WIRELESS SENSOR SYSTEM, COMMUNICATION DEVICE, SENSOR TAG AND COMMUNICATION METHOD

Abstract

Wireless sensor system (1), comprising: a sensor tag (200, 200A, 200B, 200C, 200D, 200E, 200F) configured to contain a radio frequency (RF) tag; and a communication device (100) configured to communicate wirelessly with one or more sensor tags (200, 200A, 200B, 200C, 200D, 200E, 200F), wherein each of the one or more sensor tags (200, 200A, 200B, 200C, 200D, 200E, 200F) is configured to receive a measurement signal from one or more sensor circuits (220, 220_1, 220_2) and to store identification information that is distinguishable from that of other sensor tags (200, 200A, 200B, 200C, 200D, 200E, 200F), wherein the communication device (100) comprises a transmission means configured to transmit a command signal to the one or more sensor tags (200, 200A, 200B, 200C, 200D, 200E, 200F), wherein the command signal contains designation information for designating a sensor tag (200, 200A, 200B, 200C, 200D, 200E, 200F) serving as an object, wherein each of the one or more sensor tags (200, 200A, 200B, 200C, 200D, 200E, 200F) generates measurement data based on the measurement signal if the designation information contained in the command signal received from the communication device (100) matches its own stored identification information, wherein each of the one or more sensor tags (200, 200A, 200B, 200C, 200D, 200E, 200F) begins transmitting a response signal including the generated measurement data when a predetermined response start condition is met, and wherein each of the one or more sensor tags (200, 200A, 200B, 200C, 200D, 200E, 200E, 200F) begins transmitting the response signal without causing a response delay when generation of the measurement data is completed if its own stored second identification information corresponds to a value indicating a head of a response.

Description

BACKGROUNDTechnical field

[0001] The present invention relates to a wireless sensor system configured to transmit measurement data via wireless communication, a communication device and a sensor tag used in the system, and a communication method for use in the system. Description of the state of the art

[0002] In the field of factory automation (FA), various types of control are implemented by measuring the state of a machine, a system, or the like to be controlled with a sensor and collecting the measurement data with a control unit or similar device. To realize more detailed control, it is important to arrange more sensors and collect more measurement data.

[0003] On the other hand, the arrangement of several sensors also increases the wiring effort for collecting the measurement data from the sensors.

[0004] To solve such a problem, JP 2016-165082 A, for example, discloses a wireless device capable of acquiring measurement data with a sensor via wireless communication within a predetermined enclosed space. Sensors capable of transmitting measurement data via such wireless communication can be collectively referred to as a "wireless sensor," and all systems including such sensors can be collectively referred to as a "wireless sensor system." Patent documents

[0005] WO 2008 / 046 364 A1 discloses a wireless sensor system comprising: a sensor tag configured to include a radio frequency (RF) tag; and a communication device configured to wirelessly communicate with one or more sensor tags, wherein each of the one or more sensor tags generates measurement data, and wherein each of the one or more sensor tags begins transmitting a response signal including the generated measurement data when a predetermined response start condition is met.

[0006] DE 601 07 922 T2 discloses an RFID system comprising a plurality of RFID transponders, each of the plurality of RFID transponders having a unique identification code, for receiving a signal and for generating a response signal based thereon, each of the RFID transponders having a random number generator used to determine whether to respond to a message addressed to all of the plurality of RFID transponders, a host computer for generating a message for transmission to at least one of the RFID transponders, and at least one interrogator connected to the host computer and having an interrogator transmitter and an interrogator receiver operating in half-duplex mode,wherein the interrogator transmits messages received from the host computer to the plurality of RFID transponders during a first part of the half-duplex mode and provides an illumination signal to the plurality of RFID transponders during a second part of the half-duplex mode, and wherein the interrogator receives signals from the at least one RFID transponder and provides the received signals to the host computer, characterized in that the host computer identifies each of the unique identification codes associated with each of the plurality of RFID transponders by iteratively sending a message having a variable with a predetermined initial value to each of the RFID transponders, and that only the RFID transponders that generate a random number that is greater than, less than, or within a predetermined range of the variable respond to the message by sending the identification codes,which belong to the relevant RFID transponders.

[0007] JP 2016 165082 A discloses a radio device that can appropriately collect measurement data from a sensor through radio communication in a predetermined closed space. The radio device is configured to enable radio communication with a sensor for measuring a predetermined environmental parameter in a predetermined closed space, and includes: an antenna part, arranged in a predetermined closed space, for radio communication with the sensor; and a control part that controls the transmission / reception mode of a radio wave by the antenna part in such a manner that a standing wave assumed in the predetermined closed space based on a transmission radio wave from the sensor to the antenna part, or a standing wave assumed in the predetermined closed space based on a transmission radio wave from the antenna part to the sensor changes with the lapse of time in the radio communication. OVERVIEW

[0008] When adopting a configuration in which a plurality of wireless sensors are arranged as described above and measurement data from the wireless sensors is acquired by a common device, the common device must establish communication with each wireless sensor and perform condition monitoring. Japanese Unexamined Patent Application Publication No. 2016-165082 (Patent Document 1) primarily provides a means for solving the problem of standing waves generated due to radio waves in a closed space, but does not provide a means for solving the problems described above.

[0009] A configuration is desired in which a simple arrangement of a large number of sensors and efficient acquisition of the measurement data from each sensor can be carried out.

[0010] The present invention is based on a wireless sensor system comprising a sensor tag configured to include a radio frequency (RF) tag, and a communication device configured to wirelessly communicate with one or more sensor tags. Each of the one or more sensor tags can be configured to output an external signal. Each of the one or more sensor tags generates measurement data. Each of the one or more sensor tags begins transmitting a response signal, including the generated measurement data, when a predetermined response condition is met. The invention is characterized by the following novel features: Each of the one or more sensor tags is configured to receive a measurement signal from one or more sensor circuits and to store identification information that can be distinguished from that of other sensor tags.The communication device includes a transmission means configured to transmit a command signal to the one or more sensor tags, and the command signal includes label information for identifying a sensor tag serving as an object. Each of the one or more sensor tags generates measurement data based on the measurement signal if the label information included in the command signal received from the communication device matches its own stored identification information. Furthermore, each of the one or more sensor tags starts transmitting the response signal without causing a response delay when the generation of the measurement data is completed if its own stored second identification information corresponds to a value indicating a header of a response.

[0011] Thus, each of the one or more sensor tags starts transmitting the response signal without causing a response delay when the generation of the measurement data is completed if its own stored second identification information is a value indicating a head of a response.

[0012] Preferably, the identification information includes first identification information indicating a group to which each sensor tag belongs and second identification information specifying each sensor tag.

[0013] The designation information preferably includes first designation information for designating a group serving as an object, and second designation information for individually designating a sensor tag serving as an object. Each of the one or more sensor tags generates the measurement data and transmits the response signal when its own stored first identification information matches the first identification information contained in the identification information, and its own stored second identification information matches the second identification information contained in the identification information.

[0014] The designation information preferably contains information for designating a group serving as an object. Each of the one or more sensor tags generates the measurement data and transmits the response signal if its own stored first identification information matches a group designated in the designation information.

[0015] Preferably, each of the one or more sensor tags starts transmitting the response signal after waiting until the number of times an additional command signal is transmitted from the communication device and a value indicated by its own stored second identification information satisfy a predetermined relationship when its own stored second identification information does not correspond to a value indicating a header of a response.

[0016] Preferably, each of the one or more sensor tags begins transmitting the response signal after waiting a time determined based on a value indicated by its own stored second identification information.

[0017] Preferably, the response signal contains information about a plurality of measurement signals that were collected or recorded at different times.

[0018] According to another aspect of the present invention, a communication device is provided for wireless communication with one or more sensor tags, each of which contains a radio frequency (RF) tag. Each of the one or more sensor tags is configured to receive a measurement signal from one or more sensor circuits and to store identification information that can be distinguished from that of other sensor tags. Each of the one or more sensor tags can be configured to transmit a signal to the outside. The communication device includes a transmission means configured to transmit a command signal to one or more sensor tags. The command signal contains designation information for identifying a sensor tag serving as an object.The communication device includes a receiving device configured to receive a response signal from one or more sensor tags. The response signal contains measurement data based on the measurement signal generated when the label information contained in the command signal matches the identification information stored in the sensor tag. The response signal is transmitted or sent at a time when a response start condition set in each of the sensor tags is met.

