WO2008010269A1

WO2008010269A1 - System for detecting position of mobile object

Info

Publication number: WO2008010269A1
Application number: PCT/JP2006/314260
Authority: WO
Inventors: Hiroshi Yamanaka; Yoshifumi Watabe; Yoshiaki Honda; Tomoo Otsuka; Hiromichi Goto; Kosaku Kitada; Kazuo Sawada; Hiroshi Kawada
Original assignee: Panasonic Electric Works Co., Ltd.
Priority date: 2006-07-19
Filing date: 2006-07-19
Publication date: 2008-01-24
Also published as: JPWO2008010269A1

Abstract

This system detects a position of a mobile object moving in premises, wherein an array sensor mounted on the mobile object moving in the premises receives a ultrasonic wave from a sound source set at a fixed position in the premises. The array sensor is comprised of a plurality of wave-receiving elements disposed in a two-dimensional form in which sensor coordinates are defined in disposing directions of the wave-receiving elements and a position of the mobile object is sought in the sensor coordinates for the sound source in accordance with a time lag of the ultrasonic wave arriving at each wave-receiving element. In the present system, a means is adopted for detecting an inclination of the sensor coordinates in a horizontal plane with respect to standard coordinates for specifying positions in the premises to convert the detected position of the mobile object in the sensor coordinates to a position of the standard coordinates, so that time sequential data of positions where the mobile object moves in various directions in the premises can be obtained.

Description

Specification

Moving body position detection system

Technical field

The present invention relates to a position detection system for detecting the position of a moving body that moves within a facility, and more specifically, the position of a moving body based on ultrasonic waves generated by a sound source force fixed at a fixed position of the facility. The present invention relates to a system that detects the position and transmits the detected position data to an external monitoring device.

Background art

Japanese Patent Publication JP7-140241 discloses a conventional system for detecting the position of a moving body in a facility. This system is configured to detect the position of the moving object by receiving the ultrasonic waves from the two ultrasonic transmitting sources by the moving object and determining the distance between the moving object and these two ultrasonic transmitting sources. Has been. This system requires two ultrasonic sources, making it difficult to install in the facility, and it is necessary to synchronize the ultrasonic waves from each ultrasonic source, which complicates the system. is there.

On the other hand, as disclosed in Japanese Patent Laid-Open No. 2005-49301, a method of detecting the position of an object by receiving ultrasonic waves using an array sensor in which a plurality of receiving elements are arranged. A formula has been proposed. However, when this array sensor is mounted on a moving body and combined with an ultrasonic transmission source fixed at a fixed position in the facility, the array sensor can detect the moving body within the sensor coordinates determined by the array direction of the receiving elements. The problem is that it is only possible to detect the position and it is difficult to determine the actual position of the moving object in the facility.

Disclosure of the invention

[0004] The present invention has been made in order to solve the above-mentioned problems. The array sensor is used to reduce the number of ultrasonic transmission sources and simplify the installation work in the facility. It is an object of the present invention to provide a position detection system that can accurately detect the position of a moving body at the mobile station and perform accurate flow line measurement of the moving body.

[0005] A position detection system for a moving body according to the present invention is installed at a fixed position of a facility and transmits ultrasonic waves. It is mounted on a fixed sound source equipped with a transmitting ultrasonic transmitter and a moving body that moves within the reference coordinates including the above sound source, and continuously detects the position of the moving body within the reference coordinates. A position detection module that creates time-series data of the detection positions and an output module that outputs the time-series data to an external monitoring device are provided. The position detection module includes an array sensor in which a plurality of receiving elements that receive ultrasonic waves of the ultrasonic transmitter force are two-dimensionally arranged, and a position detection unit. This array sensor has a unique sensor coordinate determined by the direction in which the plurality of receiving elements are arranged. The position detection unit detects the azimuth of the sound source in the sensor coordinates based on the time lag of the ultrasonic waves arriving at the receiving elements from the ultrasonic transmitter. A distance between one of the receiving elements and the sound source is obtained, and the position of the moving body in the sensor coordinates is determined based on the azimuth and distance. The feature of the present invention is that the position detection module further includes a tilt sensor that detects a tilt angle of the sensor coordinates with respect to the reference coordinates in a plane parallel to a horizontal plane including the sound source, and a detected tilt angle. Based on the position correction unit, the position of the moving body in the sensor coordinates is converted into the position in the reference coordinates, and this is determined as the detection position of the moving body in the reference plane. It was to have. For this reason, in the present invention, the position of the moving body in the facility can be accurately detected while the number of ultrasonic transmission sources is reduced by using the array sensor, and an accurate flow line measurement of the moving body is performed. Is possible.

