1. Field of the Invention
The present invention relates to an R/W (Reader/writer) control method that performs a read/write operation on RF tags that move on a belt conveyor or a gate in a system using an RFID (Radio Frequency Identification) and a control apparatus.
2. Description of the Related Art
In recent years, in the scene of the manufacturing or physical distribution, the administration of products using an RFID technology has been performed. In the management of products using an RFID, RFID tags (IC tags or wireless tags) are attached to the products and information that is written in the RFID tags is read out, thereby identifying the individual products. If the RFID tags are used, plural products can be detected at one time. Therefore, incoming product inspection or stocktaking that is comparison work between a list of products and actual products can be efficiently performed.
The RFID tags may be classified into two types. One is an active-type RFID tag that transmits data by itself, and the other is a passive-type RFID tag that receives a request from an R/W and executes a corresponding process in response to the request. In the description below, the description is given to the passive-type RFID tag (hereinafter, simply referred to as RF tag).
In general, each of the RF tags stores two types of data that are a UID (Unique Identifier) and user data (data used in a format that a user of the RF tag has determined depending on the intended use). Commands that are executed with respect to the RF tags include an inventory command that instructs to simultaneously read UIDs of plural RF tags, and a read command or a write command that instructs to read/write data, such as user data of the RF tag selected by designating a UID. First, a list of UIDs of plural RF tags is obtained according to the inventory command. Then, the individual UIDs are sequentially designated among the list of UIDs of the plural RF tags and the read/write command is executed, which makes it possible to perform a read/write operation on the plural RF tags.
One or more antennas are connected to the R/W that performs a read/write operation on the RF tags. When a read/write operation is performed on the RF tags using the R/W, any one of the antennas that are connected to the R/W is allowed to become active, and electromagnetic waves are radiated from the active antenna to enable communication between the R/W and the RF tags, thereby realizing a read/write operation on the RF tags.
In the case where the relative locations between the RF tags and the antennas do not change like the case where products to which the RF tags are attached are loaded on the antennas of the R/W and the RF tags are read, the inventory command is executed to read the UIDs of the RF tags, and a read/write command is executed by the antennas that have read the UIDs to read/write data of the RF tags.
However, in the case where the locations of the antennas are fixed and the RF tags move by loading the products to which the RF tags are attached on a belt conveyor or making the products pass through a gate, or in the case where the RF tags are fixed and the antennas move, that is, the relative locations between the RF tags and the antennas change, it becomes difficult to perform a read/write operation on the RF tags. This reason is as follows. When data of the RF tags is read/written, an antenna read range may be beyond a read range of the antennas that have read the UIDs due to the change in the relative locations, which fails to execute the read/write command by the antennas that have read the UIDs.
In order to solve this problem, as the related art for performing a read/write operation on the moving RF tags, there is a JP-A-2006-172101. According to the technology that is disclosed in JP-A-2006-172101, an antenna that performs a read/write operation on the RF tags is disposed such that a detection area becomes substantially continuous, so as to widen a read range, thereby increasing an accessible time with respect to the RF tags. Time for which the antenna becomes active is set in accordance with the movement speed of the RF tags and the antenna is switched in accordance with the movement of the RF tags. As a result, a read/write operation can be performed on the RF tags even if the RF tags move at a high speed.
In JP-A-2006-172101, the continuous detection area is obtained by overlapping the detection areas of the antennas. However, actually, even though the detection areas overlap, command request transmission from the R/W and response reception from the RF tags should be performed by the same antenna. In general, the R/W forces the request transmission and the response reception to be performed by the same antenna. If the RF tags move between the request transmission and the response reception, the R/W cannot receive a result that is obtained by performing a read/write operation on the RF tags. As a result, read data may not be obtained from the RF tags or it may be impossible to know whether data is successfully written in the RF tags or not. For this reason, transmission and reception of the command need to be executed by the same antenna so as to accurately perform the transmission and reception between the request transmission and the response reception.
According to an aspect of the invention, the following problems can be resolved.
In JP-A-2006-172101, it is assumed that the number of RF tags that are subjected to a read/write operation is one, and the case where plural RF tags simultaneously move is not considered. If the plural RF tags simultaneously move, a size of data that is read/written may be changed depending on each of the RF tags. In some cases, only a read operation needs to be performed in an arbitrary RF tag but both read and write operations need to be performed in another arbitrary RF tag. As a result, the process contents may be different, which cause a difference between process times of the RF tags. In this case, if it is not adjusted to execute a command with respect to an RF tag by an antenna, an antenna may be switched during the command process, which fails to perform the read and write operations.