[0019] According to yet another aspect of the present invention, a sensor tag comprising a radio frequency (RF) tag is provided. The sensor tag is configured to receive a measurement signal from one or more sensor circuits and to store identification information that can be distinguished from that of other sensor tags. The sensor tag can be configured to transmit a signal externally. The sensor tag generates measurement data based on the measurement signal if label information for identifying a sensor tag serving as an object in a command signal matches stored identification information when the command signal is received by a communication device configured to wirelessly communicate with the sensor tag. The sensor tag begins transmitting or sending a response signal including the generated measurement data when a predetermined response condition is met.

[0020] According to yet another aspect of the present invention, a communication method for use in a wireless sensor system is provided, comprising a sensor tag configured to include a radio frequency (RF) tag and a communication device configured to wirelessly communicate with one or more sensor tags. Each of the one or more sensor tags is configured to receive a measurement signal from one or more sensor circuits and to store identification information that is distinguishable from that of other sensor tags. Each of the one or more sensor tags can be configured to transmit a signal externally. The communication method comprises the step of transmitting or transmitting a command signal by the communication device to the one or more sensor tags.The command signal contains designation information for identifying a sensor target serving as an object. The communication method includes the steps of generating measurement data based on the measurement signal by each of the one or more sensor tags when the designation information contained in the command signal received by the communication device matches its own stored identification information; and starting, by each of the one or more sensor tags, the transmission of a response signal containing the generated measurement data when a predetermined response start condition is met.

[0021] According to the present invention, a simple arrangement of multiple sensors and efficient acquisition of the measurement data from each sensor can be realized. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic diagram illustrating a configuration example of a wireless sensor system according to this embodiment. Fig. 2 is a schematic diagram showing an example of a hardware configuration of a reader / writer constituting the wireless sensor system according to the present embodiment. Fig. 3 is a schematic diagram showing an example of a hardware configuration of a sensor tag constituting a wireless sensor system according to the present embodiment. Fig. 4A, Fig. 4B and Fig. 4C are schematic diagrams illustrating an example of a mounting or installation form of a sensor tag constituting the wireless sensor system according to the present embodiment. Fig. 5A, Fig. 5B and Fig. 5C are schematic diagrams illustrating an example of a mounting form of a sensor tag constituting the wireless sensor system according to the present embodiment. Fig. 6 is a flowchart showing an overview of the operation of the wireless sensor system according to the present embodiment. Fig. 7A and Fig. 7B are timing charts illustrating a sequence in the wireless sensor system according to the present embodiment. Fig. 8 is a diagram illustrating an example of a data structure held by a sensor tag in the wireless sensor system according to the present embodiment. Fig. 9A and Fig. 9B are diagrams exemplifying the data structures of a command signal and a response signal exchanged in the wireless sensor system according to the present embodiment. Fig. 10 is a diagram illustrating an example of a state transition in a SensorTag in the wireless sensor system according to the present embodiment. Fig. 11A and Fig. 11B are timing charts illustrating a processing procedure in which measurement data is collected from a sensor tag in the wireless sensor system according to the present embodiment. Fig. 12 is a timing chart illustrating a processing procedure in which measurement data is collected from a plurality of sensor tags in the wireless sensor system according to the present embodiment. Fig. 13 is a timing chart illustrating another processing method when collecting measurement data from a plurality of sensor tags in the wireless sensor system according to the present embodiment. Fig. 14A and Fig. 14B are diagrams illustrating an example of a response signal in the wireless sensor system according to the present embodiment. Fig. 15A and Fig. 15B are flowcharts illustrating a processing procedure in the wireless sensor system according to the present embodiment. DESCRIPTION OF THE EMBODIMENTS

[0022] The embodiments of the present invention will be described in detail with reference to the drawings. Furthermore, the same or corresponding parts are designated by the same reference numerals, and the description will not be repeated. <A. Kurzdarstellung des drahtlosen Sensorsystems>

[0023] First, a brief description of a wireless sensor system according to the present embodiment will be described. In the present specification, the term "wireless sensor system" refers to a system including at least one sensor capable of transmitting measurement data via wireless communication, and is not intended to exclude a sensor configured to transmit the measurement data via any wiring (wired signal). Since any frequency, modulation scheme, and transmission protocol can also be adopted in wireless communication, the present invention is not intended to be limited to a specific configuration. For convenience of description, the wireless sensor system may be simply referred to as a "system" hereinafter.

[0024] Fig. 1 is a schematic diagram showing a configuration example of a wireless sensor system 1 according to the present embodiment. Fig. Figure 1 shows an example of system 1 configured to collect measurement data from a production line, including conveyor belts 2 and 4 as an example.

[0025] In the present embodiment, System 1, which uses short-range wireless communication as a wireless communication means, is exemplified. Specifically, although a passive radio frequency identification (RFID) configuration is presented as a typical example of short-range wireless communication, the present invention is not limited thereto. For example, improved and novel systems based on RFID technology in the future may also be included within the technical scope of the present invention.

[0026] Referring to Fig. 1, the system 1 includes a communication device as a master device, which is responsible for acquiring the measurement data and managing the individual sensors. Since the communication device is often referred to as a "reader / writer," which focuses on its function in the general RFID field, the communication device is also referred to as "reader / writer 100" in the following description. However, it is not mandatory for the communication device to have both a function for reading data from the radio frequency (RF) tag (a read function) and a function for writing the data to the RF tag (a write function), and only one function may be available.

[0027] System 1 also includes a slave device with an RF tag for exchanging radio signals with the communication device (reader / writer 100). Since each slave device has one or more sensors from the RF tag, these slave devices are referred to as "sensor tags" in the following description. That is, Fig. The system 1 shown in Figure 1 may include a plurality of sensor tags 200_1 to 200_4 (hereinafter collectively referred to as “sensor tag 200”).

[0028] That is, each of the sensor tags 200 contains an RF tag, and the communication device (the reader / writer 100) communicates wirelessly with one or more of the sensor tags 200. The RF tag may also be referred to as an integrated circuit (IC) tag or RFID tag, but will be referred to as an RF tag for ease of description.

[0029] The sensor tag 200 is designed for a configuration that combines the functions of the RF tag and the sensor. As described below, the functions of the RF tag and the sensor can be integrated or implemented separately.

[0030] In the Fig. In the system 1 shown in Figure 1, an example is shown in which the sensor tag 200 is applied to a photoelectric sensor. That is, the sensor tags 200_1 and 200_2 are incorporated as part of the photoelectric sensor arranged along the conveyor belt 2, and the sensor tags 200_3 and 200_4 are incorporated as part of the photoelectric sensor arranged along the conveyor belt 4.

[0031] The sensor tags 200_1 to 200_4 detect the presence of a workpiece W and transmit the measurement data 1 to 4 including the detection results to the reader / writer 100. However, since a passive (or semi-passive) RFID is adopted in the system 1 according to the present embodiment, an interrogation signal is transmitted from the reader / writer 100 to the sensor tags 200_1 to 200_4, and the sensor tags 200_1 to 200_4 provide measurement data including the measured values ​​at that time as responses by receiving the interrogation signal.

[0032] Each measurement data set collected in the reader / writer 100 can be transferred to a host device such as a programmable logic controller (PLC) or a personal computer. <B. Hardwarekonfiguration des Lesers / Schreibers (Kommunikationsvorrichtung)>

[0033] Next, an example of a hardware configuration of the reader / writer 100 constituting the system 1 according to the present embodiment will be described.

[0034] Fig. Fig. 2 is a schematic diagram showing the hardware configuration of the read / write device 100 constituting the wireless sensor system 1 according to the present embodiment. Fig. 2, the reader / writer 100 includes a communication control unit 150 having a control unit 102 and an antenna 130. Although a configuration example in which the antenna 130 is separated from the communication control 150 is shown in Fig. 2, they can be integrated.

[0035] The communication control unit 150 includes, in addition to the control unit 102, an interface (I / F) 104, a memory unit 106, a timing unit 108, a display unit 110, and an oscillator 112.

[0036] The control unit 102 is an arithmetic processing unit configured to control various types of processes in the reader / writer 100 and is typically implemented by a processor, such as a central processing unit (CPU), that executes a program. Alternatively, all or part of the control unit 102 may be implemented in hardware, e.g., by an application-specific integrated circuit (ASIC) or a field-programmable gate array (FPGA).

[0037] The communication interface 104 corresponds to a communication unit for exchanging data with a host device. It is only necessary that the RFID system 1 is at least capable of responding to the host device with data from the reader / writer 100. Any communication means, such as Ethernet (registered trademark), serial communication, Universal Serial Bus (USB) communication, parallel communication, or various types of fieldbuses, can be used as the communication interface 104.

