1. Field of the Invention
The present invention relates to a technology of planning an installation position of an RFID tag on an object.
2. Description of the Related Art
RFID relates to a technology of attaching an IC chip (RFID tag) with an antenna to an object and contactlessly reading and writing information from and into the IC chip. The RFID enables consistent management of various information related to a life cycle of a workpiece, such as manufacturing, transportation, operation and maintenance.
The RFID is convenient because the RFID enables contactless read and write of information by using radio waves. However, a transmission distance of radio waves is limited, and the radio waves are blocked by obstacles. Thus, some kind of support is required to easily access a target RFID tag. As a technology for facilitating the access to the RFID tag, there is a technology described in Japanese Patent Laid-Open Official Gazette No. 2004-108782 (hereinafter referred to as Patent Document 1). In Patent Document 1, an RFID tag is disposed along a working route and, after an inspection work, guidance is provided based on information in the RFID tag which stores a method for moving to the next inspection position.
In management of a workpiece (which is used, in the present specification, as a broad concept including articles of various sizes such as various parts and so-called devices, and hereinafter the same) which uses an RFID tag, it is important to manage information related to the workpiece in association with the workpiece in order to maintain integrity and consistency of information. Therefore, it is required to install the RFID tag in the workpiece.
For example, pipes in a plant will be taken as an example of the workpiece. The pipes undergo various processes such as manufacturing, transportation, cutting, welding, installation, operation and maintenance. In order to completely manage information in all the processes, it is required to attach the RFID tag from an initial state, for example, from a manufacturing stage. In this event, the tag is attached to a convenient position in a state at the time of manufacturing. However, when the pipe is transported, cut, processed and further installed in the plant after manufacturing, a position and a direction of the pipe are changed. Accordingly, the tag initially attached is not always attached to a position suitable for works such as maintenance. Moreover, the tag is not always attached to apposition which enables reduction in factors that lower performance of the RFID tag, such as noise, moisture and temperature. As described above, the position of the RFID tag to be attached has not heretofore been set to an optimum position from the viewpoint of accessibility to the RFID tag and retention of tag performance by taking account of a layout state and an operation state of the workpiece after construction.
It is an object of the present invention to facilitate access to an RFID tag after construction. An RFID installation position planning technology according to the present invention is used for outputting an optimum RFID installation position, which facilitates access to an RFID tag, before construction with work pieces. Work pieces layout data storage device stores workpiece layout data including shape and disposition data of a workpiece. A working route data storage device stores working route data including position data of works involving communication with the RFID tag. RFID tag position planning means determines communication accessibility to each point on a surface of the workpiece from a work position, based on a distance between the work position and the RFID tag, presence or absence of an obstacle therebetween, and a communicatable distance of the RFID tag. Moreover, the RFID tag position planning means determines and outputs an optimum RFID tag installation position.
Specifically, according to an aspect of the present invention, provided is an RFID position planning apparatus characterized by including: a workpiece layout data storage device which stores workpiece layout data including shape and disposition data of a workpiece; a working route data storage device which stores working route data including work position data involving communications with an RFID tag; and RFID tag position planning means which determines that a position being in a communicatable range from a position specified by the work position data, and having a maximum signal intensity in communications, should be an installation range or an installation position of the RFID tag in the workpiece, based on the workpiece layout data and the working route data. Thus, the installation range or the installation position of the RFID tag in the workpiece can be determined with high accuracy.
The workpiece layout data storage device is characterized by storing noise data indicating positions of noise sources which affect communication performance of the RFID tag. Moreover, the RFID tag position planning means is characterized by determining that a position being outside a range of influences of the noise sources, being in a communicatable range from a position specified by the working position data, and having a maximum signal intensity in communication, should be an installation range or an installation position of the RFID tag in the workpiece, based on the workpiece layout data, the working route data and the noise data. Thus, the installation range or the installation position of the RFID tag in the workpiece can be determined with high accuracy while taking account of the influences of noise.
