JP2014065567A - Position measuring system and article storing facility with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a position measuring system which can calculate a height-direction position coordinate of a transmission part in addition to a position coordinate of the transmission part in a plan view with high accuracy and which is advantageous in terms of cost, and to provide an article storing facility with the position measuring system.SOLUTION: A plurality of reception parts J are arranged at positions different from each other in height and same in a plan view in a moving object space, and a position calculating part can perform a height calculation processing for calculating a height-direction position coordinate of a transmission part S2 with respect to a three-dimensional orthogonal coordinate system in the moving object space based on relative position information between each of the plurality of reception parts J and the transmission part S2 measured by a relative position measuring device.

Description

  The present invention provides a transmitter that is provided in a movable body that can move in a movement target space and that can transmit a position measurement signal for detecting the position of the movable body, and a position measurement signal transmitted from the transmitter. Based on a position detection signal transmitted from the transmission unit, a relative position measurement device that measures a relative position of the transmission unit with respect to the reception unit, and a measurement by the relative position measurement device Based on the relative position information between the transmitting unit and the receiving unit, the position calculation for calculating the position coordinates of the transmitting unit in a three-dimensional orthogonal coordinate system set in a state in which one axis extends in the vertical direction in the movement target space A position measuring system including the unit, and an article storage facility including the position measuring system.

Such a position measurement system is used, for example, to calculate the position coordinates of a forklift as a movable body that is movable in a movement space set in a storage space of an article storage facility as a movement target space. The calculated position coordinates of the forklift are used for managing the position and the like of the articles conveyed by the forklift by a host management device.
As a method for calculating the position coordinates of the forklift, for example, a wireless position detection tag as a transmitter is attached to the forklift, and a wireless positioning base station as a receiver is fixed at a predetermined position in the storage space. The positioning base station receives a radio wave as a position detection signal transmitted by the position detection tag, measures the relative position of the position detection tag with respect to the positioning base station based on the radio wave, There is one that calculates position coordinates in a plan view of a position detection tag in the storage space based on the relative position information (see, for example, Patent Document 1).

  The article storage facility provided with the position measurement system in Patent Document 1 is a so-called flat-type article storage facility that directly stores and stores articles to be transported on the floor surface. In this case, it is not necessary to grasp the position in the direction (height direction) along the vertical direction of the article conveyed by the forklift. However, in an article storage facility that stores articles to be transported in an article storage shelf provided with a plurality of storage units arranged in the height direction, the articles may be stored in storage units located at different heights. It is necessary to calculate the position coordinate in the height direction in order to know in which storage part it is stored in the height direction.

JP 2010-18408 A

  The position measurement signal may be an ultrasonic wave or the like in addition to the radio wave as described in Patent Document 1, for example. If the propagation speed of the position measurement signal such as the radio wave or the ultrasonic wave is such, the moving body moves. Depending on the size of the moving space, there is a possibility that the propagation time of the position measurement signal cannot be secured sufficiently and the position coordinates of the transmission unit cannot be calculated accurately. And since the space for a movement has the planar expansion which a mobile body moves, the dimension of a height direction is often a flat shape smaller than the dimension of the direction along a horizontal surface (it is thin in a height direction). For this reason, there is a possibility that the position coordinates of the transmitting unit cannot be accurately calculated in the height direction in which the distance between the transmitting unit and the receiving unit tends to be shorter than the direction along the horizontal plane.

  For this reason, as a method for accurately calculating the position coordinates in the direction along the height direction, for example, the displacement distance of the load handling of the forklift is measured using a measuring device such as a rotary encoder or a laser rangefinder, and the measurement is performed. It is conceivable to calculate the position coordinates in the height direction based on the values. However, in such a configuration, it is necessary to provide a separate device only for measuring the position in the height direction in addition to the device for measuring the position in plan view, which is disadvantageous in terms of cost. there were.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to accurately calculate the position coordinate in the height direction of the transmission unit in addition to the position coordinate in plan view of the transmission unit, and to reduce the cost. It is an object of the present invention to provide a position measurement system that is advantageous in terms of surface and an article storage facility including the position measurement system.