[0038] The storage unit 106 stores various types of programs to be executed by the control unit 102, as well as measurement data collected by the sensor tag 200, and the like. Since identification information is preset for the sensor tag 200 that performs communication with the reader / writer 100, an identification information list 107 for specifying such identification information is stored in the storage unit 106. With reference to the identification information list 107, various types of command signals are generated, which will be described below.

[0039] The time measuring unit 108 is a clock or a timer and supplies a time signal to the control unit 102. The display unit 110 displays various types of information according to an instruction from the control unit 102.

[0040] Oscillator 112 generates a synchronization signal for operating control unit 102. Communication control unit 150 corresponds to a communication unit configured for wireless communication with sensor tag 200. Communication control unit 150 generates electromagnetic waves to read the measurement data from sensor tag 200, decodes a response signal from sensor tag 200, and outputs a decoding result. Electromagnetic waves with a frequency in the ultra-high frequency (UHF) band can be used as electromagnetic waves, but other frequency bands can also be used.

[0041] More specifically, the communication control unit 150 includes a digital-to-analog converter (DAC) 121, a phase-locked loop (PLL) 122, mixers 123 and 124, a pair of Z-conversion circuits 124 and 126 sandwiching a power amplifier (PA) 125, an isolation circuit 127, a band-pass filter (BPF) 141, a low-noise amplifier (LNA) 142, a low-pass filter (LPF) 143, and an analog-to-digital converter (ADC) as main components.

[0042] The following describes the operation of each part to realize a communication process between the reader / writer 100 and the sensor tag 200.

[0043] First, in response to an activation command from control unit 102, PLL 122 outputs a high-frequency pulse (hereinafter also referred to as a "carrier signal"), which serves as a source of carrier waves. The carrier signal from PLL 122 is used for modulation and demodulation. That is, the carrier signal from PLL 122 is fed to mixer 123 and mixer 144.

[0044] When a predetermined condition is met, the control unit 102 outputs a control signal with a predetermined number of bits. The command signal is an instruction for the sensor tag 200 and is superimposed on the carrier signal and fed to the sensor tag 200. The command signal from the control unit 102 is converted into an analog signal by the DAC 121 and then frequency-converted (up-converted) in the mixer 123 into a frequency band of a radio signal corresponding to the carrier signal from the PLL 122.

[0045] The command signal frequency-converted by the mixer 123 is fed to the antenna 130 via the isolation circuit 127 after an impedance matching process by the Z-converter circuits 124 and 126 and an amplification process by the PA 125, so that the command signal is transmitted as electromagnetic waves to the sensor tag 200. In this way, the sensor tag 200 has a transmission function for transmitting a command signal to one or more sensor tags 200.

[0046] In the sensor tag 200, in a range where electromagnetic waves transmitted from the reader / writer 100 can be received, an induced electromotive force is generated internally by the received electromagnetic waves, and various types of internal circuits (described below) are activated by the induced electromotive force. In this state, when the command signal superimposed on the carrier waves is received, the control unit of the sensor tag 200 decodes the received command signal, executes a process according to the decoding command, generates a response signal including a processing result thereof, and finally responds to the reader / writer 100.

[0047] The response signal of the sensor tag 200 is received by the antenna 130 and fed into the BPF 141 via the isolation circuit 127. The received response signal is amplified by the LNA 142 after the noise contained in the received response signal has been removed by the BPF 141. Furthermore, the response signal amplified by the LNA 142 is fed into the mixer 144 after the LPF 143 has removed a high-frequency component. In the mixer 144, the response signal is frequency-converted (down-converted) into a frequency band of a baseband signal corresponding to the carrier signal of the PLL 122. Furthermore, after the frequency conversion, the response signal is converted into a digital signal by the ADC 145 and then fed to the control unit 102. That is, a communication result including measurement data obtained by decoding a response signal from the sensor tag 200 is fed into the control unit 102.Furthermore, the control unit 102 can output the communication result including the measurement data obtained by decoding to the communication interface 104.

[0048] The communication interface 104 responds to the host device 30 with the communication result of the control unit 102. <C. Hardware-Konfiguration des Sensor-Tags >

[0049] Next, an example of the hardware configuration of the sensor tag 200 constituting the system 1 according to the present embodiment will be described.

[0050] Fig. 3 is a schematic diagram showing an example of the hardware configuration of the sensor tag 200 constituting the wireless sensor system 1 according to the present embodiment. Fig. 3, the sensor tag 200 includes a processing circuit 210, a sensor circuit 220, an antenna 230, and a power supply circuit 240.

[0051] The 10 2017 130 061.9 210 receives electrical energy from the power supply circuit 240 and executes a process according to a command signal from the read / write device 100. Typically, the processing circuit 210 generates measurement data based on a measurement signal from the sensor circuit 220 and responds to the reader / writer 100 with the generated measurement data. That is, each of the sensor tags 200 is configured to receive a measurement signal from one or more sensor circuits 220. In addition, each or more sensor tags can be configured to output an external signal. The processing circuit 210 includes a demodulation circuit 212, a control circuit 214 with a memory unit 216, and a modulation circuit 213. These circuits are activated by being supplied with voltage or current from the power supply circuit 240.

[0052] The demodulation circuit 212 demodulates electromagnetic waves from the reader / writer 100 received by the antenna 230 and extracts a control signal contained therein. The control circuit 214 executes a specific process according to the command signal from the demodulation circuit 212. The storage unit 216 stores parameters and the like necessary for the control circuit 214 to perform the process according to the command signal. The control circuit 214 outputs a response signal containing measurement data and the like to the modulation circuit 213. The modulation circuit 213 modulates a response signal from the control circuit 214 and transmits the modulated signal to the antenna 230.

[0053] The sensor circuit 220 includes any sensor element, receives electrical power from the power supply circuit 240, and outputs a measurement signal measured by the sensor element to the processing circuit 210. Furthermore, the sensor circuit 220 can be configured to receive electrical power from a power source other than the power supply circuit 240 (e.g., a battery). Such a sensor tag corresponds to a semi-passive type and may also be referred to as a "battery-backed tag (semi-passive tag)." That is, in the semi-passive type, the electrical power associated with wireless communication is supplied by the reader / writer 100, and the electrical power of an internal sensor, processor, or the like is supplied from an external power source (e.g., a battery).

[0054] For example, in addition to the photoelectric sensor, as in Fig. 1, a proximity switch, a limit switch, and the like may be included as the sensor device. Furthermore, a sensor configured to output an analog signal as the measurement signal, such as a flow sensor, a temperature sensor, a current sensor, a voltage sensor, or an acceleration sensor, may be used.

[0055] Furthermore, a signal may be output externally from the sensor tag 200. For example, a light-emitting diode (LED), a speaker, a vibrator, and the like may be arranged to perform an external output corresponding to the signal output of the control circuit 214.

[0056] The power supply circuit 240 rectifies the electromagnetic waves received by the antenna 230 and thus generates the electrical energy required to operate the sensor tag 200.

[0057] Although the hardware configuration of the Sensor Tag 200 in Fig. 3 is shown functionally, any design can be selected according to the required performance and application.

[0058] Fig. 4A to Fig. 5C are schematic diagrams illustrating exemplary mounting forms or installation types of the sensor tag 200 constituting the wireless sensor system 1 according to the present embodiment. An example of mounting a single sensor circuit in a sensor tag 200 is shown in Fig. 4A, Fig. 4B and Fig. 4C, an assembly example with multiple sensor circuits in a sensor tag 200 is shown in Fig. 5A, Fig. 5B and Fig. 5C.

[0059] A Sensor Tag 200A, shown in Fig. 4A, contains an analog front end 250 and a sensor circuit 220 in a housing with the antenna 230. In the analog front end 250, the processing circuit 210 and the Fig. 3 shown power supply circuit 240 is mounted.

[0060] A sensor tag 200B, shown in Fig. 4B, contains an analog front end 250, a microcomputer 260 and a sensor circuit 220 in a housing with the antenna 230. In the analog front end 250 are the demodulation circuit 212, the modulation circuit 213 and the Fig. 3 is mounted on the power supply circuit 240. The microcomputer 260 provides a function that is similar to the Fig. 3 corresponds to the control circuit 214 shown.

[0061] A Sensor Tag 200C, shown in Fig. 4C, contains an analog front-end 250 in a housing with the antenna 230. The sensor circuit 220 is configured separately from the sensor tag 200C. An external sensor interface 222 is provided between the sensor tag 200C and the sensor circuit 220. The analog front-end 250 contains the processing circuit 210 and the Fig. 3 shown power supply circuit 240 is mounted.

