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
  • G01S1/00—Beacons or beacon systems transmitting signals having a characteristic or characteristics capable of being detected by non-directional receivers and defining directions, positions, or position lines fixed relatively to the beacon transmitters; Receivers co-operating therewith
  • G01S1/02—Beacons or beacon systems transmitting signals having a characteristic or characteristics capable of being detected by non-directional receivers and defining directions, positions, or position lines fixed relatively to the beacon transmitters; Receivers co-operating therewith using radio waves
  • G01S1/08—Systems for determining direction or position line
  • G01S1/20—Systems for determining direction or position line using a comparison of transit time of synchronised signals transmitted from non-directional antennas or antenna systems spaced apart, i.e. path-difference systems
• • 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
  • G01S5/0257—Hybrid positioning
  • G01S5/0263—Hybrid positioning by combining or switching between positions derived from two or more separate positioning systems
  • G01S5/0264—Hybrid positioning by combining or switching between positions derived from two or more separate positioning systems at least one of the systems being a non-radio wave positioning system
• • 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
  • G01S1/00—Beacons or beacon systems transmitting signals having a characteristic or characteristics capable of being detected by non-directional receivers and defining directions, positions, or position lines fixed relatively to the beacon transmitters; Receivers co-operating therewith
  • G01S1/02—Beacons or beacon systems transmitting signals having a characteristic or characteristics capable of being detected by non-directional receivers and defining directions, positions, or position lines fixed relatively to the beacon transmitters; Receivers co-operating therewith using radio waves
  • G01S1/68—Marker, boundary, call-sign, or like beacons transmitting signals not carrying directional information
• • 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
  • G01S1/00—Beacons or beacon systems transmitting signals having a characteristic or characteristics capable of being detected by non-directional receivers and defining directions, positions, or position lines fixed relatively to the beacon transmitters; Receivers co-operating therewith
  • G01S1/72—Beacons or beacon systems transmitting signals having a characteristic or characteristics capable of being detected by non-directional receivers and defining directions, positions, or position lines fixed relatively to the beacon transmitters; Receivers co-operating therewith using ultrasonic, sonic or infrasonic waves
  • G01S1/725—Marker, boundary, call-sign or like beacons transmitting signals not carrying directional information
• • 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
  • G01S1/00—Beacons or beacon systems transmitting signals having a characteristic or characteristics capable of being detected by non-directional receivers and defining directions, positions, or position lines fixed relatively to the beacon transmitters; Receivers co-operating therewith
  • G01S1/72—Beacons or beacon systems transmitting signals having a characteristic or characteristics capable of being detected by non-directional receivers and defining directions, positions, or position lines fixed relatively to the beacon transmitters; Receivers co-operating therewith using ultrasonic, sonic or infrasonic waves
  • G01S1/76—Systems for determining direction or position line
  • G01S1/80—Systems for determining direction or position line using a comparison of transit time of synchronised signals transmitted from non-directional transducers or transducer systems spaced apart, i.e. path-difference systems
• • 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
  • G01S11/00—Systems for determining distance or velocity not using reflection or reradiation
  • G01S11/02—Systems for determining distance or velocity not using reflection or reradiation using radio waves
  • G01S11/08—Systems for determining distance or velocity not using reflection or reradiation using radio waves using synchronised clocks
• • 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
  • G01S15/00—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems
  • G01S15/003—Bistatic sonar systems; Multistatic sonar systems
• • 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
  • G01S15/00—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems
  • G01S15/87—Combinations of sonar systems
  • G01S15/876—Combination of several spaced transmitters or receivers of known location for determining the position of a transponder or a reflector
  • G01S15/878—Combination of several spaced transmitters or receivers of known location for determining the position of a transponder or a reflector wherein transceivers are operated, either sequentially or simultaneously, both in bi-static and in mono-static mode, e.g. cross-echo mode

