Methods and systems for combining sensor data to measure vehicle movement

1. A method for determining acceleration of a vehicle during a trip using a mobile device, the method comprising:

operating one or more sensors of the mobile device to obtain motion data including acceleration data;

receiving, by a global positioning system (GPS) receiver of the mobile device, location data corresponding to a location of the vehicle;

aggregating the motion data and the location data to generate aggregated data;

modifying the aggregated data using a Kalman filter to improve an efficiency of mobile device by:

removing, using the Kalman filter, a portion of the aggregated data, wherein a remaining portion of the aggregated data includes a portion of the motion data and a portion of the location data, wherein the remaining portion of the aggregated data is more accurate than the portion of the aggregated data, and wherein using the Kalman filter reduces a rate of depletion of a power store of the mobile device;

determining, by a processor of the mobile device, a gravity vector based on the portion of the motion data;

calculating, by the processor, a yaw estimate for the vehicle, wherein the yaw estimate is determined in a direction around an axis aligned with the gravity vector;

calculating, by the processor, based on the yaw estimate for the vehicle, a first estimate of an extent to which the vehicle is turning; and

determining, by the processor, the acceleration of the vehicle based on the acceleration data and the first estimate of the extent to which the vehicle is turning.

2. The method of claim 1 , wherein the first estimate of the extent to which the vehicle is turning is quantified by calculating, by the processor, a time derivative of the yaw estimate.

3. The method of claim 2 , further comprising:

determining, by the processor, whether the time derivative of yaw exceeds a first threshold, and

in response to determining that the time derivative of yaw exceeds the first threshold, estimating that the vehicle is in a turn.

4. The method of claim 3 , further comprising:

in response to determining that the time derivative of yaw exceeds the first threshold,

correlating a period of time that the time derivative of yaw exceeds the first threshold with the acceleration data; and

excluding the acceleration data correlated with the period of time that the time derivative of yaw exceeds the first threshold from a determination of vehicle acceleration.

5. The method of claim 3 , further comprising:

in response to estimating that the vehicle is in a turn, determining, by the processor, whether the time derivative of yaw exceeds a second threshold greater than the first threshold, and

in response to determining that the time derivative of yaw exceeds the second threshold:

correlating a first period of time that the time derivative of yaw exceeds the second threshold with the acceleration data; and

excluding the acceleration data correlated with the first period of time that the time derivative of yaw exceeds the second threshold from a determination of vehicle acceleration.

6. The method of claim 5 , further comprising:

receiving, by an external information receiver of the mobile device, road map information;

correlating, by the processor, the portion of the location data of the vehicle with the road map information; and

based on a correlation of the portion of the location data of the vehicle with the road map information, determining, by the processor, a second estimate of the extent to which the vehicle is turning.

7. The method of claim 6 , wherein the determining the second estimate of the extent to which the vehicle is turning comprises identifying a road map corresponding to the portion of the location data of the vehicle; and

correlating the portion of the location data of the vehicle to the road map to identify that the portion of the location data of the vehicle corresponds to a turn on the road map.

8. The method of claim 7 , further comprising, when the second estimate indicates that the vehicle is in a turn, correlating, by the processor, a second period of time during which the portion of the location data of the vehicle identified as a turn with the acceleration data; and

determining, by the processor, the acceleration of the vehicle based on the acceleration data and a combination of the first estimate of the extent to which the vehicle is turning and the second estimate of the extent to which the vehicle is turning by excluding from the determination of vehicle acceleration at least one of the acceleration data correlated with the first period of time that the time derivative of yaw exceeds the second threshold or the acceleration data correlated with the second period of time that the portion of the location data of the vehicle identified as a turn.

