Sensor network and procedures for its operation

Abstract

Method for operating a sensor network comprising at least one RFID reader (3) for storing and transmitting location-specific and function-specific topic data, and a network (2) with a server (4) and at least one sensor (1) as a client, which has a measuring device (14) for acquiring measurement data, wherein the method comprises the following steps: A.) Transfer of the location-specific and function-specific topic data from the RFID(“Radio Frequency Identification”) reader (3) to a writable data storage device of an RFID chip of an RFID transponder (13); B.) Booting the sensor (1); C.) Querying the location-specific and function-specific topic data from the RFID transponder (13) and storing this topic data by a microprocessor (11) in bidirectional data exchange with the measuring device (14) and the RFID transponder (13); E.) Sending a request for a broker IP (“Internet Protocol”) address by the sensor (1) via its network interface (12) to the network (2); F.) Responding to the request by a network participant by transmitting a broker IP address to the sensor (1); G.) Acquisition of measurement data by the measuring device (14) and transmission of this measurement data to the microprocessor (11); H.) Form at least one message comprising a topic and content, wherein the topic includes at least some of the topic data and the content includes at least some of the measurement data; I.) Sending the message from the sensor (1) via its network interface (12) using the broker IP address to the message broker (5).

Description

[0001] The invention is based on a method for operating a sensor network according to the preamble of independent claim 1.

[0002] Such sensor networks are needed to communicate measurement data. State of the art

[0003] Sensor networks are known to experts and are currently described, for example, in the Wikipedia article “Sensornetz” http: / / de.wikipedia.org / wiki / Sensornetz as follows: A sensor network (from English wireless sensor network) is a computer network of sensor nodes, tiny (“grain of dust”) to relatively large (“shoebox”) computers that communicate wirelessly and work together either in an infrastructure-based (base stations) or in a self-organizing ad hoc network to query their environment using sensors and forward the information.

[0004] The publication DE 10 2006 018 174 A1 describes a data acquisition device for recording physical variables of a technical process in a process engineering plant, for converting the physical variable into an appropriate electrical variable, and outputting it to a communications medium. For the flexible acquisition of a plurality of measurement signals with the least possible installation effort, it is proposed to physically separate the functional group for data acquisition and the functional group for data processing and logically connect them via a wireless communication link, to connect the functional group for data processing to a higher-level device via a conductor loop, in which the power supply and the transmission of the measurement information take place via the same wire pair, and to arrange the functional group for data acquisition directly at the measuring point and supply it with power locally.

[0005] The document US 2012 / 0057581 A1 discloses a system and a method for operating a sensor node, in particular in an RFID (Radio Frequency Identification Device) environment, and an associated gateway system.

[0006] The document US 2013 / 0076491 A1 discloses a system for commissioning devices. The system comprises a first device and a second device, as well as an RFID tag and a host processor, both of which belong to the first device. The second device is arranged to generate an electromagnetic field, and the RFID tag is arranged to detect the electromagnetic field and, upon detection of the electromagnetic field, to wake up the host processor so that the second device can communicate with the host processor. Furthermore, a corresponding method for commissioning devices is disclosed. Since the RFID tag contained in the first device is designed to wake up the host processor, the first device does not need to be manually switched on by a user. This simplifies operation. Furthermore, no separate power button is required on the first device.The latter reduces costs and simplifies the design of the first device.

[0007] US 2014 / 0241373 A1 discloses devices, systems, methods, and computer program products for multiplexing data from multiple transport protocols in data processing. It also discloses dynamic, reliable, secure, and scalable systems and methods for integrating multiple device types into a network. Novel systems and methods are provided for automatically resolving communication for permanent and temporary data transmission from multiple device types in a network without requiring manual intervention, as well as for reducing security vulnerabilities. Some of the solutions described include systems and methods for multiplexing data from multiple transport protocols using a dynamic dispatcher software assembly that identifies incoming data patterns for forwarding to its dynamically reconfigurable corresponding processing logic in the processing module.

