JP2023158521A - Object positioning system - Google Patents

Abstract

To provide an object positioning system that can suppress errors in distance positioning as much as possible even if a beacon (transmitter) moves.SOLUTION: An object positioning system 100 consists of a transmitter 1 and a receiver 2. The object positioning system 100 includes a plurality of antennas 121-128 having different angles of polarization and one transmitter circuit 11. The transmitter circuit 11 is connected to the plurality of antennas 121-128 by switching for each frame of transmission. The receiver 2 calculates the distance to the transmitter using the maximum received radio wave strength among the plurality of antennas 121-128 of the transmitter 1.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to an object positioning system for knowing the position of a target object, and more specifically, an object positioning system comprising a transmitter and a receiver included in the target object, the transmitter being equipped with a plurality of antennas. Regarding.

As a power-saving method for detecting the position of a nearby monitored object, a base unit (receiver) receives the transmitted radio waves emitted from a beacon (transmitter) attached to the monitored object, and measures the strength of the received radio waves. There are widely known methods such as measuring a simple distance between a beacon and a base unit from (RSSI) or calculating the position of a beacon by three-point positioning from distance data of at least three base units.

Various services using such beacons have been considered, and various services have been released. Among them, beacons are attached to objects to be monitored as they move within the building. Specifically, these include tools and equipment used at construction sites (e.g., electric drills, generators, stepladders, and electric screwdrivers), and equipment and equipment used in hospitals (e.g., AEDs, ECMOs, oxygen cylinders, etc.). There is a beacon that can be attached to the drip metering pump).

Patent Document 1 and Patent Document 2 disclose systems for monitoring and managing target objects and people. In addition, Patent Document 2 discloses a system in which not only a beacon included in an object but also a base unit is moved.

JP 2019-165334 Publication JP2017-207366A

However, Patent Document 1 and Patent Document 2 do not describe how to solve problems related to antenna directivity. In other words, since the antenna has a direction in which the gain attenuates, the radio wave level of the transmitter and receiver differs depending on the direction. Therefore, for example, when a beacon is attached to an object that moves within a particular area, such as a construction site or a hospital, the direction of the transmitter relative to the receiver changes in various ways, and the situation of radio wave obstructions also changes. . This poses a problem in that a large error occurs in the distance to the base device calculated from the received radio wave intensity.
An object of the present invention is to provide an object positioning system that can suppress errors in distance positioning as much as possible even if a beacon (transmitter) moves.

In order to achieve the above object, the monitored object management system of the present invention includes a transmitter and a receiver, and the transmitter includes a plurality of antennas with different polarization plane angles and one transmission circuit, The transmitting circuit is connected to each antenna in a switched manner for each transmission frame, and the receiver calculates the distance to the transmitter using the maximum received radio wave intensity among the plurality of antennas of the transmitter. shall be.

As a result, even if the transmitter moves, the transmitter uses multiple antennas, so the receiver side calculates the distance to the transmitter using the maximum received radio wave strength among the transmitter's multiple antennas. Therefore, errors in distance positioning can be minimized without being affected by the directivity of each antenna of the transmitter and receiver. Furthermore, since the transmitter has only one transmitting circuit, it is inexpensive and compact. Furthermore, since the transmitter has one transmitting circuit and is connected by switching antennas, there is no antenna interference. Furthermore, by using a wireless device with an omnidirectional antenna, the influence of antenna gain deterioration is eliminated.

Further, in the object positioning system of the present invention, the receiver includes a plurality of receiving antennas having different polarization plane angles and one receiving circuit, and the receiving circuit includes a plurality of receiving antennas of the transmitter. is switched and connected to each receiving antenna each time the switching goes around, and the receiver calculates the distance to the transmitter using the maximum received radio wave intensity among the plurality of antennas of the receiver and the transmitter. is preferred.

Since the receiver has one receiving circuit, it is inexpensive and small. Furthermore, since the receiver has one receiving circuit and is connected by switching antennas, there is no antenna interference. Furthermore, by having a plurality of antennas at different angles, the effect of attenuation on antenna gain is eliminated. Furthermore, the influence of antenna gain deterioration due to the plane of polarization is also eliminated. Additionally, the receiver can receive the same power regardless of orientation.

