Position detector and fixation radio device of position detector

Abstract

To enhance the accuracy of detecting a position.SOLUTION: A position detector 100 has a fixation radio device 110 and a mobile radio device 120, and detects the position of a mobile radio device 120 on the basis of the propagation distance of a USB signal transmitted or received between the fixation radio device 110 and the mobile radio device 120. The fixation radio device 110 and the mobile radio device 120 each have an antenna 112 formed of a wire pattern in an insulation substrate 111b, and a radio absorbent 114 is provided on one surface side of the fixation radio device 110 and the insulation substrate 111b.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a position detection device that detects the position of a wireless device based on a distance measured using the wireless device, and a fixed wireless device of the position detection device.

Background Art

[0002] As a device for detecting the position of a mobile device, a technique is known in which the distance between a fixed device and a mobile device is measured using a wireless device, and the position of the mobile device is detected based on the measured distance (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When a fixed device is arranged indoors, for example, and the position of a mobile device in the room is detected, if multipath occurs due to reflection of radio waves by walls and furniture, the measurement error of the distance increases, and the detection accuracy of the position tends to decrease.

[0005] The present invention has been made in view of the above points, and an object thereof is to improve the detection accuracy of the position by the position detection device.

Means for Solving the Problems

[0006] To achieve the above object, the present invention is a position detection device including a fixed wireless device and a mobile wireless device, and detecting the position of the mobile wireless device based on a propagation distance of a UWB signal transmitted and received between the fixed wireless device and the mobile wireless device, The above fixed wireless device and mobile wireless device each have an antenna constituted by a wiring pattern formed on an insulating substrate. It is characterized in that a radio wave absorber is provided on at least one surface side of the insulating substrate in the fixed wireless device.

[0007] Thereby, the radio waves incident from the back side of the antenna can be attenuated, multipath can be suppressed, and the position detection accuracy can be improved.

Advantages of the Invention

[0008] In the present invention, multipath can be suppressed and the position detection accuracy can be improved.

Brief Description of the Drawings

[0009]

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Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0011] (Overview of the Position Detection Method) First, an overview of the position detection method by the position detection device 100 will be described. For example, as shown in FIG. 1, if four fixed wireless devices 110 are installed at predetermined known positions and the mobile wireless device 120 moves to an indefinite position, first, the distance between each fixed wireless device 110 and the mobile wireless device 120 is measured by ultra-wideband wireless communication (UWB: Ultra Wide Band) or the like. As the distance measurement method, for example, a method of measuring the round-trip propagation time of a wireless signal and converting it into a distance, a method of observing the wireless signal strength and converting it into a distance, a method of observing the arrival direction of a wireless signal, etc. are used. When the distance is obtained, the position (coordinates) of the mobile wireless device 120 can be calculated by finding the intersection points of circles with the observed distances centered on each fixed wireless device 110 as the radii. For the above position calculation, distances from three or more fixed wireless devices 110 are required. However, considering wireless communication failures (communication errors), obstacles, interference and noise from other wireless systems, etc., it is preferable to use distances from more fixed wireless devices 110, and it is preferably possible to use 4 to 5 or more directly visible (LOS state) fixed wireless devices 110 for high-precision observation.

[0012] Here, the radio waves and the like used for measurement are not particularly limited. For example, in the UWB method using a wide occupied bandwidth in a high-frequency wireless channel, the Low band from 3.4 GHz to 4.8 GHz or the High band from 7.25 GHz to 10.25 GHz can be used.

[0013] (Example of Arrangement of Fixed Wireless Device 110) The fixed wireless device 110 is usually preferably arranged close to the wall or furniture at the peripheral part of the observation target area. This is because it is desirable to widen the communication range with the mobile wireless device 120 while avoiding the influence on the available area of the observation target area. Also, it is to make it difficult for the power supply and data communication wiring to the fixed wireless device 110 to affect the convenience of the observation target area.

[0014] Specifically, for example, as shown in FIG. 2, when a plurality of fixed wireless devices 110 are arranged in the room 210, it is desirable to arrange them in the vicinity of the wall surface 211, the column 212, the window glass 213, the wall storage 214, etc. The arrangement position and the number of installed fixed wireless devices 110 are set so that as many as four or more directly visible (LOS state) fixed wireless devices 110, such as the above, exist in consideration of the positions of the desks 215 and partitions 216 installed in the room 210, etc., thereby enabling high-precision observation to be easily possible. In addition, when there are devices in the blind spot (NLOS state) where the fixed wireless device 110 and the mobile wireless device 120 cannot be directly seen, the communication results may be discarded.

[0015] (Structure of Fixed Wireless Device 110 and Mobile Wireless Device 120) When the fixed wireless device 110 is arranged in the vicinity of the wall surface 211, the column 212, furniture, etc. as described above, a plurality of radio wave transmission / reception paths (multipaths) are generated by reflection on the wall surface 211, etc., which tends to affect the accuracy of distance measurement. That is, for example, in the case of UWB distance observation, assuming that pulse modulation of 2 nS is used, a radio path difference of less than about 60 cm becomes a signal overlap generation condition, and the influence of multipath becomes strong when the distance between the reflector and the fixed wireless device 110 is less than about 30 cm.

