Method and a system for determining the location of an object

Abstract

A method for determining the location of a transmitter (respectively a receiver) in a space defined by one or more reflective surfaces, including the steps of sending a signal from the transmitter (respectively from a set of transmitters); receiving by a set of receivers (respectively by a receiver) the transmitted signal and echoes of the transmitted signal reflected by the reflective surfaces; finding by a first computing module the location of the virtual sources (respectively virtual receivers) of the echoes; mirroring by a second computing module the virtual sources (respectively virtual receivers) into the space and obtained mirrored virtual sources (respectively mirrored virtual receivers); combining by a third computing module the mirrored virtual sources (respectively mirrored virtual receivers) so as to obtain location of the transmitter (respectively the receiver). This method makes use of echoes for localizing the source (respectively receiver) when there is no line of sight between the transmitter(s) and the receiver(s).

1 . A method for determining the location of a transmitter in a space defined by one or more reflective surfaces, comprising the steps of
 sending a signal from said transmitter;   receiving by a set of receivers the transmitted signal and echoes of the transmitted signal reflected by said reflective surfaces;   finding by a first computing module the location of the virtual sources of said echoes;   mirroring by a second computing module the virtual sources into the space and obtaining mirrored virtual sources;   combining by a third computing module the locations of said mirrored virtual sources so as to obtain the location of the transmitter.   
     
     
         2 . The method of  claim 1 , the location of the set of receivers and the location and/or orientation of the reflective surfaces being known. 
     
     
         3 . The method of  claim 1 , the step of mirroring comprising applying the method of images in reverse order. 
     
     
         4 . The method of  claim 1 , the step of mirroring comprising:
 drawing the lines connecting a virtual source to the set of receivers,   finding the reflective surface which intersects said lines,   reflecting the virtual source across said reflective surface and generating a reflected virtual source,   storing the points of intersections on the reflective surface,   checking if the reflected virtual source is inside the space defined by the reflective surfaces,   repeating the previous steps if the reflected virtual source is not inside the space defined by the reflective surfaces.   
     
     
         5 . The method of  claim 1 , comprising, if the reflected virtual source is not inside the space defined by the reflective surfaces,
 drawing the lines connecting the stored points of intersections and the reflected virtual source,   finding the new reflective surface which intersects said lines,   reflecting the reflected virtual source across said reflective surface and generating a new reflected virtual source,   storing the points of intersections on the new reflective surface,   checking if the new reflected virtual source is inside the space defined by the reflective surfaces,   repeating the previous steps if the new reflected virtual source is not inside the space defined by the reflective surfaces.   
     
     
         6 . The method of  claim 1 , comprising echoes' sorting. 
     
     
         7 . The method of  claim 6 , said echo sorting comprising grouping the echoes corresponding to a single virtual source. 
     
     
         8 . The method of  claim 7 , wherein grouping the echoes corresponding to a single virtual source comprising checking if 
       
         
           
             
               
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       is less than a threshold, wherein M is the number of receivers, ŝ is the virtual source, m i  is a receiver and r i  the distance between the transmitter and the m i  receiver. 
     
     
         9 . The method of  claim 1 , comprising the optimization of the location of the transmitter. 
     
     
         10 . The method of  claim 9 , said optimization comprising a gradient descent method. 
     
     
         11 . The method of  claim 10 , comprising the tracking of the transmitter by using said optimization method, e.g. by using the gradient descent method. 
     
     
         12 . The method of  claim 1 , the reflective surfaces defining a non-convex space. 
     
     
         13 . The method of  claim 1 , the transmitter being a mobile device, the receivers being satellites. 
     
     
         14 . A system for determining the location of a transmitter, comprising:
 one or more reflective surfaces   one transmitter for sending a signal;   a set of receivers for receiving the transmitted signal and echoes of the transmitted signal reflected by said reflective surfaces;   a first computing module for finding the location of the virtual sources of said echoes;   a second computing module for mirroring the virtual sources into the room and obtained mirrored virtual sources;   a third computing module for combining the locations of said mirrored virtual sources so as to find the location of the transmitter.   
     
     
         15 . The system of  claim 14 , the first computing module, the second computing module and the third computing module being the same module. 
     
     
         16 . The system of  claim 14 , the reflective surfaces defining a non-convex space. 
     
     
         17 . The system of  claim 14 , the transmitter being a mobile device, the receivers being satellites. 
     