According to another aspect of the invention, the following problems can be resolved.
In JP-A-2006-172101, the antennas are arranged along the movement direction of the RF tags. However, in the gate or the like, in order to improve a read rate, the antennas may be arranged even in a direction that is different from the movement direction of the RF tags. For example, when products that pass through the gate are stacked high, the antennas may be disposed in a vertical direction, and groups of antennas in a vertical direction may be arranged in a movement direction of the products (movement direction of the RF tags). The antennas may be disposed at both the left and right sides of the gate, not any one of the left and right sides of the gate, and the groups of antennas at both the left and right sides of the gate may be arranged in a movement direction of the products (movement direction of the RF tags). When a read/write operation is performed on the RF tags by the antennas at both the left and right sides of the gate, there are the RF tags where a read/write operation can be performed by the antennas at only one of the left and right sides and the RF tags where a read/write operation can be performed by any of the antennas at the left and right sides. If a read/write operation is not performed by a proper antenna in accordance with the detection situation and the movement of the RF tags, the RF tags that pass without being subjected to a read/write operation may be generated.
In JP-A-2006-172101, the case where it fails to perform the read/write operation on the RF tags is not considered. If the state where it fails to perform the read/write operation on the RF tags is maintained, it hinders the following work. The read/write command may be executed again so as to improve a success rate of the read/write operation on the RF tags.
The invention provides a method and apparatus for controlling an R/W (reader/writer) that performs a read/write operation on RF tags attached to a moving body. Aspects of the invention are as follows. The RF tags that are attached to the moving body are detected using the R/W. A schedule that determines execution timing of a control command of the R/W that performs a data read/write operation on the RF tags in accordance with the detected RF tags is created. The R/W control command is executed with respect to the RF tags using the R/W in accordance with timing that is determined in the created schedule.
According to the invention, since an R/W control command is executed with respect to RF tags in accordance with execution timing that is scheduled according to the detected RF tags, it is possible to decrease a failure that occurs at the time of executing the R/W control command.
The invention may be applied to the case where plural antennas are disposed in a direction that is different from a movement direction of a moving body, and the above effects can be achieved.
Hereinafter, embodiments of the invention will be described with reference to
An R/W control apparatus 1 controls the R/W 2 to perform a data read/write operation on the RF tag, which is attached to the product or pallet as a moving body that moves by a conveyor. The R/W control apparatus 1 includes a CPU 11, a memory 12 that stores a program or data accompanied when the CPU 11 executes a program, an input device 13 that includes a keyboard or mouse and an interface thereof, an output device 14 that includes a display and an interface thereof, a communication device 15 that includes a communication interface, such as the RS-232C, the USB, or the Ethernet (registered trademark), and a storage device 16, such as a hard disk, which stores data or a program.
The storage device 16 stores arrangement information 161 that indicates the configuration or arrangement of antennas and the R/W 2 controlled by the R/W control apparatus 1, command indication information 162 that is used for an application to request the R/W 2 to execute an operation such as an incoming product inspection, command execution performance information 163 that indicates command process performance in the R/W 2, RF tag movement information 164 that indicates a movement situation of the product or pallet to which the RF tag is attached, RF tag detection information 165 that indicates information of the RF tag detected by the R/W 2, command executable time information 166 that indicates a command executable time for each antenna, execution command information 167 that indicates a list of execution scheduled commands, and reservation command information 168 that indicates a list of commands whose command execution time is reserved. In the description below, the above information and tables that store the above information are not particularly discriminated, but the discrimination between the information and the tables will be easily understood. The storage device 16 stores an R/W control program 169 that is used to control the R/W 2.
Further, data (information) that is surrounded by a solid line is data that is set before a program is executed. Data that is surrounded by a broken line is data that is dynamically created when a program is executed. The R/W 2 connects the antennas 21, 22, and 23. The R/W2 receives a command execution request from the R/W control apparatus 1, and performs a read/write operation on the RF tag while switching an active antenna.
The products P1, P2, P3, and P4 are loaded on the pallet P0. The RF tags T1, T2, T3, and T4 are attached to the products P1, P2, P3, and P4, respectively. The RF tag T0 is attached to the pallet P0. The product or pallet moves in a direction according to the order of the antennas ‘21→22→23’.