Definitions

• the present invention concerns a method for the localisation of objects within an environment to be monitored.
• the present invention further concerns a system which allows to implement the method.
• the invention concerns a method and a system of the above-mentioned type, designed and realised in particular for the short-range localisation, i.e. within some tens of metres, of collaborative (active) and non-collaborative (passive) objects, i.e. without communication means, both in internal and external localisation contexts, such as logistics, short-range navigation, security and monitoring, entertainment, goods tracking, personal tracking in risk areas, monitoring of sensible areas, safety at work, and that can be used for any other type of short-range localization.
• the today's short-range localisation networks are designed and configured to separately localise radio-transmitting devices, which are termed also collaborative or active or “tag” devices, and non-collaborative units as persons or things, therefore not provided with transmitting units, which are termed also passive or “targets", within an area to be monitored, giving rise therefore to the active localisation in the first case and the passive localisation in the second case.
• RTLS real-time locating systems
• These systems can be wired or wireless.
• the wired systems comprise a network of "anchor" nodes, i.e. a network of receiving and transmitting units, connected with each other by means of a series of wired connections, which are needed for the synchronisation of the same anchor nodes, and a central node for the processing and fusion of the information, which exchanges information with the anchor nodes .
• anchor nodes i.e. a network of receiving and transmitting units, connected with each other by means of a series of wired connections, which are needed for the synchronisation of the same anchor nodes, and a central node for the processing and fusion of the information, which exchanges information with the anchor nodes .
• These systems allow high precision position estimates of objects that are present in the environment to be monitored, because they are based on the time difference of arrival (TDoA) of the signals .
• TDoA time difference of arrival
• the wireless systems instead present the same infrastructure but are able to function without the need of synchronisation between the anchor nodes (for example the techniques utilised can be based on the estimate of the Time of Flight (ToF) or the Angle of Arrival (AoA) of the exchanged signals) .
• the techniques utilised can be based on the estimate of the Time of Flight (ToF) or the Angle of Arrival (AoA) of the exchanged signals) .
• ToF Time of Flight
• AoA Angle of Arrival
• RTLS ultrasounds systems for example "Active Bat” or “Cricket” which exploit similar radio synchronisation mechanisms for the active localisation, i.e. the mobile active devices, which are synchronised by radio, and emit ultrasounds impulses in order to be localised by a fixed nodes network which receives the ultrasounds signals emitted by the active devices.
• the radio signals are not utilised instead for the active localisation (of the nodes or mobile active devices) and the ultrasounds signals are not utilised for the passive localisation.
• a first disadvantage is represented by the separation of the active and passive localisations, the today's systems do not allow indeed to manage both localisations at the same time.
• a further disadvantage, for some systems, is represented by the need of connecting the anchor nodes by connection and synchronisation cables, which require the proximity of the same anchor nodes . It is evident that it is expensive to connect consecutive anchor nodes in the presence of physical obstacles in the environment to be monitored.
• Another object of the invention is to realise a system devoid of cable connections between anchor nodes of the localisation network.
• Another object of the invention is to speed up and reduce the exchange of data between the anchor nodes and the central processing node.
• a method for monitoring an environment utilizing a network comprising a plurality of anchor nodes synchronized with each other, each comprising a radio transceiver and an ultrasonic transceiver, characterised in that it comprises the execution of the following steps:
• step C on the basis of the responses of the environment in step B and said topology of step A:
• CI Obtaining at least an acoustic visibility map, including information about the area reachable by the ultrasonic waves emitted by each node of said plurality of anchor nodes;
• step El Combining the positions of step El with the positions of the objects in said at least an objects map, associating each of said radio transceiver devices to an object detected by ultrasonic waves and including such an association in said at least an objects map;
• step E2 said radio transceiver devices are associated to persons authorised to access said environment.
• step A the distances between said anchor nodes are estimated utilizing Ultra-Wideband radio signals.