[0008] US 2008 / 0137624 A1 discloses methods and apparatus for the architecture and protocol of a global wireless sensor network for remote monitoring, asset control, and operations management, based on localized clusters of autonomous sensor / monitoring / operational sensor nodes capable of ad hoc connection with nearby nodes and connection to gateway nodes with enhanced network functionality. These localized cluster nodes send data to gateway nodes either directly or via multi-hop transactions. The gateway nodes, in turn, are connected to other gateway nodes and operations control centers via wireless or wired data communication links. By leveraging the internet for long-distance interconnectivity, the network is scalable on a global scale.The resulting network is based on an ad hoc mesh topology to allow flexibility in network modification and expansion and consists of a tiered structure defined by increasing functionality. A current application of this technology is the remote control and monitoring of lighting systems for institutions and municipalities on a local, national, and / or global basis from centralized regional operations centers.

[0009] Document WO 2012 / 129796 A1 discloses a method for configuring a wireless device, wherein the wireless device is equipped with an RFID (Radio Frequency Identification) tag or connected to such an RFID tag. The method comprises obtaining configuration data by the RFID tag from a radio frequency (RF) signal and configuring the RFID tag according to the obtained configuration data. The embodiments of the present invention also provide a corresponding wireless system and a wireless device. By adopting the embodiments of the present invention, the wireless device can be configured effectively and at low cost.

[0010] A disadvantage of the state of the art is that the configuration of a sensor network is usually performed via one or more configuration protocols, via a web interface, and / or by changing a program code, and therefore involves considerable manual effort. A particular disadvantage is that a software update for the microprocessors of, for example, multiple sensors requires considerable manual effort, since at least some of the data, especially location-specific and / or function-specific data, must be manually re-entered after such an update. Task

[0011] The object of the invention is to reduce this configuration effort.

[0012] The problem is solved by a method of the type mentioned at the outset by the features of independent claim 1.

[0013] Advantageous embodiments of the invention are specified in the subclaims.

[0014] The invention serves to control the distribution of information, e.g. certain measured values, over the network.

[0015] One advantage of the invention is that the required manual configuration effort is at least significantly reduced.

[0016] An additional advantage is that a software update for the microprocessors of, for example, several sensors can be carried out with only minimal manual effort, since the said microprocessors can reload their respective, for example, location-specific and function-specific topic data from the writable data memory of the RFID transponder chip after such an update.

[0017] Another advantage is that the sensor can be de-energized during its configuration.

[0018] For example, current sensors that are supplied via a so-called “energy harvester,” i.e. that draw electrical energy from a mechanical change / movement / vibration, etc., can be completely encapsulated, e.g., with a plastic, since they do not require a plug connection.

[0019] In particular, such a sensor can also be configured in a stationary state and does not require any wired interfaces.

[0020] A particular advantage is that the sensor can identify itself automatically in the network and, at least at the application level, does not require any assignment in the form of an IP address and / or a location over the network.

[0021] Configuration information can thus be easily transferred to the sensor from a mobile device, such as a tablet or a smartphone, which in this case, for example, takes on the function of an RFID reader with an additional device.

[0022] In a preferred embodiment, information transmission between the sensor and the network can take place contactlessly and in particular also during movement of the sensor.