     
         18 . The system of  claim 14 , the signal being a UWB signal, the transmitter being a UWB transmitter, and the receivers being an array of UWB receivers. 
     
     
         19 . A computer program product, comprising:
 a tangible computer usable medium including computer usable program code for determining the location of a transmitter sending a signal received by a set of receivers, the set of receivers receiving also echoes of the transmitted signal reflected by one or more reflective surfaces, the computer usable program code being used for
 finding by a first computing module the location of the virtual sources of said echoes; 
 mirroring by a second computing module the virtual sources into the space and obtained mirrored virtual sources; 
 combining by a third computing module the locations of said mirrored virtual sources so as to obtain the location of the transmitter. 
   
     
     
         20 . A method for determining the location of a receiver in a space defined by one or more reflective surfaces, comprising the steps of
 sending a signal from a set of transmitters;   receiving by said receiver the transmitted signal and echoes of the transmitted signal reflected by said reflective surfaces;   finding by a first computing module the location of the virtual receivers of said echoes;   mirroring by a second computing module the virtual receivers into the space and obtained mirrored virtual receivers;   combining by a third computing module the locations of said mirrored virtual receivers so as to obtain the location of the receiver.   
     
     
         21 . The method of  claim 20 , the location of the set of transmitters and the location and/or orientation of the reflective surfaces being known. 
     
     
         22 . The method of  claim 20 , the step of mirroring comprising applying the method of images in reverse order. 
     
     
         23 . The method of  claim 20 , the step of mirroring comprising:
 drawing the lines connecting a virtual receiver to the set of transmitters,   finding the reflective surface which intersects said lines,   reflecting the virtual receiver across said reflective surface and generating a reflected virtual receiver,   storing the points of intersections on the reflective surface,   checking if the reflected virtual receiver is inside the space defined by the reflective surfaces,   repeating the previous steps if the reflected virtual receiver is not inside the space defined by the reflective surfaces.   
     
     
         24 . The method of  claim 20 , comprising, if the reflected virtual receiver is not inside the space defined by the reflective surfaces,
 drawings the lines connecting the stored points of intersections and the reflected virtual receiver,   finding the new reflective surface which intersects said lines,   reflecting the reflected virtual receiver across said reflective surface and generating a new reflected virtual receiver,   storing the points of intersections on the new reflective surface,   checking if the new reflected virtual receiver is inside the space defined by the reflective surfaces,   repeating the previous steps if the new reflected virtual receiver is not inside the space defined by the reflective surfaces.   
     
     
         25 . The method of  claim 20 , the mirroring comprising echoes' sorting. 
     
     
         26 . The method of  claim 20 , comprising the optimization of the position estimate. 
     
     
         27 . The method of  claim 26 , said optimization of the position estimate comprising a gradient descent method. 
     
     
         28 . The method of  claim 27 , comprising the tracking of the receiver by using the optimization method, e.g. the gradient descent method. 
     
     
         29 . The method of  claim 20 , the reflective surfaces defining a non-convex space. 
     
     
         30 . A system for determining the location of a receiver, comprising:
 one or more reflective surfaces   a set of transmitters for sending a signal;   said receiver for receiving the transmitted signal and echoes of the transmitted signal reflected by said reflective surfaces;   a first computing module for finding the location of the virtual receivers of said echoes;   a second computing module for mirroring the virtual receivers into the room and obtained mirrored virtual receivers;   a third computing module for combining the locations of said mirrored virtual receivers so as to find the location of the receiver.   
     
     
         31 . The system of  claim 30 , the first computing module, the second computing module and the third computing module being the same module. 
     
     
         32 . The system of  claim 30 , the reflective surfaces defining a non-convex space. 
     
     
         33 . The system of  claim 30 , the receiver being a mobile device, the transmitters being satellites. 
     
     
         34 . The system of  claim 30 , the signal being a UWB signal, the transmitters being an array of UWB transmitters and the receiver being a UWB receiver. 
     
     
         35 . A computer program product, comprising:
 a tangible computer usable medium including computer usable program code for determining the location of a receiver receiving a signal transmitted by a set of transmitters, the receiver receiving also echoes of the transmitted signal reflected by one or more reflective surfaces, the computer usable program code being used for
 finding by a first computing module the location of the virtual receivers of said echoes; 
 mirroring by a second computing module the virtual receivers into the space and obtained mirrored virtual receivers; 
 combining by a third computing module the locations of said mirrored virtual receivers so as to obtain the location of the receiver.