• said plurality of anchor nodes comprises a master anchor node and a plurality of slave anchor nodes, the synchronisation operations preceding step A being performed by said master anchor node, the mutual distances of step A being the distances between said master node and said slave nodes.
• all the steps are executed using the subdivision of master anchor node and slave anchor nodes, in such a way that the master node organises the actions of and collects the information from the slave anchor nodes.
• each of said anchor nodes sends, on a rotating basis, to each other anchor node ultrasonic pulse-type signals, according to the principle of operation of the multi-static sonars.
• said master anchor node sends suitable periodic synchronisation radio signals termed "beacons", said beacons signals containing the behaviour mode of each node of the network, i.e. the time information of the synchronisation steps that the node must perform.
• each anchor node in step B, is configured to receive and sample both the response to pulses sent from itself, as a mono-static sonar, and the response to pulses sent from other nodes, as multi-static sonar, utilising predefined information of synchronisation.
• said objects map and/or said visibility map in step C is three-dimensional .
• step A the measurement of said distances by radio ranging is compared with the measurement of the same distances by ultrasounds according to the following steps:
• a ultrasonic transducer is associated, which is oriented with respect to a reference direction, and in that:
• the orientation information of each node is used, in particular provided by orientation sensors associated to said anchor nodes, which detect the acoustic emission direction with respect to said reference direction, as well as the temperature information provided by the temperature sensor associated to said nodes .
• a system for the monitoring of an environment comprising a network which includes a plurality of anchor nodes synchronised with each other, a control unit for the control of said anchor nodes and a central processing unit configured to process the data coming from said control unit and provide control information to said control unit, characterised in that said central processing unit comprises a series of processing modules installed on it and configured to obtain at least an objects map containing the position of static and/or dynamic objects in said monitored environment and at least a acoustic visibility map representing the acoustic visibility field of the nodes of said plurality of anchor nodes, according to steps A-F of the method of the invention.
• each anchor node an ultrasonic transducer is associated, oriented with respect to a reference direction, as well as a temperature sensor, and in that said series of processing modules comprises a processing module configured to use the orientation information of each node as provided by said orientation sensors and the temperature information provided by temperature sensors to execute step A.
• figure 1 shows the architecture of the system of the invention during a step of self-configuration and initial synchronisation of the units composing it;
• figure 2 shows the architecture of the system of figure 1 during a step of virtual reconstruction of the environment wherein it is placed;
• figure 3 shows the architecture of the previous system during a step of identification of passive objects, or targets, which have smaller dimensions and are moving, and are in the environment wherein it is placed;
• figure 4 shows the architecture of the previous system during a step of identification of active objects, or tags, which are in the environment wherein it is placed;
• figure 5 shows a functional block diagram of a processing unit of the system that is subject matter of the invention.
• the system S is placed within an environment to be monitored and possibly to be represented graphically, and comprises a wireless fixed or moving localisation network.
• a wireless fixed or moving localisation network can have different topologies, for example it can be star-shaped, or cluster-shaped, in order to manage multi-cell localisation systems.
• the network is composed by a plurality of master and slave anchor nodes, in particular a master anchor node 1, and a plurality of slave anchor nodes 2a, 2b, ... , 2n.
• the system S further comprises a central processing unit U which processes the information received by the master anchor node 1 by using a set of processing modules comprised by it, as it will be widely described in the following.
• An anchor node at a time transmits an acoustic impulse, whilst all the nodes "hear" the environment response.
• the data must be processed together by the central processor in order to execute imaging and localisation.
• Such data are therefore transmitted by each slave anchor node to the master anchor node, and from the latter to the central processing unit (by means of the channel C) .
• Such transmissions of data occur by radio, and they have been shown in the figure by unidirectional arrows, from the slave anchor nodes to the master anchor node.