[0023] It is particularly advantageous if the network is structured according to a so-called "publisher-subscriber model" and in particular according to the MQTT ("Message Queue Telemetry Transport") standard, because such a network enables topic-specific processing of the respective information, for example, topic-specific control and / or selection of certain messages. Thus, a so-called "publisher", which is designed, for example, as a current sensor and can represent a client in the network, can publish messages under a specific topic via a so-called "message broker". This message broker can be a device specifically designed for this purpose. However, it can also be a device that already fulfills another function in the network, for example another such sensor that thus assumes that of such a message broker in addition to its actual function.However, it could also be a server, for example. Using this message broker, the sensor can publish messages under a specific topic according to the publisher-subscriber model. It can query the topic for the messages it is to send using its microprocessor, particularly from the writable memory of its RFID transponder. The RFID transponder has previously received the data containing this topic from an RFID reader, particularly a stationary RFID reader. The topic can already be present in the RFID reader in a publisher-subscriber network-compatible format, i.e., as a so-called "topic," and can be transmitted to the RFID transponder in this format.A so-called "subscriber," such as a network PC, a signal light, another current sensor, or any other client that has subscribed to this topic or a corresponding topic area, thus receives the message formed with this topic and can evaluate its content, such as a corresponding measured value or any other content.

[0024] A network participant can simultaneously fulfil the function of both a publisher and a subscriber in the network.

[0025] In a preferred embodiment, the message broker can be formed by the server. The sensors are preferably publishers. This is particularly advantageous because relevant messages can be transmitted via the message broker between the sensors and other clients of the network, regardless of their addressing and the physical structure of the network, without the need for central configuration. In particular, at least one of the sensors can be a publisher. This is particularly advantageous because the sensor can then publish the measured values ​​it determines.

[0026] In a preferred embodiment, the sensor is a current sensor. However, the described situation also applies to other, particularly electrically operated, sensors, for example temperature, pressure, brightness, humidity, smoke, or any other type of sensor. The current sensor is used, for example, to measure the current that is conducted through a specific busbar and also fulfills a specific purpose. In the area of ​​this busbar, for example, a permanently installed RFID reader can be located. In a preferred embodiment, however, a mobile RFID reader can also be used, which is brought, e.g., by a user, into the area of ​​the respective sensor. The RFID reader can already contain data containing the location and / or function of the current sensor / busbar, or this data can be entered into the RFID reader by the user at short notice.The RFID reader transmits this data, which is preferably topic data, to the current sensor's RFID transponder. This data is then stored in the writable memory of the RFID transponder's RFID chip. Therefore, it is sufficient to boot the current sensor only now. The current sensor's microprocessor now requests the said data from the RFID transponder's RFID chip. This data is then transmitted from the RFID transponder to the microprocessor. The current sensor's microprocessor thus receives information about the location and / or function of the relevant busbar / current sensor. It can use this information as a so-called "topic," i.e., as a subject for messages in a publisher-subscriber format, particularly the MQTT format.

[0027] For cost reasons, it is particularly advantageous to use a mobile RFID reader and to use it to supply several current sensors with such topic data one after the other.

[0028] With such topic data, the microprocessor is able to create messages with a corresponding topic according to a program stored in its memory: As the content of these messages, the current sensor can continue to use the currently measured values ​​for the current strength, e.g. in the form of a metric.

[0029] In order to be able to send such a message over the network, the sensor needs its own IP (“Internet Protocol”) address.

[0030] For this purpose, in a preferred embodiment, the current sensor can have a so-called “IPV6 address” which, as is known to those skilled in the art, can be considered globally unique due to its size.

[0031] In another embodiment, it can receive an IP address from a DHCP (Dynamic Configuration Host Protocol) server, which is designed to assign such IP addresses and transmit them to clients, in this case, to the sensor. Such an IP address can, for example, be a so-called "IPV4" address, whose address space is significantly smaller than that of an IPV6 address.

[0032] The flow sensor then sends a request for a message broker to the network using its IP address. A message broker, or any other network participant that knows the IP of a message broker (i.e., a broker IP address), transmits this information (i.e., this broker IP address) to the flow sensor. If several such response messages arrive, the flow sensor can select one of them based on a predefined criterion, e.g., it can use the broker IP address of the first incoming message.

[0033] Using this broker IP address, the flow sensor can now publish its messages via the corresponding message broker. The message can then be stored in the message broker and delivered to and / or retrieved by any subscriber subscribed to the corresponding topic.

