength of the ultrasonic wave, the time
difference between the times at which the ultrasonic waves reach the adjacent wave receiving
elements 21a becomes small, and detection of the time difference becomes difficult. As the wave
receiving element 21a, for example, a piezoelectric wave receiving element (piezoelectric
element) that converts an ultrasonic wave into an electric signal by a piezoelectric effect, or a
capacitive wave receiving element that converts an ultrasonic wave into a change in capacitance
It is possible to adopt widely known elements as ultrasonic wave receiving elements such as
elements, but in order to reduce reverberation as in the ultrasonic wave transmitting unit 11, a
capacitive type wave receiving element It is desirable to adopt the structure of
[0037]
In this embodiment, a capacitive microphone as shown in FIG. 6 is adopted as the wave receiving
element 21a. The capacitive microphone having the configuration shown in FIG. 6 is formed
using micromachining technology, and is a rectangular frame-shaped frame 41 formed by
providing a window hole 41a penetrating in the thickness direction in a silicon substrate. And a
cantilever-type pressure receiving portion 42 disposed on one surface side of the frame 41 so as
to straddle two opposing sides of the frame 41. Here, a thermal oxide film 45, a silicon oxide film
46 covering the thermal oxide film 45, and a silicon nitride film 47 covering the silicon oxide film
46 are formed on one surface side of the frame 41, and one end portion of the pressure receiving
portion 42. Is supported by the frame 41 via the silicon nitride film 47, and the other end is
opposed to the silicon nitride film 47 in the thickness direction of the silicon substrate. In
addition, a fixed electrode 43 a made of a metal thin film (for example, a chromium film or the
like) is formed on the surface of the silicon nitride film 47 facing the other end of the pressure
receiving portion 42. A movable electrode 43b formed of a metal thin film (for example, a
chromium film or the like) is formed on the opposite side to the opposite surface of A silicon
nitride film 48 is formed on the other surface of the frame 41. The pressure receiving portion 42
is formed of a silicon nitride film formed in a process separate from the silicon nitride films 47
and 48 described above.
[0038]
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In the wave receiving element 21a composed of the electrostatic capacitance type microphone
shown in FIG. 6, a capacitor having the fixed electrode 43a and the movable electrode 43b as an
electrode is formed, so that the pressure receiving portion 42 receives the pressure of the sound
wave. Thus, the distance between the fixed electrode 43a and the movable electrode 43b
changes, and the capacitance between the fixed electrode 43a and the movable electrode 43b
changes. Therefore, if a DC bias voltage is applied between the pads (not shown) provided on the
fixed electrode 43a and the movable electrode 43b, a minute voltage change occurs between the
pads according to the sound pressure of the ultrasonic wave. And the sound pressure of the
ultrasonic wave can be converted into an electrical signal.
[0039]
The structure of the capacitance type microphone used as the wave receiving element 21a is not
particularly limited to the structure of FIG. 6, and for example, it is formed by processing a silicon
substrate or the like by micromachining technology or the like to receive ultrasonic waves.
Between the movable electrode consisting of the diaphragm part and the fixed electrode
consisting of the back plate part facing the diaphragm part, from the insulating film which
defines the gap length between the diaphragm part and back plate part in the state not receiving
ultrasonic waves The spacer portion may be interposed, and a plurality of exhaust holes may be
provided through the back plate portion. In such a capacitive microphone, the capacitance
between the movable electrode and the fixed electrode is changed by the diaphragm portion
receiving ultrasonic waves and being deformed to change the distance between the diaphragm
portion and the back plate portion. Change.
[0040]
By the way, the Q value of the resonance characteristic of the wave receiving element 21a
consisting of the capacitance type microphone shown in FIG. 6 is about 3 to 4, and the Q value is
sufficiently smaller than that of the piezoelectric element. As compared with the case where a
piezoelectric element is used for the wave element and the wave receiving element, the dead
zone due to the reverberation component in the ultrasonic wave transmitted from the ultrasonic
wave transmitting unit 11 can be shortened, and the wave receiving element 21a Since the
reverberation time of the received wave signal generated when the ultrasonic wave is received
can be shortened and the dead zone due to the reverberation component in the received wave
signal output from the wave receiving element 21a can be shortened, the angular resolution It
can be improved.
05-05-2019
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[0041]
The trigger signal reception unit 23 may use, for example, a photodiode when adopting light as a
trigger signal transmitted from the trigger signal transmission unit 13, and, for example, when
receiving a radio wave as a trigger signal, for example, radio wave reception An antenna may be
used.
In short, the trigger signal reception part 23 should just be what can receive a trigger signal,
convert a trigger signal into an electric signal (trigger reception signal), and can output it.
[0042]
The identification information signal reception unit 25 may use, for example, a photodiode when
adopting light as the identification information signal transmitted from the identification
information signal transmission unit 15, and when employing a radio wave as the identification
information signal, for example, For example, a radio wave receiving antenna may be used. When
a sound wave is used as the identification information signal, for example, a capacitive wave
receiving element may be used. In short, the identification information signal receiving unit 25
only needs to be capable of receiving the identification information signal, converting the
identification information signal into identification information formed of an electrical signal, and
outputting the identification information.
[0043]
The position calculation unit 22 is based on the time difference between the time when the
sound wave is received by each wave receiving element 21 a of the ultrasonic wave reception
unit 21 (hereinafter referred to as the wave reception time) and the arrangement position of each
wave receiving element 21 a. The direction of arrival of the sound wave, that is, the direction in
which the transmitter 1 is present is determined. Here, the arrival direction of the ultrasonic
wave is determined as each angle between the xz plane and the yz plane at the orthogonal
coordinates shown in FIG. Hereinafter, the angle in the xz plane is described as θx, and the angle
in the yz plane is described as θy. That is, the arrival direction of the ultrasonic wave is
represented by a pair of (θx, θy).
