GPS and MEMS hybrid location-detection architecture

• US 8,362,949 B2
• Filed: 06/27/2011
• Issued: 01/29/2013
• Est. Priority Date: 06/27/2011
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Google Inc. (Alphabet Inc.)
• Inventors: Yang, Qingxuan, Chang, Edward, Li, Guanfeng
• Primary Examiner(s): Issing, Gregory C
• Application Number:
  US13/169,711
• Publication Number:
  US 20120326922A1
• Time in Patent Office: 582 Days
• Field of Search: 342/357.3, 342/357.31, 342/357.32, 342/357.74, 701/472
• US Class Current: 342/357.31
• CPC Class Codes: G01S 19/34 Power consumption
• CPC Class Codes: G01S 19/49 whereby the further system is an inertial position system, e.g. loosely-coupled
• CPC Class Codes: G01S 5/015 between indoor and outdoor environments
• CPC Class Codes: G01S 5/019 Energy consumption

Abstract

The present application describes a computer-implemented method and system for obtaining position information for a moving mobile device with increased accuracy and reduced power consumption. The subject of the present application combines information from a GPS location sensor with information from MEMS devices such as an acceleration detector and a gyroscope using statistical analysis techniques such as a Kalman filter to estimate the location of the device with greater accuracy while using numerical methods such as the Newton-Raphson Method to minimize power consumption. Minimizing power consumption is possible because GPS signals sampled at a lower rate can conserve power, while GPS sampled at a lower rate and working together with MEMS devices can achieve the same level of location prediction accuracy as a GPS alone sampled at a higher rate.

Claims

1. A system for providing accurate location information for a moving mobile device, the system comprising:

a location sensor, coupled to the mobile device, that determines an absolute location of the mobile device at a first time;

an acceleration detector, coupled to the mobile device, that determines an acceleration magnitude that corresponds to a speed of the mobile device at a time after the first time and before a second time occurring after the location sensor determines the absolute location;

a gyroscope, coupled to the mobile device, that determines a direction of movement of the mobile device at a time after the first time and before the second time;

a sensor fusion module that;

determines an updated location of the mobile device based on the acceleration magnitude and direction of movement, the updated location relative to the absolute location, the updated location information representing the location of the mobile device at the second time more accurately than the absolute location that is determined by the location sensor; and

determines information about an external environment of the mobile device at least based on information received from the location sensor; and

a parameter setting module that sets parameters modifying operation of the location sensor, the acceleration detector and the gyroscope to optimize overall power consumption for a given operating accuracy, wherein

the parameter setting module retrieves optimum parameter values from a closure database connected to the parameter setting module that stores initial values of the parameters, and the optimum parameter values are selected based on the initial values and the information about the external environment of the mobile device, the optimum parameter values optimizing overall power consumption for given operating accuracy.

2. The system of claim 1, further comprising a user input module that allows a user to set the operating accuracy used by the parameter setting module.

3. The system of claim 1, wherein the parameter setting module iteratively uses the Newton-Raphson method to optimize overall power consumption.

4. The system of claim 1, further comprising a sensor register that receives the parameters that have been optimized by the parameter setting module and transmits them to the location sensor, the acceleration detector, and the gyroscope to be implemented.

5. The system of claim 1, wherein the sensor fusion module uses a Kalman filter to determine the updated location information with increased accuracy by deriving an updated location based on a weighted average of information provided to the signal fusion module.

6. The system of claim 1, wherein the sensor fusion module uses numerical integration to transform acceleration information including the acceleration magnitude into velocity information and the velocity information into the updated location information.

7. The system of claim 1, wherein the location sensor is a GPS sensor, and wherein the acceleration detector and movement direction detector are MEMS devices.

8. The system of claim 1, further comprising an additional MEMS device that provides information about the position, orientation, or movement of the mobile device to the sensor fusion module for use in determining the updated location.

9. The system of claim 1, further comprising a data extraction module that receives measurement data from the sensor fusion module and filters the measurement data to provide signal object information that is characteristic of at least one of position, orientation, change of position, and change of orientation of the device.

10. The system of claim 9, further comprising using the data extraction module to filter relative information that is characteristic of at least one of position, orientation, change of position, and change of orientation of the device and transform the relative information into absolute information.

11. The system of claim 9, wherein the data extraction module corrects the output of the acceleration detector for the effects of gravity.

12. The system of claim 1, wherein the location sensor determines the absolute location of the mobile device with a location sensor accuracy that depends on the environment of the mobile device and power allocated to the location sensor, and wherein the parameter setting module is further configured to dynamically allocate power resources by increasing or decreasing the power allocated to the acceleration detector or the gyroscope to achieve a given operating accuracy when the location sensor accuracy changes, based on changes to the environment of the mobile device, while optimizing overall power consumption.

