Abstract:
A method for reconstructing the map of an environment ( 20 ) surrounding a wireless device ( 100 ), the environment ( 20 ) being equipped with one or more radio frequency tags (1) set in a number dependent on the level of detail to be obtained in the reconstruction, the method including the steps of: receiving identification and localization data of the one or more radio frequency tags (1) over a wireless connection by at least one wireless receiver ( 3 ) of the wireless device ( 100 ); storing the identification and localization data of the one or more radio frequency tags (1) into a filing and/or storage component ( 5,6 ) by a processor ( 2 ) of the wireless device ( 100 ); and providing on an output component ( 7 ) of the wireless device ( 100 ) at least one map of the environment ( 20 ) built on the basis of the identification and localization data of the radio frequency tags (1).

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a method for reconstructing a map of an environment surrounding a wireless device, so as to allow a user of the device to locate his/her own position within said environment. 
     The present invention also relates to a wireless device implementing such a method. 
     2. Present State of the Art 
     Various systems are known in the art which are finalized to localize a device, and hence its user, within a certain environment (e.g. public buildings, shopping centres, museums, town halls, hospitals). 
     More in particular, such systems are based mainly on information deriving from communication between a radio frequency reader, built in the device, and a plurality of radio frequency identifiers (i.e. RFID tags), arranged within the environment according to a predetermined layout. 
     Such tags include information about their own position, which information is transmitted to a local server. 
     In order to be able to operate, therefore, these systems require the device to be connected to a network (whether a local area network or a wide area network) and to know the URL address of the server to which the information about the positions of the radio frequency tags are sent. 
     As an alternative, for example, it is known from Japanese patent application no. JP 2007-235496 to download data of a map of an environment from a server to a memory of the device, although this clearly implies problems related to periodic updating and to the necessity for the device to be in a known environment, since its use in unknown environments is not conceivable. 
     Furthermore, the methods currently available cannot provide the user with visual indications about the type of the elements (exits, corridors, rooms) present in the surrounding environment, which indications are often necessary for reaching a given destination; to this end, one must still use paper maps or indications available on the premises. 
     SUMMARY OF THE INVENTION 
     It is therefore one object of the present invention to provide a method for reconstructing the map of an environment surrounding a wireless device which can provide a sufficiently accurate graphic representation of the environment where the device is located. 
     It is another object of the present invention to provide a method for reconstructing the map of an environment surrounding a wireless device which can be used without having previously obtained information about the environment itself. 
     It is a further object of the present invention to provide a method for reconstructing the map of an environment surrounding a wireless device which is less costly than prior-art methods. 
     These and other objects of the invention are obtained through a method for reconstructing the map of an environment surrounding a wireless device and through a wireless device implementing such method as set out in the appended claims, which are an integral part of the present description. 
     In brief, for each radio frequency tag or point to be represented on the map, all or some of the following pieces of information are made available
         absolute and geographical coordinates of the place in terms of latitude, longitude and elevation; or   coordinates (e.g. Cartesian, polar, etc.) of a known point, e.g. expressed either in absolute terms or in relative terms as distances from a given point with respect to the three dimensions;   relative geographical information, such as building number, floor, sector, staircase and the like;   information about a certain object or environmental element (door, window, wall, staircase, column and the like).       

     Based on such information, it is possible to obtain an approximate map of the place where the device is located, as well as the position thereof within that area, so as to offer the user of the device a good margin of orientation on the premises without having to make use of paper maps or other information sources. 
     Further features of the invention are set out in the appended claims, which are intended to be an integral part of the present description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above objects will become more apparent from the following detailed description of a method for reconstructing the map of a surrounding environment and of a wireless device implementing such method, with particular reference to the annexed drawings, wherein: 
         FIG. 1  is a block diagram showing the operation of a preferred embodiment of the device according to the invention; 
         FIG. 2  shows the structure of a possible reference environment; 
         FIG. 3  shows a possible arrangement of radio frequency tags in the reference environment of  FIG. 2 ; 
         FIG. 4  shows some values of a table of identification and localization data relating to the radio frequency tags of  FIG. 3 ; 
         FIG. 5  shows the current position of a wireless device according to the invention in the reference environment of  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As aforementioned, the object of the present invention is a method which, by using information about the radio frequency tags 1, in particular RFID tags, can provide an approximate map of the premises where a device  100  according to the present invention is located. 