[0062] A Sensor Tag 200D, shown in Fig. 5A, contains an analog front end 250 and a plurality of sensor circuits 220_1, 220_2, ... in a housing with the antenna 230. In the analog front end 250, the processing circuit 210 and the Fig. 3 shown power supply circuit 240 is mounted.

[0063] A Sensor Tag 200E, shown in Fig. 5B, contains an analog front end 250, a microcomputer 260 and a plurality of sensor circuits 220_1, 220_2, ... in a housing with the antenna 230.

[0064] A Sensor Tag 200F, shown in Fig. 5C, contains an analog front end 250 in a housing with the antenna 230. A plurality of sensor circuits 220_1, 220_2, ... are arranged separately from the sensor tag 200F. An external sensor interface 222 is provided between the sensor tag 200F and each of the plurality of sensor circuits 220_1, 220_2, 220_2, ...

[0065] The present invention is not limited to the Fig. 4 and Fig. 5 shown assembly examples, and any design can be selected. <D. Übersicht über die Funktionsweise des drahtlosen Sensorsystems>

[0066] Next, an overview of the operation of the wireless sensor system 1 according to the present embodiment will be given. Fig. Figure 6 is a flowchart that provides an overview of the operation of the wireless sensor system 1 according to the present embodiment. An example of the exchange between the four sensor tags 200_1 to 200_4 and the reader / writer 100 is shown in Fig. 6 is shown as an example.

[0067] Referring to Fig. 6, the reader / writer 100 sends a measurement data acquisition or collection command to a plurality of sensor tags 200_1 to 200_4. Although only one specific sensor tag 200 can be specified or designated in the measurement data acquisition command, as described below, an example in which the measurement data acquisition command is transmitted to all sensor tags 200 is shown in Fig. 6 shown.

[0068] When the measurement data acquisition command is received by the reader / writer 100, each of the sensor tags 200_1 to 200_4 activates its internal circuit, acquires a measurement signal from the corresponding sensor circuit, and responds to the reader / writer 100 with measurement data based on the acquired measurement signal. If the sensor tags 200_1 to 200_4 respond simultaneously at this time, the reader / writer 100 cannot perform the corresponding reception operation.

[0069] Therefore, in the wireless sensor system 1 according to the present embodiment, each of the sensor tags 200_1 to 200_4 responds with measurement data after a response delay has elapsed. The response delay is preset so that there is no overlap between the sensor tags 200 that simultaneously receive the measurement data acquisition command from the same reader / writer 100. As a method for setting such a response delay, unique identification information can be preset in each of the sensor tags 200_1 to 200_4, and the response delay of each sensor tag 200 can be calculated from the set identification information.

[0070] In the Fig. In the example shown in Figure 6, upon receiving the measurement data acquisition command from the reader / writer 100, the sensor tag 200_1 responds to the reader / writer 100 with measurement data 1 based on the measurement signal from its own sensor circuit. Subsequently, the sensor tag 200_2 responds to the reader / writer 100 with measurement data 2 based on the measurement signal from its own sensor circuit only after a response delay Td (starting) from the response of the sensor tag 200_1. Subsequently, the sensor tag 200_3 responds to the reader / writer 100 with measurement data 3 based on the measurement signal from its own sensor circuit only after the response delay Td from the response of the sensor tag 200_2. Finally, the sensor tag 200_4 responds to the reader / writer 100 with measurement data 4 based on the measurement signal from its own sensor circuit only after the response delay Td (starting) from the response of the sensor tag 200.

[0071] The measurement data of the sensor tags 200_1 to 200_4 can be collected with one measurement data collection command by setting each response delay at which the response of such measurement data starts to be different.

[0072] Such a series of measurement data acquisition processes is executed at an appropriate time. Furthermore, the measurement data acquisition command of the reader / writer 100 can be transmitted periodically or every time upon request from a host device, etc. <E. Drahtloses Kommunikationsprotokoll>

[0073] Next, a wireless communication protocol adopted by the wireless sensor system 1 according to the present embodiment will be described.

[0074] At the time of writing, IS0 18000-6 was standardized as a radio protocol in the UHF band between the reader / writer and the RF tag. IS0 18000-6 is a standard corresponding to Class 1 Generation 2 (Gen 2) of an EPCglobal Network system.

[0075] From the perspective of implementing secure communication or similar, ISO 18000-6 defines a wireless communication protocol between the reader / writer and the RF tag, so five states are defined according to each session sequential transition. Specifically, there are five states, including a ready state, an acknowledged state, an open state, a secured state, and a killed state.

[0076] That is, in order for the reader / writer to exchange data with the RF tag, it is necessary to repeat the transmission of the command signal and the reception of the response signal to cause the state of the RF tag to transition sequentially.

[0077] Although a wireless communication protocol defined in ISO 18000-6 is preferable in the sense that secure communication can be implemented, there is a possibility that a requirement specified regarding a real-time characteristic may not be met when the system is deployed as a wireless sensor system. For example, for an existing sensor configured to transmit measurement data via a wired signal, the response time, even with a long response time, is approximately several milliseconds. It is also preferable to implement a response characteristic (a real-time characteristic) in a wireless sensor system that is similar to that of an existing sensor via a wired signal.

[0078] In the wireless sensor system 1 according to the present embodiment, by adopting a wireless communication protocol simpler than the wireless communication protocol defined in ISO 18000-6, it is possible to implement a response characteristic (a real-time characteristic) required for a system configured to collect measurement data from the sensor.

[0079] Fig. 7A and Fig. 7B are timing diagrams illustrating a sequence in the wireless sensor system 1 according to the present embodiment. A sequence in the configuration of the wireless sensor system 1 according to ISO 18000-6 is shown in Fig. 7A as a comparative example and a sequence in the wireless sensor system 1 according to the present embodiment is shown in Fig. 7B.

[0080] If the wireless sensor system 1 is configured according to ISO 18000-6, the reader / writer selects according to Fig. 7A first selects a sensor tag, which serves as a collection object for measurement data (sequence SQ10). The reader / writer then sends a query command (sequence SQ11). In response to this query command, the sensor tag responds to the reader / writer with a 16-bit random number (RN16), which is used in communication with the reader / writer (sequence SQ12).

[0081] When the 16-bit random number is received from the sensor tag, the reader / writer sends an acknowledgement (ACK) response to the sensor tag (sequence SQ13). In response to this ACK response, the sensor tag responds to the reader / writer with its own electronic product code (EPC), a protocol control code (PC code), and a checksum (cyclic redundancy check (CRC)) (sequence SQ14).

[0082] When a code is received from the sensor tag, the reader / writer sends a query command with a previously received 16-bit random number (sequence SQ15). In response to this query command, the sensor tag responds to its reader / writer with its own handle value (sequence SQ16).

[0083] When the handle value is received from the sensor tag, the reader / writer sends a measurement data acquisition command (Start Sensing) to the sensor tag (sequence SQ17). In response to this measurement data acquisition command, the sensor tag responds to the reader / writer with measurement data based on the measurement signal from the sensor circuit (sequence SQ18).

[0084] On the other hand, in the wireless sensor system 1 according to the Fig. In the present embodiment illustrated in Figure 7B, the reader / writer 100 transmits a measurement data acquisition command (Get GPI) to the sensor tag (sequence SQ21). In response to the measurement data acquisition command, the sensor tag responds to the reader / writer with measurement data based on the measurement signal from the sensor circuit (sequence SQ22).

[0085] That is, in the wireless sensor system 1 according to the present embodiment, a sequence for establishing communication between the reader / writer 100 and the sensor tag 200 is omitted. By adopting such a simplified sequence, a response characteristic (a real-time characteristic) can be improved.

[0086] In the wireless sensor system 1 according to the present embodiment, the measurement data acquisition command (Start Sensing) transmitted from the reader / writer 100 includes designation information for designating the sensor tag 200 serving as the object from which measurement data is collected. Even if multiple sensor tags 200 receive the measurement data acquisition command at the same time, no problem such as collision occurs because only the selected sensor tag 200 responds with measurement data.

[0087] As described below, a group ID (SelectedGr) and an individual ID (SelectedID) can be used as label information. <F. Datenspeicherung durch Sensor-Tag>

[0088] Next, the data stored by the sensor tag 200 will be described. Each of the sensor tags 200 stores identification information that can be distinguished from that of other sensor tags 200.

[0089] Fig. Fig. 8 is a diagram showing an example of a data structure held by the sensor tag 200 in the wireless sensor system 1 according to the present embodiment. Fig. The data structure shown in Figure 8 is based on 1S0 18000-6.