05-05-2019
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[0044]
Hereinafter, processing for obtaining the direction of arrival (.theta.x, .theta.y) of the ultrasonic
wave in the position calculation unit 22 will be described, but in order to simplify the description,
the wave receiving element 21a of the ultrasonic wave receiving unit 21 is shown in FIG. It is
assumed that they are arranged one-dimensionally at equal intervals on the same plane (in fact,
they are arranged two-dimensionally as described above). Assuming that the angle of the wave
front of the ultrasonic wave with respect to the surface on which the wave receiving element 21a
is arranged is θ0, the arrival direction of the ultrasonic wave (ie, the existence of the ultrasonic
wave transmitting unit 11 with respect to the ultrasonic wave receiving unit 21). Azimuth angle)
is θ0. In this case, the velocity of the ultrasonic wave is c, and the wave front of the ultrasonic
wave at the time when it reaches one of the wave receiving elements 21a of the adjacent wave
receiving elements 21a and the center of the other wave receiving element 21a. Assuming that
the distance between them (delay distance) is d0 and the distance between the centers of
adjacent wave receiving elements 21a is L, the time difference Δt0 (see FIG. 8) of the wave
fronts of ultrasonic waves reaching between adjacent wave receiving elements 21a is Δt0 = d0 /
c = L · sin θ0 / c. Accordingly, since θ0 = sin <−1> (Δt0 · c / L), the direction of arrival θ0 of
the ultrasonic wave can be obtained by obtaining the time difference Δt0.
[0045]
8 (a) to 8 (c) show the reception of each of the wave receiving elements 21a of FIG. 7 when the
ultrasonic wave transmitting unit 11 transmits an ultrasonic wave of approximately one cycle
(see FIG. 5 (a)). 8 (a) shows the wave receiving signal of the wave receiving element 21a at the
top of FIG. 7, FIG. 8 (b) shows the wave receiving signal of the wave receiving element 21a in the
middle of FIG. 8 (c) shows the wave receiving signal of the wave receiving element 21a at the
bottom of FIG. Here, the position calculation unit 22 includes a signal processing unit 22c having
a function of obtaining the arrival direction of the ultrasonic wave. The signal processing unit
22c is a wave receiving signal obtained by delaying the wave receiving signal which is an electric
signal output from each wave receiving element 21a of the ultrasonic wave receiving unit 21 by
a delay time according to the arrangement pattern of each wave receiving element 21a. Compare
the magnitude relationship between the peak value of the output waveform of the adder and the
appropriate threshold and compare the delay means that outputs the signals in pairs, the adder
that adds the set of received signals delayed by the delay means, and the appropriate threshold.
Since the determination means determines the direction corresponding to the delay time set by
the delay means as the arrival direction of the ultrasonic wave when the peak value exceeding is
obtained, the ultrasonic wave to the ultrasonic wave receiver 21 is The direction of arrival can be
05-05-2019
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determined. Here, in addition to the above-described signal processing unit 22c, the position
calculation unit 22 converts analog reception signals output from the respective reception
elements 21a of the ultrasonic wave reception unit 21 into digital reception signals. The A / D
converter 22a which outputs the data, and the data storage 22b in which the output of the A / D
converter 22a is stored only for a predetermined reception period from the time when the trigger
reception signal from the trigger signal receiver 23 is input. The above-mentioned signal
processing unit 22c sets the reception period when the trigger reception signal is input to the
data storage unit 22b, operates the A / D conversion unit 22a only during the reception period,
and receives the signal. The arrival direction of the ultrasonic wave is determined based on the
data of the received wave signal stored in the data storage unit 22b during the period.
[0046]
By the way, in this embodiment, since the above-mentioned heat excitation type ultrasonic wave
generation element 11a is used as ultrasonic wave transmission part 11, as shown in Drawing 9,
each wave reception element 21a of ultrasonic wave reception part 21 is shown. If ultrasound
waves arrive from two arrival directions θ 1 and θ 2, the ultrasound waves arriving from arrival
direction θ 1 will arrive earlier than the ultrasound waves arriving from the direction of arrival
direction θ 2, as shown in FIG. As shown in a) to (c), the two receiving signals output from the
respective receiving elements 21a do not overlap easily, and the arrival directions θ1 and θ2 of
the ultrasonic waves can be determined. Here, in FIG. 10, (a) shows two receive signals of the
receive element 21a at the top of FIG. 9, and (b) shows two receive signals of the receive element
21a in the middle of FIG. c) shows two received wave signals of the bottom wave receiving
element 21a of FIG. 9, and the left received wave signal in each of (a) to (c) corresponds to the
ultrasonic wave that arrived from the arrival direction θ1 , And the received signal on the right
side corresponds to the ultrasonic wave that has arrived from the arrival direction .theta.2. The
distance between the wave front of the ultrasonic wave at the time when the wave front of the
ultrasonic wave from the arrival direction θ1 reaches one of the adjacent wave receiving
elements 21a of the wave receiving elements 21a and the center of the other wave receiving
element 21a. Assuming that (delay distance) is d1 (see FIG. 9), the time difference .DELTA.t1 (see
FIG. 10) in which the wave fronts of ultrasonic waves reach between adjacent wave receiving
elements 21a is .DELTA.t1 = d1 / c = L.sin .theta.1 / c Accordingly, θ1 = sin <−1> (Δt1 · c / L),
and the time difference Δt1 can be obtained to obtain the arrival direction θ1 of the ultrasonic
wave. Similarly, between the wave front of the ultrasonic wave at the time when the wave front of
the ultrasonic wave from the arrival direction θ2 reaches one wave receiving element 21a of the
adjacent wave receiving elements 21a and the center of the other wave receiving element 21a.