[0006] As the ultrasonic transmitter, a support substrate, a heating element layer formed on one surface side of the support substrate, and a support substrate and a heating element layer interposed on the one surface side of the support substrate are interposed. It is desirable to use an ultrasonic generating element that includes a heat insulating layer and generates ultrasonic waves as the temperature of the heating element layer changes with energization of the heating element layer. An ultrasonic transmitter with such a configuration can generate an ultrasonic wave with a short reverberation time with a small Q value of the resonance characteristics and a short generation period, and shortens the dead zone due to the reverberant component of the ultrasonic wave. Accurate position detection.

[0007] In addition, it is desirable that the wave receiving element is composed of a capacitance type microphone that converts the sound pressure of ultrasonic waves into a change in capacitance. In this case, the Q value of the resonance characteristics of the receiving element can be reduced, and the residual in the received signal that is generated when ultrasonic waves are received by the receiving element. The reverberation time can be shortened, and the dead zone caused by the reverberation component in the received signal output from the receiving element can be shortened, so that accurate position detection can be performed.

[0008] Preferably, the sound source includes a trigger signal transmitter that transmits a trigger signal, and a controller that transmits the ultrasonic wave in synchronization with the trigger signal. In this case, the position detection module includes a trigger signal receiver that receives the trigger signal, and the position detection unit receives the trigger signal and one of the receiving elements receives the ultrasonic wave. The distance between the sensor array and the sound source is determined from the difference from the time. For this reason, the array sensor can be used to measure the distance between the sound source and the moving object, and the position of the moving object is detected.

[0009] Further, a trigger signal transmitter that transmits a trigger signal to the mobile body may be provided, and the sound source may be provided with a controller that transmits the ultrasonic wave when the trigger signal is received. It is. In this case, the position detection unit obtains the distance between the sensor array and the sound source from the difference between the time when the trigger signal is transmitted and the time when one of the receiving elements receives the ultrasonic wave. Thus, the distance between the sound source and the moving object can be measured.

[0010] Further, in the present invention, it is possible to include a plurality of sound sources so as to detect the position of the moving body within a wide area. In this case, each sound source includes an identification code transmitter for transmitting a unique identification code, and the position detection module is provided with a sound source identification unit for receiving the identification code. The sound source identification unit is configured to associate the received identification code with the time-series data described above, whereby a plurality of sound sources can be identified, and a wide range of facilities in a facility covered with a plurality of sound sources can be identified. It is possible to accurately detect the position of the moving body that moves across the area.

[0011] When a plurality of sound sources are provided, in addition to an identification code transmitter that transmits a unique identification code, each sound source includes a controller that transmits ultrasonic waves in synchronization with the identification code. It is possible to provide. In this aspect, the position detection module is provided with a sound source identification unit that receives the identification code, and the sound source identification unit gives the time when the identification code is received to the position detection unit. The position detection unit includes the time when the identification code is received and one of the receiving elements that receives the ultrasonic wave. The distance between the sensor array and the sound source is obtained from the deviation from the digit time, and the sound source identification unit is configured to associate the received identification code with the time-series data. According to this configuration, it is possible to detect the position of the moving body in a wide area, and the distance between the moving body and the sound source can be obtained using the identification code.

[0012] The advantages of the present invention described above and other advantages will become apparent from the following detailed description of embodiments with reference to the accompanying drawings.

Brief Description of Drawings

FIG. 1 is a schematic diagram showing an example of use of a position detection system for a moving body according to the present invention.

FIG. 2 is a schematic diagram showing the relationship between sensor coordinates of an array sensor used in the present invention and reference coordinates that specify the position of a moving object in a facility.

FIG. 3 is a plan view showing an arrangement method of receiving elements in the array sensor same as above.

FIG. 4 is a block diagram showing the configuration of a system according to an embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a method for detecting the direction of a sound source using the above array sensor.

[FIG. 6] (A), (B), (C), and (D) are explanatory diagrams showing a method for detecting the direction of the sound source.

FIG. 7 is an explanatory diagram showing the direction of the sound source from the moving body.

FIG. 8 is a schematic diagram illustrating a method for detecting the position of a moving object.