A first characteristic configuration of a position measurement system according to the present invention for solving the above-described problem is a position measurement signal provided for a movable body that is movable in a movement target space and for detecting the position of the movable body. Based on the position measuring signal transmitted from the transmitting section, the receiving section capable of receiving the position measuring signal transmitted from the transmitting section, and the position measuring signal transmitted from the transmitting section, the relative position of the transmitting section to the receiving section And a tertiary set in a state where one axis is aligned in the vertical direction in the space to be moved based on relative position information of the transmitting unit and the receiving unit measured by the relative position measuring device. A position calculation system comprising: a position calculation unit that calculates position coordinates of the transmission unit in an original orthogonal coordinate system,
A plurality of the reception units are provided at different heights in the movement target space and at the same position in plan view, and the position calculation unit transmits the transmission to each of the plurality of reception units measured by the relative position measurement device. Based on the relative position information with respect to the unit, the height calculation process for calculating the position coordinate in the height direction for the three-dimensional orthogonal coordinate system in the movement target space of the transmission unit is configured to be executable. is there.

That is, since a plurality of receiving units are provided at the same position in plan view in different heights in the movement target space, the position coordinates for the three-dimensional orthogonal coordinate system in the movement target space of the plurality of receiving units are The position coordinates at are the same, and only the position coordinates in the height direction are different.
Then, the position calculation unit is configured to move the transmission unit based on the relative position information between the reception unit and the transmission unit, which have the same position coordinates in plan view but differ only in the height direction as described above. The position coordinates in the height direction for the three-dimensional orthogonal coordinate system in the space are calculated.

A difference in relative position information between each of a plurality of receiving units having the same position coordinates in plan view and the transmitting unit can be grasped as a difference in height between each of the receiving units and the transmitting unit.
That is, if the position coordinates in the height direction of the plurality of receiving units and the three-dimensional relative distance between these receiving units and the transmitting unit are known, the position coordinates in the height direction of the transmitting unit can be determined.
Therefore, among the errors included in the plurality of relative position information measured by the relative position measuring device, the influence of the position coordinate error in plan view is eliminated, and the three-dimensional orthogonal coordinate system in the movement target space of the transmission unit The position coordinates in the height direction can be calculated with high accuracy.

  In addition, as described above, the configuration used to calculate the position coordinates in the conventional plan view can be used without separately installing a measuring device for measuring the position coordinates in the height direction. The position coordinates in the direction can be calculated with high accuracy.

  That is, according to the first characteristic configuration of the position measurement system according to the present invention, the position coordinate in the height direction of the transmission unit can be accurately calculated in addition to the position coordinate in the plan view of the transmission unit, and the cost is reduced. An advantageous position measurement system can be provided.

  In a second characteristic configuration of the position measurement system according to the present invention, in addition to the first characteristic configuration, the position calculation unit includes, as the height calculation process, the tertiary in the movement target space of each of the plurality of reception units. Based on the position coordinates in the height direction of the original orthogonal coordinate system and the relative position information of the transmission unit and each of the plurality of reception units measured by the relative position measurement device, the movement target of the transmission unit It is the point comprised so that the position coordinate of the height direction about the said three-dimensional orthogonal coordinate system in space may be calculated.

  That is, the position coordinate in the height direction for the three-dimensional orthogonal coordinate system in the movement target space of the transmission unit is compared with the position coordinate in the height direction for the three-dimensional orthogonal coordinate system in the movement target space of each of the plurality of reception units. It can be calculated based on the relative position information of the transmission unit and the plurality of reception units measured by the position measurement device.

Thus, as a method of calculating the position coordinates in the height direction of the transmission unit based on the position coordinates in the height direction of each of the plurality of reception units and the relative position information of each of the transmission unit and the plurality of reception units, For example, since the intersecting line of a plurality of spheres having a radius as a distance between the receiving unit and the transmitting unit as the relative position information between the receiving unit and the transmitting unit is centered on each of the receiving units, the horizontal plane follows this line. It is conceivable to obtain the position coordinates in the height direction of the horizontal plane including the intersection line.
In this case, an equation for a plurality of spheres is set up with each receiving unit as the center and the distance between the receiving unit and the transmitting unit as a radius, and the height direction of the three-dimensional orthogonal coordinate system is calculated from the equations of the plurality of spheres. The position coordinates of are calculated. Here, assuming that the coordinate value of the three-dimensional orthogonal coordinate system is (x, y, z), since the value of (x, y) in the position coordinate of each receiving unit is equal, x and y are eliminated from the above equation. To obtain an equation for z. Thereby, the z coordinate of a transmission part can be calculated | required.

