JPH0869583A - Moving body discriminating method - Google Patents

Abstract

PURPOSE: To surely and quickly discriminate plural moving bodies existing in the service area of an interrogator by accurately performing communication between the interrogator and plural responders. CONSTITUTION: An. interrogator 14 transmits a transmission command to plural responders 12 in a service area 16, and each responder selects one of plural time slots in accordance with random numbers to transmit its own discrimination information ID by this time slot when receiving the command from the interrogator, and the interrogator receives discrimination information ID from respective responders to give permission to the responder whose discrimination information ID is transmitted by the earliest time slot without collision, and the responder to which permission is given transmits data to the interrogator in the reflection type modulation system. When data reception from one responder is terminated, the interrogator transmits the transmission command to the other responders again to repeat the same control. This control is repeated till the end of data reception of all responders existing in the service area and discriminates each moving body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to people, vehicles, articles,
Attach a transponder to a moving body such as livestock or products on a production line, and when the moving body moves the transponder into the service area of the interrogator, the interrogator transmits / receives data to / from the responder. The present invention relates to a moving body identifying method for identifying a moving body.

[0002]

2. Description of the Related Art In recent years, when a wireless tag called a transponder is attached to a person, an article, a car, etc., a transponder called an interrogator is used to read data contents of the transponder to identify a moving body. Depending on the technology, the technique of writing new data to the transponder is being used in various fields. For example, application to an automatic reader for a commuter pass made of a wireless card at a railway ticket gate, an automatic fee collection system using a wireless card at an expressway, and the like are under consideration.

As shown in FIG. 7, a conventional movement identifying apparatus for which various applications as described above are being studied, for example, is a moving body 3 such as a luggage having a responder 2 attached thereto by a belt conveyor 1.
Are transmitted one by one with a certain interval, and an interrogator 4 consisting of a transceiver is installed on the way, and when the mobile unit 3 passes through the service area 5 of the interrogator 4, the interrogator 4 causes the responder to respond. Read and write the data set to 2. Thereby, the moving body 3 is identified, and the information added to the moving body 3 is read out or rewritten. Incidentally, conventionally, the transportation of the moving body 3 is controlled so that only one responder 2 exists in the service area 5 of the interrogator 4.

By the way, there are several types of mobile identification devices depending on their configurations and systems. For example, if classified according to the difference in access method, RO (read only) type that only reads the contents of the transponder but does not write, RW (read / write) type that reads and writes the contents of the transponder, and writing to the transponder W that can be read only once and then read only
ORM (write once read many) type etc.

There are various reading methods, but a method called reflection type modulation is often used. The characteristic of the reflection type modulation system is that the transponder does not generate a carrier when transmitting data from the transponder to the interrogator.

That is, when the interrogator reads data from the transponder, first, the interrogator sends a data read command to the transponder as shown in FIG. Receive the command as shown in (b). Then, the interrogator sends an unmodulated carrier to the responder as shown in (a) of FIG. 8, and the responder receives the unmodulated carrier as shown in (b) of FIG. The reflected wave (modulated wave) is transmitted to the interrogator. The interrogator receives this reflected wave and reads the data of the responder.

When the interrogator writes data to the transponder, the interrogator transmits a data write command to the transponder, and then transmits a carrier modulated with write data instead of the unmodulated carrier. Good.

When there is only one responder in the service area of the interrogator, there is no interference problem, but when there are multiple responders in the service area, each responder simultaneously responds to the interrogator. Then, interference occurs and accurate data transmission / reception becomes impossible.

As an identification device for solving this, for example, Japanese Patent Laid-Open No. 5-290192 is known. In this publication, a plurality of transponders are set with different delay times, and the plurality of transponders called by the interrogator respond to each other based on the different delay times to avoid collision with each other. ing. In addition, a code, which is a synchronization code, is commonly set between the interrogator and the transponder, and the transmission / reception of this code is used as the measurement start point of the delay time to improve the certainty of communication and to use several transponders with this code. The number of transponders that can be handled is increased by dividing into groups. Furthermore, a huge number of transponders are handled by combining discrimination using this code, discrimination by frequency (different frequencies can be set from transponder to interrogator, interrogator to transponder), and discrimination by delay time. It states that it is possible.