FIG. 9 is a schematic diagram illustrating a method for detecting the position of a moving object.

FIG. 10 is a schematic diagram illustrating a method for detecting the position of a moving object.

FIG. 11 is a cross-sectional view of a thermal excitation type ultrasonic generator used in the system described above.

FIG. 12 is a waveform diagram of ultrasonic waves generated by the thermal excitation type ultrasonic generating element.

FIG. 13 is a partially cutaway perspective view showing the configuration of a capacitive microphone used in the system described above.

FIG. 14 is a cross-sectional view of the electrostatic capacity microphone of the above.

BEST MODE FOR CARRYING OUT THE INVENTION

As shown in FIGS. 1 to 4, the position detection system for a moving body according to the present invention is preferably used for detecting the position of the moving body M in a facility and measuring the flow line of the moving body. Is what Thus, for example, the sound source 10 is fixed at a predetermined position on the ceiling, and the position measuring device 30 is mounted on the moving body M. The sound source 10 includes an ultrasonic transmitter 20 and intermittently transmits ultrasonic waves having a short reverberation time. The position measurement device 30 includes a position detection module 40 and an output module 90 that wirelessly transmits time-series data related to the position measured by the position measurement module to the external monitoring device 100.

The position detection module 40 includes an array sensor 50 that receives ultrasonic waves from the ultrasonic transmitter 20, and the array sensors 50 are equally spaced in a two-dimensional plane on a substrate 51 as shown in FIG. It is composed of six receiving elements 52 to 52 arranged in four, and four receiving elements 52 to 52

The direction in which 1 6 1 4 are arranged in a row is the X axis, and three receiving elements 52, 52, 52 are arranged perpendicular to this

2 5 6 Form sensor coordinates with the y-axis in the direction. The array sensor 50 is installed on the moving body M so that its x-y plane is parallel to the horizontal plane of the facility. As shown in Fig. 2, the sensor coordinates are in a plane parallel to the horizontal plane including the sound source 10 with respect to the reference coordinates that ultimately determine the position of the moving body within the facility depending on the orientation of the moving body M. Tilt at an inclination angle (Θ)

1 will be skewed. The reference coordinates are defined by the X, Y, and Z axes shown in the figure, and share the sensor coordinates and the Z axis. The center distance d of the receiving element is set to 0.5 to 5 times the wavelength of the ultrasonic wave used.

[0016] The sound source 10 is provided with a trigger signal generator 16 and a controller 14 that periodically transmit a trigger signal by light or radio waves, and the controller 14 outputs the above-described ultrasonic wave in synchronization with the trigger signal. To do. For example, a trigger signal and an ultrasonic wave are transmitted every second. The position detection module 40 includes a trigger receiver 46 that receives a trigger signal, recognizes the time when the trigger signal is received, and then analyzes the ultrasonic waves that reach the array sensor 50, and will be described below. As described above, the orientation of the moving body M with respect to the sound source 10 and the distance S between the sound source 10 and the moving body M are obtained, and the position of the moving body M is determined.

When ultrasonic waves from the sound source 10 are received by the receiving elements 52 to 52 of the array sensor 50,

1 6

The receiving elements 52 to 52 output an electric signal corresponding to the receiving element 52 to 52, and the electric signal is converted into an AZD converter.

1 6

The intensity value of the converted ultrasonic wave is held in the data buffer 42 together with the time determined by the output of the trigger receiver 46 described above. The position detection module 40 is provided with a position detection unit 60. The position detection unit 60 reads the data in the data buffer 42, and the sound source 10 And the distance S between the sound source 10 and the moving body M are obtained. First, the method for determining the direction will be described with reference to FIGS. In the description below, the position of the sound source 10 is displayed at the origin of the X—Y horizontal plane in the reference coordinates and the x—y horizontal plane in the sensor coordinates.

[0018] The azimuth of the moving body M, that is, the array sensor 50 with respect to the sound source 10 is determined by the azimuth angle (θ X) in the vertical plane including the X axis of the sensor coordinates and the azimuth angle (Θ y in the vertical plane including the y axis). These azimuth angles (0 χ, θ γ) are determined by the receiving elements 52 to 52 arranged along the X axis, and the y axis

1 Receiver elements lined up 4 4

2, 52

5, Based on the time shift of the ultrasonic wave reaching 52 6

Determined.