  As described above, when the movement target space is formed in a dimension in which the direction along the vertical direction is smaller than the direction along the horizontal plane, the transmission unit is more horizontally than the distance away from the reception unit in the vertical direction. The distance away from each other tends to be larger. Therefore, when the transmission unit is spaced apart from the reception unit in the horizontal direction, the distance between each reception unit and the transmission unit is accurately measured by the position measurement device, so this equation is solved for the variable z. Thus, the value of the variable z, that is, the position coordinate in the height direction of the three-dimensional orthogonal coordinate system in the movement target space of the transmission unit can be calculated with high accuracy.

  Thus, according to the second feature configuration, a preferred embodiment of the position measurement system of the first feature configuration can be provided.

  A third characteristic configuration of the position measurement system according to the present invention is that, in addition to the first or second characteristic configuration, the number of the plurality of receiving units is two.

That is, as described above, the three-dimensional orthogonality in the movement target space of the transmission unit is based on the relative position information of the reception unit and the transmission unit, which have the same position coordinates in plan view but differ only in the height direction. When calculating the position coordinates in the height direction for the coordinate system, if the relative position information of at least two receiving units and the transmitting unit is obtained, the movement target space of the transmitting unit is based on the two relative position information. The position coordinates in the height direction for the three-dimensional orthogonal coordinate system in can be calculated.
Therefore, by increasing the number of receiving units provided at the same position in plan view in different heights in the movement target space, it is possible to suppress an increase in the installation cost of the device as compared with the case where three or more receiving units are provided. In addition, the configuration for calculating the position coordinates in the height direction of the transmission unit can be simplified.

  According to the present invention, the characteristic configuration of the article storage facility including the position measurement system according to any one of the first to third characteristic configurations is configured such that the movement target space is set in a storage space for storing articles, The mobile body is a forklift that includes a cargo handling part that is movable in a moving space set as the storage space and that can move up and down while supporting the article to convey the article in the height direction, The transmitting unit is configured to move up and down integrally with the cargo handling unit.

That is, in an article storage facility including a forklift that moves a movement target space set in a storage space for storing an article and conveys the article, the position measurement system includes a movement target space of the fluctuation transmission unit of the fluctuation transmission unit. Since the position coordinate in the height direction of the three-dimensional orthogonal coordinate system can be calculated with high accuracy, the variable transmission unit is attached so that the article on the forklift can be moved up and down integrally with the cargo handling part that can be moved up and down. Then, the lifting / lowering height of the cargo handling part of the forklift and the article supported by the cargo handling part can be accurately calculated.
For example, when managing the storage position of an article by an inventory management system or the like, if the information related to the cargo handling part of the forklift calculated as described above and the height of the article supported by the cargo handling part is used, the storage part When an article is stored in an article storage shelf provided with a plurality of items arranged in the vertical direction, it is possible to appropriately manage in which stage of the storage unit the vertical direction the article is stored.

Top view of article storage facility provided with position measurement system of embodiment Partial perspective view of goods storage facility Overall perspective view of a forklift as an example of a moving body Plan view of forklift as an example of moving body Block diagram showing the configuration of the position measurement system Flow chart showing the height calculation process Diagram showing how to calculate the height of a variable tag Diagram showing how to calculate the height of a variable tag

Hereinafter, an embodiment of an article storage facility provided with the position measurement system of the present invention will be described based on the drawings.
FIG. 1 is a plan view of a warehouse A as an article storage facility of the present embodiment, and FIG. 2 is a perspective view showing a part of the warehouse A.
The warehouse A of the present embodiment is configured by being surrounded by a wall body Aw, and a plurality of article storage shelves 5 provided with an article storage unit 5S arranged in the width direction of the shelf and the vertical direction of the shelf in the internal space 2; A receiving platform 6 is installed for delivery. In addition, a space in the internal space 2 of the warehouse A where the article storage shelf 5 or the cargo receiving platform 6 is not provided becomes a movement target space in which the forklift 1 serving as a moving body that conveys the article B travels.

