WO2014135213A1 - Positionnement et localisation de nœuds dans un réseau - Google Patents

Positionnement et localisation de nœuds dans un réseau Download PDF

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Publication number
WO2014135213A1
WO2014135213A1 PCT/EP2013/054647 EP2013054647W WO2014135213A1 WO 2014135213 A1 WO2014135213 A1 WO 2014135213A1 EP 2013054647 W EP2013054647 W EP 2013054647W WO 2014135213 A1 WO2014135213 A1 WO 2014135213A1
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WO
WIPO (PCT)
Prior art keywords
antenna
node
array system
array
signal
Prior art date
Application number
PCT/EP2013/054647
Other languages
English (en)
Inventor
Emanuele FRANCIONI
Sergey Igorevich VLADIMIROV
Fulvio VENTURELLI
Charlotte ALDERWISH
Original Assignee
Hokuto Bv
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hokuto Bv filed Critical Hokuto Bv
Priority to PCT/EP2013/054647 priority Critical patent/WO2014135213A1/fr
Publication of WO2014135213A1 publication Critical patent/WO2014135213A1/fr

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S3/00—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received
    • G01S3/02—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received using radio waves
    • G01S3/14—Systems for determining direction or deviation from predetermined direction
    • G01S3/46—Systems for determining direction or deviation from predetermined direction using antennas spaced apart and measuring phase or time difference between signals therefrom, i.e. path-difference systems
    • G01S3/50—Systems for determining direction or deviation from predetermined direction using antennas spaced apart and measuring phase or time difference between signals therefrom, i.e. path-difference systems the waves arriving at the antennas being pulse modulated and the time difference of their arrival being measured
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/87—Combinations of radar systems, e.g. primary radar and secondary radar
    • G01S13/878—Combination of several spaced transmitters or receivers of known location for determining the position of a transponder or a reflector
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
    • G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
    • G01S5/0205—Details
    • G01S5/021—Calibration, monitoring or correction
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
    • G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
    • G01S5/04—Position of source determined by a plurality of spaced direction-finders
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
    • G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
    • G01S5/12—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves by co-ordinating position lines of different shape, e.g. hyperbolic, circular, elliptical or radial