[0019] As shown in FIG. 5, the four receiving elements arranged on the X-axis are time-shifted to an electrical signal in which the ultrasonic wave from the sound source 10 is incident at 0 angle and the receiving element force is also output. Occurs. This temporal shift is a function of the incident angle Θ X and is expressed by the following equation, where d is the center-to-center distance between the receiving elements and c is the speed of sound.

[0020] [Equation 1]

[0021] Considering this time lag, the total value of the intensity of the ultrasonic waves reaching all the receiving elements is obtained, and the incident angle (Θ X) when this total value exceeds a predetermined value Force Determines the direction of sound source 10 in the vertical plane including the X axis.

That is, the other three receiving waves are added to the electric signal output from one receiving element 52 shown in FIG.

Four

The three receiving elements 52, 52, and 52 are also matched to match the time of the output electrical signal.

one two Three

The electrical signal from the wave element is delayed through the delay circuits 55, 55, 55 to receive one wave

one two Three

Add to the electrical signal output from the element using adders 56, 56, 56, and add the total value.

one two Three

Compare with a predetermined value. In this calculation, 0 χ is changed over the range of 45 ° to + 45 °, and the angle Θ X when the total value exceeds a predetermined value is calculated as the angle Θ X in the plane including the X axis. Determine the direction of the sound source. For example, in Fig. 6, if the spacing between the receiving elements is d2 = d3 = d4 = 4mm, the speed of sound is c = 340m / s, and the direction of the sound source (θ χ) is 5 °, Θ χ = 5 °, that is, when the delay time is 1 μs, the signals of each receiving element are added. Thus, the total value exceeds a predetermined value. Other than that, for example, as shown in FIGS. 6A, 6C and 6D, 0x is set to 0 ° (delay time = 0 3), 10 ° (delay time = 2 3), 45 ° (delay time = 8 s) Sometimes, the total value that the output signals from the receiving elements are not added at the same time falls below a predetermined value. Similarly, the azimuth (Θ y) of the sound source in the vertical plane including the y axis is obtained.

[0023] In the position detection unit 60, from the difference between the time when the trigger signal is received and the time when the ultrasonic wave is received by one of the receiving elements, the array sensor 50, that is, the moving object M and the sound source The distance S is calculated, and the position p (xl, yl, Zl) of the moving body M in the sensor coordinates is determined based on the θ χ, Θ y and force obtained above, and the following formula, and is shown in Fig. 9. Find the azimuth angle (Θ s) for the sound source in the horizontal plane in the sensor coordinates.

[0024] [Equation 2] χ _χ -Ζ _χ · tan θκ

[0025] [Equation 3]

= Z ₁ -tan ^ y

[0026] [Equation 4]

[0027] [Equation 5]

ΘΞ = tany L,

[0028] The position detection module 40 detects the inclination angle (0) of the moving body M in the horizontal plane.

1 Tilt sensor 70 is provided. As this tilt sensor, for example, a gyro sensor or a geomagnetic sensor is used, and the tilt angle (Θ) of the X axis of the sensor coordinates with respect to the X axis of the reference coordinates is set.

1 Ask. This tilt angle (Θ) is related to the time of the data buffer.

1 Holds at 42.

[0029] The position detection module 40 further includes a sensor coordinate based on the tilt angle (0). Position of the mobile _{p (xl, y l, Zl} ), the position P of the moving body at the reference coordinates (XI, Yl, Zl) is the position correcting unit 72 that converts the provided with.

In this conversion, as shown in FIG. 10, the orientation (Θ r) of the array sensor 50 with respect to the sound source in a plane parallel to the horizontal plane including the sound source is obtained by the following equation.

[0031] Garden

[0032] Based on this azimuth, the position, (XI, Yl, Z1) in the reference coordinates of the moving body is determined by the following equation.

[0033] [Equation 7]

X = L _X .cos

[0034] [Equation 8]

Y ₁ = 丄-sin

[0035] [Equation 9]