[0016] Therefore, in the fixed wireless device 110 of the present embodiment, as shown in FIGS. 3 and 4, a radio wave absorber 114 is provided in the vicinity of the antenna 112. Specifically, the main body of the fixed wireless device 110 is, for example, a circuit component mounted on an insulating substrate 111b which is a sub-substrate attached to an insulating substrate 111a which is a base substrate, and the antenna 112 is formed by a wiring pattern. The main body is housed in the housing 113 so as to be covered by the housing 113, and the radio wave absorber 114 is disposed between the antenna 112 and the outer wall surface of the housing 113, for example, on at least one surface side of the insulating substrate 111a. The method of attaching the radio wave absorber 114 is not particularly limited, but for example, it is attached so as to be inserted into a slot 113a formed in the housing 113 as shown in FIG. 5. Further, for example, as shown in FIG. 6, it may be attached to the insulating substrate 111b or the like by a holder 115. Note that the radio wave absorber 114 may be brought into close contact with the inner surface of the housing 113 as much as possible, or may be brought into close contact with the back surface side of the antenna 112 (insulating substrate 111b).

[0017] Here, in order to obtain an equivalent radio wave absorption effect in the vertical, horizontal, and other directions, the radio wave absorber 114 desirably has a size larger than that of the antenna or dimensions that are equal in the vertical and horizontal directions with respect to the antenna 112. Further, the outer shape may be adapted to the outer shape of the antenna 112, but is not limited thereto, and may be set in consideration of installation conditions such as versatility for antennas other than circular ones such as rectangular shapes, and the relationship with the shapes of other components such as the substrate and the housing. That is, for example, for a circular antenna, although a circular shape may be an efficient shape for the radio wave absorber, it may be made square in terms of processing and mounting costs. Further, the arrangement of the radio wave absorber 114 may be adapted to the arrangement of the antenna 112, or may be arranged symmetrically about the center of the substrate or the housing in consideration of, for example, the fact that the antenna arrangement is usually at the center in the left-right direction of the substrate or the housing. Further, it may be arranged on the entire surface of the substrate or the housing.

[0018] As shown in FIG. 7, the mobile radio device 120 differs from the fixed radio device 110 only in the presence or absence of the radio wave absorber 114, and by configuring the radio wave absorber 114 to be detachable or easily detachable, the parts of the fixed radio device 110 and the mobile radio device 120 can be made common, reducing the manufacturing cost and enhancing the flexibility of switching between the two.

[0019] The fixed radio device 110 configured as described above can have, for example, an antenna gain (reception sensitivity characteristic) as shown in FIG. 8. That is, for example, when the antenna gain of the mobile radio device 120 without the radio wave absorber 114 has an omnidirectional (antenna characteristic uniform in all directions) as shown in FIG. 9, on the back side, the radio wave incident from an oblique direction is more attenuated than the radio wave incident from the vertical direction to the radio wave absorber 114. Therefore, as shown in FIG. 10, the radio wave reflected by the wall surface 211 or furniture in the room 210 and incident on the back side of the radio wave absorber 114, or the radio wave reflected on the back side of the antenna 112 and on the surface side of the radio wave absorber 114 is attenuated, and the distance can be measured with high accuracy mainly by the radio wave incident on the antenna 112 from the surface side.

Explanation of Reference Numerals

[0020] 100 Position detection device 110 Fixed radio device 111a Insulating substrate 111b Insulating substrate 112 Antenna 113 Housing 113a Slot 114 Radio wave absorber 115 Holder 120 Mobile radio device 210 Room 211 Wall surface 212 Column 213 Window glass 214 Wall cabinet 215 Desk 216 Partition

Claims

1. A position detection device comprising a fixed wireless device and a mobile wireless device, and detecting the position of the mobile wireless device based on the propagation distance of a UWB signal transmitted and received between the fixed wireless device and the mobile wireless device, wherein the fixed wireless device and the mobile wireless device each have an antenna constituted by a wiring pattern formed on an insulating substrate, and a radio wave absorber is provided on at least one surface side of the insulating substrate in the fixed wireless device. The position detection device is characterized by this.

2. The position detection device according to Claim 1, wherein the wiring pattern constituting the antenna of the fixed wireless device and the wiring pattern constituting the antenna of the mobile wireless device are formed identically. The position detection device is characterized by this.

3. The position detection device according to Claim 2, wherein the antenna of the fixed wireless device and the antenna in a state where the radio wave absorber of the mobile wireless device is absent have antenna characteristics that are uniform in all directions. The position detection device is characterized by this.

4. The position detection device according to Claim 1, wherein the radio wave absorber of the fixed wireless device is provided detachably. The position detection device is characterized by this.

5. The position detection device according to Claim 1, wherein the radio wave absorber of the fixed wireless device is attached to a housing that covers the insulating substrate. The position detection device is characterized by this.

6. The position detection device according to Claim 1, wherein the fixed wireless device is installed such that the radio wave absorber is positioned between the antenna and a nearby wall surface or furniture. The position detection device is characterized by this.

7. The fixed wireless device of the position detection device according to Claim 1, having the antenna constituted by a wiring pattern formed on the insulating substrate, and a radio wave absorber is provided on one surface side of the insulating substrate. The fixed wireless device of the position detection device is characterized by this.

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