FIG. 1 is a block diagram showing main parts of the object positioning system according to the present embodiment. A is a plan view showing the directivity of one antenna of this embodiment, B is a plan view showing the directivity of eight antennas, and C is a diagram showing antenna switching.

Hereinafter, a mode for carrying out the present invention will be described with reference to embodiments and drawings, but the embodiments shown below are not intended to limit the present invention to what is described herein, and the present invention is not intended to be limited to what is described herein. The invention can equally be applied to various modifications without departing from the technical idea shown in the claims. In addition, in the drawings used for explanations in this specification, each member is shown at a different scale in order to make each member recognizable on the drawing. The dimensions are not shown to scale.

[Embodiment]
The main parts of the object positioning system 100 of this embodiment will be explained using FIG. As shown in FIG. 1, the object positioning system 100 includes a transmitter 1 that is a BLE (Bluetooth Low Energy) beacon, a receiver 2 that is a base device, and a server (not shown).

Note that in the illustration, one transmitter 1 and one receiver 2 are each shown, but in an actual system, a plurality of transmitters 1 and receivers 2 can be used, and the transmitter 1 is attached to each object. Further, the receiver 2 is communicably connected to a management server device (not shown).

As shown in FIG. 1, the transmitter 1 includes a transmitting circuit 11, eight first to eighth antennas 121 to 128 each having a different angle of polarization plane, an RF switch 13, a control circuit 14, a RAM 15, It consists of ROM16. The transmitting circuit 12 transmits data related to its own device information etc. to the receiver 2 from the connected first to eighth antennas 121 to 128. The RF switch 13 connects the first to eighth antennas 121 to 128 selected by the instruction signal of the control circuit 14 to the transmission circuit 11. The control circuit 14 operates by executing a program stored in the ROM 16. The RAM 15 is a volatile memory that stores temporary data necessary for executing programs and the control circuit 14. The ROM 16 is, for example, a nonvolatile memory such as an EEPROM, and stores programs and data necessary for executing the control circuit 14.

As shown in FIG. 1, the receiver 2 includes a receiving circuit 21, eight first to eighth antennas 221 to 228 each having a different polarization plane angle, an RF switch 23, a control circuit 24, a RAM 25, It consists of ROM26. The receiving circuit 22 receives the transmitted data from the transmitter 1 from the first to eighth antennas 221 to 228, which are connected receiving antennas, and outputs the received radio wave intensity at that time to the control circuit 24. The RF switch 23 connects the first to eighth antennas 221 to 228 selected by the instruction signal of the control circuit 24 to the receiving circuit 22. The control circuit 24 operates by executing a program stored in the ROM 26, and calculates the distance to the transmitter using the received radio wave intensity from the receiving circuit 22. The RAM 25 is, for example, a volatile memory, and stores temporary data necessary for executing programs and the control circuit 24. The ROM 26 is a non-volatile memory such as an EEPROM, and stores programs and data necessary for the execution of the control circuit 24.

[antenna]
Antenna switching will be explained using FIG. 2. FIG. 2A is a plan view showing the directivity of one first antenna 121, FIG. 2B is a plan view showing the directivity of a combination of eight first to eighth antennas 121 to 128, and FIG. 2C is a plan view showing the directivity of a transmitter. 1 is a diagram showing switching timings of eight first to eighth antennas 121 to 128 of receiver 1 and eight first to eighth antennas 221 to 228 of receiver 2. FIG.

The first to eighth antennas 121 to 128 and the eight first to eighth antennas 221 to 228 of the receiver 2 are λ/4 antennas, and one first antenna 121 is omnidirectional in the vertical direction. . However, in the horizontal direction, there is a figure-8 directivity, as shown in FIG. 2A. Therefore, as shown in FIG. 2B, the eight first to eighth antennas 221 to 228 of the transmitter 1 are radially arranged in two-dimensional, even directions on a plane. Since it is omnidirectional in the vertical direction, it becomes an antenna group that is substantially omnidirectional in three dimensions. The eight first to eighth antennas 221 to 228 of the receiver 2 are also arranged in the same manner, forming a substantially omnidirectional antenna group.