Assuming that the distance (delay distance) is d2 (see FIG. 9), the time difference .DELTA.t2 (see
FIG. 10) for the wave front of ultrasonic waves to reach between adjacent wave receiving
elements 21a is .DELTA.t2 = d2 / c = L.sin .theta.2 / Since c is obtained, θ2 = sin <−1> (Δt2 · c /
05-05-2019
18
L), and the time difference Δt2 can be obtained to obtain the arrival direction θ2 of the
ultrasonic wave.
[0047]
Although in the examples of FIGS. 7 and 9 the wave receiving elements 21a are arranged in a
straight line for the sake of simplicity, in actuality, a plurality of wave receiving elements are
respectively received in the x and y directions on one plane. Since the wave elements 21a are
arrayed, the arrival direction θx in the xz plane and the arrival direction θy in the yz plane can
be determined simultaneously. That is, the arrival direction of the ultrasonic wave can be
determined by a combination of (θx, θy).
[0048]
Further, the signal processing unit 22 c of the position calculation unit 22 determines the
reception device 2 and the transmission device 1 from the relationship between the time when
the trigger signal is received by the trigger signal reception unit 23 and the time when the
ultrasonic wave is received by the wave receiving element 21 a. The distance calculating means
is provided to obtain the distance of (in essence, the distance between the ultrasonic wave
receiving unit 21 of the receiving device 2 and the ultrasonic wave transmitting unit 11 of the
transmitting device 1). Here, by adopting a signal having a sufficiently high speed as compared
with an ultrasonic wave such as light or radio wave as a trigger signal as described above, the
arrival time of the trigger signal from the transmitter 1 to the receiver 2 is transmitted Since the
arrival time of the trigger signal can be regarded as zero, which is sufficiently short (negligibly
short) as compared with the arrival time of the ultrasonic wave from the device 1 to the
reception device 2, the distance calculation means ) To (c), the time when the trigger reception
signal ST is received via the data storage unit 22b, and the time when the wave reception signal
SP from the wave receiving element 21a is first received after the reception of the trigger
reception signal ST, and The distance between the receiving device 2 and the transmitting device
1 is determined by the time difference T of the above and the velocity of the ultrasonic wave. The
distance calculating means of the signal processing unit 22c is realized by mounting an
appropriate program in a microcomputer constituting the signal processing unit 22c.
[0049]
The data storage unit 22b stores data as many as [number of wave receiving elements 21a] ×
[number of data of wave receiving signals from each wave receiving element 21a]. Assuming that
05-05-2019
19
the number of elements 21a is eight, the receiving period is 30 ms, and the sampling period of
the A / D converter 22a is 1 μs, one data is one word and a capacity of 240 k words is required.
An SRAM or the like may be used.
[0050]
By the way, in the present embodiment, as described above, it is necessary to obtain the
coordinate position of the reception device 2 at the global coordinates XG-YG. Therefore, the
reference is known that the coordinate position of the global coordinates XG-YG is known to the
mobile body A. Position in position.
[0051]
Now, as shown in FIG. 12, it is assumed that a reference position Ps is set on the floor surface
100 at which the coordinate position of the global coordinates XG-YG is known, and the moving
object A is positioned at the reference position Ps.
Here, since the position of the transmitter 1 with respect to the mobile A does not change, the
position of the mobile A will be described as representing the position of the transmitter 1.
A coordinate position at global coordinates XG-YG of the reference position Ps is (XG11, YG11).
In order to obtain the coordinate position of the receiving device 2 at the global coordinates XGYG, first, the mobile body A is positioned at the reference position Ps while the position
calculating unit 22 is set to the calibration mode for obtaining the position of the receiving
device 2 .
[0052]
Since the position calculation unit 22 of the receiving device 2 can obtain the coordinate position
of the transmitting device 1 at the local coordinates XL-YL, this coordinate position is taken as
(XL11, YL11). Here, if the constraint condition that the direction of the coordinate axes of the
global coordinate XG-YG and the local coordinate XL-YL coincide is set, the coordinate position
(XG11, YG11) and the local in the global coordinate XG-YG for the reference position Ps The
difference from the coordinate position (XL11, YL11) at the coordinate XL-YL is the coordinate
position (XR, YR) of the receiving device 2 at the global coordinate XG-YG. That is, the coordinate
05-05-2019
20
position of the receiving device 2 can be obtained as XR = XG11-XL11 and YR = YG11-YL11.
[0053]
The coordinate position (XR, YR) of the reception device 2 at the global coordinate XG-YG is
stored in the coordinate conversion processing unit 22 d and used for the subsequent processing
in the signal processing unit 22 c. The coordinate conversion processing unit 22d also stores
coordinate positions (XG11, YG11) of the reference position Ps at the global coordinates XG-YG.
Here, since the change frequency of the data stored in the coordinate conversion processing unit
22d is small, it is desirable to use a non-volatile memory such as an EEPROM for the coordinate
conversion processing unit 22d. The coordinate position (XG11, YG11) is set based on the result
of mounting the reference position Ps at the global coordinate XG-YG. That is, in the operation
mode for determining the coordinate position of the transmitting device 1 at the global
coordinates XG-YG, the coordinate position of the transmitting device 1 is calculated by using the
coordinate position of the receiving device 2 stored in the coordinate conversion processing unit
22d. It is In addition, since the measurement of the reference position Ps is performed on the
floor surface 100, the operation is easy.