In addition, EP0494114A2 (Publicat
The ion number) publication discloses a technique for simultaneously reading multiple transponders. FIG. 5 has 3 interrogators
The timing chart shown in FIG. 9 for reading one transponder is disclosed.

In FIG. 9, (a) is the interrogator signal, and (b)
~ (D) is the response signal from each transponder, (e) ~ (g) is the response enable signal for each transponder, and (h) is when the interrogator receives valid data from each transponder ( This signal is output when the transponder is recognized). The response enable signal means that the response is stopped when it becomes low level, and the response enable signal becomes low level when the response from the transponder is completed.

In this example, since there are three transponders, the signal (h) is output three times with a time shift. Immediately after outputting this signal, the interrogator sets the signal in (a) to low level for a short time and sends a signal (ACK) to the transponder that recognition has been completed, and the transponder that received it sets the enable signal to low level. Stop responding.

Further, the response signals from the respective transponders initially overlap with each other in time, but deviate in the next repetition. That is, the response repetition cycle is different. This is because each transponder randomly determines the repetition cycle. However, the repetition time once decided at random is repeatedly repeated until the reading from each responder is completed. In this way, the response repetition cycle is made different in each transponder to prevent the response collision.

The above-mentioned EP0494114A2 publications are summarized as follows.

Each responder activated by the interrogation signal randomly determines the repetition time. The response is repeated in this cycle to see the change in the interrogation signal. Immediately after the interrogator recognizes the responder, the interrogation signal is momentarily cut off. As a result, the transponder knows that it has been recognized and stops the response by setting the enable signal to the low level.

This series of procedures is performed until the transponder passes the reading area, that is, while the interrogation signal continues to be output.

[0017]

[Patent Document 1] Japanese Unexamined Patent Publication No. 5-29019
The method of setting a delay time unique to each transponder as in Japanese Patent No. 2 has a problem that the required delay time increases as the number of transponders handled increases. Therefore, when there is a transponder with a long delay time, the system has poor responsiveness. Further, when a transponder having a short delay time and a transponder having a long delay time are mixed in the service area, a wasteful time is left between the respective responses.

Therefore, if the delay time interval set in each responder is shortened in order to solve this problem as much as possible, the time available for data transmission also becomes shorter (the data transmission time is equal to the delay time interval), and the amount of data that can be sent. Will decrease.

Further, when the delay time becomes long, the accumulation of errors becomes a problem. Originally there was a problem of delay of radio wave propagation,
Strictly speaking, in the place where the ringing signal (start signal of delay time measurement) does not reach each responder at the same time, it is not possible to have a timer with high accuracy from the viewpoint of cost and size. Accumulation of error cannot be ignored. For this reason, there is a risk that a part of the transmission data (response) will collide between transponders having substantially the same delay time.

Further, in the method of EP0494114A2, collisions are repeated during the reading when the repeat cycle generated at first is the same among several transponders or when some transponders overlap. This means that the advantage of randomly generating delays cannot be used at all, so it is necessary to increase the delay time as the number of responders increases, and unless a lot of wasteful time that is not related to the original communication is taken. Will not happen.

Also, when ACK is returned after recognizing the responder, the method of interrupting the interrogation signal for a moment also causes malfunction because the interrogation of the interrogation signal can easily occur due to noise or multipath.

Therefore, the present invention provides a mobile body identification method capable of accurately communicating between an interrogator and a plurality of responders, and reliably and quickly identifying a plurality of mobile bodies existing in the service area of the interrogator. provide.

Further, according to the present invention, even in a system having a plurality of interrogators, accurate communication can be performed between the interrogator and the plurality of responders, and a plurality of mobile bodies existing in the service area of the interrogator can be reliably secured. Moreover, a moving object identification method that can be identified quickly is provided.