Definitions

  • the present invention relates to positioning and/or tracking of nodes in a network. More specifically the invention relates to positioning and/or tracking of RFID nodes.
  • Bluetooth and Zigbee provide positioning possibilities, but behave poorly in the neighborhood of walls, people and water sources. This is due to the fact that these technologies operate in a bandwidth that has been conceived for data transmission purposes and they are improperly employed in poorly designed short range tracking solution. Other known GPS or GPRS/3G solutions are expensive and provide best localization outdoors only .
  • an antenna- array system for determining a current location of a node.
  • the antenna-array system can comprise two or more antenna elements configured to receive an input signal from the node.
  • the antenna elements can be positioned in an antenna-array such that the input signal arrives at two neighboring antenna elements at different times resulting in a first intermediate signal from a first antenna element and a second intermediate signal from a second antenna element neighboring the first antenna element.
  • the antenna-array system can further comprise comparator electronics configured to compare the first
  • a method in an antenna-array system for determining a current location of a node.
  • the method can comprise receiving in two or more antenna elements of an input signal from the node.
  • the antenna elements can be positioned in an antenna-array such that the input signal arrives at two neighboring antenna elements at different times resulting in a first intermediate signal from a first antenna element and a second intermediate signal from a second antenna element neighboring the first antenna element.
  • the method can further comprise comparing in comparator
  • the signal transmitted by the node is received at the antenna elements in the antenna array. Variations in the timing of the reception of the signal at the different antenna elements are used to measure the direction from which the signal is received. Thus, the angle of the signal can be determined, which can be used for positioning and tracking of the node.
  • claims 2 and 17 advantageously enable the angle of the input signal to position the node.
  • claims 3 and 18 advantageously enable calibration of the analog parts of the antenna elements, resulting in more accurate timing measurements.
  • the embodiments of claims 4 and 19 advantageously enable an additional measurement of the angle of the signal, making the measurements more precise.
  • the embodiment of claim 5 advantageously provides for an antenna-array configuration that reduces background
  • claims 6 and 7 advantageously enable more precise measurement of the input signal.
  • a communication network comprising one or more antenna-array systems as described above.
  • the embodiment of claim 11 advantageously enables a server to determine the position of the node.
  • the embodiment of claim 12 advantageously enables tracking of nodes by their identifier.
  • the embodiment of claim 13 advantageously enables positioning and tracking of persons or pets.
  • claims 14 and 15 advantageously enable communication between nodes on top of tracking and/or tracing of the nodes.
  • Fig.l shows a network of an exemplary embodiment of the invention
  • Fig.2a shows a front view of an antenna-array of an exemplary embodiment of the invention
  • Fig.2b shows a side view of an antenna-array of an exemplary embodiment of the invention
  • Fig.3, Fig.4 and Fig.6 show parts of a printed board circuit of an exemplary embodiment of the invention
  • Fig.5 shows signals before and after processing by parts of a printed board circuit of an exemplary embodiment of the invention
  • Fig.7 shows an effect of a time difference of arrival of a signal and how this can be used to calculate an angle of arrival
  • Fig.8 shows a graph of energy levels at antenna elements .
  • the invention enables positioning and tracking of nodes by using an antenna-array system as described in more detail below.
  • the nodes and antenna-array system can form a communication network wherein the nodes communicate with the antenna-array system or with other nodes directly or via the antenna-array system.
  • the antenna-array system is preferably configured such that long-range positioning and tracking and communication are possible.
  • Fig.l shows an exemplary embodiment of a network with three antenna-array systems la-lc and six nodes 2a-2f that can be positioned and tracked by the antenna-array systems la-lc.
  • Each of the nodes 2a-2f may be, depending on its location, capable of wirelessly communicating with one or more of the antenna-array systems la-lc.
  • this is depicted by the arrows that, as an example, show a wireless communication
  • a signal from a node 2a-2f may be received by at least one antenna-array system la-lc.
  • antenna-array system la-lc may relay messages between nodes.
  • the nodes 2a-2f are small, i.e. sized such that they may be worn or carried by humans or pets. For health- safety reasons and increased battery life the nodes preferably have low gain requirements.
  • the nodes may e.g. be active RFID tags embedded on flat badges or small garments like wristbands.
  • the nodes may be used both indoor and outdoor and are preferably adaptable to noisy environments.
  • the communication between the antenna-array system la ⁇ ic and a node 2a-2f may use one of the known RFID frequency bands as defined in the international standard ISO/IEC 18000 or any other suitable RFID frequency band.
