JP4836536B2 - Existence range identification system, existence range identification method, and program - Google Patents

Description

  The present invention relates to an existence range identification system, an existence range identification method, and a program.

  Various techniques such as GPS (Global Positioning System) have been proposed as a technique for identifying the position of a specific moving body in space. Among them, there is a method using a wireless tag and a reader as a method for identifying a position in a relatively narrow space.

A moving body position identification method using a conventional wireless tag and reader will be described with reference to FIG.
As shown in FIG. 12A, a mobile object (person or the like) is provided with a wireless tag including a weak wireless transmission unit. The reader is arranged so that the receivable ranges for the radio waves transmitted by the radio tag do not overlap, and the radio tag periodically transmits weak radio waves. This mobile unit position identification device utilizes the fact that the reach of radio waves is extremely narrow (several meters), and if there is a reception response in the reader, it can be seen that the wireless tag exists within a few meters of the reader. The position of the moving body can be identified with high accuracy.
However, this method is costly because a large number of readers are required to increase the area for identifying the position.

  In order to widen the area for identifying the position of the wireless tag, a method using a wireless tag including a specific low power wireless transmission unit and a reader can be considered. However, the output of the specific low-power radio is much stronger than that of the weak radio, and the distance of radio waves is long. For this reason, as shown in FIG. 12B, the receivable ranges of the reader with respect to the radio wave transmitted by the wireless tag overlap, and the accurate position of the wireless tag cannot be identified.

An example of a technique using a moving body position identification device in consideration of such a problem is disclosed in Patent Document 1.
JP-T-2002-517050

The moving body position identification device disclosed in Patent Literature 1 includes a wireless tag including a specific low-power wireless transmission device, and at least two readers. Each reader is connected to one system processor. The reader is arranged so that a part of a receivable range for a transmission radio wave of a certain wireless tag overlaps a part of a receivable range for a transmission radio wave of a certain wireless tag of another reader.
In this mobile unit position identification device, a system processor determines to which reader the transmission radio wave of the wireless tag is received. If there is a reception response in one reader, the position of the wireless tag can be identified within the receivable range of the reader that has received the reception response and does not overlap the receivable range of other readers. If there are reception responses in a plurality of readers, the position of the wireless tag can be identified in the overlapping range of the receivable ranges of the readers that have received reception reactions.

The output of the specific low power radio is much stronger than that of the weak radio, and the distance of radio waves is long. Therefore, even if the position of the wireless tag is identified in a certain range with the mobile body position identification device of Patent Document 1, the range is wide and the position of the wireless tag is higher than that of the mobile body position identification device configured with weak wireless. It cannot be identified with accuracy.
If the transmission output of the wireless tag is increased in this way, the position of the wireless tag can be identified in a wide area, but the position of the wireless tag cannot be identified with high accuracy.

  The present invention has been made in view of the above problems, and an object thereof is to provide an existence range identification system, an existence range identification method, and a program capable of identifying the existence range of a radio wave radiation device with high accuracy. .

In order to achieve the above object, an existence range identifying system according to a first aspect of the present invention includes a plurality of first output levels and a second output level lower than the first output level. A presence range identification system for sequentially identifying different output levels and identifying a range in which a radio wave emission device that emits radio waves including transmission output data representing the output level exists, the radio wave emitted from the radio wave emission device A radio wave receiving means for receiving, an output level specifying means for specifying an output level when the radio wave is radiated based on the transmission output data included in the radio wave received by the radio wave receiving means, and the output level specifying means Based on the specified result, whether or not a radio wave radiated at the first output level from the radio wave radiation device has been received and radiated at the second output level. A received radio wave discriminating means for discriminating whether or not a radio wave has been received; and a radio wave radiated at the second output level by the received radio wave discriminating means is not received, but is radiated at the first output level. If it is determined that the received radio wave is received, the radio wave receiving means can receive the radio wave radiated at the second output level from the first range in which the radio wave radiated at the first output level can be received. A third range excluding the second range is acquired as a range where the radio wave emission device exists, and a radio wave radiated at the first output level and a radio wave radiated at the second output level When there is a determination that both are received, the second range is acquired as a range in which the radio wave emission device exists, and there is provided presence range acquisition means.

  Further, in the presence range identification system, each of the radio wave receiving means that includes a plurality of the radio wave receiving means, and the presence range acquisition means receives the radio waves radiated from the radio wave radiation device among the plurality of radio wave reception means. The second or third range is acquired according to the determination result by the received radio wave determination unit, and the range where the acquired second or third range overlaps is the range where the radio wave emission device exists. You may make it acquire as.

  Furthermore, in the presence range identification system, the presence range acquisition unit is configured to cause all of the radio wave reception units that have received radio waves radiated from the radio wave emission device to the second output level among the plurality of radio wave reception units. If the received radio wave discriminating unit determines that the radio wave radiated at the first output level has been received but has not received the radiated radio wave, the reception strength is acquired for each radio wave receiving unit. Based on the range in which the third ranges for all of the radio wave receiving means that have received the radio waves radiated from the radio wave emitting device overlap each other and the reception intensity acquired by the reception intensity acquiring means. Thus, a range where the radio wave emission device exists may be identified.