Although not shown in the drawings, in order to detect when the product or pallet becomes closer or the moving speed thereof, the R/W control apparatus 1 may be connected to a sensor or a camera and an image recognition device, so as to cooperate with each other. The R/W control apparatus 1 receives movement information of the product or pallet from the image recognition device, such as the sensor or the camera. The handling process of the movement information that the R/W control apparatus 1 has received will be described below.
The RF tag in the ‘executable range’ is called an RF tag in a command executable state. Further, the distance between the antennas does not mean a distance between the centers of the antennas but means a distance between an executable range of an arbitrary antenna and an executable range of an adjacent antenna, that is, a distance at which the RF tag cannot perform communication with all of the antennas.
In
A command executable range of the antenna 21 is 25 cm. The R/W 2 performs a read/write operation on the RF tag while passing through a distance of 25 cm near the antenna toward the movement direction of the RF tag. The next adjacent antenna of the antenna 21 is the antenna 22, and a distance between the antenna 21 and the antenna 22 is 25 cm.
When the UID of the RF tag starts from 01, there is command indication information indicating that a read command is executed and two blocks of the first and second blocks of the user data of the RF tag are read. In this example, it is assumed that the UID starts from 01 in the RF tag for a product and detailed information of the product is stored in the first and second blocks of the user data. Although not shown in the drawings, the priority of the commands from the application may be set for each of contents of the command indication information. The priority is used in a schedule creation program, which will be described below.
When a UID starts from 00 or 01, it indicates that the UID is 00 or 01 from the head.
The R/W control program 169 starts the RF tag detection program (S1691). If the RF tag detection program is executed, the RF tag detection information 165 that indicates a list of RF tags is obtained. An operation example of the RF tag detection program will be described below.
The R/W control program 169 starts a schedule creation program (S1692). The schedule creation program creates the reservation command information 168 on the basis of the RF tag detection information 165. An operation example of the schedule creation program will be described below.
The R/W control program 169 executes a command execution program (S1693). The command execution program executes a reserved command on the basis of the reservation command information 168. An operation example of the command execution program will be described below.
The RF tag detection program executes the following processes (S1710 to S1725) by the predetermined number of times (S1705 and S1730). The inventory command is executed while the antenna for RF tag detection (for example, defined by the arrangement information 161) is switched, thereby detecting the RF tag. In the arrangement information 161 shown in
The RF tag detection program executes an antenna switching command such that the antenna 21 becomes active (S1715). The RF tag detection program executes the inventory command to detect the RF tag (S1720). Information of the detected RF tag is stored as the RF tag detection information 165.
In the above description, the antenna switching command and the inventory command are executed by the predetermined number of times. The predetermined number of times includes the number of times that is needed to detect all moving RF tags. For example, when it can be known from a previous operation test that all of the moving RF tags can be detected by repeating the process three times, the number of numbers is set to three times, and the process is repeated three times when the RF tag detection program is executed. In addition to the method using the predetermined number of times, a method may be used in which the process may be repeated until a new RF tag is not detected.
The schedule creation program creates command executable time information 166 on the basis of the arrangement information 161 and the RF tag movement information 164 (S1750).
The start time and the termination time are set as follows. Since the antenna 21 is an antenna for detection, a command executable start time as a relative time with a detection time of the antenna 21 is set as +0.000 second, and +0.250 second obtained by adding 250 ms that is the executable time of the antenna 21 is set as a termination time. Since it can be seen from the arrangement information 161 of
When the movement speed of the RF tag at the belt conveyor is determined in advance, the previously created command executable time information 166 may be used without executing Step S1750.
The schedule creation program adjusts the command executable time information 166 in accordance with a termination reservation time of the present program (S1755). Since the RF tag moves while the RF tag detection program and the schedule creation program are executed, this needs to be reflected on the command executable time. If the time when the RF tag has been detected is set as 10:00:00.000 and a termination anticipation time of the schedule creation program is set as 10:00:00.200 on the basis of the RF tag detection information 165, the command executable start time of the antenna 21 in the command executable time information 166 is at 10:00:00.000 (=10:00:00.000+0.000) and the command executable termination time is at 10:00:00.250 (=10:00:00.000+0.250). Thus, it can be understood that the RF tag exists at a place of the antenna 21 when the schedule creation program is terminated. Accordingly, the command executable time of the antenna 21 is set as 250 ms−200 ms=50 ms, which is obtained by calculating subtraction between a termination reservation time of the schedule creation program and the command executable termination time of the antenna 21.
The schedule creation program creates execution command information 167 on the basis of the command indication information 162, the command execution performance information 163, and the RF tag detection information 165 (S1760).
