Systems and methods to determine a location of a mobile device

Abstract

Systems and methods to determine a location of a mobile device by combining a radio frequency navigation system and an inertial navigation system, where the radio frequency navigation system determines a location of the mobile device in reference to a map of radio frequency signals and the inertial navigation system based on dead reckoning the position of the mobile device based on measurements from motion sensors. When a set of successive locations determined by the radio frequency navigation system is found to have a predetermined pattern (e.g., within a minimum distance from each other, or separated by more than a maximum distance), the mobile device discards the location results from the radio frequency navigation system for the period of time, in favor of the location results from the inertial navigation system.

What is claimed is: 
     
         1 . A method to determine a location of a mobile device, the method comprising:
 storing a map of radio frequency signal characteristics in a region identified in the map;   receiving, from a transceiver of the mobile device, radio frequency signals in the region emitted from a plurality of beacons located within the region;   determining characteristics of the radio frequency signals received from the transceiver;   matching the characteristics of the radio frequency signals with the frequency signal characteristics of the map to determine two successive first locations;   receiving, via sensors of the mobile device, motion data, including orientation data and acceleration data of the mobile device;   computing two successive second locations from the motion data;   determining a confidence level of the two successive first locations and a confidence level of the two successive second locations; and   determining two successive third locations of the mobile device, the determining being based at least on computed weighted averages of the two successive first locations and the two successive second locations, the computed weighted averages being based on the confidence levels of the two successive first locations and the two successive second locations.   
     
     
         2 . The method of  claim 1 , further comprising:
 computing a heading of a user of the mobile device based on the two successive third locations of the mobile device,   wherein the orientation data is ignored during the computing of the heading of the user.   
     
     
         3 . The method of  claim 2 , wherein the orientation data includes measurements from a magnetic field sensor. 
     
     
         4 . The method of  claim 2 , wherein the orientation data includes measurements from gyroscopes. 
     
     
         5 . The method of  claim 1 , wherein the mobile device is configured to perform dead reckoning positions of the mobile device based on the acceleration data from the sensors of the mobile device. 
     
     
         6 . The method of  claim 5 , wherein the sensors include accelerometers to generate the acceleration data. 
     
     
         7 . The method of  claim 1 , wherein the characteristics of the radio frequency signals received from the transceiver of the mobile device include an identifier of a source located within an indoor environment that transmits the radio frequency signals. 
     
     
         8 . The method of  claim 7 , wherein the characteristics of the radio frequency signals received from the transceiver of the mobile device include strength level indicators of the radio frequency signals transmitted from the source. 
     
     
         9 . A non-transitory computer storage medium storing instructions which when executed by a server, cause the server to perform a method in determining a location of a mobile device, the method comprising:
 storing a map of radio frequency signal characteristics in a region identified in the map;   receiving, from a transceiver of the mobile device, radio frequency signals in the region emitted from a plurality of beacons located within the region;   determining characteristics of the radio frequency signals received from the transceiver;   matching, the characteristics of the radio frequency signals with the frequency signal characteristics of the map to determine two successive first locations;   receiving, via sensors of the mobile device, motion data, including orientation data and acceleration data of the mobile device;   computing two successive second locations from the motion data;   determining a confidence level of the two successive first locations and a confidence level of the two successive second locations; and   determining two successive third locations of the mobile device, the determining being based at least on computed weighted averages of the two successive first locations and the two successive second locations, the computed weighted averages being based on the confidence levels of the two successive first locations and the two successive second locations.   
     
     
         10 . A server system, comprising:
 at least one a memory;   at least one microprocessor;   wherein the at least one memory and at least one processor are configured to perform the following operations:
 receiving, from a transceiver of the mobile device, radio frequency signals in the region emitted from a plurality of beacons located within the region; 
 determining characteristics of the radio frequency signals received from the transceiver; 
 matching the characteristics of the radio frequency signals with the frequency signal characteristics of the map to determine two successive first locations; 
 receiving, via sensors of the mobile device, motion data, including orientation data and acceleration data of the mobile device; 
 computing two successive second locations from the motion data; 
 determining a confidence level of the two successive first locations and a confidence level of the two successive second locations; and 
 determining two successive third locations of the mobile device, the determining being based at least on computed weighted averages of the two successive first locations and the two successive second locations, the computed weighted averages being based on the confidence levels of the two successive first locations and the two successive second locations. 
   
     
     
         11 . The server system of  claim 10 , wherein the at least one memory and at least one processor are further configured for computing a heading of a user of the mobile device based on the two successive third locations of the mobile device, and wherein the orientation data is ignored during the computing of the heading of the user. 
     
     
         12 . The server system of  claim 11 , wherein the orientation data includes measurements from a magnetic field sensor. 
     
     
         13 . The server system of  claim 11 , wherein the orientation data includes measurements from gyroscopes. 
     
     
         14 . The server system of  claim 10 , wherein the sensors include accelerometers for generating the acceleration data from the sensors of the mobile device. 
     
     
         15 . The server system of  claim 14 , wherein the sensors further include at least one of: gyroscopes and a magnetic field sensor. 
     
     
         16 . The server system of  claim 15 , wherein the orientation data from the magnetic field sensor is ignored during the computing of the heading of the user. 
     
     
         17 . The server system of  claim 10 , wherein the characteristics of the radio frequency signals received from the transceiver include:
 an identifier of a source that transmits the radio frequency signals; and   a signal strength level of the radio frequency signals transmitted from the source.   
     
     
         18 . The server system of  claim 10 , wherein the radio frequency signals are signals for wireless local area networking or wireless personal area networking. 
     
     
         19 . The server system of  claim 10 , wherein the at least one memory and at least one processor are further configured to filter position determination results of the radio frequency navigation system based on the confidence level of the position determination results of the radio frequency navigation system.