  • the free sub- Ghz ISM band standard is used to avoiding interference problems with other systems.
  • use of RFID bands is becoming more and more problematic due to over ⁇ crowding the frequency bands by systems including Wireless LAN systems, 2-way radios, Modems, Passive systems and Zigbee.
  • Another advantage of the sub-Ghz ISM band is its capability of achieving a long range of options with very limited power consumption .
  • FIG.2a An antenna-array 1 of an antenna-array system of an exemplary embodiment of the invention is shown in Figs.2a and 2b, wherein Fig.2a depicts a front view of the antenna-array 1 and Fig.2b depicts a side view of the antenna-array 1.
  • the antenna-array 1 may be used with the sub-Ghz ISM RFID frequency band and may be a part of the antenna-array systems la-lc of Fig.1.
  • the antenna-array 1 may consist of at least two antenna elements 12 positioned on an antenna base 11.
  • the antenna element 12 is preferably a quarter wave monopole antenna, also known as Marconi antenna, but may be any other suitable
  • omnidirectional antenna such as e.g. a half-wave antenna or a co-linear antenna, with an omnidirectional radiation pattern in the azimuth plane, i.e. radiating equally well in all horizontal directions .
  • the antenna element 12 is formed by a conductor ⁇ /4 in length ( ⁇ being the wave length) , fed in the lower end, which is near the base 11 that works as a reflector.
  • the current in the reflected image has substantially the same direction and phase as the current in the real antenna.
  • the quarter-wave conductor and its image together form a half-wave dipole that radiates in the upper half of space. In this upper side of space the emitted field has substantially the same amplitude of the field radiated by a half-wave dipole fed with the same current. Therefore, the total emitted power is approximately one-half the emitted power of a half-wave dipole fed with the same current.
  • the radiation resistance (real part of series impedance) will be one-half of the series impedance of a half- wave dipole.
  • the fields above ground are substantially the same as for the dipole. Because only half the power is applied the gain is twice (3dB over) that for a half-wave dipole ( ⁇ /2).
  • the quarter-wave antenna element 12 uses a ground plane to work properly.
  • the ground plane typically extends a minimum of one wavelength in each direction from the base of the antenna element 12.
  • the ground plane is a substantially flat conducting surface that serves as part of the antenna by reflecting radio waves from other antenna elements, and is formed by the base 11.
  • the base 11 is preferably built on a plastic base 11a with a reflector layer lib of e.g. copper and a protective layer 11c, as shown in Fig.2b.
  • antenna elements 12 placed on the base 11 for sending and receiving signals to and from RFID nodes. It is to be understood that any other number of antenna elements 12 may be used instead.
  • a larger number of antenna elements 12 may be advantageous for aligning the analog signals that arrive at the antenna elements 12 before digitizing. Due to possible
  • signals may travel at different speeds through the analog lines. Since time differences between signals are measured, variations in timing of the signal travelling from the antenna element to the digital processing part due to the imperfections are to be compensated for. This compensation may be achieved by using multiple measurements from multiple pairs of antenna elements 12 and averaging the signal delays from the different pairs of antenna elements.
  • the distance between the antenna elements may be small, e.g. 10 cm.
  • the best possible clock (oscillator) currently on the open market may be used as it oscillates with frequency of 3 Ghz, thus providing the required resolution of 3.3*10 ⁇ 10 s.
  • a smaller number of antenna elements 12 may be used if the timing variation can be compensated otherwise, e.g. by using Time-to-Digital converters (TDC) .
  • TDC Time-to-Digital converters
  • a TDC can precisely measure a time between two energy peaks and are known to have a lOps (i.e. 10 _11 s) resolution, i.e. TDCs can measure a smallest time
  • TDCs are currently being developed that have an even higher resolution of 3.6ps.
  • a TDC may be thus used to measure a time difference very precisely.
  • the TDC may be used as a calibration device by installing the TDC at the end of analog part, just before the digital processing part.
  • the TDC is then used to calibrate the analog parts of the antenna elements 12.
  • the antenna element 12 is replaced by a signal generator to simulate analog signals being received at the antenna element.
  • the TDC measures the time differences in the signals received from the generator for different antenna elements.
  • the delays are measured.
  • the timing variations are calculated.
  • a correctional value may be defined and applied to the timing of the signals at the different antenna elements 12 when the system is in operation.
  • the antenna elements 12 are typically placed such that each antenna element 12 is equally far away from another one at a distance equal to 1/2 wave length, which is a safe distance to prevent negative radio effects of one emitter antenna element 12 onto another.
  • Each antenna element 12 is connected to a printed board circuit which performs computational and controlling tasks of the antenna-array 1.