[0036] The position P (X1, Yl, Zl) of the moving body in the reference coordinates obtained as described above is related to the time output from the timer 47 that is started by receiving the trigger signal, and the time elapses. Is stored in the memory 80 in the form of a data table indicating the movement of the position of the moving object. The output module 90 periodically reads the data table in the memory 80 and transmits it to the external monitoring device 100 wirelessly. As a result, the monitoring device 100 is configured by a computer, processes the time-series data of the position information shown in the data table transmitted from the mobile unit M, displays the flow line result of the mobile unit on the monitor, Configured to issue a report. The output module 90 includes, for example, a serial transfer interface such as TIAZEIA-232-E or USB, or a parallel transfer interface such as SCSI, etc., and is held in the memory 80. The above time-series data is transmitted to the monitoring apparatus 100. [0037] The sound source 10 is further provided with an identification code transmitter 18. When the identification code for identifying the sound source is transmitted by light or radio waves and a plurality of sound sources are provided to cover a wide facility, Sound source 10 is identified. Correspondingly, the position detection module 40 includes an identification code receiver 48 that receives an identification code and a sound source identification unit 49 for identifying a sound source based on the received identification code. The sound source identification unit 49 adds an identification code indicating the identified sound source to the data table of the position data held in the memory 80 described above. Thereby, when there are a plurality of sound sources, the monitoring apparatus 100 can process the positional information in association with the corresponding sound sources, and can accurately perform the flow line measurement of the moving body over a wide area. For this reason, the location information of each sound source in the facility is included in the identification code. That is, the time series data in the memory 80 is given, for example, in the data table format shown in Table 1 below, and the monitoring device 100 can process this data to obtain the movement line trajectory of the moving object.

Note that after the creation of this data, the position detection module 40 discards the data in the data buffer 42 and accumulates new data.

[0038] [Table 1]

[0039] The ultrasonic transmitter 20 is configured to intermittently generate an ultrasonic wave having a short reverberation time, that is, to intermittently generate an ultrasonic wave having a short generation period. For this reason, a thermally excited element having a structure as shown in FIG. 11 is used. This element has a heating element layer 23 made of a metal thin film (for example, a tungsten thin film) through a thermal insulating layer 22 having a porous silicon layer force on the upper surface of a support substrate 21 having a single crystal p-type silicon substrate force 23. And a pair of pads 24 electrically connected to the heating element layer 23 is formed on the upper surface side of the support substrate 21. In such a thermal excitation type ultrasonic wave generating element, it passes between the pads 24 at both ends of the heating element layer 23. When electricity is applied to cause a temperature change in the heating element layer 23, a temperature change occurs in the air coming into contact with the heating element layer 23. The air in contact with the heating element layer 23 expands when the temperature of the heating element layer 23 rises and contracts when the temperature of the heating element layer 23 decreases, so by appropriately controlling energization to the heating element layer 23 Ultrasonic waves that propagate in the air can be generated.

[0040] In this thermal excitation type ultrasonic generating element, an ultrasonic wave is generated in accordance with a temperature change of the heating element layer 33 accompanying energization to the heating element layer 23, and a drive voltage applied to the heating element layer 23 Or, if the waveform of the drive current is a sine wave waveform with a frequency of fl, for example, an ultrasonic wave having a frequency approximately twice the frequency f 1 can be generated. By applying a wave as a drive voltage between the pair of pads 24, it is possible to generate an ultrasonic wave of approximately one cycle with a short reverberation time and a short generation period as shown in FIG. With a thermal excitation type ultrasonic wave generator, the frequency of the generated ultrasonic wave can be changed over a wide range. If the waveform of the drive voltage or drive current is an isolated wave, it is almost 1 as shown in Fig. 12. Periodic ultrasonic waves can be generated.

[0041] In this thermal excitation type ultrasonic wave generating element, a p-type silicon substrate is used as the supporting substrate 21, and the thermal insulating layer 22 is constituted by a porous silicon layer having a porosity of approximately 70%. A porous silicon layer serving as the thermal insulating layer 22 can be formed by anodizing a part of the silicon substrate used as the support substrate 21 in an electrolyte solution composed of a mixed solution of hydrogen fluoride aqueous solution and ethanol. it can. Here, by appropriately setting the conditions for anodizing treatment (for example, current density, energization time, etc.), it is possible to set each of the porous pore thicknesses of the porous silicon layer serving as the thermal insulating layer 22 to a desired value. it can. The porous silicon layer has a lower thermal conductivity and heat capacity as the porosity increases, for example, thermal conductivity is 148WZ (m'K), heat capacity is 1.63 X 10 ⁶ j / (m ³ 'K) A porous silicon layer formed by anodizing a single crystal silicon substrate with a porosity of 60% has a thermal conductivity of 1 WZ (m'K) and a heat capacity of 0.7 X 10 ⁶ j / ( m ³ 'K). In this embodiment, as described above, the thermal insulating layer 22 is composed of a porous silicon layer having a porosity of approximately 70%, the thermal conductivity of the thermal insulating layer 22 is 0.12 WZ (m′K), and the heat capacity. Is 0.5 X 10 ⁶ jZ (m ³ 'K). The thermal conductivity and heat capacity of the thermal insulating layer 22 are made smaller than the thermal conductivity and thermal capacity of the support substrate 21, and the product of the thermal conductivity and thermal capacity of the thermal insulation layer 22 is the thermal conductivity of the support substrate 21. By making the temperature sufficiently smaller than the product of temperature and heat capacity, the temperature change of the heating element layer 23 can be efficiently transmitted to the air, and efficient heat exchange between the heating element layer 23 and air can be achieved. And the support substrate 21 can efficiently receive the heat from the heat insulating layer 22 and release the heat from the heat insulating layer 22, and the heat from the heating element layer 23 is accumulated in the heat insulating layer 22. Can be prevented.

