Accelerometer system and method

• US 20120221276A1
• Filed: 07/10/2009
• Published: 08/30/2012
• Est. Priority Date: 07/10/2009
• Status: Active Grant

• Current Assignee: Bridgestone Mobility Solutions BV (Bridgestone Corporation)
• Original Assignee: TomTom Telematics BV (Bridgestone Corporation)
• Inventors: Schmidt, Alexander, Kreim, Stefan, Wikler, Tom
• Granted Patent: US 9,658,079 B2
• Time in Patent Office: Days
• US Class Current: 702/104
• CPC Class Codes: G01C 21/165 combined with non-inertial navigation instruments
• CPC Class Codes: G01C 25/005 initial alignment, calibration or starting-up of inertial devices
• CPC Class Codes: G01P 21/00 Testing or calibrating of apparatus or devices covered by the preceding groups

Abstract

A vehicle accelerometer system comprises an accelerometer (290) for installation in a vehicle (500), a processor (210) for selection of accelerometer output data items for inclusion in an accelerometer output data set representative of measurements by the accelerometer (290) at a plurality of different vehicle locations, each accelerometer output data item being representative of a respective measurement by the accelerometer (290), and a storage device (230) for storing the accelerometer output data set, wherein the processor (210) is configured to process the accelerometer output data set to determine an orientation output representative of the orientation of the accelerometer (290) with respect to the vehicle (500).

Claims

1. A vehicle accelerometer system comprising:

an accelerometer for installation in a vehicle;

a processor for selection of accelerometer output data items for inclusion in an accelerometer output data set representative of measurements by the accelerometer at a plurality of different vehicle locations, each accelerometer output data item being representative of a respective measurement by the accelerometer; and

a storage device for storing the accelerometer output data set, wherein the processor is configured to process the accelerometer output data set to determine an orientation output representative of the orientation of the accelerometer with respect to the vehicle, characterised in that

the processor is configured to select an accelerometer output data item for inclusion in the accelerometer output data set in dependence on the speed of the vehicle at the time of the accelerometer measurement, as determined from GPS data obtained from a location determining unit which is comprised in, or with which the system is configured to communicate.

2. A system according to claim 1, wherein the orientation output is the orientation of the accelerometer with respect to the vehicle.

3. A system according to claim 1, wherein the orientation output comprises a reference output representative of the output from the accelerometer when the vehicle is on level ground.

4. A system according to claim 1, wherein the processing of the accelerometer output data set comprises determining a mean or median value of the accelerometer measurements represented by the accelerometer output data set, and using the determined mean or median value to determine the orientation output.

5. A system according to claim 1, wherein each output data item included in the accelerometer output data set is representative of a respective measurement by the accelerometer when the vehicle is substantially stationary.

6. A system according to claim 1, wherein the processor is configured to select an accelerometer output data item for inclusion in the accelerometer output data set in dependence on the location of the vehicle at the time of the accelerometer measurement.

7. A system according to claim 1, wherein the processor is configured to select an accelerometer output data item for inclusion in the accelerometer output data set in dependence on the separation of the location of the vehicle at the time of the measurement from the location of the vehicle at the time of measurements represented by other output data items.

8. A system according to claim 1, wherein the processor is configured to select an accelerometer output data item for inclusion in the accelerometer output data set in dependence on the value of an environmental parameter at the time of the accelerometer measurement.

9. A system according to claim 3, wherein the processor is configured to provide a plurality of accelerometer output data sets each corresponding to a respective range or value of an environmental parameter, and to process each accelerometer output data set to determine a reference output for each range or value of the environmental parameter.

10. A system according to claim 9, wherein the processor is configured to select one of the accelerometer output data sets in which to include an accelerometer output data item in dependence on the value of the environmental parameter at the time of the accelerometer measurement represented by that accelerometer output data item.

11. A system according to claim 8, wherein the environmental parameter comprises temperature.

12. A system according to claim 1, wherein the processor is configured to process the accelerometer output data set to determine the orientation output if the number of output data items in the accelerometer output data set is greater than a predetermined threshold.

13. A system according to claim 1, wherein the processor is configured to remove accelerometer output data items that are representative of old accelerometer measurements from the accelerometer output data set.

14. A system according to claim 1, wherein the processor is configured to receive an acceleration output data item from the accelerometer and to determine the acceleration of the vehicle in dependence on the acceleration output data item and the orientation output so as to compensate for the orientation of the accelerometer with respect to the vehicle.

17. A method of operation of an accelerometer system comprising:

receiving accelerometer output data items from an accelerometer, each accelerometer output data item being representative of a respective measurement by the accelerometer at a different location;

selecting a plurality of the accelerometer output data items for inclusion in an accelerometer output data set;

storing the accelerometer output data set; and

processing the accelerometer output data set to determine an orientation output representative of the orientation of the accelerometer with respect to a vehicle, characterised in that

the selection of accelerometer output data items for inclusion in the accelerometer output data set depends on the speed of the vehicle at the time of the accelerometer measurement, as determined from GPS data obtained from a location determining unit.

18. A computer program product comprising computer readable instructions that are executable to cause a computer to perform a method according to claim 17.