[0090] A memory bank 218 arranged in the memory unit 216 contains, according to Fig. 8 an EPC (Electronic Product Code) area 2180, a TID (Tag ID) area 2184, and a payload area 2186. Information for identifying each sensor tag 200 is stored in the TID area 2184. Any payload data is stored in the payload area 2186.

[0091] In addition to a checksum (stored CRC) and a PC code (stored PC), the EPC data 2181, which is identification information of the sensor tag 200, is stored in the EPC area 2180. In the wireless sensor system 1 according to the present embodiment, a group ID 2182 and an individual ID (unit ID) 2183 are included as part of the EPC data 2181. A value stored in the group ID 2182 corresponds to first identification information indicating a group to which each sensor tag 200 belongs, and a value stored in the individual ID 2183 corresponds to second identification information specifying each sensor tag 200. The group ID and the individual ID can be stored in the payload area 2186.

[0092] Between one or more sensor tags 200 arranged in an area in which command signals can be received from the same reader / writer 100 (e.g., an area of ​​approximately several meters to several tens of meters around the reader / writer 100), a combination of the group ID 2182 and the individual ID 2183 is preset as unique.

[0093] In addition, it is not necessary to use both the group ID 2182 and the individual ID 2183, and only the individual ID 2183 can be used. Also, from the point of view of controlling the response delay as described below, it is preferable to assign the individual ID 2183 so that the individual ID 2183 is incremented by each predetermined number between the sensor tags 200 that can receive the same command signal (for example, by 1). <G. Befehlssignal / Antwortsignal>

[0094] Next, an example of command signals exchanged between the reader / writer 100 and the sensor tag 200 is described.

[0095] Fig. 9A and Fig. 9B are diagrams illustrating an example of a data structure of a command signal and a response signal exchanged in the wireless sensor system 1 according to the present embodiment. An example of a data arrangement of a measurement data acquisition command 300 is shown in Fig. 9A and an example of a data arrangement of a response signal 320 to the measurement data acquisition command 300 in Fig. 9B.

[0096] The Fig. The measurement data acquisition instruction 300 shown in Figure 9A stores some data, and each piece of data is defined by a predetermined number of bits. The measurement data acquisition instruction 300 includes a preamble portion 302, a command portion 304, a group ID portion 306, an individual ID portion 308, and a checksum portion 310.

[0097] In the preamble part 302, a data string indicating a command signal and / or a data string indicating a header of the command signal is stored.

[0098] The command part 304 stores a data string that specifies the details of a command given to the sensor tag 200.

[0099] Designation information (hereinafter also referred to as "group ID") for designating a group to which the one or more sensor tags 200 belong, which serve as objects from which measurement data is collected, is stored in the group ID part 306. Designation information (hereinafter also referred to as "individual ID") for designating a sensor tag 200, which is an object from which measurement data is collected, is stored in the individual ID part 308. That is, the designation information in the measurement data acquisition command 300 includes a group ID, which serves as first designation information for designating an object group, and a group ID, which serves as second designation information for separately designating the target sensor tag 200 ID.

[0100] In the checksum part 310, a checksum is stored, which can be used to determine whether or not an error is contained in the received command signal on a receiving side of the command signal.

[0101] By adopting a data structure as in Fig. 9A, as a measurement data acquisition command, which is an example of a command signal, it is possible to include label information (a group ID and / or an individual ID) for identifying the sensor tag 200 serving as an object of the measurement data.

[0102] When the data acquisition command 300 is received from the reader / writer 100, the sensor tag 200 compares the group ID and the individual ID stored in the group ID part 306 and the individual ID part 308 in the received data acquisition command with the group ID 2182 and the individual ID 2183 contained in the EPC data 2181 to determine whether the data acquisition command is addressed to the sensor tag 200 or not. <H. Zustandsübergang des Sensor-Tag>

[0103] Next, an example of a state transition in the sensor tag 200 in the wireless sensor system 1 according to the present embodiment will be described.

[0104] Fig. 10 is a diagram showing an example of a state transition in the sensor tag 200 of the wireless sensor system 1 according to the present embodiment. Fig. 10, when the measurement data acquisition command (Get GPI) is received from the reader / writer 100, the sensor tag 200 is activated by receiving the electrical power obtained through the measurement data acquisition command and the first transitions to the standby state ST1 occur. The sensor tag 200 then determines, based on the group ID and the individual ID contained in the received measurement data acquisition command, whether the received measurement data acquisition command is addressed to the sensor tag 200 or not. This means that if the group ID and / or the individual ID contained in the measurement data acquisition command do not match the group ID 2182 and / or the individual ID 2183 (see Fig. 9A and Fig. 9B) stored in the memory bank 218 of the memory unit 216, the standby state ST1 is maintained until the power supply is interrupted.

[0105] However, if the group ID and / or the individual ID contained in the measurement data acquisition command matches the group ID 2182 and / or the individual ID 2183 stored in the memory bank 218 of the memory unit 216, the sensor tag 200 goes into the active state ST2.

[0106] In the active state ST2, the sensor tag 200 generates measurement data based on a measurement signal from the corresponding sensor circuit. After completing the measurement data generation, the sensor tag 200 transitions to the response delay state ST3.

[0107] As shown in the continuous transition from the standby state ST1 to the active state ST2 and the response delay state ST3, each of the sensor tags 200 generates measurement data based on a measurement signal when the designation information (group ID and / or individual ID) contained in the command signal received from the reader / writer 100 (from the communication device) matches its own stored identification information.

[0108] In the response delay state ST3, it waits for a response of the measurement signal until a predetermined response start condition is met. That is, the transmission timing of the response signal including the measurement signal is delayed depending on whether the predetermined response start condition is met. In this specification, the "response start condition" refers to a condition enabling the transmission of a response signal in each of the sensor tags 200. Some examples of the response start condition are described in detail below.

[0109] When the specified response condition is met, the sensor tag 200 transmits the response signal including the generated measurement data to the reader / writer 100. After transmitting the response signal, the sensor tag 200 returns to the standby state ST1. Thus, each of the sensor tags 200 starts transmitting a response signal including the generated measurement data when the specified response condition is met.

[0110] In addition, a measurement data acquisition command (Get GPI) is newly received from the reader / writer 100 in the response delay state ST3, and the sensor tag 200 starts a process by transitioning to the active state ST2 again when a group ID and / or an individual ID included in the received measurement data acquisition command matches a group ID 2182 and / or an individual ID 2183 stored in the memory bank 218 of the storage unit 216.

[0111] If it is determined that no transition from the standby state ST1 occurs, an interruption of the operation of the sensor tag 200 may also be performed. <I. Auswahl des Sensor-Tags>

[0112] Next, a configuration and method for acquiring measurement data by selecting a specific sensor tag 200 from the reader / writer 100 is described.

[0113] Fig. 11A and Fig. 11B are timing diagrams illustrating a processing procedure in which measurement data is collected from a sensor tag 200 in the wireless sensor system 1 according to the present embodiment. Fig. 11A and Fig. 11B, an example is assumed in which three sensor tags 200_1 to 200_3 are arranged for one reader / writer 100.

[0114] It is assumed that the same group ID "0" is set in sensor tags 200_1 and 200_2, and a different group ID of "1" is set in sensor tag 200_3. It is assumed that the individual IDs of "0" and "1" are set in sensor tags 200_1 and 200_2, so that no collision occurs within the same group. It is also assumed that the individual ID of sensor tag 200_3 is set to "0."

[0115] In Fig. Figure 11A shows an example in which the measurement data acquisition command 400 is transmitted, in which the group ID "0" and the individual ID "0" are designated. Since in this case, valid values ​​are set for both the group ID and the individual ID in the measurement data acquisition command, only the sensor tag 200 in which both the group ID and the individual ID match will provide a response. In the Fig. In the example shown in Figure 11A, only the sensor tag 200_1 that matches both the group ID and the individual ID specified in the measurement data acquisition command provides a response.

[0116] That is, when a predetermined transmission time Tx has elapsed after the transmission of the measurement data acquisition command 400, the sensor tag 200_1 generates measurement data based on a measurement signal from a corresponding sensor circuit and transmits a response signal 402 including the generated measurement data. A receiving operation is performed in the reader / writer 100 when a predetermined processing delay time Ty has elapsed after the transmission of the response signal 402.

[0117] According to the process series described above, a process for collecting the measurement data from the sensor tag 200_1 is completed.

