Systems and methods of accuracy mapping in a location tracking system

Abstract

Systems and method of accuracy mapping in a location tracking system are provided. Methods include identifying a position of at least one location anchor on a site rendering, determining, for a plurality of positions on the site rendering, an estimated error value of location accuracy as a function of position on the site rendering, generating an overlay rendering of the estimated error values of location accuracy for the plurality of position on the site rendering, and the site rendering with the overlay rendering therewith.

What is claimed is: 
     
         1 . A method comprising:
 identifying a position of at least one location anchor on a site rendering;   determining, for a plurality of positions on the site rendering, an estimated error value of location accuracy as a function of position on the site rendering;   generating a overlay rendering of the estimated error values of location accuracy for the plurality of positions on the site rendering; and   displaying the site rendering with the overlay rendering therewith.   
     
     
         2 . The method of  claim 1  wherein the overlay rendering includes a set of contours of common error values. 
     
     
         3 . The method of  claim 1  wherein identifying the position of the at least one location anchor on the site rendering includes at least one of receiving coordinates of the position or receiving user input identifying the position as a position with respect to the site rendering. 
     
     
         4 . The method of  claim 3  further comprising:
 receiving user input specifying a limit to the estimated error value for at least one specified area or volume in the site rendering; and 
 generating a set of recommended coordinates for the at least one location anchor, wherein the estimated error value is less than the limit for all positions within the at least one specified area or volume. 
 
     
     
         5 . The method of  claim 4  wherein a first specified area is associated with a first limit, wherein a second specified area is associated with a second limit, wherein the first limit is different from the second limit, and wherein the set of recommended coordinates for the at least one location anchor is adjusted to ensure the estimated error value is less than the respective limit for each specified area. 
     
     
         6 . The method of  claim 5  further comprising:
 providing a pre-existing set of location anchors; and 
 generating the set of recommended coordinates using coordinates of the pre-existing set of location anchors and adding coordinates for an additional set of location anchors to ensure the estimated error value is less than the respective limit for each specified area. 
 
     
     
         7 . The method of  claim 6  further comprising providing a bill of materials for the additional set of location anchors. 
     
     
         8 . The method of  claim 1  wherein identifying the position of the at least one location anchor on the site map includes receiving the position of the at least one location anchor as GPS coordinates. 
     
     
         9 . The method of  claim 1  wherein determining, for the plurality of positions on the site rendering, the estimated error value of location accuracy includes:
 determining an upper bound limit as a function Euclidean distance to the at least one location anchor for each of the plurality of positions on the site rendering; and 
 for each of the plurality of positions on the site rendering, combining each of the upper bound limits to derive the estimated error value. 
 
     
     
         10 . The method of  claim 9  wherein the function of Euclidian distance is based on received signal strength and wherein determining the upper bound limit and the estimated error value for each of the plurality of positions on the site map is based on determining a mean value RSSI, an expected standard deviation of RSSI, and an upper bound on the RSSI as a function of the Euclidian distance. 
     
     
         11 . The method of  claim 10  wherein determining the upper bound limit includes using the Euclidean distance to determine an expected average RSSI and using the expected average RSSI to determine the upper bound limit, wherein the upper bound limit depends on a user input specifying a desired level of confidence in location accuracy. 
     
     
         12 . The method of  claim 9  wherein the function of Euclidean distance is based on time of flight and wherein determining the upper bound limit and the estimated error value for each of the plurality of positions on the site rendering is based on determining a mean value of time of flight, an expected standard deviation of time of flight, and an upper bound of time of flight as a function of the Euclidean distance. 
     
     
         13 . The method of  claim 10  wherein the mean value of RSSI and the expected standard deviation of RSSI are based on measurements obtained in an RF site survey at a plurality of positions at the site. 
     
     
         14 . The method of  claim 10  wherein the mean value of RSSI and the expected standard deviation of RSSI are based on an RF propagation model that takes into account a presence of equipment and buildings at the site. 
     
     
         15 . The method of  claim 10  further comprising receiving user input specifying a desired level of confidence in location accuracy, and using the user input to determine the upper bound on the RSSI. 
     
     
         16 . The method of  claim 15  wherein a value of a number of RSSI standard deviations is used to determine the upper bound on the RSSI. 
     
     
         17 . The method of  claim 1  further comprising:
 determining a second position of the at least one location anchor on the site rendering based on user input; 
 determining, for the plurality of positions on the site rendering, a second estimated error value of location accuracy as a function of position on the site rendering; 
 generating a second contour map of the second estimated error value of location accuracy for the plurality of positions on the site rendering; and 
 displaying the second contour map. 
 
     
     
         18 . The method of  claim 17  further comprising:
 identifying a position of a second location anchor on the site rendering; 
 determining, for the plurality of positions on the site rendering, a second estimated error value of location accuracy as a function of position on the site rendering; 
 generating a second contour map of the second estimated error value of location accuracy for the plurality of positions on the site rendering; 
 displaying the second contour map; 
 generating an inventory of contour maps; and 
 determining a cost before moving the at least one location anchor, a cost after moving the at least one location anchor, a cost before adding the second location anchor, and a cost after adding the second location anchor. 
 
     
     
         19 . The method of  claim 1  further comprising generating a bill of materials for the at least one location anchor at the site. 
     
     
         20 . The method of  claim 1  wherein each of the estimated error values includes one of a worst case error value or an average error value. 
     
     
         21 . A system comprising:
 executable control software stored on a non-transitory computer readable medium; and   at least one programmable processor for:
 identifying a position of a plurality of location anchors on a site rendering; 
 determining, for a plurality of positions on the site rendering, an estimated error value of location accuracy as a function of distance from each of the plurality of location anchors; and 
 generating an overlay rendering of the estimated error values of location accuracy for the plurality of positions on the site rendering. 
   
     
     
         22 . The system of  claim 21  further comprising a graphical user interface for displaying the overlay rendering. 
     
     
         23 . The system of  claim 21  further comprising user inputs for adding, moving, or deleting at least one of the plurality of location anchors. 
     
     
         24 . A method comprising:
 determining an accuracy of a location estimate for each of a plurality of locations on a site rendering;   generating an overlay rendering visually displaying the determined accuracy of the location estimate for each of the plurality of locations on the site rendering; and   communicating the overlay rendering to a user.   
     
     
         25 . The method of  claim 24  wherein determining the accuracy of the location estimate for each of the plurality of locations on the site rendering includes determining an RSSI for each of the plurality of locations on the site rendering as a function of distance from a plurality of location anchors.