Also, the existence range identification method according to the second aspect of the present invention sequentially switches a plurality of different output levels including a first output level and a second output level lower than the first output level. And a radio wave receiving step for receiving a radio wave radiated from the radio wave radiation device, wherein the radio wave radiation device radiates a radio wave including the transmission output data representing the output level. Based on the transmission output data included in the radio wave received by the radio wave receiving step , based on the output level specifying step for specifying the output level when the radio wave is radiated, and the specifying result by the output level specifying step, Whether or not a radio wave radiated at the first output level from the radio wave radiation device has been received, and a radio wave radiated at the second output level is received. A radio wave radiated at the first output level although the radio wave radiated at the second output level is not received by the received radio wave discrimination step. When it is determined that the radio wave is received, the radio wave receiving step receives a second radio wave radiated at the second output level from a first range in which the radio wave radiated at the first output level can be received. The third range excluding the range is acquired as the range where the radio wave emission device exists, and the radio wave radiated at the first output level and the radio wave radiated at the second output level are received together. A presence range acquisition step of acquiring the second range as a range in which the radio wave emission device exists.

The program according to the third aspect of the present invention sequentially switches between a plurality of different output levels including a first output level and a second output level lower than the first output level. a computer to identify a range of radio emission device is present which emits a radio wave including the transmission output data representative of the output level, the transmission output data included in the radio wave radiated from the radio wave emitting device received by the radio waves receiving unit Based on the output level specifying procedure for specifying the output level when the radio wave is radiated and the specifying result by the output level specifying procedure, the radio wave radiated from the radio wave emitting device at the first output level is A received radio wave determination procedure for determining whether or not a radio wave radiated at the second output level has been received, and a received radio wave determination procedure. If the radio wave radiated at the second output level is not received but it is determined that the radio wave radiated at the first output level is received, the radio wave reception procedure is performed at the first output level. A range in which the radio wave emission device exists is a third range in which a second range in which radio waves radiated at the second output level can be received is excluded from a first range in which radiated radio waves can be received. And when it is determined that both the radio wave radiated at the first output level and the radio wave radiated at the second output level are received together, the radio wave radiation device exists in the second range. And an existence range acquisition procedure to be acquired as a range to be executed.

  By adopting such a configuration, it is possible to provide an existence range identification system, an existence range identification method, and a program that can identify the existence range of the radio wave emission device with high accuracy.

  Hereinafter, based on the drawings, a position identification device according to an embodiment of the present invention will be described in detail.

  The mobile object position identification device is connected to the wireless tag 100 installed on the mobile object, a plurality of readers 200-i (0 ≦ i ≦ n−1) installed at predetermined positions, and the reader 200-i. And a position identification terminal 300.

  As shown in FIG. 1, the wireless tag 100 includes a wireless transmission unit 10, a control circuit 1, a vibration sensor 2, and a power supply 3.

  The wireless transmission unit 10 includes an oscillation circuit 11, a modulation circuit 12, a frequency multiplication circuit 13, an RF (Radio Frequency) output circuit 14, and an antenna 15. The oscillation circuit 11 is a circuit for generating a carrier wave. The modulation circuit 12 is a circuit for modulating the carrier wave generated by the oscillation circuit 11. The frequency multiplier circuit 13 is a circuit for generating a high frequency signal from the harmonic component included in the output of the oscillation circuit 11. The RF output circuit 14 is a circuit that amplifies the high-frequency signal generated by the frequency multiplication circuit 13. The antenna 15 is an element for transmitting a high-frequency signal from the RF output circuit 14 as a radio wave.

  The vibration sensor 2 is connected to the control circuit 1 and sends an activation signal that activates the control circuit 1 when vibration is detected.

The control circuit 1 is connected to the oscillation circuit 11 of the wireless transmission unit 10, the modulation circuit 12, and the RF output circuit 14, and based on the activation signal from the vibration sensor 2, the oscillation circuit 11 of the wireless transmission unit 10. Start up. In addition, the control circuit 1 sends to the modulation circuit 12 a wireless tag ID (Identity) that is identification data of the wireless tag 100 and transmission output data representing a transmission output level.
Further, the control circuit 1 transmits a transmission output control signal for sequentially switching the transmission output level to a two-level output level when the high-frequency signal modulated with these data is transmitted from the wireless transmission unit 10. 14

  In the present embodiment, the RF output circuit 14 outputs a high-frequency signal every second, and in this one-time output, as shown in FIG. 2, the transmission output level is weak from a strong output level (for example, 1 mW). It is switched to an output level (for example, 0.1 mW). Also, the value of the transmission output data representing the transmission output level is “1” when the output power level is high, and “2” when the output power level is weak. By sending transmission output data representing such a transmission output level to each reader 200-i, it becomes possible to correct even if the reception intensity at each reader 200-i varies due to the influence of the surrounding environment. .

  The power source 3 supplies power to the wireless tag 100. The antenna 15 is generally a built-in antenna, but is shown outside the wireless tag 100 in the drawing for convenience.

  As illustrated in FIG. 1, the reader 200-i includes a wireless reception unit 20, a control circuit 4, a communication unit 5, and a power source 6.