[0118] An example in which the measurement data acquisition command 400, in which the group ID “0” and the individual ID “1” are designated, is transmitted, is shown in Fig. 11B. Since in this case valid values ​​are set for both the group ID and the individual ID in the measurement data acquisition command, only the sensor tag 200 in which both the group ID and the individual ID match will provide a response. In the Fig. In the example shown in Figure 11B, only the sensor tag 200_2, which corresponds to both the group ID and the individual ID specified in the measurement data acquisition command, provides a response and sends a response signal 404 with the generated measurement data.

[0119] A method for transmitting the response signal including the measurement data is similar to the method described above.

[0120] In the Fig. 11(A) and Fig. 11(B). 11(A) and 11(B) described above, each of the sensor tags 200 performs the generation of the measurement data and the transmission of the response signal when its own stored group ID (first identification information) matches a group ID (first label information) included in the label information within the measurement data acquisition command 40, and its own stored individual ID (second identification information) matches an individual ID (second label information) included in the label information. <J. Einstellung der Antwortverzögerung>

[0121] A processing process in which measurement data is collected from a sensor tag 200 is shown in Fig. 11A and Fig. 11B. In Fig. 11(A) and Fig. 11(B), after receiving a measurement data acquisition command 400, the two sensor tags 200_1 and 200_2 immediately start a process related to transmitting the response signal without causing a response delay. Since only one sensor tag 200 is specified when transmitting a measurement data acquisition command that specifies both the group ID and the individual ID, it is unnecessary to cause a response delay.

[0122] That is, when each of the sensor tags 200 receives the measurement data acquisition command specifying both the group ID and the individual ID, each of the sensor tags 200 starts a measurement data transmission process without any response delay. In this case, since the response start condition described above is always met, the sensor tag 200 essentially immediately enters the "ready state ST1" even if the transition from the "active state ST2" to the Fig. 10 shown “response delay state ST3”.

[0123] On the other hand, when measurement data is collected from a plurality of sensor tags 200 using the same measurement data collection command, a collision may occur if the sensor tags 200 provide responses at the same time. An example of a method for setting a response delay in each sensor tag 200 to prevent such a collision will be described. (j1: Method in which reader / writer 100 controls the response delay)

[0124] Fig. Fig. 12 is a timing chart illustrating a processing procedure in which measurement data is collected from a plurality of sensor tags 200 in the wireless sensor system 1 according to the present embodiment. It is assumed that similar settings as in Fig. 11A and Fig. 11B in the Fig. 12 sensor tags 200_1 to 200_3 are preset.

[0125] An example in which a measurement data acquisition command 400 is transmitted with a valid group ID “0” and an invalid individual ID “FF” is shown in Fig. 12. Since in this case only one valid value is set in the group ID in the measurement data acquisition command, one or more sensor tags 200 that match the group ID will respond. Fig. In the example shown in Figure 12, the sensor tags 200_1 and 200_2, which match the group ID specified in the data acquisition command, provide responses.

[0126] That is, in the Fig. In the processing example shown in FIG. 12, each of the sensor tags 200 performs the generation of the measurement data and the transmission of the response signal when its own stored group ID (first identification information) matches a group ID (first label information) included in the label information of the measurement data acquisition command 400. Specifically, when the transmission time Tx has elapsed after the reader / writer 100 transmits the measurement data acquisition command 400, each of the sensor tags 200_1 and 200_2 generates measurement data based on the measurement signal from the corresponding sensor circuit.

[0127] When measurement data generation is complete, if its stored individual ID (second identification information) is a value indicating the head of a response, each of the sensor tags 200 starts transmitting a response signal without causing a response delay. The "value indicating the head of a response" corresponds to a value that has a meaning indicating that a response should be provided first among all the identification information indicating the response order within the same group. As a simple example, if the value of the individual ID is considered to correspond to the response sequence, the sensor tag 200 with the smallest individual ID provides a response first.

[0128] For example, if the individual ID defines "0" as the smallest value because the sensor tag 200_1 has the individual ID "0," the sensor tag 200_1 transmits the response signal 402 including the generated measurement data without any response delay. The reception process in the reader / writer 100 is executed after a predetermined processing delay time Ty (starting) from the transmission of the response signal 402.

[0129] On the other hand, if its own stored individual ID (second identification information) is not a value indicating the header of the response, each of the sensor tags 200 starts transmitting the response signal after waiting until the number of times an additional command signal is transmitted from the reader / writer 100 and the value indicated by its own stored individual ID (second identification information) satisfy a predetermined relationship. The "additional command signal" is a type of trigger for defining a transmission timing of the response signal to the sensor tag 200 that is not the first responding sensor tag 200.

[0130] In this way, when multiple sensor tags 200 send response signals, each sensor tag 200 sends a response signal at a predetermined timing according to its own individual ID and an additional command signal from the reader / writer 100. That is, the start condition described above is based on the individual ID of each sensor tag 200 and the additional command signal from the reader / writer 100.

[0131] In the Fig. In the example shown in Figure 12, upon receiving a response signal from the sensor tag 200_1, the reader / writer 100 sends a frame synchronization signal 408 as an additional command signal to the measurement data acquisition command 400. After receiving the measurement data acquisition command 400, the sensor tag 200_2, in which the individual ID is set to "1," starts sending a response signal 410 when the first frame synchronization signal 408 is received. That is, the sensor tag 200_2 is in a state (response delay 406) in which the transmission of a response signal is waited until the first frame synchronization signal 408 after receiving the measurement data acquisition command 400.

[0132] Although not shown, if a sensor tag 200 with an individual ID "2" exists, the frame synchronization signal 408 is further transmitted from the reader / writer 100 and the sensor tag 200 with the individual ID "2" starts transmitting a response signal.

[0133] In this way, after receiving the measurement data acquisition command 400, the transmission timing of the response signal 410, etc., is controlled according to the number of transmissions and the transmission timing of the frame synchronization signal 408. That is, the response start condition in each of the sensor tags 200 is defined by the individual ID set in each sensor tag 200 and the number of receptions of the frame synchronization signal 408.

[0134] According to the process series described above, a process for collecting the measurement data from the sensor tags 200_1 and 200_2 is completed.

[0135] Although an example of a method for determining a transmission timing of a response signal (ie, a length of a response delay) by determining the number of transmissions of the frame synchronization signal 408 after the transmission of the measurement data acquisition command 400 on the sensor tag 200 side is illustrated in the timing chart shown in Fig. 12, the individual ID of the sensor tag 200 serving as the object for transmitting the response signal may be designated in the frame synchronization signal 408 (ie, the additional command signal). For example, in the Fig. 12, by designating “1” as the individual ID in the frame synchronization signal 408, the sensor tag 200_2 can be configured with the individual ID “1” to start the transmission of the response signal. (j2: diagram in which each of the sensor tags 200 controls the response delay)

[0136] Although the reader / writer 100 controls a response delay in each sensor tag 200 by setting the number of transmissions and a transmission time of the frame synchronization signal 408 in the Fig. 12, each of the sensor tags 200 can be configured to independently determine its own response delay.

[0137] Fig. Fig. 13 is a timing chart illustrating another processing method when collecting measurement data from a plurality of sensor tags 200 in the wireless sensor system 1 according to the present embodiment. It is assumed that similar settings as in Fig. 12 in the Fig. 13 shown sensor tags 200_1 to 200_3 are preset.

[0138] In the Fig. In the processing method illustrated in Figure 13, each sensor tag 200 determines the response delay length based on its individual ID. For example, a unit time length of a predetermined response delay is preset in each sensor tag 200, and each sensor tag 200 determines a response delay time length by multiplying a value of its own individual ID by the unit time length of the response delay.

[0139] For example, in sensor tag 200_1 with the individual ID set to "0," the response delay time is calculated as "0." In sensor tag 200_2 with the individual ID set to "1," a response delay Td is calculated, which is obtained by multiplying a unit response delay time Td by "1." Although not shown, for a sensor tag 200 with an individual ID of "2," the response delay is set to "2×Td."

[0140] Since individual IDs are uniquely set in the sensor tags 200 in which the same group ID is set, different response delays are calculated in the sensor tags 200. In this way, the use of different response delays can prevent a collision caused by the simultaneous transmission of response signals from the plurality of sensor tags 200. In this way, the Fig. 13, the above-described response start condition is applied to the individual ID of each sensor tag 200.

[0141] In this way, each of the sensor tags 200 starts transmitting the response signal after a waiting time determined based on a value indicated by its own stored individual ID (second identification information).

[0142] By calculating the response delay as described above for each sensor tag 200, when a transmission time Tx has elapsed after the transmission of the measurement data acquisition command 400, each of the sensor tags 200_1 and 200_2 generates measurement data based on a measurement signal from a corresponding sensor circuit through the reader / writer 100. Then, the sensor tag 200_1 transmits the response signal 402 including the generated measurement data without generating the response delay. On the other hand, the sensor tag 200_2 starts transmitting the response signal 410 after waiting for the response delay Td (response delay 407) calculated based on the individual ID.