Moreover, the apparatus is characterized by further including an operation data storage device which stores operation data including operation conditions of the workpiece. The RFID tag position planning means is characterized by determining presence or absence of a covering material on the workpiece and determining an attachment/detachment range of the covering material, based on the operation data, the workpiece layout data and the working route data. Moreover, the RFID tag position planning means is characterized by determining an installation range or position of the RFID tag in the workpiece by limiting the range or position to the determined attachment/detachment range. Thus, it is possible to reduce a work for attachment/detachment of covering material for communications with the RFID tag.
As described above, according to the present invention, the installation position for facilitating the access to the RFID tag installed in the workpiece can be determined before construction based on a workpiece layout condition. Thus, there is an advantage that the RFID tag installation position can be easily optimized.
With reference to the drawings, description will be given below of an example of an RFID installation position planning apparatus according to a first embodiment of the present invention.
The workpiece layout data storage device 101 stores workpiece layout data that is information concerning shapes and layout of workpieces, such as piping and equipment, which are installed, for example, in a facility such as a plant.
As a data format stored in the shape data column, for example, as shown in
The working route data storage device 102 stores: route data indicating a route by which a working moves; and working site data indicating a position where the operator performs works along the route data.
The RFID tag position planning means 105 shown in
Next, a projection shape of the polygon is obtained by setting respective positions and directions in work site data as a projection direction (Step 702). The projection shape is obtained by projection conversion by setting a workpiece coordinate system as a world coordinate system and by setting a position and a direction of a work site as a position and a direction of a camera coordinate system. It is assumed that the world coordinate system is V(X, Y, Z), the camera coordinate system is v(x, y, z), projection plane coordinates are s(u, v), a rotation matrix from the world coordinate system to the camera coordinate system is R, a translation matrix is T, and a projection focal distance is f. R and T can be obtained from the direction and the position in the work site data. Moreover, f and a projection plane width W (u and v range) can be obtained by the following equation from a read angle range θ of a reader of the RFID tag.
θ=2*tan−1(w/2f) [Equation 1]
Here, a projection formula from the camera coordinate system v to the projection plane coordinates s is expressed as follows.
[Equation 2]
,where Pij is a ij component of the following matrix.
[Equation 3]
Next, in a screen coordinate system, a screen pixel included in a projected polygon shape, a depth value z thereof, and a world coordinate value are obtained (Step 703). The pixel is determined by obtaining an intersection point between a scan line y=y1 and a projected triangle of the polygon and by obtaining a screen pixel existing within the intersection points.
In order to obtain the value z, a formula of a plane including P1, P2 and P3 is obtained and the following equation is established.
ax+by+cz+d=0
Thus, the depth value z at the screen coordinates (u, v) can be obtained by the following equation.
z=−(ax+by+d)/c
Furthermore, camera coordinates are obtained by the following equations.
x=u*z/f, y=v*z/f, z=depth value
Moreover, world coordinates are obtained by the following equation.
V=Rv+T
The above-described processing in Step 703 is performed for all the screen pixels or pixels at certain intervals within the polygon shape. The results obtained are stored in workpiece coordinate data shown in
Next, visibility of each pixel in the target workpiece ID is determined (Step 704). In this Step 704, Steps 701 to 703 are carried out for all workpiece shapes or for workpiece shapes in a region limited to only a display range after the workpiece in which the RFID tag is to be installed, the workpiece being specified by the user. Thereafter, data having the same screen coordinates are searched through the workpiece coordinate data. If there are the data as a result of the search and if the value z is smaller than the stored value, it is determined that there is an obstacle. Accordingly, in an obstacle presence/absence column shown in
Next, in Step 705, an RFID tag installation range and an optimum installation position are outputted. Note that, by the processing of Steps 701 to 704, a position (range) that is visible from a work site on an object is obtained. In addition, radio waves for RFID communications are considered to be transmitted while going approximately straight. Thus, a visible range from the work site, which is obtained by the processing of Steps 701 to 704, can be regarded as approximately the same as a communicatable range of the RFID tag. Therefore, it is possible to know a communicatable position in the target workpiece.