• a plurality of passive targets N is present, as fixed or moving objects or persons without communication units, and a plurality of active tags A is also present, usually electronic devices, which should be localised and possibly represented graphically.
• the master anchor node 1 processes and reorganises the information acquired by the slave anchor nodes 2a, 2b, ... , 2n and by tags A present in the environment by means of known algorithms of imaging, trilateration and triangulation, filtering, tracking, identification and the like, as will it be described in detail in the following.
• the slave anchor nodes 2a, 2b, ... , 2n deal with acquiring information on the surrounding environment by means of heterogeneous technologies working in close synergy, as it will be described in the following.
• the electronic devices A exchange information with the slave anchor nodes 2a, 2b, ... , 2n in order to allow to be detected, identified and localised in the environment.
• Such electronic devices A are provided with a radio interface which is able to communicate and perform range estimate operations with the slave anchor nodes 2a, 2b, ... , 2n of the network.
• , 2n comprises in turn an internal processing unit, for example a microcontroller, not shown in figure, a radio communication interface R comprised of an antenna, which is used for the active localisation, the identification and the data exchange between nodes, and is also provided with a functionality of ranging, between the transmitting node and the receiving node, and an acoustic transceiver which receives and transmits ultrasonic signals of the impulsive type and is utilised for the passive localisation, the representation of the environment and the refining of the active localisation.
• a radio communication interface R comprised of an antenna, which is used for the active localisation, the identification and the data exchange between nodes, and is also provided with a functionality of ranging, between the transmitting node and the receiving node, and an acoustic transceiver which receives and transmits ultrasonic signals of the impulsive type and is utilised for the passive localisation, the representation of the environment and the refining of the active localisation.
• the radio interface R allows performing the information exchange without the necessity of using cable connections between the network nodes.
• the master anchor node 1 is further equipped with a communication interface C, for example USB, Ethernet or the like, to exchange information with the central processing unit U.
• a communication interface C for example USB, Ethernet or the like
• the information flow between the nodes is based on communication standards for wireless sensors network (WSN) , for example of the IEE 802.15.4 or IEEE 802.15.4a type.
• WSN wireless sensors network
• the master anchor node 1 and slave anchor node 2a, 2b, ... , 2n allow direct construction of the virtual image of the surrounding environment, individuating possible objects/persons which are in the environment, as it will be described in detail in the following.
• the system allows to map objects and persons of the real world with precise references to their current geographical position and, therefore, to place them within a virtual space representing the area to be monitored.
• system S employs integrated heterogeneous technologies .
• the radio communication interface R allows to synchronise the ultrasonic modules T of the master anchor nodes 1 and slave anchor nodes 2a, 2b, ... , 2n, enabling the functionality of monostatic/multistatic sonar even in the absence of direct acoustic visibility between the anchor nodes.
• the anchor nodes are in direct acoustic visibility with each other (i.e. if the ultrasounds can run without obstacles between the nodes) , they can synchronise with each other also a posteriori, i.e. being known the reciprocal positions between the anchor nodes and the instant of reception of the impulse emitted by one of the anchor nodes, it is possible to calculate the instant in which the impulse has been emitted by that anchor node.
• the radio communication interface R can emit a radio signal in order to synchronise the anchor nodes of the network even in the absence of mutual direct visibility.
• the master anchor nodes 1 and slave anchor nodes 2a, 2b, ... , 2n, of the network can be communicated by the master anchor nodes 1 and slave anchor nodes 2a, 2b, ... , 2n, of the network to the central processing unit U, such as the orientation of the nodes or the ambient temperature .
• the nodes are equipped with suitable sensors, such as inclinometer, electronic compass and temperature sensor, and can be utilised by the central processing unit U in order to improve the detection of network configuration and the estimate of the ambient parameters influencing the localisation process, such as for example the sound propagation speed.
• suitable sensors such as inclinometer, electronic compass and temperature sensor
• the central processing unit U comprises a set of processing modules.
• a first module 2 for the processing of the ultrasonic responses and the data of radio ranging or "raw data processing module” processes and conditions in real time the input data;