  As shown in FIGS. 1 to 4, the forklift 1 is configured to include a fork 1n as a cargo handling part that is guided by a mast 1m provided in front of a vehicle body 1h and is movable up and down. Then, the operator rides on the driving operation portion provided in the vehicle body 1h, performs the traveling operation of the vehicle body 1h, and operates the raising and lowering of the fork 1n, thereby inserting the fork pawl 1nf into the hole of the pallet Bp. The article B is conveyed in a form in which the article B is placed and supported. In this embodiment, when the article B is stored in the storage unit 5S, the article B is transferred from the transfer source in a state of being placed on the pallet Bp, and the forklift 1 is set corresponding to the storage unit 5S to be stored. When arriving at the predetermined position, the article B is unloaded and received together with the pallet Bp. On the other hand, when the article B is unloaded from the storage unit 5S, the article B is unloaded together with the pallet Bp and conveyed to the conveyance destination.

  The forklift 1 is provided with a tag S that can transmit a radio wave as a position measurement signal for detecting the position of the forklift 1. The tag S is composed of two fixed tags S1 of the first fixed tag S1a and the second fixed tag S1b, and one variable tag S2. In the present embodiment, the fluctuation tag S2 corresponds to the transmission unit. In the present embodiment, it is desirable that the tag S be an active tag in order to improve responsiveness.

The first fixed tag S1a and the second fixed tag S1b are attached to the roof portion 1r of the operation unit of the forklift 1 so as to be separated in the lateral width direction of the forklift 1. The variable tag S2 is attached to the upper end of a support 1p attached to the fork 1n in front of the forklift 1. The support column is configured to be positioned close to the roof portion 1r when the fork 1n is positioned at the lower limit position.
In the present embodiment, the variable tag S2 is attached to the upper end of the support column 1p when the article B is placed and supported on the fork 1n, behind the article B that is placed and supported on the fork 1n. This is to prevent communication with the access point J described later from being hindered. The two fixed tags S1 are attached to detect the direction of the forklift 1.

  As shown in FIGS. 1 and 2, in the internal space 2 of the warehouse A, a plurality of access points J that can receive radio waves transmitted from the tag S are arranged in a vertical direction (height direction) at a position where they overlap in a plan view. A plurality of sets are provided in such a manner that two access points J that are separated from each other (indicated by the Z axis in FIG. 2) are distributed as a set in a plan view of the warehouse A. Hereinafter, of the two access points J, the access point J located on the lower side is referred to as the lower access point J1, and the access point J located on the lower side is referred to as the upper access point J2. Point J is referred to as an access point pair Jt.

  In the present embodiment, 7.25 GHz to 10.25 GHz radio signals of the ultra-wideband radio (UWB) system are used as the position measurement signals, and a plurality of tags when the tag S outputs a short pulse signal of several nanoseconds are used. The relative position measuring device to be described later measures the time lag for reaching the access point J, so that the three-dimensional position measurement of the tag S can be performed with high accuracy with an average error of about 30 cm.

A positioning computer H is installed at a location different from the internal space 2 of the warehouse A.
Although not shown, the positioning computer H includes a calculation unit and a storage unit, and further includes a display unit, a keyboard, a mouse, and the like as input / output devices.

As shown in FIG. 5, the positioning computer H is configured to be able to communicate with other computers, and communicates with a management computer HU as an upper management device that manages the inventory of the articles B stored in the warehouse A. Communication is possible. The positioning computer H is configured to be able to communicate with the plurality of access points J via a network device such as a hub.
Although not shown in the figure, the item B is attached with an RFID or bar code in which item identification information is recorded, and can be identified separately. The management computer HU performs inventory management by managing the identification information of the article B in association with the storage unit identification information assigned to the storage unit 5S.