The schedule creation program sorts commands that are included in the execution command information 167 (S1765). The sort reference (condition) is as follows: (1) setting commands where a total sum of reservation times for every RF tag is large to a high level, and (2) setting commands where a degree of demand of command indication is high (for example, defined by the command indication information 162) to a high level. In this case, the process with respect to the same RF tag is continuously executed, and the commands are sorted using the sort reference of (1). The total sum of anticipation times of commands with respect to the RF tag T0 is 120 ms+160 ms=280 ms, and is larger than 100 ms that is an anticipation time for each command with respect to the other RF tags T1 to T4. The commands are sorted such that the RF tag T0 is at a high level.
The schedule creation program executes the following steps S1775 to S1785 by the number of commands that are included in the execution command information 167 (S1770 and S1790). First, the commands 1671 and 1672 with respect to the same RF tag are selected and Steps S1775 to S1785 are executed.
The schedule creation program searches an antenna that can execute a command (S1775). The commands 1671 and 1672 are commands that are executed with respect to the RF tag T0, and a total sum of command execution anticipation times is 280 ms. If referring to the command executable time information 166 of
The schedule creation program investigates whether there is an antenna that can execute a command (S1780). When there is no antenna that can execute a command, the program is terminated. In addition to the termination of the program, a warning or a message that requires stop or deceleration may be output to a person who is in charge of a belt conveyor or a pallet. Then, the schedule creation program may be executed again at a low speed.
The schedule creation program adds a command to the reservation command information 168 (S1785).
Next, the command 1673 is selected from the execution command information 167 of
The schedule creation program selects the antenna 22 that is adjacent to the antenna 21 and registers the command 1673 as the command 1684 in the reservation command information 168 of
In the same method, Steps S1775 to S1785 are executed with respect to the commands 1674, 1675, and 1676 of the execution command information 167 of
The schedule creation program adds an antenna switching command to the reservation command information 168 (S1795). In addition to the read/write operation on the RF tags T0 to T4, the antenna switching operation needs to be performed from the antenna 21 to the antenna 22 and from the antenna 22 to the antenna 23. In order that the command execution starts at the start time of the command executable time information 166 of
A current point of time is set as a point of time when the RF tag is detected using the RF tag detection program, the reservation command information 168 is created using the schedule creation program, and the detected RF tag enters in a command executable range of the antenna 22 (immediately before the time 0.460 of
The command execution program extracts commands from the reservation command information 168 one by one and sequentially executes the extracted commands. First, the command 1681 that has the high priority temporally is selected.
The command execution program is in a waiting state until the command execution scheduled start time (time 0.460 of
Hereinafter, the command execution program executes the commands 1682 to 1689 in the reservation command information 168 of
As described above, according to the first embodiment, an execution schedule of the commands to be executed is created and each command is executed on the basis of a sequence of the created schedule, and thus it is allowed that a response from the R/W is delayed for a short time. In particular, when the number of commands that are-scheduled at one time is small, the schedule creation time is shortened, which is advantageous to the allowance of the short-time response delay.
Hereinafter, a second embodiment will be described with reference to
The configuration that is shown in
In the second embodiment, the processes of the command execution program and the schedule creation program that starts by the R/W control program 169 of
Since Steps S2000 to S2015 of the schedule creation program of
The schedule creation program executes the following Steps S2025 to S2040 by the number of commands that are included in the execution command information 167 (S2020 and S2045). First, the commands 1671 and 1672 with respect to the same RF tag of
The schedule creation program searches an antenna that can execute a command (S2025). The commands 1671 and 1672 are commands that are executed with respect to the RF tag T0, and a total sum of command execution anticipation times is 280 ms. If referring to the command executable time information 166 of
The schedule creation program investigates whether there is an antenna that can execute a command (S2030). When there is no antenna that can execute a command, the process is terminated. In addition to the termination of the process, a warning may be output to a control device of a belt conveyor to stop the belt conveyor or delay the movement speed thereof, and the schedule creation program may be executed again at a low speed.
The schedule creation program determines whether a command needs to be added to the reservation command information 168 on the basis of a predetermined determination reference (condition) (S2035). The determination reference (condition) includes (1) a command that can be executed by only one antenna and (2) a command that has a degree of demand of command indication more than a predetermined value (for example, defined by command indication information 162). In this embodiment, the determination reference of (1) is adopted. Since the commands 1671 and 1672 can be executed by only the antenna 22, a reservation is needed.