     In  FIG. 1  one can see that said device  100 , in order to be able to operate, comprises:
         at least one wireless reception means  3  for receiving data;   at least one processing means  2 , e.g. consisting of at least one CPU;   at least one filing means  5  and/or one storage means  6 ;   optionally, at least one reader  4  of radio frequency tags 1, for detecting and subsequently reading one or more radio frequency tags 1 arranged within a reference environment in accordance with a predefined layout;   at least one output means, e.g. consisting of at least one display  7 , for displaying the results, preferably as at least one map of said environment.       

     It is also conceivable that the output means, instead of consisting of said display  7 , consists of one or more different audio playback devices  8  or tactile-stimulus generators  9 , which would make the map recognizable also to blind people. 
     The processing means  2  receives, through the wireless reception means  3 , identification and localization information about the radio frequency tags 1 via radio signals  16 , and stores it into the storage means  6  and/or the filing means  5 . Upon receiving a command from the processing means  2 , the reader  4  of radio frequency tags 1 may optionally detect the presence of any radio frequency tags 1 within its own coverage range through radio signals  16  received by said reader  4  in a manner substantially known in the art. 
     Then the processing means  2  updates the storage means  6  that contains the data for localization of the radio frequency tags 1, and subsequently it processes the localization data of the radio frequency tags 1 in the storage means  6  and outputs an updated map through the output means, e.g. by displaying it on the display  7  (or equivalent), possibly also indicating the current position. 
     The above-described operating cycle is carried out repeatedly, so as to allow for constant updating of the map being displayed as the user of the wireless device  100  is moving. 
     The data received through the wireless reception means  3  can be stored, for example, in the form of a table like the one shown in  FIG. 4 , wherein the number of rows and fields corresponds to the number of described radio frequency tags 1, the columns showing all or some of the following pieces of information:
         univocal identifier of the radio frequency tag 1;   coordinates of the position of the device (latitude, longitude), or its three-dimensional position relative to a given geographical point;   floor number;   type of radio frequency tag 1 (perimeter, door, window, room, corridor);   area identifier.       

     It should not however be excluded that other rather different elements of interest present in the environment may also be included as references, such as: lifts, ramps, fire extinguishers, power outlets, trap doors, radiators, boilers, air intakes, and the like. For example, the display  7  may show symbols indicating the single radio frequency tags 1, in particular:
         different types of radio frequency tags 1 are characterized by different symbols;   in some cases, the information may be arranged in a particular order, so as to provide a sorted sequence of steps (e.g. radio frequency tags 1 for a corridor may be identified in a predetermined order that allows reconstructing a sequence of linear steps; likewise, radio frequency tags 1 of a perimeter of a certain area may be represented by means of a continuous line going through them in an orderly manner);   radio frequency identifiers 1 belonging to the same logic geographical unit or to a more complex environmental structure made up of multiple elements (e.g. doors and windows afferent to the same room, or rooms belonging to the same department or office) are characterized by a common identification datum which allows to group them and to represent them within the area involved;   the actual distances, which can be deduced from the coordinate indication, are represented on the basis of a given scale such that they appear as realistic as possible, which scale may be resized by means of a specific command available on the device (e.g. buttons  10  or on-screen commands  7 ).       

     The devices capable of efficiently implementing the method described herein may be of different types, such as:
         mobile devices (e.g. smartphones), comprising a display  7  (possibly, but not necessarily, a touch screen  9 ), a reader  4  of radio frequency tags 1 and/or an optical sensor  11 , a wireless reception means  3 , a processor  2 , a storage means  6  and/or a filing means  5 , as well as possible further components such as buttons  10  or audio playback devices  8 ;   devices for blind users, comprising button or voice commands  10 , an audible-signal generator  8  or a tactile-stimulus generator  9 , a reader  4  of radio frequency tags and/or an optical sensor  11 , a wireless reception means  3  equipped with a processor  2 , a storage means  6  and a filing means  5 .       