[0042] The heating element layer 23 is formed of tungsten, which is a kind of refractory metal, and has a thermal conductivity of 174 WZ (mK) and a heat capacity of 2.5 X 10 ⁶ jZ (m ³ 'K). Yes. The material of the heating element layer 23 is not limited to tungsten, and for example, tantalum, molybdenum, iridium, or the like may be employed.

[0043] It should be noted that in the above thermal excitation type ultrasonic generating element, the thickness of the support substrate 21 is 525 m, the thickness of the thermal insulating layer 22 is 10 μm, the thickness of the heating element layer 23 is 50 nm, Although the thickness of the pad 34 is 0.5 μm, these thicknesses are merely examples and are not particularly limited. In addition, the force of adopting Si as the material of the support substrate 21 The material of the support substrate 31 is not limited to Si, and other materials such as Ge, SiC, GaP, GaAs, and InP can be made porous by anodizing treatment. Other semiconductor materials may be used.

[0044] As a receiving element used for the array sensor 50, a capacitive microphone is used in order to reduce reverberation in the same manner as an ultrasonic wave generating element. This microphone is formed by using a micromachining technique. As shown in FIGS. 13 and 14, a rectangular frame 150 having a window hole 151 penetrating in a thickness direction in a silicon substrate, And a cantilever-type pressure-receiving film 152 disposed so as to straddle two opposing sides. A thermal oxide film 155, a silicon oxide film 156, and a silicon nitride film 157 are formed on the upper surface side of the frame 150. The pressure receiving film 152 is a silicon film formed separately from the silicon nitride film 156. One end of the frame is supported on the frame 150 via the silicon nitride film 157 on one side of the frame, and the free end is opposed to the silicon nitride film 157 on the other side of the frame. A fixed electrode 153 made of a metal thin film (for example, a chromium film) is formed on the silicon nitride film 157 on the frame facing the free end of the pressure receiving film 152, and the fixed electrode 153 is formed on the free end of the pressure receiving film 152. A movable electrode 154 made of a metal thin film (for example, a chromium film) is formed on the upper surface opposite to the facing surface. Silicon nitride on the bottom of the frame 150 A film 158 is formed.

In the wave receiving element 52 configured as described above, a capacitor having the fixed electrode 153 and the movable electrode 154 as electrodes is formed, and the pressure receiving film 152 receives the pressure of the ultrasonic wave so that the fixed electrode 1 53 and The distance between the movable electrode 154 changes, and the electrostatic capacity between the fixed electrode 153 and the movable electrode 154 changes. Therefore, if a DC bias voltage is applied between pads (not shown) provided on the fixed electrode 153 and the movable electrode 154, a minute voltage change occurs between the pads in accordance with the sound pressure of the ultrasonic waves. The sound pressure of ultrasonic waves can be converted into electrical signals.

Note that the structure of the capacitive microphone used as the wave receiving element 52 is not particularly limited to the above structure. For example, it is formed by processing a silicon substrate or the like using a micromachine technology or the like. The gap length between the diaphragm and back plate in a state where no ultrasonic waves are received is defined between the movable electrode that receives the force of the diaphragm and the fixed electrode that consists of the back plate facing the diaphragm. It may have a structure in which a spacer portion made of an insulating film is interposed and a plurality of exhaust holes are provided through the back plate portion. In such a capacitance type microphone, the diaphragm part receives ultrasonic waves and deforms to change the distance between the diaphragm part and the back plate part, so that the electrostatic capacity between the movable electrode and the fixed electrode is changed. Changes.