The schedule creation program adds a command to the reservation command information 168 (S2040).
Next, the command 1673 is selected from the execution command information 167 and Steps S2025 to S2040 are executed.
The schedule creation program searches an antenna that can execute the command 1673 (S2025). Since the anticipation time of the command 1673 is 100 ms, if referring to the command executable time information 166 of
Since the command 1673 can be executed by plural antennas 22 and 23, the schedule creation program does not need to make a reservation on the basis of the above-described determination reference (S2035).
In the same method, if Steps S2025 to S2040 are executed with respect to the commands 1674, 1675, and 1676, it is assumed that there is no command that does not need to be reserved. Accordingly, only the commands 1682 and 1683 are included in the reservation command information 168 of
The schedule creation program adds an antenna switching command to the reservation command information 168 (S2050). In addition to the read/write operation on the RF tags T0 to T4, the antenna switching operation needs to be performed from the antenna 21 to the antenna 22 and from the antenna 22 to the antenna 23. First, the execution scheduled start time of the antenna switching command is set such that the command execution starts at the start time of the command executable time information 166 of
The schedule creation program adds a command indicating termination to the reservation command information 168, such that the command execution program is terminated when the RF tag is beyond a command executable range of the final antenna (S2050). Since the antenna 23 is the final antenna, the command 1685 is added to the reservation command information 168 of
In the current situation, in
The command execution program obtains a command 1681, which is not executed and is at the head, from the reservation command information 168 of
The command execution program investigates whether there is a command that can be executed by a current active antenna, before executing the command obtained in Step S2070 (S2075). The command execution program searches a command that can be executed by the current active antenna 21 before executing the command 1681. If the current time is set to 10:00:00.200 of
The command execution program determines whether the command obtained in Step S2070 is a termination command (S2085). Since the command 1681 is not a termination command, the process proceeds to Step S2090.
The command execution program is in a waiting state until a set time and then executes the selected command (S2090). Therefore, the command execution program is in a waiting state until 10:00:00.460, and executes an antenna switching command 1681 for switching the antenna into the antenna 22. It is assumed that the time of 40 ms is needed to execute the antenna switching command, and the time becomes 10:00:00.500.
The command execution program obtains a command 1682 from the reservation command information 168 of
Since the current time is at 10:00:00.500, the command execution program immediately executes the command 1682 (S2090). It is assumed that the time of 120 ms is needed to execute the corresponding command, as shown in the execution command information 167 of
The command execution program obtains the command 1683 from the reservation command information 168 of
The command execution program obtains a command 1684 from the reservation command information 168 shown in
The command execution program executes the command 1673 (S2080). It is assumed that the time of 100 ms is needed to execute the corresponding command, as shown in the execution command information 167 of
In the same method as the above method, Steps S2070 to S2080 are executed and the command 1674 is executed. It is assumed that the time of 100 ms is needed to execute the corresponding command, as shown in the execution command information 167 of
The command execution program investigates a command that can be executed by the current active antenna 22 before executing the command 1684 (S2075). Since the current time is at 10:00:00.980, the start time of the command 1684 is at 10:00:01.210, and the command executable termination time of the antenna 22 is at 10:00:01.000 from the command executable time information 166 shown in
The command execution program is in a waiting state until the time 10:00:01.210 and then executes the antenna switching command 1684 for switching the antenna into the antenna 23 (S2090). It is assumed that the time of 40 ms is needed to execute the corresponding command, and the time becomes 10:00:01.250.
Hereinafter, Steps S2070 to 2080 are repeatedly executed, and the commands 1675 and 1676 are executed. As a result, it is assumed that the time becomes 10:00:01.450.
The command execution program obtains a command 1685 from the reservation command information 168 shown in
As described above, according to the second embodiment, since the command execution schedule is created under a predetermined determination reference, there is an advantage in that the schedule creation time is short. This advantage is particularly remarkable in the case where the number of commands is large. During the command execution and for command execution waiting time, in consideration of the current time, the execution sequence of commands that is suitable for the command execution situation and the current time is dynamically determined. Thus, if all of the commands can be executed, a response delay from the R/W can be allowed within a range in which the RF tag can communicate with the antenna. In particular, when the number of commands that are scheduled at one time is small, the schedule creation time is shortened, which is advantageous to the allowance of the short-time response delay.