[0024]

According to a first aspect of the present invention, a transponder attached to each of a plurality of moving bodies and a command is transmitted to the transponder when the transponder is in a service area. Then, if there are multiple transponders in the service area of the interrogator, the interrogator will be sent to all the transponders in the service area at once. When the responder receives a command from the interrogator, it selects one of a plurality of preset time slots according to a random number, and transmits its own identification information to the interrogator in this selected time slot. When the interrogator receives the identification information from each responder, it gives permission to send and receive data to the responder that transmitted in the earliest time slot without collision,
The transponder to which permission is given by the interrogator transmits / receives data to / from the interrogator, and when the interrogator completes transmission / reception of data to / from the transponder to which permission is given, the transponders simultaneously send to the remaining responders. A command is transmitted, the same control is repeated, and this control is repeated until all the responders in the service area have finished transmitting and receiving data to identify the mobile unit.

According to the second aspect of the present invention, a responder attached to each of a plurality of moving bodies and a data for this responder after transmitting a command to this responder when the responder is in the service area. When there are multiple responders in the service area of the interrogator, the interrogator first performs carrier sense and other interrogators respond to the responder. After confirming that transmission / reception control is not being performed, commands are sent to all responders in the service area all at once, and when each responder receives a command from the interrogator, it sends 1 command from multiple preset time slots. One according to a random number, and transmits its identification information to the interrogator in this selected time slot,
When the interrogator receives the identification information from each responder, it gives permission to send and receive data to the responder that sent in the earliest time slot without collision, and the responder given permission from the interrogator asks the question. Send and receive data to and from
When the interrogator completes the data transmission / reception with the transponder that has given permission, it repeats the same control by sending commands to the remaining transponders at once, and all the transponders existing in the service area are This control is repeated until data transmission / reception is completed to identify the mobile unit, and the interrogator
When data transmission / reception with all transponders existing in the service area is completed, the operation is suspended for a certain period of time after that, carrier sense is performed after a certain period of time, and transmission / reception control for the transponders is restarted.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 11 denotes, for example, a belt conveyor.
A plurality of moving bodies 13 such as luggage attached with are transported in the direction of the arrow in the figure.

An interrogator 14 is installed near the outside of the belt conveyor 11, and the interrogator 14 is connected to a host computer 15. The moving bodies 13 that convey the belt conveyor 11 are randomly placed, and a plurality of moving bodies 13 may intervene in the service area 16 of the interrogator 14.

The interrogator 14 and the responder 12 are constructed as shown in FIG. That is, the interrogator 14 has a host controller 15 which controls the main controller 21 to send and receive information to and from the host computer 15, a data buffer RAM 23, a PS / SP (parallel-serial / serial
A serial-parallel) conversion unit 24 is connected. The PS / SP converter 24 includes a modulator 25 and a demodulator 26.
, And an oscillator 27 is also connected to the modulator 25.

The serial data from the PS / SP converter 24 is supplied to the transmitting antenna 28 via the modulator 25 and wirelessly transmitted to the outside, and the signal received by the receiving antenna 29 from the outside is also demodulated by the demodulator. 26 through the PS
The signal is supplied to the / SP converter 24. In addition,
Reference numeral 30 is a power supply unit that supplies electric power to each unit.

The responder 12 has a data memory 32, a demodulator 33, and a modulator 34 connected to the main controller 31. A transmitting antenna 35 is connected to the modulating unit 25, and a receiving antenna 37 is connected via a changeover switch 36. The receiving antenna 37 is connected to the demodulation unit 33 via the changeover switch 36. 38
Is a battery that supplies electric power to each unit.

The main controller 31 of the responder 12 includes a time base for generating a preset time slot, a slot controller for generating a random number to determine a slot, a transmission / reception controller, a memory read / write controller, and the like. It is provided.

In the embodiment having such a structure, if three mobile units 13 are provided in the service area 16 of the interrogator 14 as shown in FIG. Transmission / reception control is performed with the responder 12 in the procedure shown in FIG.

First, the interrogator 14 operates as shown in FIG.
As shown in (a) above, send a send command requesting a send. This transmission command is received by each responder 12 as shown in (b) to (d) of FIG. Each responder 12 that has received the transmission command determines the slot for transmitting the identification information ID according to a random number by the slot control means at the beginning of the period T2.