[0054]
By the way, in the above description, the constraint condition is set that the direction of the
coordinate axis of the global coordinate XG-YG and the coordinate axis of the local coordinate
XL-YL coincide with each other. The installation direction of the apparatus 2 must be constructed
so as to have a fixed relationship with the coordinate axes of the global coordinates XG-YG.
Therefore, although it is not necessary to consider the coordinate position at the time of
installation and construction of the receiving device 2, although installation and construction
becomes easy, it still has to be considered in relation to the coordinate axes of the global
coordinates XG-YG. Since a line along the coordinate axis may be provided on the ceiling surface
200, installation and installation are relatively easy in that case).
[0055]
Therefore, hereinafter, a technology will be described in which installation and installation can be
performed without any restriction on the mounting direction of the receiving device 2. In the
above operation, only the coordinate position of the receiver 2 in the global coordinate XG-YG is
05-05-2019
21
determined, and the rotation angle of the coordinate axis is not taken into consideration.
Therefore, the unknown number is 2 and two expressions for one reference position Ps as
described above If you set, you can find the unknown. On the other hand, when considering the
rotation angle of the coordinate axis, it is necessary to obtain the rotation angle θR of the
coordinate axis of the local coordinate XL-YL relative to the coordinate axis of the global
coordinate XG-YG, so three unknowns (XR, YR, θR) Become. That is, the unknowns can not be
obtained by only two equations obtained from one reference position Ps. Therefore, two
reference positions are set.
[0056]
Now, as shown in FIG. 13, with respect to one reference position Ps1 of the two reference
positions Ps1 and Ps2 (Ps2 is not shown), in the receiving device 2, coordinate positions (XG11,
YG11) at global coordinates XG-YG. Is known, and the coordinate position (XL11, YL11) at the
local coordinate XL-YL is measured. Here, the relationship between the unknowns (XR, YR, θR)
regarding the receiving device 2 and their coordinate positions (XG11, YG11), (XL11, YL11) can
be expressed as in the following equation 1.
[0057]
[0058]
Similarly, also for the reference position Ps2, the relationship between the coordinate position
(XG12, YG12) at the global coordinate XG-YG and the coordinate position (XL12, YL12) at the
local coordinate XL-YL can be expressed as in the following formula 2 .
[0059]
[0060]
Here, if (XR, YR) is eliminated from Eq. 1 and Eq. 2, the following Eq. 3 regarding θR can be
obtained.
[0061]
05-05-2019
22
[0062]
Furthermore, if Equation 3 is applied to Equation 1 and Equation 2, (XR, YR) can be obtained.
[0063]
Therefore, in order to obtain the coordinate position of the receiving device 2, first, move the
moving body A at the reference position Ps1 to obtain the coordinate position (XL11, YL11) at
the local coordinates XL-YL, and then move the moving body A to the reference position When
the coordinate position (XL12, YL12) at the local coordinate XL-YL is determined by positioning
at Ps2, the position of the reception device 2 at the global coordinate XG-YG is determined
including the rotation angle θR of the coordinate axis at the local coordinate XL-YL Can.
[0064]
The transmitting device 1 is provided with a directivity adjusting unit 18 that adjusts the
directivity of the ultrasonic wave transmitted from the ultrasonic wave transmitting unit 11.
Here, the directivity adjusting unit 18 is wavelength adjusting means for adjusting the directivity
of the ultrasonic wave by changing the wavelength of the ultrasonic wave generated by the
ultrasonic wave transmitting unit 11, and the ultrasonic wave transmitting unit 11 The
wavelength of the ultrasonic wave is changed by changing the frequency of the drive voltage or
the waveform of the drive current applied from the driver 12 to be driven to the ultrasonic wave
transmission unit 11 composed of the above-mentioned heat excitation type ultrasonic wave
generation element 11a.
Here, the directivity adjusting unit 18 is configured to be able to appropriately adjust the
wavelength of the ultrasonic wave generated by the ultrasonic wave transmitting unit 11 in
accordance with the operation of the operation unit (not shown).
[0065]
By the way, when the ultrasonic wave transmission surface of the ultrasonic wave transmission
unit 11 is a square, for example, assuming that the wavelength of the sinusoidal ultrasonic wave
is 60 kHz and the size of the ultrasonic wave transmission surface is 3 mm □, it is orthogonal to
the ultrasonic wave transmission surface. The directivity angle θ defined by the angle between
05-05-2019
23
the center line and the directivity Ds (θ) normalized with the sound pressure at 0 ° being 1 is in
the relationship as shown in FIG. Although the directivity Ds (θ) gradually decreases as D
increases, an inflection point exists.
Here, the relationship between the directivity angle θ and the directivity Ds (θ) is given by the
following equation 4 when the length of one side of the ultrasonic wave transmission wavefront
is 2a, the wavelength of the ultrasonic wave is λ, and the directivity angle is θ. It is known to be
represented.
[0066]
[0067]
Here, for example, as shown in FIG. 15, the moving range of the movable body A is determined to
some extent, and in the ultrasonic wave receiving unit 21, the viewing angle θxm = 40 ° in the
xz plane and the viewing angle θym = in the yz plane If a field of view E of 40 ° is required,
assuming that the ultrasonic wave transmission wavefront is a square of 10 mm on one side, the
frequency of the ultrasonic wave may be adjusted to 34 kHz from λ calculated using Equation 4
.
