INFERENCE OF VEHICULAR TRAJECTORY CHARACTERISTICS WITH PERSONAL MOBILE DEVICES

• US 20140278206A1
• Filed: 03/15/2013
• Published: 09/18/2014
• Est. Priority Date: 03/15/2013
• Status: Active Grant

• Current Assignee: Cambridge Mobile Telematics, Inc.
• Original Assignee: Cambridge Mobile Telematics, Inc.
• Inventors: Girod, Lewis D., Balakrishnan, Hari, Madden, Samuel Ross
• Granted Patent: US 9,228,836 B2
• Time in Patent Office: Days
• US Class Current: 702/141
• CPC Class Codes: G01C 15/00 Surveying instruments or accessories not provided for in groups G01C1/00 - G01C13/00
• CPC Class Codes: G01C 21/10 by using measurements of speed or acceleration G01C21/24, G01C21/26 take precedence
• CPC Class Codes: G01C 21/165 combined with non-inertial navigation instruments
• CPC Class Codes: G01C 21/20 Instruments for performing navigational calculations G01C21/24, G01C21/26 take precedence
• CPC Class Codes: G01P 15/0891 with indication of predetermined acceleration values G01P15/135 takes precedence

Abstract

Accurate longitudinal acceleration, lateral acceleration (perpendicular to the principal direction of motion, and velocity, is inferred by processing raw data from a commodity three-axis accelerometer that may be oriented arbitrarily in a moving vehicle (or carried by a moving user), and whose orientation and position may change arbitrarily during the motion. The approach is applicable to a range of applications, including insurance telematics, driver behavior and risk assessment, and road surface quality assessment.

Claims

1. A method comprising inferring vehicular trajectory characteristics, said inferring comprising:

acquiring using a machine-implemented processor data representing a sequence of acceleration-related measurements of a device, the device being in an unknown and changeable orientation relative to the frame of reference of a vehicle in which the device is traveling;

forming using a machine-implemented processor a plurality of time segments of the acceleration-related data, wherein the orientation of the device relative to the vehicle when acquiring the data differs between at least some of the time segments;

for each time segment of a plurality of time segments, using a machine-implemented processor,

determining data characterizing an orientation of the device relative to a frame of reference of the vehicle during that time segment,

forming motion-related data in the frame of reference of the vehicle during the time segment, and

determining data characterizing trajectory characteristics of the vehicle in the time segment; and

storing data characterizing trajectory characteristic of the vehicle determined from the data characterizing the trajectory characteristics in multiple of the time segments.

2. The method of claim 1 wherein forming the plurality of time segments comprises detecting times of substantial relative motion of the device relative to the vehicle, and forming the time segments between said detected times.

4. The method of claim 1 wherein determining data characterizing an orientation of the device comprises determining a time varying orientation of the device relative to the frame of reference of the vehicle.

5. The method of claim 1 wherein determining data characterizing an orientation of the device in a time segment comprises determining a vertical direction.

6. The method of claim 30 wherein determining a time interval in which the vehicle is stationary uses a threshold picked from statistics of the acceleration-related measurements.

7. The method of claim 1 wherein the device comprises a personal mobile device that is held or is on the person of a driver or passenger of the vehicle.

8. The method of claim 1 wherein the data characterizing trajectory characteristics of a vehicle comprise at least one of longitudinal acceleration, lateral acceleration, longitudinal velocity, and distance traveled of the vehicle.

9. The method of claim 1 wherein acquiring the data representing the sequence of acceleration-related measurements of the device comprises measuring acceleration values on multiple axes using accelerometers in the device.

10. The method of claim 1 wherein the inferring further comprises:

accessing map data characterizing a road network;

processing the data characterizing the trajectory characteristics of the vehicle according to the map data to determine data characterizing traversal of the road network by the vehicle.

11. The method of claim 1 further comprising applying map traversal data in determining the data characterizing the trajectory characteristics of the vehicle.

12. The method of claim 1 wherein the inferring further comprises:

acquiring data representing environmental characteristics of the device; and

wherein determining the trajectory characteristic of the vehicle includes using the data representing the environmental characteristics.

13. The method of claim 12 wherein the data representing environmental characteristics includes data representing an acoustic environment of the vehicle, where said data provides information related to velocity of the vehicle.

14. The method of claim 1 wherein the inferring further comprises:

acquiring data from a gyroscope on the device; and

wherein determining the trajectory characteristic of the vehicle includes using the gyroscope data.

15. The method of claim 14 wherein the use of the gyroscope data is in the forming of the time segments.

16. The method of claim 14 wherein the use of the gyroscope data is in the forming of the motion-related data in the frame of reference of the vehicle during the time segment.

17. The method of claim 1 wherein the inferring further comprises:

acquiring position or velocity data of the device using a radio or positioning sensor in the device; and

wherein determining the trajectory characteristic of the vehicle includes using the position data.

18. The method of claim 17 further comprising determining when to acquire the position or velocity data at least in part according to the determined trajectory characteristics determined from the acceleration-related measurements of a device.

19. The method of claim 17 further comprising determining when to acquire the position or velocity data at least in part according to the determined motion state of the device in the frame of reference of the vehicle.

20. The method of claim 17 further comprising:

accessing map data characterizing a road network;

processing the data characterizing the trajectory characteristics of the vehicle according to the map data to determine data characterizing traversal of the road network by the vehicle.

21. The method of claim 1 further comprising providing software to the device for execution on the device for causing a processor in the device to perform the inferring.

22. The method of claim 1 further comprising providing the data characterizing trajectory characteristic of the vehicle via a radio interface of the device.

23. The method of claim 22 wherein providing the data includes providing the data to a server computer and at least some of the steps of claim 1 are performed at said server.

24. The method of claim 1 further comprising providing the data characterizing the trajectory characteristics to a second party for use in usage-based insurance applications.

25. The method of claim 1 further comprising providing the data characterizing the trajectory characteristics to a second party with a contractual relationship with a first party comprising at least one of a user of the device and party in control of the vehicle.

26. The method of claim 25 wherein the contractual relationship is governed at least in part according to trajectory characteristics of the vehicle.

27. The method of claim 25 further comprising forming the contractual relationship between the first party and the second party.

29. The method of claim 1 wherein forming the plurality of time segments comprises determining said segments such that the orientation of the device relative to the vehicle is relatively fixed as compared to changes of the orientation at transitions between said segments.

30. The method of claim 1 wherein, for each time segment of a plurality of time segments, the method further comprises

determining whether there is a time interval in the time segment in which the vehicle is stationary.

31. The method of claim 5 further comprising using a distribution of sensed motion in a plane orthogonal to the vertical direction to determine a direction of travel of the vehicle.

3. (canceled)

28. Software stored on a non-transitory machine-readable medium comprising instructions for causing a processor to:

acquire data representing a sequence of acceleration-related measurements of a device traveling in a vehicle;

form a plurality of time segments of the acceleration-related data, such that the orientation of the device relative to the vehicle when acquiring the data differs between at least some of the formed time segments;

for each of a plurality of the time segments,

determine data characterizing an orientation of the device relative to a frame of reference of the vehicle,

form motion-related data in the frame of reference of the vehicle during the time segment, and

determine data characterizing trajectory characteristics of the vehicle in the time segment; and

store data characterizing trajectory characteristic of the vehicle determined from the data characterizing the trajectory characteristics in multiple of the time segments.