The number of slots is the service area 16
It may be determined depending on how many transponders are present in the inside. Also, if the number of slots is not determined when the transponder is manufactured, it is necessary to transmit the number of slots used by the interrogator 14 together with the first command during system operation.

The interrogator 14 transmits the command and then the period T
At 2, the unmodulated carrier is transmitted as shown in FIG. Each responder 12 receives an unmodulated carrier as shown in (b) to (d) of FIG. 3 and transmits the identification information ID to the interrogator 14 in the determined time slot.

Here, the responder 12 of FIG. 3C transmits the identification information ID in the first slot, and the responder 12 of FIG.
The responder 12 of (d) transmits the identification information ID in the second slot.

The interrogator 14, which has received the identification information ID from each responder 12, gives the responder 12 of FIG. 3C a right to transmit data in the next fixed period. That is,
In the period T3, the permission ID designating the transponder is transmitted to the transponder 12 of FIG. 3 (c). Thus, the transmission right is given to the transponder 12 which has transmitted the ID in the earliest slot without collision (interference).

When the responder 12 of FIG. 3C receives the permission ID, it modulates the unmodulated carrier from the interrogator 14 with data and transmits it to the interrogator 14 in the period T4. That is, the transponder 12 transmits data by the reflection modulation method.

In this way, the interrogator 14 receives the data from the responder 12 of FIG. 3C, analyzes the content of the data, and identifies the moving body 13 to which the responder 12 of FIG. 3C is attached. I do.

The transponder 12 shown in FIG. 3C is the interrogator 14 once.
After the data is transmitted to, the ID is not transmitted even if the read command is transmitted from the interrogator 14.

When the data transmission / reception to / from the responder 12 shown in FIG. 3C is completed in this way, the interrogator 14 again transmits the read command. The remaining responder 12 of FIGS. 3B and 3D determines the slot for transmitting the identification information ID according to the random number by the slot control means.

The interrogator 14 transmits an unmodulated carrier following the command transmission. Responder 12 shown in FIGS. 3 (b) and 3 (d)
Receives the non-modulated carrier and transmits the identification information ID to the interrogator 14 in the determined time slot.

In this way, the interrogator 14 gives the transponder 12 that has transmitted the ID in the earliest slot the right to transmit data, as in the previous time.

By repeating the above control a certain number of times, data can be read from all the responders 12.
All the moving bodies 13 in the service area 16 can be reliably identified.

Then, the responder 12 transmits the identification information ID of the short data to the interrogator 14 to obtain the transmission right, and then transmits the data in the next step.
Uses a number of slots prepared by random numbers, so it is possible to share time slots.

Therefore, even if the number of transponders increases, the problem that the delay time increases as in the conventional case does not occur. That is, the slot interval can be shortened by transmitting the short data of the identification information ID, and the entire time can be limited by sharing the slot so that the increase of the delay time when the number of responders increases can be minimized. it can.

Therefore, it is possible to quickly identify a plurality of moving objects existing in the service area of the interrogator.

When the interrogator 14 determines the transponder 12 to which the right of transmission is given, the interrogator 14 transmits the permission ID for designating the transponder to the transponder. ACK can be accurately returned.

Although the interrogator 14 is fixed in this embodiment, the interrogator may move if the interrogator is portable. Even when the interrogator moves in this way, a plurality of moving bodies existing in the service area can be identified by the same method.

Although the case where there is one interrogator 14 has been described above, the case where there are a plurality of interrogators 14 is also applicable.

Another embodiment using a plurality of interrogators will be described below. When there are a plurality of interrogators 14, transmission / reception control is performed according to the procedure shown in FIG. Each interrogator 14 performs carrier sense CS before starting transmission / reception control with the responder 12 shown in FIG. 3 to confirm that no other interrogator is communicating.

That is, the interrogator 14 performs control based on the flowchart shown in FIG. First, in ST1, it is checked whether the result of carrier sense is OK or NG. If it is OK, that is, if another interrogator is not communicating, a transmission command and its own identification information ID are transmitted in ST2. This identification information I
This is for distinguishing D from other interrogators.