Hereinafter, a third embodiment will be described with reference to
Similar to the first embodiment, the product and the pallet passes through the front portion (peripheral portion) of the antenna that is connected to the R/W 2. In regards to the antennas, a group of antennas 21 and 22, a group of antennas 23 and 24, and a group of antennas 25 and 26 are arranged in a vertical direction. The product or pallet moves in a direction according to the order of antennas 21→23→25 and antennas 22→24→26. When the variation is generated in a height-wise direction of the attachment location of the RF tag to the product or the pallet, plural antennas may be disposed in parallel to a movement direction of the RF tags, in order to widen a range of a height-wise direction in which the RF tags can be read. Further, when the product and the pallet pass through the gate, the antennas may be disposed parallel to each other (opposite to each other) at the left and right sides of the gate.
Each of the group of antennas 21 and 22, the group of antennas 23 and 24, and the group of antennas 25 and 26 are arranged in a direction that is different from the movement direction of the RF tag, and when the RF tag moves, the antennas of each group are used in parallel (at the time of actually using the antennas, any one of the groups of antennas is activate and used). When the RF tag exists in front of the group of antennas 21 and 22, the antennas 21 and 22 are used in parallel and a read/write operation is performed on the RF tag. When the RF tag exists in front of the group of antennas 23 and 24, the antennas 23 and 24 are used in parallel and a read/write operation is performed on the RF tag. When the RF tag exists in front of the group of antennas 25 and 26, the antennas 25 and 26 are used in parallel and a write/read operation is performed on the RF tag. As such, the group of antennas that are used in parallel is changed according to the movement location of the RF tag. In order to indicate the group of antennas used in parallel by using the arrangement information 161 shown in
Like the ‘antennas 21→23→25’ and ‘antennas 22→24→26’, the group of antennas that are arranged in the movement direction of the RF tag is designated as a movement direction group and a movement direction group number is given to a group element. For example, a movement direction group number (symbol) A is given to the antennas 21, 23, and 25 of individual elements that constitute the movement direction group ‘antennas 21→23→25’. The movement direction group is a group that corresponds to the height of the attachment location of the RF tag that is attached to the moving product. Thus, the RF tag that is detected by an arbitrary antenna may be subjected to a read/write operation by another antenna that belongs to the same movement direction group as the corresponding antenna, as long as the product does not fall or cause collapse of cargo.
Since the group of antennas is disposed in parallel to correspond to the height-wise direction of the RF tag, in regards to the RF tag at the middle location of the group of antennas, the RF tag may be detected by the antennas that belong to plural movement direction groups or subjected to a read/write operation.
The configuration that is shown in
The third embodiment is different from the first embodiment in the command execution program and the schedule creation program started by the R/W control program 169 of
The schedule creation program creates the command executable time information 166, the execution command information 167, and the reservation command information 168 on the basis of the RF tag detection information 165. The process flow of the schedule creation program is the same as that of the schedule creation program (
The command execution program executes reserved commands on the basis of the command executable time information 166, the execution command information 167, and the reservation command information 168 and executes non-reserved commands in an available time in which a reservation is not made.
The schedule creation program creates the command executable time information 166 on the basis of the arrangement information 161 (
The schedule creation program adjusts the command executable time information 166 in accordance with a termination anticipation time of the schedule creation program (S2005). When the termination anticipation time of the schedule creation program is set as 10:00:00.240, the corresponding program is executed in the same method as the first embodiment (S1755 of
The schedule creation program creates the execution command information 167 on the basis of the command indication information 162 (
Since the RF tag T0 is detected by the antenna 22, the antenna 22 is set as the detection antenna. Meanwhile, since the RF tag T2 is detected by the two antennas 21 and 22, the antennas 21 and 22 are set as the detection antennas. In the antennas that belong to the same movement direction group as the antenna that have detected the RF tag, the possibility of performing a read/write operation on the corresponding RF tag is high, and thus these antenna are set as execution antennas. For example, since the antennas that belong to the same movement direction group B as the antenna 22 are the antennas 22, 24, and 26, the antennas 22, 24, and 26 are set as the execution antennas of the command 1671 with respect to the RF tag T0 that has been detected by the antenna 22.
The schedule creation program sorts commands that are included in the execution command information 167 (S2015). Since the sort reference is the same as that of the first embodiment, the commands 1671 and 1672 become high-level commands.
The schedule creation program executes Steps S2025 to S2040 by the number of commands that are included in the execution command information 167 (S2020 and S2045). First, the commands 1671 and 1672 with respect to the same RF tag are selected.