  The wireless reception unit 20 includes an antenna 24, an RF input circuit 21, a demodulation circuit 22, and an oscillation circuit 23. The antenna 24 is an element for receiving radio waves. The RF input circuit 21 includes a tuning unit and an amplification unit, selects a desired wave from the received radio wave, and amplifies a high-frequency signal obtained from the selected desired wave. The oscillation circuit 23 generates a carrier wave. The demodulation circuit 22 generates an intermediate frequency from the carrier wave generated by the oscillation circuit 23 and the desired wave obtained by the RF input circuit 21, and detects this intermediate frequency.

  The demodulation circuit 22 is connected to the control circuit 4, and the control circuit 4 is connected to the position identification terminal 300 via the communication unit 5. The control circuit 4 measures the electric field strength (reception strength) of the radio wave received by the radio reception unit 20 and reads the radio tag ID and transmission output data from the radio wave. Then, the control circuit 4 sends an RFID tag ID, transmission output data, and an RSSI (Received Signal Strength Indicator) value indicating the measured reception strength to the position identification terminal 300 via the communication unit 5. This RSSI value is represented by S1 to S9 in order from, for example, the weakest.

  The power source 6 supplies power to the reader 200-i. The antenna 24 is a generally built-in antenna, but is shown outside the reader 200-i for convenience in the drawings.

  Further, as shown in FIG. 1, the position identification terminal 300 includes a control unit 30, a communication unit 7, a storage unit 8, and a power source 9.

  The communication unit 7 receives the wireless tag ID, the transmission output data, and the RSSI value transmitted from each reader 200-i and sends these data to the control unit 30.

  The control unit 30 includes, for example, a ROM (Read Only Memory) 31, a CPU (Central Processing Unit) 32, and a RAM (Random Access Memory) 33.

  The CPU 32 controls the operation of each part of the position identification terminal 300 by appropriately executing various programs stored in the ROM 31 using the RAM 33 as a work memory. The CPU 32 is connected to the communication unit 7 and the storage unit 8.

  Further, the RAM 33 is provided with a reception data analysis buffer for analyzing reception data at each reader 200-i. As shown in FIG. 3 (a), the reception data analysis buffer includes identification data of each reader 200-i, a reception or read pointer value i, a receivable range flag value, and a reception flag value. The RFID tag ID, which is the identification data of the RFID tag 100 that has transmitted the radio wave received by the reader 200-i, is stored in association with the RSSI value.

  The receivable range flag is a 2-bit flag indicating whether or not the wireless tag 100 exists within the receivable range of the reader 200-i. Here, the receivable range refers to a range in which the reader 200-i can receive a radio wave transmitted from the wireless tag 100 at a predetermined output level.

  In the present embodiment, a range in which the reader 200-i can receive a radio wave transmitted from the wireless tag 100 at an output level of 1 mW, specifically, as shown in FIG. A range within a radius of 40 m from i is defined as a first receivable range. Further, the second reception is performed within a range in which the reader 200-i can receive a radio wave transmitted from the wireless tag 100 at an output level of 0.1 mW, specifically, a range within a radius of 12 m from the reader 200-i. To the extent possible.

  When the value of the transmission output data sent from the reader 200-i is “1”, that is, when the reader 200-i receives a radio wave sent from the wireless tag 100 at an output level of 1 mW, the wireless tag 100 reads the reader. The value of the receivable range flag shown in FIG. 3A is updated to “1”, assuming that it exists within the first receivable range of 200-i. When the value of the transmission output data is “2”, that is, when the reader 200-i receives a radio wave transmitted from the wireless tag 100 at an output level of 0.1 mW, the wireless tag 100 reads the reader 200-i. The value of the receivable range flag is updated to “2”.

  By periodically checking the value of such a receivable range flag, it is possible to know the state of movement of the mobile object in which the wireless tag 100 is installed. For example, as shown in FIG. 4B, if the moving body is at a position P (t0) at time T0, the reader 200-i only receives radio waves transmitted from the wireless tag 100 at an output level of 0.1 mW. In addition, radio waves transmitted at an output level of 1 mW cannot be received. For this reason, the value of the receivable range flag remains “0” as shown in FIG. Thereafter, as shown in FIG. 4A, when the moving body moves to the position P (t1) at time T1, the reader 200-i receives a radio wave transmitted from the wireless tag 100 at an output level of 1 mW. On the other hand, it is impossible to receive radio waves transmitted at an output level of 0.1 mW. Therefore, the value of the receivable range flag is updated to “1” as shown in FIG.

  As shown in FIG. 4A, when the moving body reaches a position P (t2) that is substantially the same as the position of the reader 200-i at time T2, the reader 200-i It is possible to receive not only radio waves transmitted at the output level but also radio waves transmitted at the output level of 0.1 mW. Therefore, the value of the receivable range flag is updated to “2” as shown in FIG. Thereafter, as shown in FIG. 4A, when the moving body advances to a position P3 (t3) at time T3, the reader 200-i receives a radio wave transmitted from the wireless tag 100 at an output level of 1 mW. On the other hand, it is impossible to receive radio waves transmitted at an output level of 0.1 mW. Therefore, the value of the receivable range flag is updated to “1” as shown in FIG. Further, as shown in FIG. 4A, when the moving body moves to a position P4 (t4) at time T4, the reader 200-i only receives radio waves transmitted from the wireless tag 100 at an output level of 0.1 mW. In addition, radio waves transmitted at an output level of 1 mW cannot be received. Therefore, the value of the receivable range flag is “0” as shown in FIG.