In this state, in ST3, the reception of the identification information ID from the responder 12 is awaited. If the received identification information ID can be received without collision, the data transmission right is granted to the responder 12 corresponding to the identification information ID of the earliest slot in ST4. Then, in ST5, the corresponding transponder 1
The data from 2 is received and the mobile body 13 is identified.

If the above control is not repeated n times, for example, the transmission command and its own identification information ID are transmitted again to the remaining responder 12 in ST2. Note that n
Is set to a sufficient number for the interrogator 14 to recognize all the responders 12 in the area.

When the reception of the identification information ID from the transponder 12 received in ST3 fails, no data is received. If the control is not repeated n times, the transponder 12 returns to ST2. The transmission command and its own identification information ID are transmitted.

In this way, when the control is repeated n times, the timer pauses for a fixed period in ST6. This idle period provides another interrogator 14 with the opportunity to acquire the right to contact the transponder 12.

The responder 12 also performs control based on the flowchart shown in FIG. First, in ST11, the command from the interrogator 14 is awaited, and when the transmission command from the interrogator 14 is received, the identification information ID of the interrogator 14 included in the transmission command is read in ST12.

Then, in ST13, it is checked whether the identification information ID of the interrogator 14 read out is new information, and if it is new information, the identification information ID is stored in the memory.
If it is the identification information ID already stored in the memory, the response to the interrogator is stopped so that the same interrogator 14 is not repeatedly responded, and the process returns to the ST11 command waiting.

When the new identification information ID is received and stored in the memory, in ST14, the slot control means determines a slot for transmitting its own identification information ID according to a random number. Then, in ST15, it transmits to the interrogator 14 in the time slot in which its own identification information ID is determined.

Subsequently, in ST16, when waiting for the reception of the data transmission permission from the interrogator 14, if the data transmission permission is given,
In ST17, the data is transmitted by the reflection modulation method, and then the process returns to the ST11 command waiting. When the interrogator 14 does not permit the data transmission, the ST
Return to 11 command standby.

Therefore, for example, three interrogators 141, 14
When there are 2 and 143, as shown in FIG. 4, the interrogator 141 first performs the carrier sense CS, and the other interrogators 1
After confirming that 42 and 143 are not in communication, communication with the transponder 12 as shown in FIG. 3 is repeated n times.

If the interrogator 143 performs the carrier sense CS during this communication, the carrier sense CS becomes NG.

When the interrogator 141 completes the communication with the responder 12 n times, the interrogator 141 pauses for a certain period. When the interrogator 142 performs the carrier sense CS during this pause, the interrogators 141 and 143 are not in communication, so the communication with the responder 12 is OK.

In this way, the interrogator 142 repeats communication with the responder 12 as shown in FIG. 3 n times. If the interrogator 143 performs the carrier sense CS during this communication, the carrier sense CS becomes NG.

When the interrogator 142 completes communication with the responder 12 n times, it pauses for a certain period. When the interrogator 143 performs the carrier sense CS during this pause period, the interrogators 141 and 142 are not in communication, so the communication with the responder 12 is OK.

As described above, when there are a plurality of interrogators 14, the carrier sense C before the communication with the responder 12 is started.
Since the communication with the responder 12 is started after performing S to confirm that the other interrogator is not communicating, the communication with the corresponding responder 12 does not occur due to radio wave interference between the interrogators, that is, no interference. Can be done reliably.

Further, each interrogator 14 has a corresponding responder 1
Since the operation is suspended for a certain period after the communication with the communication device 2 is repeated n times, another interrogator can perform the carrier sense CS during this period to start the communication with the corresponding responder 12. , Switching of communication of each interrogator can be done smoothly.

In each of the above embodiments, the data transmission between the interrogator and the responder is performed by using the reflection type modulation method, but the present invention is not limited to this, and another modulation method is used. Data may be transmitted by transmitting the data. In each of the above embodiments, the case where the interrogator reads the data from the responder has been described as an example, but it is needless to say that the present invention can be applied to the case where the data is read and written.