• a second module 3 of estimate of the network geometry or "inter-A ranging module” estimates the relative distances between all the anchor nodes of the network, on the basis of the received ultrasonic and radio ranging data;
• a third module 4 for the processing of the network geometry or "AN network geometry estimation module” calculates exactly the network geometry on the basis of the data received by the second module 3;
• a fourth module 5 for the management of the control signals to the network or "sensor Network Manager module” manages the functioning of the network in a dynamic and adaptive way;
• a fifth module 6 for the construction of a map or "quasi-static image formation module” constructs a three-dimensional map of the environment by means of imaging operations of the known type;
• a sixth module 7 for the detection of the targets N or “dynamic target localisation module” detects the position and the displacement of the targets N within the environment to be monitored
• the master node 1 and slave nodes 2a, 2b, .. , 2n of the system S are positioned according to a suitable topography, within the same environment.
• the system S must auto-configure, during a step of auto-configuration.
• the master anchor node 1 works as coordinator of the network because it sends signals, such as functioning and synchronisation parameters, to the slave anchor nodes 2a, 2b, ... 2n.
• the auto-configuration step consists of automatic procedures for the measurement of the reciprocal distances between the master node 1 and the slave nodes 2a, 2b, ... , 2n of the network.
• radio ranging In a first part of the first step, termed radio ranging, the measurement of the distances occurs by means of known radio ranging operations, according to which two nodes estimate the reciprocal distance by transmitting to each other data packets and by estimating their time of flight (ToF) , i.e. the time needed by the data packets in order to travel from one node of the network to the other.
• TOF time of flight
• the radio ranging step gives back a measurement Dr expressed in metres or centimetres.
• UWB ultra-wide band
• the system S executes a second ultrasonic estimate, or ultrasonic ranging, wherein a further estimate of the distances between the nodes is effected by acoustic measurements, in order to make more accurate the estimate of the reciprocal distances obtained in the previous radio ranging.
• each slave anchor node 2a, 2b, 2n of the network sends in rotation ultrasonic signals of the impulsive type which are received by the other slave anchor nodes 2a, 2b, ... , 2n of the network, according to the functioning principle of the known sonar multi- static systems.
• each nodes can estimate a ToF, i.e. the time elapsed between the emission of the signal and its reception.
• the ultrasonic ranging step gives back a measurement Ds in metres or centimetres.
• Dr is approximately equal to Ds, one assumes as valid measurement of the distance between the nodes the value Ds because it represents a more accurate measurement .
• Dr is smaller than Ds by a certain predefined quantity ⁇ , then one assumes as valid measurement of the distance between the nodes the value Dr because in this case one assumes that there is no acoustic visibility between the nodes.
• Dr is larger than Ds by a certain predefined quantity ⁇ , is not very significant because it happens when there is already an acoustic visibility between the nodes, therefore one presumes there is also radio visibility.
• All the data obtained in the radio ranging step and ultrasonic ranging step are transmitted to the master anchor node 1 and, thereby, to the data processing central server U and in particular to the first module 2, second module 3, and third module 4.
• the first module 2 processes in real time the ultrasonic responses and the data relevant to the radio rangings received by the master anchor node 1.
• these received data are suitably- filtered and averaged in order to reduce the effects of the random disturbances.
• the impulsive multistatic and monostatic responses coming from the ultrasonic transducers T are elaborated by eliminating possible disturbances of self-coupling that are in the signal.
• residual time deviations between the signals are eliminated by applying known techniques for the estimate of the time of arrival ToA.
• the second module 3 starting from the data of the first module 2, estimates the relevant distances between all the master anchor node 1 and slave anchor nodes 2a, 2b, ... , 2n.
• the third module 4 on the basis of relative distance information provided by the second module 3, elaborates the overall geometry of the network .
• This third module 4 moreover, during the construction of the geometry of the network, takes into account the additional information relevant to the inclination or orientation of the nodes. Such information can be provided automatically by the sensors network or inserted manually by the technician or user of the system S.
• the coordination performed by the master anchor node 1 by the radio transmission of suitable synchronisation or periodic beacon signals is important .