  Thus, as shown in FIG. 4B, the value of the receivable range flag changes from “0” → “1” → “2” → “1” → “0” with time. Thus, it can be seen that the moving body approaches the reader 200-i, passes through the periphery of the reader 200-i, and eventually moves away from the reader 200-i. Furthermore, in addition to the change in the value of the receivable range flag, the change in the RSSI value is also taken into consideration so that the movement of the moving object can be known. The situation can be known with higher accuracy.

  The receiving flag shown in FIG. 3A is a 1-bit flag indicating whether data is received from the reader 200-i, and when data reception from the reader 200-i is started, The value is updated to “1”, and when the process ends, the value is updated to “0”.

  The storage unit 8 shown in FIG. 1 is composed of a hard disk drive, for example, and stores a range data table and the like. As shown in FIG. 5A, this range data table shows the identification data of each reader 200-i, the value i of the read pointer, and the range excluding the second receivable range from the first receivable range. Range data #i and range data # n + i indicating the second receivable range are stored in association with each other. Such range data includes, for example, data (position coordinate data) indicating a plurality of position coordinates on the plane coordinates with the position of the position identification terminal 300 as the origin. Specifically, as shown in FIG. 5B, the range data #i is included in a circle having a radius of 12 m from position coordinate data included in a circle having a radius of 40 m centered on the position coordinates of the reader 200-i. The data indicating the second receivable range is a plurality of position coordinate data included in a circle having a radius of 12 m centered on the position coordinates of the reader 200-i. Consists of

  Hereinafter, the operation of the moving body position identification device will be described with reference to the drawings.

  When detecting the vibration, the vibration sensor 2 sends an activation signal for activating the control circuit 1. The control circuit 1 sends a control signal to the wireless transmission unit 10 based on the activation signal of the vibration sensor 2.

  When the wireless transmission unit 10 receives a control signal from the control circuit 1, the oscillation circuit 11 generates a carrier wave having a predetermined frequency and sends the generated carrier wave to the modulation circuit 12. The control circuit 1 further sends transmission output data representing the wireless tag ID, which is identification data of its own wireless tag, and the transmission output level of the radio wave to the modulation circuit 12.

  The modulation circuit 12 modulates the carrier wave with the data sent from the control circuit 1 and sends the modulated carrier wave to the frequency multiplication circuit 13. The frequency multiplication circuit 13 frequency-multiplies the modulated carrier wave to generate a high frequency signal, and sends the generated high frequency signal to the RF output circuit 14. The control circuit 1 connected to the RF output circuit 14 sends a transmission output control signal for switching the transmission output level to the RF output circuit 14 at regular time intervals.

  The RF output circuit 14 transmits the high-frequency signal generated by the frequency multiplication circuit 13 on the basis of the transmission output control signal of the control circuit 1 via the antenna 15 while switching the transmission output level at regular time intervals. When the moving body moves in this manner, the vibration is detected, and the wireless tag 100 transmits radio waves by switching the transmission output level at regular time intervals.

  The radio wave transmitted from the wireless tag 100 is received by the antenna 24 of the reader 200-i. The RF input circuit 21 extracts and amplifies a high frequency signal from the received radio wave. The oscillation circuit 23 generates a carrier wave, and the demodulation circuit 22 generates an intermediate frequency from the carrier wave generated by the oscillation circuit 23 and a high-frequency signal obtained from the received radio wave, detects the intermediate frequency, and wirelessly A tag ID and transmission output data are extracted.

  The wireless tag ID and transmission output data taken out by the wireless receiving unit 20 are sent to the control circuit 4. The control circuit 4 reads the wireless tag ID and the transmission output data sent from the wireless reception unit 20 and sends them to the position identification terminal 300 via the communication unit 5.

  In this way, when the reader 200-i receives the radio wave of the wireless tag 100, the reader 200-i reads the wireless tag ID and transmission output data of the wireless tag 100 and sends each read data to the position identification terminal 300.

  In the position identification terminal 300, in response to a timer interrupt that the CPU 32 periodically generates (for example, every 2 milliseconds), a received data analysis process, a mobile object existence range narrowing process, a mobile object existence range identification process, Are executed sequentially.

  First, the details of the received data analysis process executed by the CPU 32 will be described with reference to the flowchart shown in FIG. In this process, as shown in FIG. 6, the CPU 32 first receives the data sent from the reader 200-i by checking the value of the receiving flag corresponding to the value i of the reception pointer provided in the RAM 33. It is determined whether it is in the middle (step S1). Here, if the value of the reception flag is “0”, it is determined that reception is not being performed (step S1; No), and then the input state of the port corresponding to the reader 200-i of the communication unit 7 is checked. Thus, it is determined whether or not reception of data from the reader 200-i is started (step S2).

  If it is determined in step S2 that reception of data from the reader 200-i has started (step S2; Yes), the reader 200-i transmits radio waves transmitted from the wireless tag 100 at an output level of 1 mW. It is determined that the received data is received, and the wireless tag ID and RSSI value included in the received data are stored in the storage area corresponding to the value i of the received pointer in the received data analysis buffer (steps S3 and S4). The value of the receivable range flag corresponding to the value i of the reception pointer is updated to “1” (step S5). Thereafter, the value of the receiving flag corresponding to the value i of the reception pointer is also updated to “1” (step S6).