13. The system of claim 12, wherein the parameter setting module is configured to dynamically allocate power resources by:

identifying an environmental change in which the mobile device changes from an outside environment to an indoor environment, wherein the location sensor accuracy decreases without changing power allocated to the location sensor; and

increasing power allocated to the acceleration detector or the gyroscope to preserve operating accuracy while optimizing overall power consumption.

14. The system of claim 12, wherein the parameter setting module is configured to dynamically allocate power resources by:

identifying an environmental change in which the mobile device changes from an indoor environment to an outside environment, wherein the location sensor accuracy increases without changing power allocated to the location sensor; and

decreasing power allocated to the acceleration detector or the gyroscope to preserve operating accuracy while optimizing overall power consumption.

15. A computer-implemented method for providing accurate location information for a moving mobile device, the method comprising:

determining, using a location sensor coupled to the mobile device, an absolute location of the mobile device at a first time;

determining, using an acceleration detector coupled to the mobile device, an acceleration magnitude of the mobile device at a time after the first time and before a second time occurring after the location sensor determines the absolute location;

determining, using a gyroscope coupled to the mobile device, a direction of movement of the mobile device at a time after the first time and before the second time;

determining an updated location of the mobile device based on the acceleration magnitude and direction of movement, the updated location relative to the absolute location, the updated location information representing the location of the mobile device at the second time more accurately than the absolute location that is determined by the location sensor;

determining information about an external environment of the mobile device at least based on information received form the location sensor; and

setting parameters modifying operation of the location sensor, the acceleration detector and the gyroscope to optimize overall power consumption for a given operating accuracy, wherein the setting comprises retrieving optimum parameter values from a closure database that stores initial values of the parameters, and the optimum parameter values are selected based on the initial values and the information about the external environment of the mobile device, the optimum parameter values optimizing overall power consumption for a given operating accuracy.

16. The computer-implemented method of claim 15, further comprising using user input to set the operating accuracy used by the parameter setting module.

17. The computer-implemented method of claim 15, wherein the optimizing comprises iteratively using the Newton-Raphson method to optimize overall power consumption.

18. The computer-implemented method of claim 15, further comprising:

receiving, by a sensor register, the parameters that have been optimized by the parameter setting module and transmitting them to the location sensor, the acceleration detector, and the gyroscope to be implemented.

19. The computer-implemented method of claim 15, further comprising:

using a Kalman filter to determine the updated location information with increased accuracy by deriving an updated location based on a weighted average of information provided to the signal fusion module.

20. The computer-implemented method of claim 15, further comprising:

using numerical integration to transform acceleration information including the acceleration magnitude into velocity information and the velocity information into the updated location information.

21. The computer-implemented method of claim 15, wherein the location sensor is a GPS sensor, and wherein the acceleration detector and movement direction detector are MEMS devices.

22. The computer-implemented method of claim 15, further comprising:

using an additional MEMS device to provide information about at least one of the position, orientation, movement of the mobile device to the sensor fusion module for use in determining the updated location.

23. The computer-implemented method of claim 15, further comprising:

receiving measurement data from the sensor fusion module; and

filtering the measurement data to provide signal object information that is characteristic of at least one of position, orientation, change of position, and change of orientation of the device.

24. The computer-implemented method of claim 23, further comprising:

filtering, relative information that is characteristic of at least one of position, orientation, change of position, and change of orientation of the device; and

transforming the relative information into absolute information.

25. The computer-implemented method of claim 23, further comprising:

correcting, the output of the acceleration detector for the effects of gravity.

26. The computer-implemented method of claim 15, wherein determining the absolute location of the mobile device has a location sensor accuracy that depends on the environment of the mobile device and power allocated to the location sensor, and wherein the dynamically allocating power resources comprises increasing or decreasing the power allocated to the acceleration detector or the gyroscope to achieve a given operating accuracy when the location sensor accuracy changes, based on changes to the environment of the mobile device, while optimizing overall power consumption.

27. The computer-implemented method of claim 26, wherein dynamically allocating power resources comprises:

identifying an environmental change in which the mobile device changes from an outside environment to an indoor environment, wherein the location sensor accuracy decreases without changing power allocated to the location sensor; and

increasing power allocated to the acceleration detector or the gyroscope to preserve operating accuracy while optimizing overall power consumption.

28. The computer-implemented method of claim 26, wherein dynamically allocating power resources comprises:

identifying an environmental change in which the mobile device changes from an indoor environment to an outside environment, wherein the location sensor accuracy increases without changing power allocated to the location sensor; and

decreasing power allocated to the acceleration detector or the gyroscope to preserve operating accuracy while optimizing overall power consumption.