Note that, in the case where transmission of the radio waves is not almost completely straight but it is required to also consider transmission toward a periphery by diffraction, reflection or the like, coordinates of an object around the visible range are also determined to be the communicatable range. Thus, the communicatable position can be specified.
Moreover, as to the optimum installation position of the RFID tag, a position (point) that is the closest to the work site among the communicatable positions is determined to be the optimum installation position of the RFID tag. Thereafter, the communicatable position and the optimum installation position of the RFID tag, which are determined, are outputted. Moreover, in this event, a direction of installation of the RFID tag can also be indicated by adding an arrow AR1 indicating a direction of the work site to the optimum installation position.
Note that it is difficult to strictly specify one point among the work sites (positions indicated by the circles in
As described above, by allowing a researcher carrying an RFID reader or the like to move along the maintenance route, it is possible to acquire various information concerning life cycles of the workpieces, which are stored in the RFID tags installed in the workpieces. Thus, it is possible to compare the data obtained with the previous research data or to pay attention to data having a large difference from a standard value or a predicted value and to data having a small difference from a use limit value.
As described above, by use of the RFID tag installation position planning technology according to this embodiment, based on the workpiece layout and the work (maintenance), the installation position of the RFID tag can be determined by taking account of accessibility to the RFID tag installed in the workpiece along the maintenance route. Thus, there is an advantage that maintenance work is facilitated. Furthermore, the installation position is determined by taking account of communication properties of the RFID tag, particularly, linearity of radio waves and presence or absence of an obstacle. Thus, there is an advantage that maintenance work more suitable for an actual facility can be performed.
Next, with reference to the drawings, description will be given of an RFID installation position planning technology according to a second embodiment of the present invention. In the RFID installation position planning technology according to this embodiment, the workpiece layout data storage device 101 shown in
In Step 1203, a distance between the noise generation position and each point in the workpiece coordinate data is obtained. If the distance obtained is not more than the noise avoidance distance, noise ID data are additionally stored in the obstacle presence/absence column. In Step 1203, in addition to the processing in Step 704 shown in
As described above, in the RFID installation position planning technology according to this embodiment, the RFID installation position is determined by taking account of the influence of the sources of noise. Thus, in a plant having sources of noise, there is an advantage that the RFID installation position can be determined with higher accuracy.
Next, with reference to the drawings, description will be given of an RFID installation position planning technology according to a third embodiment of the present invention. In this embodiment, adopted is a configuration obtained by adding an operation data storage device to the configuration in each of the embodiments described above. RFID position planning means can determine a position of an RFID tag by additionally utilizing operation conditions.
As a heat insulator attachment/detachment portion, a welded part subjected to in-service inspection corresponds thereto. Thus, if a welded part spot is stored in the noise generation data among the target workpieces, the corresponding position is set as the heat insulator attachment/detachment portion. On the other hand, if the welded part spot is not stored therein, portions at both ends of the workpiece are set as the heat insulator attachment/detachment position. Furthermore, a position within 100 mm from the end position of the workpiece, which is the welded part, is set as the attachment/detachment position. Setting of a value of an attachment/detachment range can be specified by the user. Thereafter, a character string “heat insulator present” is additionally stored in each point of the workpiece coordinate data other than the determined heat insulator attachment/detachment position.
Next, in Step 1504, an RFID tag installation position is determined. In addition to the processing in Step 705 shown in
By the processing as described above, a heat insulator attachment/detachment portion is determined. In this heat insulator detachable portion, the heat insulator is attached or detached more easily than in the heat insulator portions other than the heat insulator attachment/detachment portion. Thus, a work for attaching/detaching the heat insulator for installing the RFID tag is simplified. Consequently, there is an advantage that a work for communicating with the RFID tag is simplified. As described above, according to the respective embodiments of the present invention, the RFID tag installation position for facilitating the access to the RFID tag installed in the workpiece can be determined before construction based on a workpiece layout condition. Thus, there is an advantage that the RFID tag installation position can be easily optimized.
Besides maintenance and inspection of the plant, the present invention is also applicable to maintenance and inspection of other buildings and structures.
Number | Date | Country | Kind |
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2005-176741 | Jun 2005 | JP | national |