The positioning computer H is configured to be able to load a program module stored in the storage unit into the arithmetic unit and execute the program module, and is configured to be able to execute a plurality of program modules.
As a program module, a relative position calculation program for calculating a relative distance between the access point J and the tag S and an angle of the tag S viewed from the access point J based on at least information acquired from the access point J, and the relative position A tag in a three-dimensional orthogonal coordinate system (coordinate system indicated by the three axes of XYZ in FIG. 2) set in a state where the Z axis extends along the vertical direction in the internal space 2 based on the calculation result in the calculation program A position coordinate calculation program for calculating the position coordinates of S is executed (a method for calculating the position coordinates will be described later).
In FIG. 5, the positioning computer H includes a relative position calculation unit H1 by mounting the relative position calculation program, and includes a position calculation unit H2 by mounting the position calculation program.

  When carrying out the item B from the item storage shelf 5 or when storing the item B in the item storage shelf 5, the management computer HU sends the position coordinates of the tag S transmitted from the positioning computer H (plan view position and position). On the basis of the position in the height direction, the storage unit 5S in which the article B is stored or unloaded is identified.

The height calculation process executed by the positioning computer H will be described based on the flowchart of FIG. The positioning computer H also calculates the position coordinates of the fixed tag S1 in plan view, but only the method for calculating the position coordinates of the variable tag S2 in the height direction will be described here.
The positioning computer H issues an inquiry request to each of the plurality of access point pairs Jt in order to acquire the position coordinates of the tag S (variation tag S2) (step # 1).

Each of the access point pairs Jt radiates an inquiry signal radio wave toward the internal space 2 of the warehouse A at the same time when the inquiry request is issued. When the fluctuation tag S2 receives the inquiry signal radio wave, it transmits a return radio wave including its own identification number. Each of the access points J belonging to the plurality of access point pairs Jt receives the transmitted radio wave from the variation tag S2.
The positioning computer H selects the access point pair Jt that first receives radio waves from the tag S received by the access point J among the plurality of access point pairs Jt as the access point pair Jt for position calculation. Thereafter, calculation is performed using the selected access point pair Jt as the receiving unit of the present invention (step # 2).

  As shown in FIG. 7, the relative position calculation unit H1 in the positioning computer H receives the radio waves from the fluctuation tag S2 received by the lower access point J1 and the upper access point J2 belonging to the access point pair Jt as described above. Based on the time, a relative distance D1 between the lower access point J1 and the variation tag S2 and a relative distance D2 between the upper access point J2 and the variation tag S2 are calculated (step # 3).

  The relative distance D1 and the relative distance D2 can be accurately obtained if the distance between the access point J and the variation tag S2 is sufficiently large. That is, since the radio wave steered between the tag S and the access point J has a high propagation speed, when the distance between the tag S and the access point J is short, the influence of errors and the like caused by the detection timing of the device. However, if the distance between the tag S and the access point J is long, the influence of the error or the like is reduced, and the distance between the tag S and the access point J (relative distance D1 and relative distance D2) is reduced. It can be obtained with high accuracy.

  In the present embodiment, the forklift 1 moves through the internal space 2 of the warehouse A configured in a flat shape whose length in the height (Z) direction is thinner than the length in the plan view (XY) direction. Therefore, the distance between the access point J and the variable tag S2 is likely to be greater in the X direction or Y direction than in the Z direction. For this reason, the relative distance D1 and the relative distance D2 are easily obtained with high accuracy.

  The positioning computer H substitutes the relative distance D1 and the relative distance D2 calculated in step # 3 into the following arithmetic expression (formula 1) to calculate the position coordinate of the variation tag S2 in the Z-axis direction (step #). 4).

  Here, z1 is the position coordinate in the Z-axis direction of the lower access point J1, and z2 is the position coordinate in the Z-axis direction of the upper access point J2.

Hereinafter, the derivation method and mathematical meaning of this mathematical formula will be described.
If the position coordinates of the lower access point J1 in the three-dimensional orthogonal coordinate system are (x1, y1, z1), the position coordinates of the upper access point J2 in the three-dimensional orthogonal coordinate system are the positions in the X-axis direction and the Y-axis direction. Since they are the same, (x1, y1, z2) is obtained.