[0068]
In the position detection system of the present embodiment described above, the receiving device
2 receives an ultrasonic wave transmitted from the ultrasonic wave transmitting unit 11 and
converts the received ultrasonic wave into a received wave signal as an electrical signal. The
ultrasonic wave receiving unit 21 is composed of an array sensor in which a plurality of wave
receiving elements 21a to be arranged are arrayed on the same substrate 21b, and the position
calculating unit 22 uses the respective wave receiving elements 21a of the ultrasonic wave
receiving unit 21. Based on the time difference of the time of receiving the ultrasonic wave and
the arrangement position of each receiving element 21a, the direction in which the transmitting
device 1 exists is determined for the receiving device 2, and the distance between the receiving
device 2 and the transmitting device 1 Since the determination is made so as to obtain the
relative position of the transmitter 1 with respect to the receiver 2, the relative position of the
transmitter 1 with respect to the receiver 2 can be determined based on the output of one
receiver 2. , Construction will be easier
[0069]
In addition, since the directivity adjustment unit 18 for adjusting the directivity of the ultrasonic
05-05-2019
24
wave transmitted from the ultrasonic wave transmission unit 11 is provided, the movement space
D of the moving body A is determined to some extent. It is possible to suppress that the
ultrasonic wave is transmitted from the transmitter 1 to an unnecessary area regardless of the
movement space D of the body A, and the accuracy of position detection is reduced due to the
influence of the reflected wave. While being able to raise the utilization efficiency of a sound
wave, it becomes possible to raise the accuracy of position detection.
[0070]
In the above embodiment, although the trigger signal transmission unit 13 is provided in the
transmission device 1 and the trigger signal reception unit 23 is provided in the reception device
2, the trigger signal transmission unit 13 is provided on the reception device 2 side and the
trigger signal reception is provided. The control unit 17 controls the driver 12 so that ultrasonic
waves are transmitted from the ultrasonic wave transmission unit 11 based on the output of the
trigger signal reception unit 23 by providing the unit 23 on the transmission apparatus 1 side,
The signal processing unit 22c in the calculation unit 22 obtains the distance to the transmission
device 1 from the relationship between the time when the trigger signal is transmitted from the
trigger signal transmission unit 13 and the time when the ultrasonic wave is received by the
wave receiving element 21a. May be
Here, the control unit 17 may control the driver 12 immediately when the trigger reception
signal output from the trigger signal reception unit 23 is input, or may control the driver 12 after
a predetermined time. It is also good.
[0071]
Second Embodiment The basic configuration of the position detection system of the present
embodiment is substantially the same as that of the first embodiment, and the ultrasonic wave
transmitting unit 11 has the same plurality of ultrasonic wave generating elements 11a as shown
in FIG. The directivity adjustment unit 18 is arranged in a two-dimensional array on the substrate
11 b, and the directivity adjustment unit 18 adjusts the directivity of ultrasonic waves by
changing the area of the ultrasonic wave transmission surface of the ultrasonic wave
transmission unit 11. The difference is that it is configured.
The center-to-center distance (arrangement pitch) L1 of the ultrasonic wave generating elements
05-05-2019
25
11a is preferably set as short as possible so that a set of ultrasonic wave generating elements
11a that actually generate ultrasonic waves can be regarded as one sound source. So, it is set to
5 mm.
The other configuration is the same as that of the first embodiment, so the illustration and the
description will be omitted.
[0072]
Here, assuming that the vertical direction in FIG. 16 is the y direction and the horizontal direction
is the x direction, the ultrasonic wave transmitting unit 11 generates ultrasonic waves among the
ultrasonic wave generating elements 11a arranged in the y direction. The number of 11a can be
selected by a plurality of changeover switches SWy arranged in the y direction, and the number
of ultrasonic wave generating elements 11a generating ultrasonic waves among the ultrasonic
wave generating elements 11a arranged in the x direction is x It can be selected by a plurality of
selection switches SWx arranged in a direction, and ultrasonic transmission can be performed by
operating the directivity adjustment unit 18 and appropriately controlling each changeover
switch SWy and each selection switch SWx. The area of the ultrasonic wave transmission surface
of the wave unit 11 can be changed.
In FIG. 16, an example in which all the selection switches SWx are turned on and all the
changeover switches SWy are switched not to be energized to the ultrasonic wave generating
elements 11a other than the ultrasonic wave generating element 11a at the bottom in FIG. The
ultrasonic wave generation elements 11a that generate ultrasonic waves with energization to the
pair of input terminals 11c and 11c of the ultrasonic wave transmission unit 11 are hatched.
[0073]
By the way, as described in the first embodiment, assuming that the ultrasonic wave transmission
surface of the ultrasonic wave transmission unit 11 is a square of which one side is 2a, the
relationship between the directivity angle θ and the directivity Ds (θ) is the above. It is
expressed by equation 4.
Here, for example, as shown in FIG. 17, the moving direction B of the moving body A is
05-05-2019
26
determined to some extent, and in the ultrasonic wave receiving unit 21, the viewing angle θxm
= 40 ° in the xz plane and the viewing angle θym in the yz plane. If a field of view E of 8 ° is
required, the ultrasonic wave transmission unit 11 may design the shape of the ultrasonic wave
transmission surface so that Ds (40 °) is 50% of Ds (0 °), Assuming that the wavelength λ of
the ultrasonic wave is 5.67 μm (that is, the frequency of the ultrasonic wave is 60 kHz), the
length in the x direction in the ultrasonic wave transmission wavefront is 26 mm, and the length
in the y direction is 5.6 mm Know what to do.