The schedule creation program searches an antenna that can execute a command (S2025). The commands 1671 and 1672 are commands that are executed with respect to the RF tag T0, and a total sum of command execution anticipation times is 280 ms. If referring to the command executable time information 166 of
In the schedule creation program, the commands 1671 and 1672 can be executed by the antenna 24 (S2030), and can be executed by only the antenna 24. It is assumed that the commands need to be reserved (S2035), and the commands 1671 and 1672 are added to the reservation command information 168 as the commands 1682 and 1683 (S2040).
The schedule creation program selects the command 1673 from the execution command information 167 of
In the same method, if Steps S2025 to 2040 are executed with respect to the commands 1674, 1675 and 1676 of the execution command information 167 of
The schedule creation program adds an antenna switching command to the reservation command information 168 (S2050). The current active antenna 22 needs to be switched into the antenna 23 or 24, and the antenna 23 or 24 needs to be switched into the antenna 25 or 26. It can be understood that it takes 40 ms to switch the antenna on the basis of the command execution performance information 163 of
The command, which is reserved to be executed after switching the antenna according to the command 1681, is the command 1682 that is executed by the antenna 24. Accordingly, the antenna switching destination in the command 1681 is changed from the antenna 23 or 24 to the antenna 24.
The schedule creation program adds a command indicating termination to the reservation command information 168, such that the command execution program is terminated when the RF tag is beyond a command executable range of the final antenna (S2055). Since the antenna 26 is the final antenna, the schedule creation program adds a command 1685 to the reservation command information 168 of
In this embodiment, since only the commands 1671 and 1672 are reserved, the reservation is made by only one antenna 24 between the parallel antennas (antennas 23 and 24). For example, when a reservation is already made to use the antenna 24 and the antenna 23 is reserved, it is needed to determine whether the program can be executed including the switching command used to switch the antenna into the antenna 23. When the reservation is added, an antenna switching command needs to be also added.
As described above, the process flow of the schedule creation program of
The command execution program obtains a command from the reservation command information 168 (S2100). Accordingly, the command execution program obtains a command, which is not executed and at the head, from the reservation command information 168 of
Before executing the command that is obtained in Step S2100, the command execution program investigates whether there is a command that can be executed by the current active antenna (S2105). The command execution program searches a command that can be executed by the current active antenna 22 before executing the command 1681. If the current time is set to 10:00:00.240, the start time of the command 1681 is at 10:00:00.460, the command executable termination time by the current active antenna 22 is 10:00:00.250 from the command executable time information 166 of
Before executing the command that is obtained in Step S2100, the command execution program investigates whether there is a command that can be executed by an antenna parallel to the current active antenna (S2115). The antenna that is disposed parallel to the current active antenna 22 is the antenna 21, but there is no command that can be executed within 10 ms.
The command execution program determines whether the command obtained in Step S2100 is a termination command (S2125). The command 1681 is not the termination command.
The command execution program investigates whether the selected command 1681 is a non-designated antenna switching command (S2130). The command 1681 is an antenna switching command for switching the antenna into the antenna 24, and is not a command that does not designate an antenna.
The command execution program is in a waiting state until the set time, and then executes the command obtained in Step S2100 (S2140). Accordingly, the command execution program is in a waiting state until 10:00:00.460, and executes an antenna switching command 1681 for switching the antenna into the antenna 24. It is assumed that the time of 40 ms is needed to execute the command, and the time becomes 10:00:00.500.
The command execution program obtains a command 1682 from the reservation command information 168 of
The command execution program investigates whether there is a command that can be executed by the current active antenna 24 before executing the command 1682 (S2105). Since the current time is 10:00:00.500 and the start time of the command 1682 is at 10:00:00:500, the command executable time by the antenna 24 becomes 0 ms. This command does not exist. There is no command that can be executed by the antenna 23 that is disposed parallel to the current active antenna 24 at 0 ms (S2115). The command 1682 is not a termination command (S2125). The command 1682 is a read command, and is not a non-designated antenna switching command (S2130).
Since the current time is at 10:00:00.500, the command execution program immediately executes the command 1682 (S2140). It is assumed that the time of 120 ms is needed to execute the command 1682, and the time becomes 10:00:00.620.
The command execution program obtains the command 1683 from the reservation command information 168 of
The command execution program investigates a command that can be executed by the current active antenna 24 before executing the command 1683 (S2105). Since the execution scheduled start time is not set, the command 1683 is a command that is immediately executed after the previous execution of the command 1682. Accordingly, there is no command that can be executed before executing the command 1683, and there is no command that can be executed by the antenna 23 that is disposed parallel to the current active antenna 24 (S2115). The command 1683 is not a termination command (S2125).