By the way, in the thermal excitation type sound wave generating element shown in FIG. 11, the Q value of the resonance characteristic is about 1, and the wave receiving element 52 having the electrostatic capacity type microphone force shown in FIG. 13 and FIG. The Q value of the resonating characteristics is about 3 to 4, and the dead zone caused by the reverberation component in the ultrasonic wave transmitted from the sound source 10 can be shortened, and the ultrasonic wave is received by the receiving element 52. The reverberation time in the received signal that occurs sometimes can be shortened, and the dead zone caused by the reverberation component in the received signal that is output from the receiving element 52 can be shortened, so the angle resolution can be improved. . Capacitance-type microphones have a Q value with low resonance characteristics, so that the range of received frequencies can be widened. In this regard, the Q values of the resonance characteristics of the sound source 10 and the receiving element 52 are both preferably 10 or less, and more preferably 5 or less.

Claims

The scope of the claims

[1] Installed in a fixed sound source with an ultrasonic transmitter installed at a fixed location in the facility and a moving body that moves within the reference coordinates including the above sound source. A position detection module that continuously detects the position of the moving object and creates time series data of the detected position;

An output module that outputs this time-series data to an external monitoring device;

With

The position detection module includes an array sensor in which a plurality of receiving elements that receive ultrasonic waves of the ultrasonic transmitter force are two-dimensionally arranged, and a position detection unit.

The array sensor has a unique sensor coordinate determined by the arrangement direction of the receiving elements.

The position detection unit detects the direction of the sound source in the sensor coordinates based on the time lag of the ultrasonic waves arriving at the receiving elements from the ultrasonic transmitter, and Determining the position of one of the wave elements and the sound source, and determining the position of the moving body within the sensor coordinates based on the azimuth and distance; ,

An inclination sensor for detecting an inclination angle of the sensor coordinates with respect to the reference coordinates in a plane parallel to a horizontal plane including the sound source;

Based on the detected tilt angle, the position of the moving body in the sensor coordinates is converted into a position in the reference coordinates, and this is used as the detection position of the moving body in the reference plane. Position correction unit to determine

A position detection system for a moving object comprising:

[2] The ultrasonic transmitter includes a support substrate, a heating element layer formed on one surface side of the support substrate, and heat interposed between the support substrate and the heating element layer on the one surface side of the support substrate. 2. The moving body according to claim 1, further comprising: an insulating layer, and an ultrasonic wave generating element force that generates an ultrasonic wave in accordance with a temperature change of the heating element layer when the heating element layer is energized. Position detection system.

[3] The receiving element is a capacitive microphone that converts ultrasonic sound pressure into a change in capacitance. The position detection system for a moving body according to claim 1 or 2, wherein the mouthphone force is given.

[4] The sound source includes a trigger signal transmitter that transmits a trigger signal, and a controller that transmits the ultrasonic wave in synchronization with the trigger signal.

The position detection module includes a trigger signal receiver that receives the trigger signal, and the position detection unit includes a time when the trigger signal is received, and a time when one of the receiving elements receives the ultrasonic wave. 4. The position detection system for a moving body according to claim 1, wherein a distance between the sensor array and the sound source is obtained from a deviation of the position.

[5] A trigger signal transmitter for transmitting a trigger signal to the mobile body is provided,

The sound source includes a controller that transmits the ultrasonic wave when the trigger signal is received,

The position detection unit obtains a distance between the sensor array and the sound source from a difference between a time when the trigger signal is transmitted and a time when one of the receiving elements receives the ultrasonic wave. The position detection system of the moving body according to any one of claims 1 to 3.

[6] A plurality of the above sound sources are provided,

Each sound source has an identification code transmitter that transmits a unique identification code,

The position detection module is provided with a sound source identification unit that receives the identification code,

6. The position detection system for a moving body according to claim 1, wherein the sound source identification unit is configured to associate the received identification code with the time-series data.

[7] A plurality of the above sound sources are provided,

Each sound source includes an identification code transmitter that transmits a unique identification code, and a controller that transmits the above ultrasonic wave in synchronization with the above identification code,

The sound source identification unit gives the time when the identification code is received to the position detection unit, The position detection unit obtains the distance between the sensor array and the sound source from the difference between the time when the identification code is received and the time when one of the receiving elements receives the ultrasonic wave.

4. The moving body position detection system according to claim 1, wherein the sound source identification unit is configured to associate the received identification code with the time-series data.