9. The method of claim 1 , wherein the one or more sensors comprise at least one of an accelerometer or a gyroscope.

10. A mobile device operable to determine acceleration of a vehicle, the mobile device comprising:

a location determination sensor operable to obtain location measurements of the vehicle in which the mobile device is disposed during a trip;

a movement determination sensor operable to obtain movement measurements of the vehicle; and

an acceleration determination engine comprising:

a Kalman filter operable to improve an efficiency of the mobile device, wherein the acceleration determination engine is configured use the Kalman filter to:

aggregate the movement measurements and the location measurements to generate aggregated data; and

remove a portion of the aggregated data, wherein a remaining portion of the aggregated data includes a portion of the movement measurements and a portion of the location measurements, wherein the remaining portion of the aggregated data is more accurate than the portion of the aggregated data, and wherein using the Kalman filter reduces a rate of depletion of a power store of the mobile device;

a turn identification engine configured to identify a turn in the vehicle based on the portion of the movement measurements or the portion of the location measurements;

a subset determination engine configured to determine a subset of the portion of the movement measurements that correspond to the turn in the vehicle that was identified by the turn identification engine; and

an acceleration estimation engine configured to remove the subset of the portion of the movement measurements identified by the subset determination engine from the portion of the movement measurements obtained by the movement determination sensor, and determine acceleration of the vehicle based on a remaining portion of the movement measurements.

11. The mobile device of claim 10 , wherein the turn identification engine is further configured to:

receive yaw measurements from the movement determination sensor and calculate a yaw estimate for the vehicle, wherein the yaw estimate is determined in a direction around an axis aligned with a gravity vector; and

calculate, based on the yaw estimate for the vehicle, a first estimate of an extent to which the vehicle is turning.

12. The mobile device of claim 11 , wherein the subset determination engine is further configured to determine that the yaw measurements exceed a threshold during a first time period; and

determine a first subset of accelerometer measurements that was obtained during the first time period,

wherein the first subset of accelerometer measurements that was obtained during the first time period is excluded from determination of acceleration of the vehicle.

13. The mobile device of claim 12 , wherein the subset determination engine is further configured to determine that location measurements received from location determination sensor during a second time period correspond to a turn on a road map, wherein the second time period is different than the first time period; and

determine a second subset of accelerometer measurements that was obtained during the second time period,

wherein the second subset of accelerometer measurements that was obtained during the second time period is excluded from determination of acceleration of the vehicle.

14. The mobile device of claim 10 , wherein the subset determination engine is further configured to determine that location measurements received from location determination sensor during a second time period correspond to a turn on a road map; and

determine a subset of accelerometer measurements that were obtained during the second time period,

wherein the subset of accelerometer measurements that were obtained during the second time period is excluded from determination of acceleration of the vehicle.

15. The mobile device of claim 10 , wherein the location determination sensor comprises a global positioning system (GPS) receiver.

16. The mobile device of claim 10 , wherein the movement determination sensor comprises at least one of an accelerometer or a gyroscope.

17. A method for determining acceleration of a vehicle during a trip, the method comprising:

receiving, by a global positioning system (GPS) receiver of a mobile device disposed in the vehicle, location data corresponding to a location of the vehicle;

receiving, by an external information receiver of the mobile device, road map information;

operating one or more sensors of the mobile device to obtain motion data including acceleration data;

aggregating the motion data and the location data to generate aggregated data;

modifying the aggregated data using a Kalman filter to improve an efficiency of mobile device by:

removing, using the Kalman filter, a portion of the aggregated data, wherein a remaining portion of the aggregated data includes a portion of the motion data and a portion of the location data, wherein the remaining portion of the aggregated data is more accurate than the portion of the aggregated data, and wherein using the Kalman filter reduces a rate of depletion of a power store of the mobile device;

correlating, by a processor of the mobile device, the portion of the location data with the road map information;

based on a correlation of the location data with the road map information, determining, by the processor, an estimate of an extent to which the vehicle is turning; and

determining, by the processor, the acceleration of the vehicle based on the portion of the motion data that corresponds to the acceleration data and the estimate of the extent to which the vehicle is turning.

18. The method of claim 17 , further comprising:

wherein the determining the extent to which the vehicle is turning comprises identifying a road map corresponding to the portion of the location data of the vehicle; and

correlating the portion of the location data to the road map to identify that the portion of the location data of the vehicle corresponds to a turn on the road map.

19. The method of claim 18 , further comprising:

in response to estimating that the vehicle is in a turn:

correlating, by the processor, a period of time during which the portion of the location data identified as a turn with the acceleration data; and

excluding from a determination of the acceleration of the vehicle the acceleration data correlated with the period of time that the portion of the location data identified the vehicle as being in a turn.

20. The method of claim 17 , wherein the one or more sensors comprise at least one of an accelerometer or a gyroscope.