  On the other hand, if it is determined in step S2 that reception of data from the reader 200-i has not been started (step S2; No), steps S3 to S6 are skipped, The process proceeds to S11.

  Also, if the value of the receiving flag is “1” in the processing of step S1, it is determined that reception is in progress (step S1; Yes), and the port corresponding to the reader 200-i of the communication unit 7 is input. By checking the state, it is determined whether or not the reception of data from the reader 200-i is completed (step S7). If it is determined in step S7 that reception of data from the reader 200-i has not been completed yet (step S7; No), the value of the transmission output data included in the received data is “ 2 ”, the reader 200-i receives not only radio waves sent from the wireless tag 100 at an output level of 1 mW but also radio waves sent at an output level of 0.1 mW. It is determined whether or not (step S8).

  At this time, if the value of the transmission output data is “2”, it is determined that the reader 200-i has received a radio wave transmitted from the wireless tag 100 at an output level of 0.1 mW (step S8; Yes), the value of the receivable range flag corresponding to the value i of the reception pointer is updated to “2” (step S9). On the other hand, if the value of the transmission output data remains “1” (step S8; No), the process of step S9 is skipped and the process proceeds to step S11.

  If it is determined in step S7 that the reception of data from the reader 200-i has ended (step S7; Yes), the value of the receiving flag corresponding to the value i of the reception pointer is set to “0”. (Step S10).

  After executing the processing in steps S1 to S10, the CPU 32 adds and updates the value of the reception pointer by “1” (step S11), and whether or not the updated reception pointer value i becomes n + 1. Is determined (step S12). At this time, if the updated value i of the reception pointer is a numerical value other than n + 1 (step S12; No), the process returns to step S1. On the other hand, if the updated reception pointer value i matches n + 1 (step S12; Yes), it is determined that all reception states of data from each reader 200-i have been checked, and the reception pointer is changed. The initial value “0” is set (step S13), and the received data analysis process is terminated.

  Next, details of the moving object presence range narrowing process executed by the CPU 32 will be described with reference to the flowchart shown in FIG. In this process, as shown in FIG. 7, the CPU 32 first determines whether or not the value of the reception flag corresponding to the value i of the read pointer is “1” (step S21). At this time, if it is determined in the process of step S21 that the value of the receiving flag is “1” (step S21; Yes), it is assumed that the reception of data from the reader 200-i has not ended yet. The process proceeds to step S34.

  On the other hand, when it is determined in the process of step S21 that the value of the receiving flag is “0” (step S21; No), the value of the receivable range flag corresponding to the read pointer value i is “ Whether it is “0” or not is determined (step S22). At this time, when it is determined that the value of the receivable range flag is “0” (step S22; Yes), it is determined that data from the reader 200-i is not received, and the process proceeds to step S34.

  Further, when it is determined that the value of the receivable range flag is a numerical value other than “0” (step S22; No), it is further assumed that the reception of data from the reader 200-i has ended, and this receivable is possible. It is determined whether the value of the range flag is “1” or “2” (step S23). Here, if the value of the receivable range flag is “1”, the reader 200-i was able to receive the radio wave transmitted from the wireless tag 100 at the output level of 1 mW, but it was transmitted at the output level of 0.1 mW. It is determined that the received radio wave has not been received (step S23; Yes), and the reader 200-i outputs 0.1 mW from the range in which the radio wave transmitted at the output level of 1 mW can be received (first receivable range). Range data #i indicating a range excluding the range in which radio waves transmitted at the level can be received (second receivable range) is acquired from the range data table shown in FIG. 5A (step S24).

  On the other hand, if the value of the receivable range flag is “2”, the reader 200-i is not only transmitted with the output level of 1 mW from the wireless tag 100 but also with the output level of 0.1 mW. Range data # indicating a range (second receivable range) in which the reader 200-i can receive a radio wave transmitted at an output level of 0.1 mW. n + i is acquired from the range data table shown in FIG. 5A (step S25). At this time, the RSSI value consideration unnecessary flag value indicating that the RSSI value is not considered in the identification of the position of the moving body is updated to “1” (step S26).

  After executing the process of step S24 or S26, the receivable range flag is initialized and its value is updated to “0” (step S27). Thereafter, the CPU 32 determines whether or not a work area for identifying the existence range of the wireless tag 100 indicated by the wireless tag ID corresponding to the read pointer value i has already been created in the RAM 33 (step S28). . When it is determined that the work area for identifying the existence range of the wireless tag 100 indicated by the wireless tag ID is not formed in the RAM 33 (step S28; No), the work area is formed in the RAM 33 ( Step S29). Then, the CPU 32 stores the range data acquired in step S24 or S25 in the work area created in step S29 (step S30).

  In addition, an identification waiting time timer for measuring the waiting time from the creation of the work area in the process of step S29 to the identification of the existence range of the wireless tag 100 indicated by the wireless tag ID is formed in the RAM 33. A predetermined initial value is set in the identification waiting time timer and countdown is started (step S31).