[0034] Furthermore, it is advantageous if additional network participants, e.g., additional power or other sensors, signal lights, network PCs, or sensors, are provided as so-called "subscribers," each of which also has a microprocessor and a data memory in which a software program is stored that is suitable for receiving a message from the network, particularly via the microprocessor, because in this way, the network participants can select the messages relevant to them, particularly according to a specific topic / topic area. The data memory of the respective subscriber can be part of the associated microprocessor.

[0035] In a preferred embodiment, the message broker knows the topics of the subscribers and, in a lower layer of the network, their IP addresses. This means that only those subscribers receive a specific message over the network if their topic matches their subscription. This has the advantage of avoiding unwanted data traffic in the network. Depending on the size of the network, i.e. in particular the number of clients, especially subscribers, the data traffic is advantageously reduced considerably. Conversely, much larger networks are possible with the same data throughput. Nevertheless, the network is structured according to the "publisher-subscriber model" at a higher layer because it behaves accordingly in programming and use. In particular, in the OSI (Open Systems Interconnection) model, the aforementioned IP layer can be built as a network layer on top of a network layer, e.g. Ethernet or WLAN or similar.A TCP layer can be placed on top of this IP layer as a transport layer, upon which the publisher-subscriber model is built as an application. In particular, the publisher-subscriber model can be structured according to the MQTT protocol. Example

[0036] An embodiment of the invention is illustrated in the drawings and explained in more detail below. They show: Fig. 1 a schematic representation of a sensor network; Fig. 2 a flow chart of network structure and information transfer.

[0037] The figures contain partially simplified, schematic representations. In some cases, identical reference symbols are used for identical, but possibly not identical, elements. Different views of identical elements may be scaled differently.

[0038] The Fig. 1 shows a sensor network comprising three current sensors 1, 1', 1'', which are constructed identically, but for reasons of clarity only one current sensor 1 with its components is explicitly shown, namely with a microprocessor 11, which is in bidirectional data exchange with a network interface 12 and an RFID transponder 13 and a current measuring device 14, for example via a common data bus and / or via separate data lines.

[0039] The current sensor shown here is an example. It could just as easily be other sensors, especially electrically operated ones, such as temperature, pressure, brightness, humidity, smoke, or any other type of sensor, even in combination with one another.

[0040] The sensor network further comprises a network 2, via which the sensors 1, 1', 1'' are connected to each other as well as to a server 4 and two message brokers 5, 5'. Furthermore, in the present illustration, an RFID reader 3, 3', 3'' is provided at the location of each current sensor 1, 1', 1'', which is capable of sending topic data to the respective RFID transponder 13, ... of the associated current sensor 1, 1', 1''.

[0041] In another embodiment, a mobile RFID reader (“handheld reader”) not shown in the drawing can be used instead of the stationary RFID readers 3, 3', 3'' shown, by bringing it one after the other to the locations where the permanently installed RFID readers 3, 3', 3'' shown in the drawing are located, in order to transmit the subject data to their respective RFID transponders 13, ...

[0042] The Fig. 2 shows a flowchart of a corresponding procedure.

[0043] RFID reader 3 can store thematic data in its data memory, which could, for example, concern the function and location of the respective power measurement. This data can also be entered at short notice, particularly into the mobile RFID reader. Such a mobile RFID reader can be a smartphone or a tablet with a corresponding additional device.

[0044] These topic data are transmitted to the RFID transponder 13 of the current sensor 1 in process step A.

[0045] Only now does sensor 1 need to be booted in process step B.

[0046] The microprocessor 11 of the current sensor 1 can then query these topic data from the data memory of the RFID chip of the RFID transponder 13 in method step C.