  Here, as shown in FIG. 8, a sphere G1 centered on the position coordinates (x1, y1, z1) of the lower access point J1 and having a radius D1 as a relative distance D1 between the lower access point J1 and the variable tag S2. When a sphere G2 having a relative distance D2 between the upper access point J2 and the variation tag S2 with the position coordinates (x1, y1, z2) of the upper access point J2 as the center is drawn, a sphere G1 and a sphere G2 are drawn. And intersect at a position including the coordinates (x3, y3, z3) of the existence position of the variation tag S2, and an intersection line (intersection circle) Cz between the sphere G1 and the sphere G2 appears.

  Since the lower access point J1 and the upper access point J2 are arranged along the Z axis, the intersection line (intersection circle) Cz is in an attitude along the XY plane orthogonal to the Z axis. Therefore, the position coordinate in the Z-axis direction of the intersection line (intersection circle) Cz between the sphere G1 and the sphere G2 becomes the position coordinate in the Z-axis direction where the variation tag S2 is located.

  The equation of the sphere G1 is as (Equation 2). The equation of the sphere G2 is as shown in (Equation 3).

Subtracting (Expression 3) from (Expression 2) to delete the first term and the second term on the left side deletes the variables x1, y1, x3, and y3, and (Expression 1) is derived.
In (Formula 1), z1 which is the installation height of the lower access point J1 and z2 which is the installation height of the upper access point J2 are known and can be given with high accuracy. The relative distance D1 between the lower access point J1 and the variation tag S2 and the relative distance D2 between the upper access point J2 and the variation tag S2 can be given with high accuracy as described above. Therefore, z3 calculated from z1, z2, D1, and D2 can also be calculated with high accuracy.

  As described above, according to the present invention, based on the relative position information between the two access points J and the variation tag S2 that are provided at the same position in plan view in different heights, the variation tag S2 The position coordinates in the height direction of the three-dimensional orthogonal coordinate system in the movement target space can be calculated with high accuracy.

[Another embodiment]
(1) In the above-described embodiment, the UWB wireless signal is used as the position measurement signal. However, the present invention is not limited to such a configuration. For example, the wireless LAN (specified in IEEE 802.11) is used. It is also possible to employ a configuration using radio signals, ultrasonic waves, etc.

(2) In the above embodiment, the relative position between the two access points J arranged in the Z-axis direction and the tag S is measured, and the position coordinate of the variable tag S2 in the Z-axis direction is calculated based on the measurement result. However, a configuration in which three or more access points J arranged in the Z-axis direction may be provided.

(3) In the above-described embodiment, the configuration in which the position measurement system is provided in the article storage facility as the indoor space surrounded by the wall body is described. However, the configuration is not limited to such a configuration, and the outdoor storage facility The position measurement system of the present invention may be applied.
In addition, the applicable application is not limited to the article storage facility, and can be applied to various facilities as long as the facility needs to calculate the position coordinates in the height direction of the moving body.

(4) In the above-described embodiment, a configuration in which only one variation tag S2 is provided in the movable part has been described. However, two or more variation tags S2 may be provided.
In this case, a plurality of position coordinates in the Z-axis direction of each of the plurality of variable tags S2 are calculated. If the average value of these is calculated, the position coordinates in the Z-axis direction of the movable part can be calculated more accurately. it can.

(5) In the above embodiment, the relative position calculation unit provided in the program format of the positioning computer H has been described as an example of configuring a relative position measurement device that measures the relative position of the UWB tag with respect to the access point J. You may make it comprise the said relative position measuring apparatus by J. In this case, information on the relative position of the UWB tag with respect to the detected access point J may be configured to be transmitted to the positioning computer H via a network such as a LAN.

(6) In the above embodiment, the configuration in which the tag S is the active tag has been illustrated, but the tag S may be configured as a passive tag.