  On the other hand, when it is determined that the work area for identifying the existence range of the wireless tag 100 indicated by the wireless tag ID is formed in the RAM 33 (step S28; Yes), the process of step S24 or S25 is performed. Range data common to the range data acquired in the process and the range data stored in the work area is acquired (step S32). In the process of step S32, the position coordinate data common to the position coordinate data constituting the range data acquired in step S24 or S25 and the position coordinate data constituting the range data stored in the work area is the same. Extracted and range data consisting of the position coordinate data is acquired.

  Then, the range data acquired in step S32 is overwritten and saved in the work area (step S33). In this way, the CPU 32 can sequentially narrow down the existence range of the wireless tag 100 indicated by the wireless tag ID, more specifically, the existence range of the mobile object in which the wireless tag 100 is installed.

  After executing the processing of steps S21 to S33, the CPU 32 adds “1” to the value of the read pointer and updates it (step S34), and whether or not the updated read pointer value i becomes n + 1. Is discriminated (step S35). At this time, if the updated read pointer value i is a numerical value other than n + 1 (step S35; No), the process returns to step S21. On the other hand, if the updated read pointer value i matches n + 1 (step S35; Yes), it is determined that all the data stored in the received data analysis buffer has been checked, and the read pointer is initialized. A value “0” is set (step S36), and the moving object existence range narrowing process is terminated.

  Next, details of the moving object presence range identification process executed by the CPU 32 will be described with reference to the flowchart shown in FIG. In this process, as shown in FIG. 8, the CPU 32 first updates the timer values in all identification waiting time timers formed in the RAM 33 by subtracting 1 (step S41). Next, the CPU 32 checks the timer value in the updated identification waiting time timer, and determines whether or not there is an identification waiting time timer that has timed out due to the timer value becoming “0” (step S42).

  Here, when it is determined that there is no timed-out identification waiting time timer (step S42; No), the moving object existence range identification process is terminated as it is. On the other hand, if it is determined that there is an identification waiting time timer that has timed out (step S42; Yes), the range data stored in the work area of the wireless tag ID corresponding to this identification waiting time timer is read out. This is acquired as data indicating the existence range of the wireless tag 100 indicated by the wireless tag ID, more specifically, the existence range of the mobile object in which the wireless tag 100 is installed (step S43). In this way, the CPU 32 can identify the position of the moving object on which the wireless tag 100 is installed with high accuracy.

  Subsequently, the CPU 32 checks an RSSI value consideration unnecessary flag provided in the RAM 33, and determines whether or not to identify the position of the moving object in consideration of the RSSI value (step S44). Here, if the value of the RSSI value consideration unnecessary flag is “0”, it is determined that the position of the moving body is identified in consideration of the RSSI value (Step S44; No), and the process of Step S43 is performed. In addition to the acquired range data, the position of the moving body is identified in consideration of the RSSI value corresponding to the wireless tag ID indicating the wireless tag 100 (step S45).

  For example, the position coordinate data of the moving body is acquired by comparing the RSSI values of the readers 200-i that have received the radio waves from the wireless tag 100 whose existence range has been acquired in the process of step S43, Range data including position coordinate data included in a circle having a predetermined radius centered on the position coordinate indicated by the position coordinate data is acquired. The range data common to the range data and the range data acquired in step S43 is the range in which the wireless tag 100 indicated by the wireless tag ID exists, more specifically, the movement in which the wireless tag 100 is installed. Acquired as data indicating the existence range of the body. In this way, the CPU 32 has the wireless tag 100 installed even when none of the readers 200-i receives the radio wave transmitted from the wireless tag 100 at the output level of 0.1 mW. The position of the moving body can be identified with high accuracy.

  On the other hand, if the value of the RSSI value consideration unnecessary flag is “1”, it is determined that the position of the moving body is not identified in consideration of the RSSI value (step S44; Yes), and the RSSI value consideration is unnecessary. After updating the value of the flag to “0” (step S46), the process proceeds to step S47.

  After executing the processing in steps S41 to S46, the CPU 32 obtains the wireless tag ID of the wireless tag 100 whose existence range has been acquired in the processing in step S43 and the RSSI value corresponding to the wireless tag ID in the received data analysis buffer. Erasing from the storage area (step S47).

  The operation of the above-described moving body position identification device will be described with a specific example.

  When the reader 200-i can receive not only the radio wave transmitted at the output level of 1 mW from the wireless tag 100 installed on the moving body but also the radio wave transmitted at the output level of 0.1 mW, the reader 200-i As shown in FIG. 9A, the value of the receivable range flag corresponding to is updated to “2” (step S9). From the range data table shown in FIG. 5A, range data # n + i indicating a range (second receivable range) in which the reader 200-i can receive a radio wave transmitted at an output level of 0.1 mW is obtained. Obtained (step S25).

  The readers 200-i + 1 and 200-i + 2 can receive radio waves transmitted from the wireless tag 100 with an output level of 1 mW, but cannot receive radio waves transmitted with an output level of 0.1 mW. In this case, the values of the receivable range flags corresponding to the readers 200-i + 1 and 200-i + 2 are both updated to “1” as shown in FIG. 9A (step S5). Then, from the range data table shown in FIG. 5A, each of the readers 200-i + 1 and 200-i + 2 is set to 0 from the range where the radio waves transmitted at the output level of 1 mW can be received (the first receivable range). Range data # i + 1 and # i + 2 indicating a range excluding the range in which radio waves transmitted at an output level of 1 mW can be received (second receivable range) are acquired (step S24).