Here, it is also conceivable to design the size of the ultrasonic wave transmission wavefront to a
large size in advance and to provide a mask having an aperture corresponding to the size of the
ultrasonic wave transmission wavefront determined by the above equation 4. Since it is
necessary to design and manufacture a mask in accordance with the movement space D, the cost
is increased.
[0074]
On the other hand, in the present embodiment, the directivity adjustment unit 18 is configured
by a microcomputer or the like, and the value of the viewing angles θxm and θym of the
ultrasonic wave reception unit 21 is input to use the above equation 4 Then, calculation is
performed to obtain the length of each side along the x direction and y direction of the
rectangular ultrasonic wave transmission surface, and the length of each side of the ultrasonic
wave transmission surface obtained by the calculation is calculated. The state of each changeover
switch SWy and each selection switch SWx is controlled.
[0075]
Thus, in the position detection system according to the present embodiment, the ultrasonic wave
transmission unit 11 has a plurality of ultrasonic wave generation elements 11a arranged in a
two-dimensional array, and generates ultrasonic waves. The area of the ultrasonic wave
transmission surface of the ultrasonic wave generation unit 11 can be changed by independently
adjusting the number of 11a in each of the x direction and the y direction orthogonal to each
other, thereby increasing versatility and cost reduction Can be
[0076]
Third Embodiment In the first embodiment, the transmitter 1 is mounted on the movable body A,
and the receiver 2 is fixed at a fixed position such as a ceiling surface. However, in the position
detection system of the present embodiment, 18, the receiver 2 includes the gyro sensor 29, and
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27
as shown in FIG. 19, the transmitter 1 is fixed at a fixed position on the ceiling surface 200, and
the receiver 2 is mounted on the mobile body A, etc. It is different.
In addition, the same code | symbol is attached | subjected to the component similar to
Embodiment 1, and description is abbreviate | omitted.
[0077]
Also in the present embodiment, the position of the transmission device 1 obtained using the
output of the ultrasonic wave reception unit 21 of the reception device 2 is the relative position
of the transmission device 1 with respect to the reception device 2 and is set in the reception
device 2 It is obtained as the coordinate position of the local coordinate XL-YL.
Here, also in the present embodiment, the height from the floor surface 100 to the ceiling
surface 200 is regarded as constant, and the height position of the receiving device 2 does not
change in the moving space D of the moving body A, so the local coordinates XL Treat YL as twodimensional coordinates on the floor surface 100.
As described later, the coordinate position of the transmitter 1 at the global coordinates XG-YG is
stored in the receiver 2, and the output of the ultrasonic wave receiver 21 is used to coordinate
the transmitter 1 at the local coordinates XL-YL. By determining the position, it is possible to
determine the coordinate position of the receiving device 2 at the global coordinates XG-YG.
The global coordinates XG-YG are also considered as two-dimensional coordinates on the floor
surface 100 without considering the height.
[0078]
Also in the present embodiment, calibration of the receiving device 2 is necessary, and at the
time of calibration, the position calculating unit 22 uses the output of the ultrasonic wave
receiving unit 21 to transmit at the local coordinates XL-YL. The coordinate position of the
device 1 is determined, and when the receiving device 2 is located at a known coordinate
position in the global coordinates XG-YG, the coordinate position of the transmitting device 1 at
05-05-2019
28
the global coordinates XG-YG is determined using both coordinate positions. In addition, after the
coordinate position of the transmission device 1 at the global coordinates XG-YG is obtained, the
coordinate position of the transmission device 1 at the local coordinates XL-YL is used to obtain
the reception device 2 at the global coordinates XG-YG. Coordinate position can be determined.
[0079]
That is, the operation mode (calibration mode) for obtaining the coordinate position of the
transmission device 1 at the global coordinates XG-YG using the coordinate position of the
transmission device 1 at the local coordinates XL-YL in the reception device 2 and the global
coordinates There is an operation mode (operation mode) for obtaining the coordinate position of
the reception device 2 in XG-YG.
[0080]
In the memory 24, the coordinate position of the receiving device 2 at the global coordinate XGYG determined by the position calculation unit 22 and the time when it was located at the
coordinate position (the time when the trigger signal was received by the trigger signal reception
unit 23 And the identification data of the receiving device 2 are stored in association with each
other.
The data stored in the memory 24 is read by the control unit 27 as necessary, and is output to an
external management apparatus or the like through the output unit 28. The detection result
extracted from the output unit 28 is used in a separately provided management device, and in
the present embodiment, the movement line is measured by tracking the path of movement of
the mobile body A. Here, since the receiving device 2 is mounted on the mobile unit A, it is
desirable to wirelessly transmit the detection result extracted from the output unit 28 to the
managing device.
[0081]
Also in the present embodiment, the relative distance of the transmitter 1 to the receiver 2 can
be known. That is, since the direction and distance of the transmitter 1 can be known, the
receiver 2 can obtain the three-dimensional position of the transmitter 1. However, as described
above, in the present embodiment, the coordinate position in the two-dimensional coordinate on
the floor surface 100 is obtained. That is, two-dimensional coordinates on the floor surface 100
05-05-2019
29
can be determined by using a known height dimension for the three-dimensional position. This
calculation is performed in the signal processing unit 22c.