[0143] In this way, in the Fig. 13, various response delays are calculated based on the individual IDs set for the sensor tags 200, and a transmission timing of a response signal is adjusted according to each calculated response delay. <K. Antwortsignal>

[0144] Next, a response signal with measurement data from the sensor tag 200 is described. (k1: measurement data)

[0145] In addition to digital data indicating either ON / OFF, analog data indicating a measured value can also be used as measurement data to be included in the response signal. Although digital data only requires at least one bit to be assigned to a data portion, it is preferable to use multiple bits to allow for error detection and / or error correction, taking into account the noise immunity due to data transmission via wireless communication.

[0146] A plurality of measured values ​​sampled in the same sensor circuit at intervals shorter than the transmission cycle of the measurement data acquisition command, as well as measurement data collected at a single measurement time, can also be transmitted together. By applying this method, it is possible to perform sampling (oversampling) at intervals shorter than the acquisition cycle of the measured data using the measurement data acquisition command.

[0147] In this way, information about a large number of measurement signals collected at different times can be incorporated into the response signal.

[0148] Even when analog data is transmitted, quantization occurs within a dynamic range corresponding to the number of bits assigned to each measured value. If the number of assigned bits is small, measurement data can be generated after preprocessing, e.g., averaging or peak detection of the measurement signal is performed by the sensor circuit. On the other hand, if the number of bits is sufficiently large, oversampling can be performed as described above. (k2: Specification of the sensor tag of the transmitting source)

[0149] As in Fig. 12 and Fig. 13 and described above, even when a plurality of sensor tags 200 transmit response signals with respect to the same measurement data acquisition command, it is possible to basically specify the sensor tag 200 of the transmission source based on a reception order and a reception timing of the response signal.

[0150] However, in order to avoid an influence of jitter or the like in the response signal, the response signal may contain information for specifying the sensor tag 200 of the transmitting source. Fig. 14A and Fig. 14B diagrams illustrate an example of a response signal in the wireless sensor system 1 according to the present embodiment.

[0151] One in Fig. The response signal 450 shown in Figure 14A includes a value indicating the unique ID of the sensor tag 200 of the transmitting source. That is, the response signal 450 includes a region 452 configured to store the unique ID of the sensor tag 200 of the transmitting source and a region 454 configured to store the measurement data. Upon receiving such a response signal 450, the reader / writer 100 can specify the sensor tag 200 of the transmitting source based on a value stored in the region 452 of the received response signal 450.

[0152] The Fig. The response signal 460 shown in Figure 14B can be configured to store encoded data obtained by encoding measurement data using unique information (e.g., a unique data string with a group ID and an individual ID) of the sensor tag 200 of the transmitting source. When a response signal 460 is received, the reader / writer 100 attempts to decode using the preset identification information of the sensor tag 200 and specifies the sensor tag 200 of the transmitting source based on its success or failure. By adopting a data structure as in the response signal 460 shown in Fig. 14B, the necessary amount of data can be compared to the data structure as shown in Fig. 14A. (k3: Notification of sensor tags outside the setting)

[0153] In the wireless sensor system 1 according to the present embodiment, identification information is preset in the sensor tag 200, which exchanges with the reader / writer 100. However, if there is a sensor tag 200 for which the setting of the identification information is incorrect, if there is a sensor tag 200 for which wireless communication with the reader / writer 100 is not provided, or the like, an unscheduled response signal is received from the sensor tag 200.

[0154] In such a case, the reader / writer 100 may communicate information to a user or host device indicating that there is a sensor tag 200 that differs from the preset sensor tag 200. <L. Verarbeitungsverfahren».

[0155] Next, a processing procedure in the wireless sensor system 1 according to the present embodiment will be described.

[0156] Fig. 15A and Fig. 15B are flowcharts illustrating a processing procedure in the wireless sensor system 1 according to the present embodiment. Fig. 15A illustrates a processing process in the reader / writer 100 and Fig. 15B illustrates a processing procedure in a sensor tag 200.

[0157] With reference to Fig. 15A, the reader / writer 100 determines whether a measurement data acquisition request has been received (step S100). The measurement data acquisition request may be received from a host device or the like, or generated internally according to a predetermined schedule. If the measurement data acquisition request has not been received (if NO in step S100), the processing of step S100 is repeated.

[0158] When the measurement data acquisition request is received (in the case of YES in step S100), the reader / writer 100 determines a sensor tag 200 serving as an object from which measurement data is collected with reference to the identification information list 107 based on a received measurement data acquisition request (step S102), and sends a measurement data acquisition command designating the determined sensor tag 200 (step S104).

[0159] Next, the reader / writer 100 waits for a response signal to be received from the sensor tag 200 (step S106). When the response signal is received from the sensor tag 200, the reader / writer 100 decodes the received response signal to recover the measurement data (step S108) and specifies the sensor tag 200 that serves as the transmission source of the received response signal (step S110). Then, the reader / writer 100 adds information specifying the sensor tag 200 as the transmission source to the recovered measurement data and outputs the recovered measurement data with the added information (step S112).

[0160] Next, the reader / writer 100 determines whether there is a sensor tag 200 from which no measurement data has yet been collected among the objects from which the measurement data is being collected (step S114). If the measurement data has been collected from all the sensor tags 200 determined as the objects from which the measurement data is being collected (NO in step S114), the process is completed.

[0161] If, however, there is a sensor tag 200 from which no measurement data has yet been acquired (YES in step S114), the reader / writer 100 sends a frame synchronization signal (an additional command signal) (step S116). Then, the reader / writer 100 performs the processing from step S106 onward. The processing from steps S106 to S116 is repeated until the acquisition of measurement data from all sensor tags 200 identified as objects is completed.

[0162] Referring to Fig.15B, when any command signal is received from the sensor tag 200, the processing of step S200 is performed using the electric energy contained in the received command signal.

[0163] Specifically, the sensor tag 200 specifies details of the received command signal (step S200). If the received command signal is a command other than the measurement data acquisition command ("other" in step S200), the sensor tag 200 executes a process according to the received command (step S202).

[0164] If, however, the received command signal is the measurement data acquisition or collection command (the case of the "measurement data collection command" in step S200), the sensor tag 200 determines whether the sensor tag 200 is an object from which measurement data is collected based on a group ID and / or an individual ID included in the received measurement data acquisition command (step S204). If the sensor tag 200 is not an object from which measurement data is collected (the case of NO in step S204), the process is aborted.

[0165] If, however, the sensor tag 200 is an object from which measurement data is collected (if YES in step S204), the sensor tag 200 generates measurement data based on a measurement signal from the sensor circuit 220 (step S206). Subsequently, the sensor tag 200 determines whether the response start condition is met based on the group ID and / or the individual ID included in the received measurement data collection command and its own individual ID (step S208).

[0166] If the response start condition is met (the case of YES in step S208), the sensor tag 200 sends a response signal containing the measurement data generated in step S206 (step S210). The process is then terminated.

[0167] If, however, the response start condition is not met (the case of NO in step S208), the sensor tag 200 waits for the frame synchronization signal (the additional command signal) to be received from the reader / writer 100 (step S212). If the frame synchronization signal is received, the processing of step S208 is repeated. The processing of steps S208 and S212 is repeated until the transmission of the response signal in each sensor tag 200 is completed. <M. Schlussfolgerung>

[0168] In the wireless sensor system 1 according to the present embodiment, it is possible to easily measure a state of a machine, a facility, or the like by arranging one or more of the sensor tags 200 including the sensor circuits at an arbitrary location and jointly arranging the reader / writer 100 for acquiring measurement data via wireless communication with these sensor tags 200.

[0169] In the wireless sensor system 1 according to the present embodiment, since a transmission timing of the response signal is automatically adjusted on the sensor tag 200 side so that a collision does not occur merely by the transmission of a common command signal, it is also possible to minimize the number of man-hours for management in a case where the number of sensor tags 200 is increased.