  Furthermore, when the reader 200-i + 3 cannot receive the radio wave transmitted from the wireless tag 100 at the output level of 0.1 mW as well as the radio wave transmitted at the output level of 1 mW, the reception corresponding to 200-i + 3 is performed. The value of the possible range flag remains “0” as shown in FIG. 9A and is not updated.

  In the process of step S32, when the range data common to the range data # n + i, the range data # i + 1, and the range data # i + 2 is extracted and then the identification waiting time timer times out (step S42; Yes) ), And is acquired as data indicating the existence range of the moving object in the process of step S43. Thereby, the CPU 32 can identify the position of the moving body within the shaded area shown in FIG. 9B.

  Thereafter, the moving body moves, and as shown in FIG. 10A, the value of the receivable range flag corresponding to the reader 200-i becomes “1”, and the receivable range flag corresponding to the reader 200-i + 1 If the value is “2”, the range data common to the range data #n, the range data # n + i + 1, and the range data # i + 2 is extracted in the process of step S32. In the process of step S43, the common range data is acquired as data indicating the existence range of the moving object. As a result, the CPU 32 can identify the position of the moving body within the shaded area shown in FIG. 10B, and further, the moving body is shown in FIGS. 9B and 10B. You can know that it has moved to the lower left of the map.

  Also, none of the readers 200-i to 200-i-3 can receive radio waves transmitted from the wireless tag 100 at an output level of 0.1 mW, and the value of the receivable range flag is as shown in FIG. As shown in a), when there are only “1” and “0”, as shown in FIG. 11 (b), the range of the hatched portion becomes wide, and the position of the moving body is set with high accuracy. It cannot be identified.

  In such a case, since the RSSI value consideration unnecessary flag value “0” is not updated (step S44; No), in addition to the range data acquired in the process of step S43, the readers 200-i to 200- The position of the moving body is identified in consideration of the RSSI value measured in i-2. As a result, even when any of the readers 200-i to 200-i-3 cannot receive the radio wave transmitted from the wireless tag 100 at the output level of 0.1 mW, the CPU 32 The position of the installed moving body can be identified with high accuracy.

  As described above, according to the mobile unit position identification device according to the present embodiment, the reader 200-i transmits not only the radio wave transmitted from the wireless tag 100 at the output level of 1 mW but also the output level of 0.1 mW. If the received radio wave can also be received, it is determined that the moving body exists within a range (second receivable range) in which the mobile wave can be received at an output level of 0.1 mW. In contrast, the reader 200-i can receive radio waves transmitted from the wireless tag 100 at an output level of 1 mW, but cannot receive radio waves transmitted at an output level of 0.1 mW. In this case, the mobile unit can receive radio waves transmitted at an output level of 0.1 mW (second reception range) from a range in which radio waves transmitted at an output level of 1 mW can be received (first reception range). It is determined that it exists in the range excluding the possible range.

  And the common range of the range obtained about each of several reader | leader 200-i is acquired as a range in which a mobile body exists. Thereby, CPU32 can identify the position of the moving body in which the wireless tag 100 was installed with high precision.

  Further, all of the plurality of readers 200-i can receive radio waves transmitted from the wireless tag 100 at an output level of 1 mW, but can receive radio waves transmitted at an output level of 0.1 mW. If not, the position of the moving body is identified in consideration of the reception intensity of each of the plurality of readers 200-i in addition to the common range obtained for each of the plurality of readers 200-i. . Thereby, even when none of the plurality of readers 200-i can receive the radio wave transmitted from the wireless tag 100 at the output level of 0.1 mW, the CPU 32 moves when the wireless tag 100 is installed. The position of the body can be identified with high accuracy.

  In addition, this invention is not limited to the said embodiment, A various deformation | transformation and application are possible. Hereinafter, modifications of the above-described embodiment applicable to the present invention will be described.

  In the above embodiment, the transmission output level of the wireless tag 100 is two, 0.1 mW and 1 mW, but the present invention is not limited to this, and can be arbitrarily changed as long as it is plural. It is.

  In the above embodiment, the program executed by the CPU 32 of the control unit 30 is stored in advance in the ROM 31 or the like. However, this invention is not limited to this, You may make it function as the position identification terminal 300 concerning the said embodiment by applying the program for performing the above-mentioned process to the existing computer.

  The method for providing such a program is arbitrary. For example, the program may be provided via a communication medium such as the Internet, or may be stored and distributed in a recording medium such as a memory card.