• each slave anchor node 2a, 2b, ... , 2n consequent to the reception of a periodic beacon, synchronises its own time reference or clock with that of all the others.
• the behaviour mode of each network node is contained, i.e. when each node must transmit a ultrasonic signal and when instead it must receive signals from other nodes, when it must re-tune and when it must transmit by radio the collected information and the samples, allowing the multistatic functioning of the network by means of exchanges without any cable.
• the system S executes a step B of three-dimensional reconstruction of the environment wherein the system S is positioned, i.e. a 3D imaging, in order to detect the position of stationary objects 0 that are in the environment.
• the second step consists of an environment inspection procedure or sounding and an environment image reconstruction procedure.
• each slave anchor node 2a, 2b, ... 2n sends acoustic signals of the impulsive type.
• Each network node samples the received response and transmits it by radio to the master anchor node 1 which, in turn, forwards it to the central processing unit U and in particular to the module 6.
• each slave anchor node 2a, 2b, ... , 2n is able to receive and sample both the response to impulses sent by itself, as monostatic sonar, and the response to impulses sent by other nodes, as multistatic sonar (each node listens to the signals emitted by each node) .
• a map is constructed, termed "iMap", of the monitored area, which represents the geography of the environment wherein the position of obstacles or static objects 0 or moving objects N is represented, and a map, termed VMap is constructed, which keeps track of the visibility of the points in space in relation to the anchor nodes and represents the acoustic visibility field of the anchor nodes 1, 2a, 2b, ... , 2n, wherein the environment acoustic response to ultrasound emitted by each anchor node 1, 2a, 2b, ... , 2n is utilized.
• the fifth module 6 combines the ultrasonic signals received by the various anchor nodes by means of known techniques derived from the decision and estimate theory, from the information theory and from machine learning algorithms .
• the environment to be monitored is discretised into a set of points, uniformly distributed or not, for each of them being evaluated the probability that an object is present, which reflects the impinging signal, and the probability that the condition of visibility with the different anchor nodes of the network is verified.
• information about the visibility from the same point to the different anchor nodes of the network is needed.
• the utilised techniques are the estimate iterative techniques and the statistical inference techniques for the determination of such 3D maps, such as known algorithms of message passing between space points or of expectation-maximisation.
• step B proceeds with the detection and localisation of the non- collaborative targets N, during step C of non- collaborative identification.
• step B also the identification and the localisation of the moving target objects N occurs, therefore the acquisition and the transmission of the information from the slave anchor nodes 2a, 2b, ... , 2n to the master node 1 and to the central processing unit U occurs in a way analogous to the foregoing, it is then the task of the central processing unit U to process information with different modes, depending on whether one wishes to localise static or dynamic objects.
• the sixth module 7 for the detection of the targets N operates on the basis of the ultrasonic responses received by the anchor nodes .
• the utilised techniques are known and belong to the field of decision and estimate theory which allow to combine in an optimal way the received ultrasonic signals, constructing, for the various points of the discretised space, optimal or sub-optimal detection metrics.
• traditional algorithms in the field of sonar/radar detection can be used, which are based on the estimate of ToA of the reflected signals and on trilateration techniques. In both cases, it is of fundamental importance the knowledge of the visibility map, VMap, provided by the fifth module 6, which allows to identify the information coming from those anchor nodes that are effectively useful for the localisation and to discard the useless signals.
• this step of continuous updating of the maps iMap and VMap begins .
• the updating step provides the following sub-steps:
• a second sub-step wherein one has the emission of ultrasounds from a subset of anchor nodes 1, 2a, 2b, ... , 2n which are in visibility, according to the map VMap of visibility with the object selected in the first sub-step;
• a collaborative object tag A i.e. a device provided with means of communication with the anchor nodes 1, 2a, 2b, ... , 2n, contained in the objects map iMap;
• each tag A coming in radio visibility of the network synchronises with the beacon signal emitted by the master anchor node 1 and sends a join request to the network, which the master anchor node 1 receives and processes. If the tag A is recognised and accepted, the master anchor node 1 and the central processing unit U know the presence and the identity of the tag A in the monitored environment . Once the tag A is recognised, the second sub-step is initiated in order to localise the tag A within the environment .