[0082]
As described above, when receiving the trigger signal from the transmitter 1, the receiver 2
calculates the arrival direction of the ultrasonic wave and the distance to the transmitter 1, and
the two-dimensional coordinates on the floor surface 100 of the mobile body A. The coordinate
position at (local coordinates XL-YL) is determined. Also, as in the first embodiment, the time
when the trigger signal is received and the identification data corresponding to the trigger signal
are stored in the memory 24.
[0083]
The coordinate position of the transmitter 1 at the local coordinates XL-YL can be determined by
the above-described process. That is, the coordinate position of the receiving device 2 at the local
coordinate XL-YL can be obtained by the data storage unit 22b and the signal processing unit
22c in the position calculation unit 22. On the other hand, in the present embodiment, it is
necessary to obtain the coordinate position of the transmission device 1 at the global coordinates
XG-YG, and therefore, the mobile body A is positioned at the reference position where the
coordinate position of the global coordinates XG-YG is known.
[0084]
The position calculation unit 22 of the reception device 2 can obtain the coordinate position of
the transmission device 1 at the local coordinates XL-YL, so this coordinate position is set to
(XL1, YL1). Here, if the constraint condition that the directions of the global coordinates XG-YG
and the local coordinates XL-YL coincide with each other is set, as shown in FIG. 20, the
coordinate position in the global coordinates XG-YG of the transmission device 1 Between (XG1,
YG1), the coordinate position (XL1, YL1) at the local coordinates XL-YL of the transmitter 1, and
the coordinate position (XR, YR) of the receiver 2 at the global coordinates XG-YG, XG1 The
relationship of = XR + XL1 and YG1 = YR + YL1 is established. That is, when the receiving device
2 is located at the coordinate position (XR, YR), using the coordinate position (XL1, YL1) at the
local coordinates XL-YL of the transmitting device 1, the transmission device 1 at the global
coordinates XG-YG Coordinate positions (XG1, YG1) can be determined. Conversely, if the
05-05-2019
30
coordinate position (XG1, YG1) at the global coordinate XG-YG is known for the transmitter 1,
the global coordinate XG-YG can be obtained by measuring the coordinate position (XL1, YL1) at
the local coordinate XL-YL. The coordinate position (XR, YR) of the receiving device 2 in the
above can be obtained.
[0085]
Here, since the position of the receiving device 2 with respect to the moving body A does not
change, hereinafter, the position of the moving body A is described as representing the position
of the receiving device 2.
[0086]
In order to obtain the coordinate position (XR, YR) of the reception device 2 at the global
coordinates XG-YG, the position operation unit 22 is set to the calibration mode, and the
coordinate positions (XG1, YG1) of the transmission device 1 at the global coordinates XG-YG are
obtained. You need to ask.
That is, a reference position at which the coordinate position of the global coordinate XG-YG is
known is set on the floor surface 100, and the mobile body A is positioned at the reference
position with the position calculation unit 22 set in the calibration mode. When mobile unit A is
positioned at the reference position, the coordinate position (XR, YR) of receiver 2 at global
coordinates XG-YG is known, and the coordinate position of transmitter 1 at local coordinates
XL-YL (XL1, YL1) Can be measured, so that the coordinate position (XG1, YG1) of the
transmission device 1 at the global coordinates XG-YG can be obtained.
[0087]
The coordinate position (XG1, YG1) of the transmission device 1 at the global coordinate XG-YG
is stored in the coordinate conversion processing unit 22d and used for the subsequent
processing in the signal processing unit 22c. The coordinate conversion processing unit 22d also
stores the coordinate position of the reference position at the global coordinate XG-YG. In
addition, the coordinate position of the reference position in global coordinate XG-YG is set by
measurement. In addition, since the measurement of the reference position is performed on the
floor surface 100, the operation is easy.
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[0088]
After the coordinate position (XG1, YG1) of the transmitting device 1 in the global coordinate XGYG is determined, the coordinate position (XR, YR) of the receiving device 2 in the global
coordinate XG-YG with the position calculating unit 22 as the operation mode You can ask for In
the operation mode, the coordinate position (XR, YR) of the reception device 2 is calculated by
using the coordinate position (XG1, YG1) of the transmission device 1 stored in the coordinate
conversion processing unit 22 d.
[0089]
By the way, in the above description, the constraint condition is set that the directions of the
global coordinate XG-YG and the coordinate axis of the local coordinate XL-YL coincide with each
other. There is a constraint. Therefore, in order to remove the above-described constraint
condition, in the present embodiment, the receiving device 2 mounted on the moving body A is
used as a direction detecting means for detecting the direction of the moving body A in a plane
parallel to the substrate 21b. A gyro sensor 29 is provided. The output of the gyro sensor 29 is
input to the signal processing unit 22c via the A / D converter 22e.
[0090]
In the above operation, the rotation angle of the local coordinates XL-YL with respect to the
global coordinates XG-YG, that is, the direction of the moving body A is not considered, so the
unknown number is 2, and 2 equations for one reference position as described above If you set,
you can find the unknown. On the other hand, when considering the rotation angle of the
coordinate axis, it is necessary to obtain the rotation angle θR of the coordinate axis of the local
coordinate XL-YL relative to the coordinate axis of the global coordinate XG-YG, so three
unknowns (XR, YR, θR) . That is, the unknown can not be determined by only two equations
obtained from one reference position. Therefore, a gyro sensor 29 is provided to obtain the
rotation angle θR.
[0091]
Considering the rotation angle θR of the coordinate axis, as shown in FIG. 21, the coordinate
position (XG1, YG1) at the global coordinates XG-YG of the transmitter 1 and the coordinate
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position (XL1, XL1 at the local coordinates XL-YL of the transmitter 1). The relationship of the
following equation 5 is established between YL1) and the coordinate position (XR, YR) of the
receiving device 2 at the global coordinates XG-YG.