It is a figure which shows the structural example of the moving body position identification apparatus which concerns on this Embodiment. It is a schematic diagram of a transmission output. (A) is a figure which shows the structural example of a received data analysis buffer, (b) is a figure which shows a 1st receivable range and a 2nd receivable range. It is a figure for demonstrating the relationship between the position of a mobile body, and a receivable range flag value. (A) is a figure which shows the structural example of a range data table, (b) is a figure which shows the range which excluded the 2nd receivable range from the 1st receivable range. It is a flowchart which shows the detail of a received data analysis process. It is a flowchart which shows the detail of a mobile body presence range narrowing-down process. It is a flowchart which shows the detail of a mobile body presence range identification process. It is a figure for demonstrating concretely the identification method of the position of the moving body in this Embodiment. It is a figure for demonstrating concretely the identification method of the position of the moving body in this Embodiment. It is a figure for demonstrating concretely the identification method of the position of the moving body in this Embodiment. It is a figure which shows the identification method of the position of the conventional mobile body.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 4 Control circuit 2 Vibration sensor 3, 6, 9 Power supply 5, 7 Communication part 8 Memory | storage part 10 Radio transmission part 11, 23 Oscillation circuit 12 Modulation circuit 13 Frequency multiplication circuit 14 RF output circuit 15, 24 Antenna 20 Wireless reception part 21 RF input circuit 22 Demodulator circuit 30 Control unit 31 ROM
32 CPU
33 RAM
100 wireless tag 200 reader 300 position identification terminal

Claims (5)

A radio wave that radiates a radio wave including transmission output data representing the output level by sequentially switching a plurality of different output levels including the first output level and a second output level lower than the first output level. A range identification system for identifying a range in which a radiation device exists,
Radio wave receiving means for receiving radio waves radiated from the radio wave radiation device;
Based on the transmission output data included in the radio wave received by the radio wave receiving means, an output level specifying means for specifying an output level when the radio wave is radiated;
Whether or not a radio wave radiated at the first output level has been received from the radio wave radiation device and whether or not a radio wave radiated at the second output level has been received based on the identification result by the output level identification means Received radio wave discriminating means for discriminating whether or not,
If the radio wave radiated at the second output level is not received by the received radio wave discriminating means, but it is discriminated that the radio wave radiated at the first output level is received, the radio wave receiving means A third range obtained by excluding a second range in which radio waves radiated at the second output level can be received from a first range in which radio waves radiated at the first output level can be received is the radio wave radiation. When it is determined that both the radio wave radiated at the first output level and the radio wave radiated at the second output level are received together as a range where the device exists, the second range is Existence range acquisition means for acquiring a radio wave emission device as an existing range;
An existence range identification system comprising: A plurality of the radio wave receiving means;
The existence range acquisition means is
The second or third range is acquired for each of the radio wave receiving means that has received the radio wave radiated from the radio wave radiation device among the plurality of radio wave receiving means, according to the determination result by the received radio wave determination means. And the range where all the acquired 2nd or 3rd range overlaps is acquired as a range where the above-mentioned radio wave emission device exists,
The existence range identification system according to claim 1. The existence range acquisition means is
Of the plurality of radio wave receiving means, not all of the radio wave receiving means that have received the radio wave radiated from the radio wave radiation device have received the radio wave radiated at the second output level, but the first output When the received radio wave determining means determines that the radio wave radiated at the level has been received, for each of the radio wave receiving means, a reception intensity acquiring means for acquiring a reception intensity is included.
The radio wave emission device based on a range in which all the third ranges of the radio wave reception units that have received radio waves radiated from the radio wave emission device overlap each other and the reception intensity acquired by the reception intensity acquisition unit. Identify the range in which
The existence range identification system according to claim 2. A radio wave that radiates a radio wave including transmission output data representing the output level by sequentially switching a plurality of different output levels including the first output level and a second output level lower than the first output level. A range identification method for identifying a range in which a radiation device exists,
A radio wave receiving step for receiving radio waves radiated from the radio wave radiation device;
Based on the transmission output data included in the radio wave received by the radio wave receiving step, an output level specifying step for specifying an output level when the radio wave is radiated;
Whether or not a radio wave radiated at the first output level has been received from the radio wave radiation device and whether or not a radio wave radiated at the second output level has been received based on the identification result of the output level identification step A received radio wave determination step for determining whether or not,
When it is determined that the radio wave radiated at the second output level is not received by the received radio wave discrimination step but the radio wave radiated at the first output level is received, the radio wave reception step includes the first radio wave reception step. A third range obtained by excluding a second range in which radio waves radiated at the second output level can be received from a first range in which radio waves radiated at the first output level can be received is the radio wave radiation. When it is determined that both the radio wave radiated at the first output level and the radio wave radiated at the second output level are received together as a range where the device exists, the second range is An existence range acquisition step of acquiring as a range in which the radio wave emission device exists;
An existing range identification method comprising: A radio wave that radiates a radio wave including transmission output data representing the output level by sequentially switching a plurality of different output levels including the first output level and a second output level lower than the first output level. In the computer that identifies the area where the radiation device exists ,
An output level specifying step of specifying an output level at which the basis of the transmission output data included in the radio wave radiated from the radio wave emitting device, the radio waves radiated received by radio waves receiving portion,
Whether or not a radio wave radiated at the first output level has been received from the radio wave radiation device and whether or not a radio wave radiated at the second output level has been received based on the identification result by the output level identification procedure A received radio wave determination procedure for determining whether or not,
If it is determined that the radio wave radiated at the second output level is not received by the received radio wave discrimination procedure, but the radio wave radiated at the first output level is received, the radio wave reception procedure A third range obtained by excluding a second range in which radio waves radiated at the second output level can be received from a first range in which radio waves radiated at the first output level can be received is the radio wave radiation. When it is determined that both the radio wave radiated at the first output level and the radio wave radiated at the second output level are received together as a range where the device exists, the second range is Existence range acquisition procedure to acquire as a range where the radio wave emission device exists,
A program for running

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