     Any different configurations of said device  100  observing the same principle of operation as the above-described preferred embodiments will still fall within the protection scope of the present invention. 
     The information about the radio frequency tags 1 may be transmitted by suitable apparatuses  14  through any radio protocol, and is such that it can be received and interpreted by the wireless device  100  through the radio signals  18 . Preferably, the information can be transmitted through a Wi-Fi network protocol, i.e. according to any standard of the IEEE 802.11 set. In particular, it is advantageous to transmit said information in the part transmitted in clear by any Wi-Fi access point, e.g. in the Wi-Fi beacon, so that any wireless device adapted to receive Wi-Fi signals can interpret it without any limitation due to the information security provided by these standards. It will thus be possible to use existing Wi-Fi networks already in use in public buildings to transmit orientation information without interfering with secure information used by authorized users having access to said networks. 
       FIG. 2  shows one possible reference environment  20  consisting of a floor of a building, comprising perimeter walls, partition walls, windows, doors and rooms. 
       FIG. 3  shows one possible arrangement of radio frequency tags 1 in the environment  20  shown in  FIG. 2 . In particular, by way of example, there are radio frequency tags 1 on doors, windows, corners of perimeter walls, and ceilings of rooms and corridors. This creates a grid of points in the environment, which allows a wireless device  100  located in the reference environment  20  to acquire information about the most significant elements present therein (rooms, corridors, passageways, escapes etc.) and to reconstruct a representation of a map of the environment that will help the user orientate him/herself. 
       FIG. 4  shows one possible table built by the processing means  2  based on the identification and localization data stored in the storage means  5  and/or contained in the filing means  6 . Each row corresponds to at least one radio frequency tag 1 and comprises a univocal identifier (Tag ID), data about its geographical position (Latitude, Longitude and Elevation), information about the type of element of the reference environment  20  associated with the radio frequency tag 1 (e.g. Perimeter, Door, Room, Window), about the identification of said element (Room ID, Corridor ID, Perimeter ID) and about the position thereof within the environment  20  (e.g. Floor, Wing, Department, Section). 
       FIG. 5  shows one possible graphic representation of the environment map that can be obtained by the wireless device  100  by starting from the data contained in the table of  FIG. 4 ; in this representation, the radio frequency tags 1 mentioned in said table have been highlighted by way of example. It roughly indicates the profile defined by the perimeter walls, the position of windows and doors, as well as the area, approximated by defect, taken up by the rooms  52 ,  53 ,  54 ,  55 ,  56 ,  57 ,  58 , wherein the associated radio frequency tags 1 (of door, window and ceiling) are characterized by the same room identifier (Room ID in  FIG. 4 ). 
     For example, the area  54  of  FIG. 5  is approximately defined by the region that includes all those radio frequency tags 1 whose Room ID is 5. 
     The corridor radio frequency tags 1 in  FIG. 5  indicate the area occupied by the corridor and may advantageously be associated with a sorted sequence, so as to indicate to the wireless device  100  a path to be followed in order to reach an escape or an emergency exit. Likewise, a sorted sequence may be associated with other types of radio frequency tags, e.g. the perimeter ones, to indicate to the wireless device  100  how to trace the profile of the perimeter walls for the purpose of obtaining a correct graphic representation, which can be done by drawing a line consecutively joining the various points (e.g. the points of a corridor that winds across the building, or of the perimetric profile of the building). 
     In order to avoid adding a field specifically dedicated to said sorted sequence, the latter may be implicitly indicated through a suitable selection or structure of the radio frequency tag (Tag ID), which may take appropriately increasing or decreasing numerical values to indicate that order. 
     If the wireless device  100  is equipped with a reader  4  of radio frequency tags, it receives radio signals  16  emitted by radio frequency tags sufficiently close to one another, which signals contain data about its geographical position and about the radio signal transmission power or other data useful for determining the distance travelled by them to reach a receiver. When radio signals  16  are received from at least three different radio frequency tags 1, the device  100  can establish its own position based on the knowledge of the position of the emitting radio frequency tags and of its own distance from such tags, which can be determined through the use of any known distance estimation technique by applying, according to the case, the known triangulation or multilateration system. 