Note that if the type of antenna changes, the arrangement may be made in accordance with the directivity of the antenna. Furthermore, although the number of antennas in this embodiment is eight for both the transmitter 1 and the receiver 2, the number can be increased or decreased. Moreover, the number of antennas of the receiver 2 can also be made singular. Further, since the λ/4 antenna is non-directional in the horizontal direction, the directions of the plane of polarization may be combined in the horizontal direction and the horizontal direction.

As shown in FIG. 2C, the connection of the first to eighth antennas 121 to 128 to the transmission circuit 11 is switched for each transmission frame by the operation of the RF switch 13 based on the instruction signal from the control circuit 14 of the transmitter 1. This transmission frame is transmitted to the receiver 2 every second.

Then, the connection of the first to eighth antennas 221 to 228 to the receiving circuit 11 is controlled by the operation of the RF switch 23 based on the instruction signal of the control circuit 24 of the receiver 2. 128 is switched every time the switching goes through one cycle. That is, the first to eighth antennas 221 to 228 are switched every 8 seconds.

In this way, all combinations of the first to eighth antennas 121 to 128 of the transmitter 1 and the first to eighth antennas 221 to 228 of the receiver 2 are performed. That is, in this embodiment, all the antennas of transmitter 1 and receiver 2 are used in 64 seconds. Then, the control circuit 24 of the receiver 2 calculates the distance to the transmitter 1 using the maximum received radio field strength among the received radio field strengths of all combinations.

Note that the actual distance calculation can be performed on the management server device side (not shown) based on the information sent from the receiver 2. Alternatively, the position of the transmitter 1 may be calculated by three-point positioning using the distances calculated by the three receivers 2.

Note that when there are multiple transmitters 1, all the transmitters 1 transmit the transmit frame within one period (for example, one second) of the transmit frame. Thereby, distances to all beacons can be calculated in a short time.

In this way, the transmitter 1 and the receiver 2 of the object positioning system 100 of this embodiment use a plurality of antennas with different polarization plane angles, so that the object to be monitored and the receiver to which the transmitter 1 is attached are Even if the antenna 2 moves, the distance to the transmitter is calculated using the combination of antennas with the highest received radio wave intensity, so the influence of antenna gain deterioration can be suppressed. In other words, variations in the power output from the transmitter 1 depending on the direction are suppressed, and variations depending on the direction in the receiver 2 are also suppressed, making it possible to minimize errors in distance positioning due to the radio wave level. .

Also, instead of using eight transmitting circuits and eight receiving circuits, one transmitting circuit 11 and one receiving circuit 21 are used by switching for the eight first to eighth antennas 121 to 128 (221 to 228). , it is inexpensive and compact, and there is no interference between antennas.

100: Target positioning system 1: Transmitter 11: Transmission circuit 121 to 128: 1st to 8th: Antenna 13: RF switch 14: Control circuit 2: Receiver 21: Transmission circuit 221 to 228: 1st to 8th 8: Antenna 23: RF switch 24: Control circuit

Claims (2)

Consists of a transmitter and a receiver,
The transmitter includes a plurality of antennas having different polarization plane angles and one transmission circuit,
The transmission circuit is connected to each antenna in a switched manner for each transmission frame,
The object positioning system is characterized in that the receiver calculates the distance to the transmitter using the maximum received radio wave intensity among the plurality of antennas of the transmitter. The receiver includes a plurality of receiving antennas having different polarization plane angles and one receiving circuit,
The receiving circuit is switched and connected to each receiving antenna every time the plurality of antennas of the transmitter are switched,
2. The object positioning system according to claim 1, wherein the receiver calculates the distance to the transmitter using the maximum received radio wave intensity among the plurality of antennas of the receiver and the transmitter.