(7) In the above embodiment, the movement target of the variation tag S2 is based on the relative position information between the two access points J and the variation tag S2 provided at the same position in plan view in different heights in the movement target space. As a method of calculating the position coordinate in the height direction for the three-dimensional orthogonal coordinate system in space, the relative position D1 between the lower access point J1 and the variation tag S2 is set with the radius being the position coordinate of the lower access point J1 as the center. Z-axis direction of the intersection line (intersection circle) Cz of the sphere G1 to be rotated and the sphere G2 whose center is the position coordinate of the upper access point J2 and whose radius is the relative distance D2 between the upper access point J2 and the variation tag S2 However, the present invention is not limited to such a configuration. For example, the lower access point J1 and the upper access point It is also possible to obtain a position coordinate in the Z-axis direction of the variation tag S2 by internally dividing the distance (z2-z1) from J2 according to the ratio between the relative distance D1 and the relative distance D2. is there.

(8) In the above-described embodiment, the configuration in which the variable tag S2 is attached to the upper end of the support 1p attached to the fork 1n in front of the forklift 1 is illustrated. However, the attachment position of the variable tag S2 The position can be arbitrarily changed as long as the height changes accordingly. Even in this case, it is desirable that the variable tag S2 is located at a position where communication with the access point J is not hindered by the article B placed and supported on the fork 1n.

(9) In the embodiment described above, the positioning computer H accesses the access point pair Jt for which the received radio waves from the tag S received by the access point J are first aligned among the plurality of access point pairs Jt for position calculation. Although the selection as the point pair Jt is illustrated, instead of this, the positioning computer H selects the access point pair Jt having the strongest average reception strength of the pair of access points J among the plurality of access point pairs Jt. May be. In addition, the positioning computer H calculates the relative distances D1 and D2 for each of the plurality of access point pairs Jt, and fluctuates based on the relative distances D1 and D2 for the access point pair Jt for which the average of these distances is maximum. It is good also as a structure which calculates the position coordinate of the Z-axis direction of tag S2. Further, the positioning computer H calculates the position coordinates in the Z-axis direction of the variation tag S2 based on the received radio waves of the plurality of pairs of access points Jt, and the average value thereof is used as the Z-axis of the final variation tag S2. A configuration in which the position coordinates in the direction may be used.

DESCRIPTION OF SYMBOLS 1 Mobile body 1n Handling part A Goods storage equipment B Goods D1, D2 Relative position information H1 Relative position measuring device H2 Position calculation part J Reception part S Transmission part

Claims (4)

A transmission unit provided in a movable body that is movable in the movement target space and capable of transmitting a position measurement signal for detecting the position of the movable body;
A receiver capable of receiving the position measurement signal transmitted from the transmitter;
Based on the position measurement signal transmitted from the transmitter, a relative position measurement device that measures the relative position of the transmitter with respect to the receiver;
Based on the relative position information of the transmitting unit and the receiving unit measured by the relative position measuring device, the transmitting unit in the three-dimensional orthogonal coordinate system set in a state in which one axis extends along the vertical direction in the movement target space. A position measurement system including a position calculation unit for calculating position coordinates,
A plurality of the receiving units are provided at the same position in plan view at different heights in the movement target space;
The position calculation unit is configured to calculate the three-dimensional orthogonal coordinate system in the movement target space of the transmission unit based on relative position information of each of the plurality of reception units and the transmission unit measured by the relative position measurement device. A position measurement system configured to freely execute a height calculation process for calculating a position coordinate in the height direction of the.   The position calculation unit, as the height calculation process, the position coordinate in the height direction of the three-dimensional orthogonal coordinate system in the movement target space of each of the plurality of reception units, and the relative position measurement device measures Based on relative position information between the transmission unit and each of the plurality of reception units, the transmission unit is configured to calculate position coordinates in the height direction of the three-dimensional orthogonal coordinate system in the movement target space. The position measurement system according to claim 1.   The position measurement system according to claim 1, wherein the plurality of receiving units are two. An article storage facility comprising the position measurement system according to claim 1,
The movement target space is set in a storage space for storing articles,
The mobile body is a forklift provided with a cargo handling part that is movable in a moving space set as the storage space and is movable up and down in a state where the article is supported to convey the article in a height direction,
The article storage facility configured such that the transmission unit moves up and down integrally with the cargo handling unit.

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