• the master anchor node 1 starts periodically the procedure of radio ranging between the tag A and the slave anchor nodes 2a, 2b, 2n of the network.
• the tag A When authorised by the master anchor node 1, the tag A exchanges information of radio ranging with the subset of slave anchor nodes 2a, 2b, ... , 2n indicated by the master anchor node 1.
• the reciprocal distances between the tag A and the slave anchor nodes 2a, 2b, ... , 2n are calculated on the basis of the estimate of the ToF of the exchanged packets and are then communicated from the tag A to the master anchor node 1, which forward them to the central processing unit U, in particular to the eighth module 8 which processes the information of radio ranging.
• the eighth module 8 is able to localise the tag A by means of known operations of triangulation/trilateration.
• step S uses the support of the fourth module 5 to manage the anchor nodes network in a dynamic and adaptive way.
• the fifth module 5 coordinates the frequencies with which the tags A are to be interrogated and specifies the list of the anchor nodes that have to be involved in the identification and localisation of the different tags A which are present. In such a way, one can select in a dynamic way the optimal subset of anchor nodes which the tag A has to interrogate in order to make itself localise by the system S.
• the fourth module 5 can request that only some anchor nodes of the network transmit ultrasonic signals for the localisation of targets N and tags A.
• the transmissions of the radio and ultrasonic signals in the proximity of the detected targets N and/or tags A can be intensified, avoiding to waste resources in the zones wherein no activity has been detected.
• this system S executes a step of integration of radio and ultrasonic data, by means of the eighth module 9, wherein the collaborative tags A are associated to moving persons detected by means of ultrasounds, thus identifying the persons authorised to transit in the monitored zone.
• the input data from the seventh module 8, relevant to the tags A are associated to the input data of the sixth module 7, relevant to moving persons or targets N, detected by ultrasounds, thus identifying the persons authorised to stay in the monitored zone.
• the information on the position of the various targets N detected by means of ultrasounds signals is combined with the positions estimated for the tags A by means of known techniques of data association, mainly based on the proximity.
• the information about the objects moving in the monitored environment are merged by means of known algorithms of clustering, which are able to distinguish and separate the single targets N.
• This integration allows to differentiate between authorised and unauthorized targets N.
• the module 9 is able to provide information about the presence and position of collaborative and non-collaborative targets N within the area.
• the last described step comprises a step of optimisation of the localisation realised by the ninth module 10.
• the information provided by the eighth module 9 are processed by means of tracking algorithms exploiting knowledge of the trajectories followed by the various targets N.
• the output of these ninth module 10 is constituted by the information about the identity and the position of the various tags A and targets N within the environment .
• Such information are provided to the fourth module 5 to the end of coordinating the future detections, and to the tenth module 11 of visualisation.
• Said tenth module 11 allows the visualisation of the position and identity of the tags A and targets N present in the environment. It allows moreover to visualise the three-dimensional map of the surrounding environment, the iMap.
• This module can also be interrogated remotely, for example by means of a web server to allow the access from Internet.
• the subject system S allows to realise, with an only integrated network, functionalities of active and passive localisation and imaging of the environmental be monitored.
• Another advantage is represented by the possibility of synchronising the nodes of the network without the use of cables.
• Another advantage is represented by the simplicity of installation of the network by means of auto- configuration procedures .

Landscapes

• Engineering & Computer Science (AREA)
• Radar, Positioning & Navigation (AREA)
• Remote Sensing (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Computer Networks & Wireless Communication (AREA)
• Alarm Systems (AREA)
• Measurement Of Velocity Or Position Using Acoustic Or Ultrasonic Waves (AREA)
• Mobile Radio Communication Systems (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=50116066

Family Applications (1)

Country Status (2)

Cited By (11)

Citations (3)

• 2013
  • 2013-12-20 IT IT000702A patent/ITRM20130702A1/it unknown
• 2014
  • 2014-12-18 WO PCT/IT2014/000339 patent/WO2015092825A1/en active Application Filing

Patent Citations (3)

Also Published As

Similar Documents

Legal Events