[0170] In the wireless sensor system 1 according to the present embodiment, a response property (a real-time property) can be implemented which cannot be realized by existing communication standards. [Description of reference symbols]

[0171] 1: wireless sensor system; 2, 4: conveyor belts; 30: host device; 200, 200A, 200B, 200C, 200D, 200E, 200F: sensor tag; 100: reader / writer; 102: control unit; 104: communication interface; 106, 216: storage unit; 107: identification information list; 108: time measuring device; 110: display unit; 112: oscillator; 123, 144: mixer; 124, 126: Z-converter circuit; 127: separation circuit; 130, 230: antenna; 150: communication control unit; 210: processing circuit; 212: demodulation circuit; 213: modulation circuit; 214: Control circuit; 218: Memory bank; 220: Sensor circuit; 222: External sensor interface; 240: Power supply circuit; 250: Analog front end; 260: Microcomputer; 300, 400: Measurement data acquisition command; 302: Preamble part; 304: Command part; 306: Group ID part; 308: Individual ID part; 310: Checksum part; 320, 402, 404, 410, 450, 460: Response signal; 406, 407: Response delay; 408: Frame synchronization signal; 452, 454: Range;2181: EPC data; 2182: Group ID; 2183: Individual ID; 2184: TID area; 2186: Payload area; ST1: Ready state; ST2: Active state; ST3: Response delay state.;

Claims

[1] Wireless sensor system (1), comprising: a sensor tag (200, 200A, 200B, 200C, 200D, 200E, 200F) configured to contain a radio frequency (RF) tag; and a communication device (100) configured to communicate wirelessly with one or more sensor tags (200, 200A, 200B, 200C, 200D, 200E, 200F), wherein each of the one or more sensor tags (200, 200A, 200B, 200C, 200D, 200E, 200F) is configured to receive a measurement signal from one or more sensor circuits (220, 220_1, 220_2) and to store identification information that is distinguishable from that of other sensor tags (200, 200A, 200B, 200C, 200D, 200E, 200F), wherein the communication device (100) comprises a transmission means configured to transmit a command signal to the one or more sensor tags (200, 200A, 200B, 200C, 200D, 200E, 200F), wherein the command signal contains designation information for designating a sensor tag (200, 200A, 200B, 200C, 200D, 200E, 200F) serving as an object, wherein each of the one or more sensor tags (200, 200A, 200B, 200C, 200D, 200E, 200F) generates measurement data based on the measurement signal if the designation information contained in the command signal received from the communication device (100) matches its own stored identification information, wherein each of the one or more sensor tags (200, 200A, 200B, 200C, 200D, 200E, 200F) begins transmitting a response signal including the generated measurement data when a predetermined response start condition is met, and wherein each of the one or more sensor tags (200, 200A, 200B, 200C, 200D, 200E, 200E, 200F) begins transmitting the response signal without causing a response delay when generation of the measurement data is completed if its own stored second identification information corresponds to a value indicating a head of a response. [2] The wireless sensor system (1) according to claim 1, wherein the identification information includes first identification information indicating a group to which each sensor tag (200, 200A, 200B, 200C, 200D, 200E, 200F) belongs, and second identification information for specifying each sensor tag (200, 200A, 200B, 200C, 200D, 200E, 200F). [3] Wireless sensor system (1) according to claim 2, wherein the designation information comprises first designation information for designating a group serving as an object and second designation information for individually designating a sensor tag (200, 200A, 200B, 200C, 200D, 200E, 200F) serving as an object, and wherein each of the one or more sensor tags (200, 200A, 200B, 200C, 200D, 200E, 200E, 200F) performs the generation of the measurement data and the transmission of the response signal when its own stored first identification information matches the first designation information included in the designation information, and when its own stored second identification information matches the second designation information included in the designation information. [4] Wireless sensor system (1) according to claim 2, where the label information contains information about the label of a group that serves as an object, and wherein each of the one or more sensor tags (200, 200A, 200B, 200C, 200D, 200E, 200F) executes the generation of the measurement data and the transmission of the response signal when its own stored first identification information matches a group designated in the designation information. [5] The wireless sensor system (1) according to claim 1, wherein each of the one or more sensor tags (200, 200A, 200B, 200C, 200D, 200E, 200F) starts transmitting the response signal after waiting until the number of times an additional command signal is transmitted from the communication device (100) and a value indicated by its own stored second identification information satisfies a predetermined relationship if its own stored second identification information does not correspond to a value indicating a header of a response. [6] The wireless sensor system (1) according to claim 4, wherein each of the one or more sensor tags (200, 200A, 200B, 200C, 200D, 200E, 200E, 200F) begins transmitting the response signal after a waiting time determined based on a value indicated by its own stored second identification information. [7] Wireless sensor system (1) according to one of claims 1 to 6, wherein the response signal contains information of a plurality of measurement signals collected at different times. [8] Communication device (100) for wirelessly communicating with one or more sensor tags (200, 200A, 200B, 200C, 200D, 200E, 200F), each of which contains a radio frequency tag (RF tag), wherein each of the one or more sensor tags (200, 200A, 200B, 200C, 200D, 200E, 200F) is configured to receive a measurement signal from one or more sensor circuits (220, 220_1, 220_1, 220_2) and to store identification information suitable for being distinguished from that of other sensor tags (200, 200A, 200B, 200C, 200D, 200E, 200F), wherein the communication device (100) comprises: a transmission means configured to transmit a command signal to the one or more sensor tags (200, 200A, 200B, 200C, 200D, 200E, 200F), the command signal containing designation information for designating a sensor tag (200, 200A, 200B, 200C, 200D, 200E, 200F) serving as an object; and a receiving means configured to receive a response signal from the one or more sensor tags (200, 200A, 200B, 200C, 200D, 200E, 200F), wherein the response signal contains measurement data based on the measurement signal generated when the designation information contained in the command signal matches the identification information stored in the sensor tag (200, 200A, 200B, 200C, 200D, 200E, 200F), wherein the response signal is transmitted at a time when a response start condition set in each of the sensor tags (200, 200A, 200B, 200C, 200D, 200E, 200F) is met, wherein each of the one or more sensor tags (200, 200A, 200B, 200C, 200D, 200E, 200E, 200F) is configured to begin transmission of the response signal without causing a response delay when generation of the measurement data is completed if its own stored second identification information corresponds to a value indicating a header of a response. [9] Sensor tag (200, 200A, 200B, 200C, 200D, 200E, 200F) with a radio frequency tag (RF tag), wherein the sensor tag (200, 200A, 200B, 200C, 200D, 200E, 200F) is configured to receive a measurement signal from one or more sensor circuits (220, 220_1, 220_2) and to store identification information suitable for being distinguished from that of other sensor tags (200, 200A, 200B, 200C, 200D, 200E, 200F), wherein the sensor tag (200, 200A, 200B, 200C, 200D, 200E, 200F) generates measurement data based on the measurement signal if designation information for designating a sensor tag (200, 200A, 200B, 200C, 200D, 200E, 200F) serving as an object contained in a command signal matches stored identification information when the command signal is received by a communication device (100) configured to wirelessly communicate with the sensor tag (200, 200A, 200B, 200C, 200D, 200E, 200F), and wherein the sensor tag (200, 200A, 200B, 200C, 200D, 200E, 200F) begins transmitting a response signal containing the generated measurement data when a predetermined response start condition is met, wherein the sensor tag (200, 200A, 200B, 200C, 200D, 200E, 200E, 200F) is configured to start transmitting the response signal without causing a response delay when generation of the measurement data is completed if its own stored second identification information corresponds to a value indicating a header of a response. [10] A communication method for use in a wireless sensor system (1) comprising a sensor tag (200, 200A, 200B, 200C, 200D, 200E, 200F) configured to include a radio frequency (RF) tag and a communication device (100) configured to wirelessly communicate with one or more sensor tags (200, 200A, 200B, 200C, 200D, 200E, 200F), wherein each of the one or more sensor tags (200, 200, 200, 200, 200, 200, 200) is configured to receive a measurement signal from one or more sensor circuits (220, 220_1, 220_2) and stores identification information that is capable of being distinguished from that of other sensor tags (200, 200A, 200B, 200C, 200D, 200E, 200F), wherein the communication method comprises the following steps: Transmitting a command signal by the communication device to the one or more sensor tags (200, 200A, 200B, 200C, 200D, 200E, 200F), wherein the command signal contains designation information for designating a sensor target serving as an object, generating measurement data based on the measurement signal by each of the one or more sensor tags (200, 200A, 200B, 200C, 200D, 200E, 200F) if the designation information contained in the command signal received from the communication device (100) matches its own stored identification information, and Starting, by each of the one or more sensor tags (200, 200A, 200B, 200C, 200D, 200E, 200F), a transmission of a response signal including the generated measurement data when a predetermined response start condition is met, Starting, by each of the one or more sensor tags (200, 200A, 200B, 200C, 200D, 200E, 200E, 200F), the transmission of the response signal without causing a response delay when the generation of the measurement data is completed if its own stored second identification information corresponds to a value indicating a head of a response.

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