  • the antenna array 1 and the printed board circuit together form the antenna-array system la-lc.
  • the main parts of the printed board circuit and its computational and controlling tasks will be explained in Figs.3-6.
  • Fig.3 shows a signal 101 originating from one of the nodes 2a-2f.
  • the signal 101 arrives at all antenna elements 12 of the antenna-array 1.
  • Fig.3 three of the antenna elements 12 are shown.
  • Each antenna element 12 may pass the signal 101 to a high frequency amplifier HFA.
  • the signal may be processed by a high frequency demodulator DM where the signal frequency is lowered and demodulated.
  • the resulting signals 103-105 envelope the originally received signal 101, as depicted by the signal 102.
  • the signal 101 transmitted from the node 2a-2f is received by the different antenna elements 12 in the antenna array 1 at (slightly) different times due to the variation in distance between the antenna elements 12 and the node 2a-2f. This time difference is measurable.
  • Fig.4 shows an example of a comparator part of the printed circuit board that may be used to measure the time difference.
  • any other electronic circuit capable of measuring the time difference in a similar manner may be used.
  • Each of the signals 103-105 from the demodulators DM may be passed to an operational amplifier OA and a trigger scheme.
  • the outputs 106 and 107 of the comparator part may contain a signal that uniquely represents the time difference between arrival of original signal 101 onto the antenna elements 12.
  • Outputs 106 and 107 are typically generated for each pair of neighboring antenna elements 12 in the antenna-array 1. For simplicity reasons Fig. only shows the comparator part for two neighboring antenna elements 12.
  • the trigger scheme in the example of Fig.4 has two D- type flip-flops, also known as data or delay flip-flops.
  • the D- type flip-flops operate as follows. If input D equals a logical "0" and the input C has a rising edge (i.e. changing from “0” to "1"), then the output Q becomes “0". If input D equals a logical "1" and the input C has a rising edge, then the output Q becomes "1". If input C does not have a rising edge then the output Q keeps its value unchanged. Together with the output Q an
  • inverted Q value is output.
  • the D-type flip flops can be forced to a set or reset state, wherein the D and C inputs are ignored. If input S equals a logical "0" and input R equals a logical "1", then output Q becomes “0". If input S equals a logical "1" and input R equals a logical "0”, then output Q becomes "1". If input S equals a logical "1” and input R equals a logical "1”, then output Q becomes “1". If inputs S and R both equal a logical "0” then the inputs D and C are evaluated as described above .
  • the wiring scheme as shown in Fig.4 results in the D- type flip-flops outputting signals 106 and 107 representing the time difference between the signals 103 and 104.
  • Fig.5 shows an example of two input signals 103 and 104 to the comparator part of Fig.4 and the resulting outputs 106 and 107.
  • one of the output signals 106 and 107 represents the time difference by having a value of "1" in the time interval representing the time difference.
  • the other of the output signals 106 and 107 will have a value of "0".
  • the outputs 106 and 107 may be aligned and given a predefined output level by using a schematic as by example shown in Fig.6.
  • Fig.6 the relevant one of the outputs 106 and 107 from the comparator part is selected and converted to an output logic 108 of e.g. 0-3V.
  • the resulting digital signal 108 is selected and converted to an output logic 108 of e.g. 0-3V.
  • the time difference or delay directly depends on the angle at which the radio wave 101 arrived at the antenna
  • the digital signal 108 may be used to calculate the angle from the receiving antenna-array system la- lc to the transmitting node 2a-2f, which essentially gives the direction in which RFID node is located.
  • Fig.7 illustrates the effect of a time difference of arrival of a signal at antenna elements and how this may be used to calculate the angle of arrival.
  • a wave front 3 travelling in the direction indicated by the arrows hits an antenna element 12 at some moment in time.
  • two antenna elements 12 are shown as “i" and "j".
  • the distance between the antenna elements i and j is predefined and is depicted as di j .
  • the radio wave 3 arrives at antenna element j first and moments later the same wave 3 arrives at antenna element i.
  • the time difference Tj_ j between these events is measured.
  • the signal strength at each antenna element may be used to determine the direction from which the wave was received.
  • Fig.8 the signal strength of three antenna elements are shown, which are physically aligned as described in Fig.2a. The three peaks are related to the three antenna element.
  • the y-axis of the graph represents the energy level of the received signal (RSSI) at the specific antenna element, as measured at the antenna element.
  • the middle antenna in this example receives the most energy. Taking into account that all antennas are capable of receiving substantially the same amount of energy from the signal wave, it may be concluded that the source of the signal is placed in front of the middle antenna element, which gives a direction from which the wave was
  • the node that transmits the signal and thus radiates the energy will be in the direction where the measured energy level is at its maximum.