[0092]
[0093]
Even in the case of considering the rotation angle θR, only the arithmetic expression is different,
and the processing is the same as the processing described above.
That is, the coordinate position (XG1, YG1) of the transmitting device 1 at the global coordinates
XG-YG in the calibration mode is determined and stored in the coordinate conversion processing
unit 22d, and the coordinate position of the receiving device 2 at the global coordinates XG-YG in
the operation mode When obtaining (XR, YR), the coordinate position (XG1, YG1) of the
transmitting device 1 stored in the coordinate conversion processing unit 22d is used.
The receiving device 2 identifies each transmitting device 1 by the identification information
signal.
[0094]
Also in this embodiment, for example, as shown in FIG. 22, the moving range of the movable
body A is determined to some extent, and in the ultrasonic wave receiving unit 21, the viewing
angle θxm = 40 ° in the xz plane, the yz plane If the field of view E with the field of view angle
θym = 40 ° is required, assuming that the ultrasonic wave transmitting wavefront is a square
of 10 mm on one side, the frequency of the ultrasonic wave is 34 kHz from λ calculated using
the above equation 4. You can adjust it to
[0095]
Also in the position detection system of the present embodiment described above, as in the first
embodiment, the relative position of the transmission device 1 with respect to the reception
device 2 can be obtained based on the output of one reception device 2. In addition, since the
directivity adjustment unit 18 for adjusting the directivity of the ultrasonic wave transmitted
from the ultrasonic wave transmission unit 11 is provided, the utilization efficiency of the
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ultrasonic wave can be enhanced, and It is possible to improve the accuracy of detection.
[0096]
(Fourth Embodiment) The basic configuration of the position detection system of this
embodiment is substantially the same as that of the third embodiment, and the ultrasonic wave
transmitting unit 11 and the directivity adjusting unit 18 are the same as those of the second
embodiment. Since only differences are present, illustration and description of the system
configuration is omitted.
[0097]
Also in the position detection system of the present embodiment, for example, as shown in FIG.
23, the moving direction B of the movable body A is determined to some extent, and the
ultrasonic wave receiver 21 has a viewing angle θxm = 40 ° in the xz plane. In the case where
the visual field E in which the visual field angle θym is 8 ° in the yz plane is required, the
ultrasonic wave transmission unit 11 sets the ultrasonic wave transmission surface so that Ds
(40 °) becomes 50% of Ds (0 °). If the wavelength λ of the ultrasonic wave is 5.67 μm (that
is, the frequency of the ultrasonic wave is 60 kHz), the length in the x direction of the ultrasonic
wave transmission surface is 26 mm, and the y direction It can be seen that the length should be
5.6 mm.
[0098]
Here, also in the present embodiment, as in the second embodiment, the directivity adjustment
unit 18 is configured by a microcomputer or the like, and the values of the view angles θxm and
θym of the ultrasonic wave reception unit 21 are input. An arithmetic operation is performed to
obtain the length of each side along the x direction and the y direction of the rectangular
ultrasonic wave transmission surface using Eq. 4, and each side of the ultrasonic wave
transmission surface determined by the calculation The state of each selector switch SWy and
each selector switch SWx is controlled according to the length of the switch.
[0099]
Therefore, also in the position detection system according to the present embodiment, the
ultrasonic wave transmission unit 11 has a plurality of ultrasonic wave generation elements 11a
arranged in a two-dimensional array, and generates ultrasonic waves to generate ultrasonic
waves. By independently adjusting the number of elements 11a in the x direction and the y
direction orthogonal to each other, the area of the ultrasonic wave transmission surface of the
ultrasonic wave generation unit 11 can be changed, thereby increasing versatility and reducing
cost. Can be
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[0100]
FIG. 1 is a system configuration diagram showing a first embodiment.
The same as the above is shown, (a) is a schematic block diagram which shows an example of
use, (b) is a schematic perspective view of an ultrasonic wave receiving part.
It is principle explanatory drawing same as the above.
It is a schematic sectional drawing of the ultrasonic excitation element of the heat excitation type
in said same.
FIG.
The capacitance-type microphone in the same as the above is shown, (a) is the schematic
perspective view which fractured | ruptured partially, (b) is a schematic sectional drawing.
FIG. FIG. FIG. FIG. FIG. It is principle explanatory drawing same as the above. It is principle
explanatory drawing in the other operation | movement same as the above. FIG. FIG. FIG. 7 is a
schematic configuration diagram of an ultrasonic wave transmission unit in Embodiment 2. FIG.
FIG. 7 is a system configuration diagram showing a third embodiment. The same as the above is
shown, (a) is a schematic block diagram which shows an example of use, (b) is a schematic
perspective view of an ultrasonic wave receiving part. It is principle explanatory drawing same as
the above. It is principle explanatory drawing in the other operation | movement same as the
above. FIG. FIG. 18 is an explanatory view of a fourth embodiment.
Explanation of sign
[0101]
A Mobile body D Moving space 1 Transmission device 2 Reception device 11 Ultrasonic wave
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transmission unit 12 Driver 13 Trigger signal transmission unit 17 Control unit 18 Directionality
adjustment unit (wavelength adjustment means, area adjustment means) 21 Ultrasonic wave
reception unit 21a Wave element 21b Substrate 22 Position calculation unit 23 Trigger signal
reception unit 24 Memory 29 Gyro sensor (direction detection means)
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