     In the example of  FIG. 5  it is assumed that the wireless device  100  is located in the point  500  and is receiving radio signals  16  from the three radio frequency tags 1A, 1B e 1C. In this case, the device  100  can estimate its own position by starting from the knowledge of the positions of 1A, 1B and 1C, received through the radio signals emitted by them, and by estimating the distance from each of them based on said radio signals by using any known technique and by applying the triangulation system to the data thus obtained. In this way, the wireless device  100  can calculate its own position through the processing means  2  and can represent it in one way or another through an output means  7 , e.g. graphically on a map screen as a suitable graphic symbol or through an audible message emitted by an audio player under the control of a voice synthesizer, which for example says to the user “You are in room 4 on the first floor”. When the map of the environment is reconstructed as a graphic representation, the actual distances (deduced from the analysis of the coordinates of the radio frequency tags 1) will be reduced according to a scale which is adequate for representing them on the display of the device (possibly resizable through a suitable command entered through a touch screen  7  or buttons  10 ). 
     The map thus built will then be filled with the points indicating doors, windows, corridors, rooms, etc. Points sharing the same area identifier (room, corridor, perimeter) may be highlighted with a special stroke or colour, thus grouping them into one set. 
     Aiming at limiting the number of applied radio frequency tags 1, and at reducing the quantity of information transmitted to the device  100  through the Wi-Fi beacon, the radio frequency tags 1 relating to any internal partition walls in the environment will not be indicated: the resulting representation of the environment will have a certain degree of approximation, which will however be such as to ensure the perception of one&#39;s position with respect to the surrounding environment. 
     If the device  100  is equipped with a compass, it will also be possible to indicate the directional orientation on the map. 
     The choice pertaining to the arrangement of the radio frequency tags 1 within the environment can be made in such a way as to ensure an even coverage of the environmental areas which are considered to be of interest: said positions are then recorded and archived to be easily made available to the device  100 . 
     It is also conceivable that the device  100  has an internal logic which can give the user (whether graphically on the display  7  or by means of audible and/or tactile signals produced by suitable audible  8  or tactile  9  signal generators) information about the environment  20  where he/she currently is, such as the type and the position of elements belonging to said environment  20  and the direction to be followed in order to reach a certain destination, which can be selected, for example, through a touch screen  7 , a voice command system or buttons  10 . 
     The advantage offered by the solution described herein is therefore apparent, in that this solution, in addition to what was already available from the prior art, adds the possibility of reconstructing, for example as a graphic representation, the approximate map of the environment  20  where a person is, the particular points of interest of which are highlighted in order to make it easier for the user to orientate him/herself in an unknown or unfamiliar place; furthermore, the radio frequency tags 1 employed may be passive ones, i.e. commercially available at low cost, and there may be a large number of them arranged in the environment as necessary. 
     Another clear advantage derives from the fact that the map can be reconstructed by using a very small quantity of information (approx. ten bytes per radio frequency tag 1). 
     Within the frame of a different implementation of the invention, it is also conceivable to replace or supplement the radio frequency tags 1 with simple QR codes or bidimensional bar codes  15 , which can be easily read through the camera built in a common smartphone device: just like the radio frequency tags 1, said code can provide a simple univocal identifier. 
     Finally, for simpler devices lacking a radio frequency tag reader  4  or a camera, it is possible to conceive a variant of the present invention which allows the user to manually enter the QR code  15 , which he/she may have learnt from a signalling available in the reference environment. 
     The method for reconstructing the map of an environment surrounding a wireless device and the wireless device implementing such method described herein by way of example may be subject to many possible variations without departing from the novelty spirit of the inventive idea; it is also clear that in the practical implementation of the invention the illustrated details may have different shapes or be replaced with other technically equivalent elements. 
     It can therefore be easily understood that the present invention is not limited to a method for reconstructing the map of an environment surrounding a wireless device and a wireless device implementing such method, but may be subject to many modifications, improvements or replacements of equivalent parts and elements without departing from the novelty spirit of the inventive idea, as clearly specified in the following claims.