  • An estimation of the distance to the source of the signal can be derived from the energy value (RSSI).
  • the angle alone may not provide enough data for determining the position of the node.
  • the distance from the antenna-array system to the node may be needed as well.
  • the distance can be calculated using geometry mathematics. In such calculation the location of the antenna-array systems is supposed to be known. Because two antenna-array systems may be located such that they have substantially a same angle to a node, as is the case with node 2e and antenna-array systems la and lc in Fig.l, preferable at least three antenna-array systems la-lc are installed at the monitored area.
  • antenna-array system la-lc may be used to perform a location search.
  • RSSI received signal strength index
  • the distance between the RFID node and an antenna-array system may be used to calculate the distance between the RFID node and an antenna-array system.
  • the approximate position of the node may thus be determined.
  • the accuracy of the position depends on the value of RSSI in the used environment and will often be less than when using multiple antenna-array systems .
  • the calculation of the distance to the node and the position of the node may be performed by one or more of the antenna-array systems la-lc. Alternatively the output signals 108 may be transmitted to a server where the calculations are made .
  • the antenna-array system la-lc may be configured to sequentially switch on and off one or more antenna elements 12 in the antenna array 1 such to emulate a rotation of the radiation lobe.
  • the following algorithm may be used in order to control transmissions of the nodes 2a-3f and prevent collisions of their signals :
  • the antenna-array system la-lc transmits a request to a node 2a-2f having a specific identifier X asking to
  • the node having identifier X sends a beacon containing the identifier
  • the antenna-array system la-lc detects the location of the node and switches into transmitting node to start the whole procedure from step 1 for the next node.
  • the antenna-array system la- lc When using this algorithm, the antenna-array system la- lc typically keeps identifiers of all known nodes 2a-2f in a memory. In order to simplify collection of identifiers in the antenna-array system la-lc it is possible to use reserved
  • a decentralized wireless communication network comprising the antenna-array system la-lc and the nodes 2a-2f may be a long-range location aware network that may be used for e.g. people or pet seek and rescue.
  • People or pets wearing a RFID node may be located and tracked, wherein the identifier stored in the node and communicated to the antenna-array system identifies the person or pet.
  • the nodes and antenna-array systems may be configured to allow communication between nodes and between a node and an antenna-array system other than exchanging the identifier.
  • One or more nodes may be configured to receive information about the whereabouts of another node. Information may be exchanged that is presented visually, by sound and/or by vibrations on the node.
  • the DASH7 protocol may be used as a communication protocol.
  • the range of the system typically depends on the possible output power of the nodes and the sensitivity of the antenna elements.
  • the controlled area range can be up to a few kilometers.
  • One embodiment of the invention may be implemented as a program product for use with a computer system.
  • the program(s) of the program product define functions of the embodiments
  • Non-writable storage media e.g., read-only memory devices within a computer such as CD-ROM disks readable by a CD-ROM drive, ROM chips or any type of solid-state non-volatile
  • writable storage media e.g., floppy disks within a diskette drive or hard-disk drive or any type of solid- state random-access semiconductor memory or flash memory
  • alterable information is stored.
  • writable storage media e.g., floppy disks within a diskette drive or hard-disk drive or any type of solid- state random-access semiconductor memory or flash memory

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  • Engineering & Computer Science (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Variable-Direction Aerials And Aerial Arrays (AREA)

Abstract

La présente invention concerne un système de réseau d'antennes destiné à déterminer une position courante d'un nœud. Selon l'invention, au moins deux éléments d'antennes sont conçus pour recevoir un signal d'entrée du nœud. Les éléments d'antennes sont disposés dans un réseau d'antennes de sorte que le signal d'entrée arrive au niveau de deux éléments d'antennes voisins à des instants différents. La différence de temps est mesurée et peut être utilisée pour calculer un angle d'arrivée du signal.
PCT/EP2013/054647 2013-03-07 2013-03-07 Positionnement et localisation de nœuds dans un réseau WO2014135213A1 (fr)

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Application Number Priority Date Filing Date Title
PCT/EP2013/054647 WO2014135213A1 (fr) 2013-03-07 2013-03-07 Positionnement et localisation de nœuds dans un réseau

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Application Number Priority Date Filing Date Title
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CN113009412A (zh) * 2021-01-06 2021-06-22 武汉理工大学 基于rfid数字化路面的定位系统及方法

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