[0047] This is also particularly advantageous because, for example, even during an update of the microprocessor 11, the data is retained in the RFID transponder and is retransmitted to the microprocessor after the update. This considerably simplifies such an update process because all current sensors 1, 1', 1'' can undergo the same update together in a single process and then request their individual data from the respective RFID transponder 13, ...

[0048] In a first embodiment, current sensor 1 can have a predefined IPV6 address. This IPV6 address has such a large address space that it can be considered globally unique. In this case, method step D is skipped.

[0049] In a second embodiment, which also includes method step D, the IP address can, in particular, also be an IPV4 address with a significantly smaller address space. This IPV4 address can, in particular, be assigned to the current sensor 1 by a DHCP server (not shown in the drawing) and transmitted to it via the network 2.

[0050] Using the sensor IP address thus obtained, the current sensor 1 can now send a request for a message broker 5, 5' to the network 2. Any other network participant, ie, another current sensor, 1', 1'', the server 4, the message broker 5, 5', which knows an IP address of a message broker, can answer this question and send a broker IP address to the current sensor in method step 4.

[0051] Subsequently, the current sensor, with its current measuring device 14, acquires measurement data in method step G. The microprocessor retrieves this measurement data, for example, from the current measuring device, and, in method step H, creates a message that has a subject and content and preferably corresponds to a publisher-subscriber model, in particular the MQTT protocol. The content of the message comprises at least part of the measurement data. The subject of the message comprises at least part of the subject data.

[0052] In process step I, the message is transmitted from sensor 1 to message broker 5.

[0053] Every subscriber who has subscribed to the subject of this message, for example, “Current strength at busbar 23 in plant 3,” receives the corresponding messages from the message broker and can evaluate their content. List of reference symbols 1, 1', 1'' current sensor 11 Microprocessor 12 Network interface 13 RFID transponders 14 Current measuring device 2 Network 3 RFID readers 4 servers 5.5' Message Broker

Claims

[1] Method for operating a sensor network, comprising at least one RFID reader (3) for storing and transmitting location-specific and function-specific thematic data, as well as a network (2) with a server (4) and at least one sensor (1) as a client, which has a measuring device (14) for acquiring measurement data, the method comprising the following steps: A.) Transferring the location-specific and function-specific topic data from the RFID (“Radio Frequency Identification”) reader (3) to a writable data memory of an RFID chip of an RFID transponder (13); B.) Booting the sensor (1); C.) querying the location-specific and function-specific topic data from the RFID transponder (13) and storing this topic data by a microprocessor (11) in bidirectional data exchange with the measuring device (14) and the RFID transponder (13); E.) Sending a request for a broker IP (“Internet Protocol”) address by the sensor (1) via its network interface (12) to the network (2); F.) Answering the request by a network participant by transmitting a broker IP address to the sensor (1); G.) Recording measurement data by the measuring device (14) and transmitting this measurement data to the microprocessor (11); H.) Forming at least one message comprising a topic and a content, wherein the topic includes at least a portion of the topic data and the content includes at least a portion of the measurement data; I.) Sending the message from the sensor (1) via its network interface (12) using the broker IP address to the message broker (5). [2] A method according to claim 1, wherein the method additionally comprises the following step: D.) Assigning and transmitting a sensor IP address to the sensor (1). [3] Method according to claim 2, characterized by that the sensor IP address is an IPV6 address. [4] A method according to any preceding claim, wherein the message has a topic comprising at least part of the topic data and a content comprising at least part of the measurement data. [5] Method according to one of the preceding claims, wherein the message corresponds to a so-called “publisher-subscriber” model. [6] Method according to one of the preceding claims, wherein at least one of the sensors (1, 1', 1'') represents a publisher, and wherein the network has at least one further client representing a subscriber. [7] Method according to claim 1, wherein the network (2) comprises at least one message broker (5). [8] Method according to claim 7, wherein the message broker (5) is formed by the server (4). [9] Method according to claim 7, wherein the message broker (5) is formed by one of the sensors (1, 1', 1'').

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