In each of the above embodiments, the case where the interrogator and the transponder communicate with each other using a single frequency has been described as an example. However, a plurality of frequencies can be used, and a response handled when a plurality of frequencies are used. The number of the interrogators can be increased, and when using a plurality of interrogators, the frequency used for each interrogator can be changed.

In each of the above-mentioned embodiments, the case where the cargo conveyed on the belt conveyor is identified as the moving body is identified. However, for example, when an answering machine is attached to an automobile or a commuter ticket is attached. The present invention can be applied to identification of various moving objects such as attaching a responder to livestock, attaching a responder to a product on a factory line, or attaching a responder to an inventory item in a warehouse.

[0072]

As described above, according to the present invention, accurate communication can be performed between the interrogator and the plurality of responders, and a plurality of moving bodies existing in the service area of the interrogator can be identified reliably and quickly. A mobile body identification method can be provided.

Further, according to the present invention, even in a system having a plurality of interrogators, accurate communication can be performed between the interrogator and the plurality of responders, and a plurality of mobile objects existing in the service area of the interrogator can be connected. It is possible to provide a moving body identification method that can be surely and quickly identified.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of an interrogator and a responder of the same embodiment.

FIG. 3 is a diagram showing a communication procedure between an interrogator and a responder of the same embodiment.

FIG. 4 is a diagram for explaining the operation of each interrogator in another embodiment of the present invention.

FIG. 5 is a flowchart showing communication control of the interrogator of the embodiment.

FIG. 6 is a flowchart showing communication control of the responder of the embodiment.

FIG. 7 is a schematic configuration diagram showing a conventional example.

FIG. 8 is a diagram showing a communication procedure between the interrogator and the responder of the conventional example.

FIG. 9 is a timing chart for explaining control of another conventional example.

[Explanation of symbols]

 12 ... Responder 13 ... Mobile 14 ... Interrogator

Claims (2)

[Claims] 1. A transponder attached to each of a plurality of moving bodies, and when the transponder is in a service area, a command is transmitted to the transponder and then data is read or written to the transponder. When there are a plurality of responders in the service area of the interrogator, the interrogator simultaneously sends a command to each responder in the service area, and each responder responds to the question. When a command from the interrogator is received, one of a plurality of preset time slots is selected according to a random number, and its identification information is transmitted to the interrogator in the selected time slot. Upon receiving the identification information from, the responder that sent in the earliest timeslot without collision gave permission to send and receive data, and was granted permission from the interrogator. The responder transmits / receives data to / from the interrogator, and when the interrogator finishes transmitting / receiving data to / from the responder to which permission has been given, the interrogator simultaneously transmits a command to the remaining responders to perform the same operation. Repeat the control of
A mobile body identification method characterized in that this control is repeated until all the transponders existing in the service area have finished transmitting / receiving data to identify the mobile body. 2. A transponder attached to each of a plurality of moving bodies, and when the transponder is in a service area, a command is transmitted to the transponder and then data is read or written to the transponder. When a plurality of interrogators exist in the service area of the interrogator, the interrogator first performs carrier sense and another interrogator performs transmission / reception control with respect to the interrogator. After sending the command from all the responders in the service area, and when the responders receive the command from the interrogator, one of the plurality of preset time slots receives one command. Selecting according to a random number, transmitting its identification information to the interrogator in the selected time slot, and the interrogator receives the identification information from each of the responders,
The transponder that has transmitted in the earliest time slot without collision gives permission to transmit / receive data, and the transponder to which the interrogator has given permission transmits / receives data to / from the interrogator. When the transponder finishes sending and receiving data to and from the transponder that has given permission, it repeats the same control by sending commands to the remaining transponders at the same time, and all transponders in the service area receive data. This control is repeated until the end of the transmission / reception of the mobile unit, and the interrogator further stops the operation for a certain period after the end of the transmission / reception of the data with all the responders existing in the service area, A mobile body identification method, characterized in that carrier sensing is performed after a lapse of a certain period of time to restart transmission / reception control for a responder.