Since the command 1683 is a write command but not a non-designed antenna switching command (S2130), the command 1683 is immediately executed (S2140). It is assumed that the time of 160 ms is needed to execute the command 1683, and the time becomes 10:00:00.780.
The command execution program obtains the command 1684 from the reservation command information 168 of
The command execution program investigates a command that can be executed by the current active antenna 24 before executing the command 1684 (S2105). Since the current time is 10:00:00.780, the start time of the command 1684 is 10:00:01.210, and the command executable termination time of the antenna 24 is 10:00:01.000, the command executable time by the antenna 24 becomes 1000 ms−780 ms=220 ms. If a command that is not reserved but can be executed is searched from the execution command information 167 of
The command execution program executes the command 1674 (S2110). It is assumed that the time of 100 ms is needed to execute the command 1674, and the time becomes 10:00:00.880.
The command execution program investigates a command that can be executed by the current active antenna 24 before executing the command 1684 (S2105). Since the current time is 10:00:00.880, the start time of the command 1684 is 10:00:01.210, and the command executable termination time of the antenna 24 is 10:00:01.000, the command executable time by the antenna 24 becomes 1000 ms−880 ms=120 ms. If a command that is not reserved but can be executed is searched from the execution command information 167 of
The command execution program investigates whether there is a command that can be executed by the antenna 23 parallel to the current active antenna 24 (S2115). Since the current time is 10:00:00.880, the start time of the command 1684 is at 10:00:01.210, and the command executable termination time of the antenna 23 is 10:00:01.000, the command executable time by the antenna 23 becomes 1000 ms−880 ms=120 ms. If the executable command is searched from the execution command information 167 of
In the command execution program, the command 1684 is not a termination command (S2125), but an antenna switching command, and the antenna that corresponds to the antenna switching destination is the antenna 25 or 26, and a non-designated antenna (S2130).
The command execution program selects the antenna that corresponds to the antenna switching destination (S2135). If referring to the execution command information 167 of
The command execution program is in a waiting state until 10:00:01.210, and executes an antenna switching command for switching the antenna into the antenna 25 (S2140). It is assumed that the time of 40 ms is needed to execute the command 1684, and the time becomes 10:00:01.250. The command execution program obtains the command 1685 from the reservation command information 168 of
Hereinafter, Steps S2105 and S2110 are repeatedly executed, and the commands 1673 and 1675 are executed. As a result, it is assumed that the time becomes 10:00:01.450. The command execution program investigates a command that can be executed by the current active antenna 25 before executing the command 1685 (S2105). The command 1676 remains in the execution command information 167 of FIG. 22. However, since the anticipation time of the command 1676 is 100 ms and the time when the antenna 25 becomes active is 500 ms−450 ms=50 ms, there is no executable command.
In the command execution program, there is also no command that can be executed by the antenna 26 that is disposed parallel to the current active antenna 25 (S2115). The command 1685 is a termination command (S2125).
The command execution program checks whether a non-executed command exists in the reservation command information 168 of
In the second and third embodiments, in the case where it fails to execute the command by the command execution program, when it is investigated whether an executable command exists, if the failed command can be executed again, the corresponding command may be selected and executed again.
If the second embodiment and the third embodiment are compared, the basic process flow is the same. However, as the process result, non-executed commands remain in the third embodiment. This is because of a restriction that it can be used by only the antenna that belongs to the predetermined movement direction group, and overhead of antenna switching when the number of antennas increases, particularly, overhead of antenna switching between the antennas forming groups (antenna switching between the movement direction groups).
As described above, the proper movement speed of the RF tag is set on the basis of the arrangement information of the antennas subjected to the restriction as hardware and execution performance information of the commands, thereby constructing a system in which commands can be executed again.
In each embodiment, the description has been given to the case where, while the antennas connected to the R/W are switched, the RF tag is detected and the R/W command is executed. That is, when the relationship between the R/W and the antennas is 1:N, it is effective for the case where the structure of the R/W is complex or a size thereof is large or the R/W is expensive. However, in the case where the structure of the R/W is simple or a size thereof is small or the R/W is cheap, the relationship between the R/W and the antenna may be 1:1. Even in this case, if the correlation between each antenna connected to each R/W and a moving RF tag is maintained as described in each embodiment, it can be understood that a technology of the invention may be easily applied.
Number | Date | Country | Kind |
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2007-235641 | Sep 2007 | JP | national |