MULTIPLE ACCELEROMETER SYSTEM

• US 20120078570A1
• Filed: 09/21/2011
• Published: 03/29/2012
• Est. Priority Date: 09/29/2010
• Status: Abandoned Application

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Rothkopf, Fletcher, Hobson, Phillip, Shedletsky, Anna-Katrina, Mittleman, Adam
• Application Number:
  US13/238,767
• Publication Number:
  US 20120078570A1
• Time in Patent Office: Days
• US Class Current: 702/141
• CPC Class Codes: G01C 19/58 Turn-sensitive devices without moving masses
• CPC Class Codes: G01C 21/10 by using measurements of speed or acceleration G01C21/24, G01C21/26 take precedence
• CPC Class Codes: G01P 15/18 in two or more dimensions
• CPC Class Codes: G06F 1/1626 with a single-body enclosure integrating a flat display, e.g. Personal Digital Assistants [PDAs]
• CPC Class Codes: G06F 1/1694 the I/O peripheral being a single or a set of motion sensors for pointer control or gesture input obtained by sensing movements of the portable computer
• CPC Class Codes: G06F 2200/1637 Sensing arrangement for detection of housing movement or orientation, e.g. for controlling scrolling or cursor movement on the display of an handheld computer

Abstract

Systems and methods for approximating angular velocity using a plurality of accelerometers are disclosed. In particular, in one embodiment, a method of approximating angular velocity including receiving linear acceleration information from a plurality of accelerometers and calculating a relative acceleration for at least one pair of the plurality of accelerometers is disclosed. The method includes obtaining a distance value for the at least one pair of the plurality of accelerometers and approximating the angular velocity by multiplying the distance value by the relative acceleration to obtain.

Claims

1. An angular velocity approximation system comprising:

a housing;

a first accelerometer positioned within the housing;

a second accelerometer positioned within the housing a known distance from the first accelerometer; and

a processor coupled to the first and second accelerometers and configured to receive acceleration signals therefrom, the processor is further configured to calculate a relative acceleration value and multiply the relative acceleration with the known distance to approximate angular velocity.

2. The angular velocity approximation system of claim 1 further comprising a third accelerometer positioned within the housing a first distance from the first accelerometer and a second distance from the second accelerometer.

3. The angular velocity approximation system of claim 1 wherein the first and second accelerometers comprise three-axis accelerometers.

4. The angular velocity approximation system of claim 1 wherein the housing comprises a rectangular shape and the first and second accelerometers are positioned near opposite corners of the housing.

5. The angular velocity approximation system of claim 4 wherein the third accelerometer is located near another corner of the housing.

6. The angular velocity approximation system of claim 4 wherein at least one of the first and second accelerometers is offset from an axis that passes through the opposite corners.

7. The angular velocity approximation system of claim 1 further comprising at least one of a global positioning device, a compass, and a user input device.

8. The angular velocity approximation system of claim 1 further comprising a display configured to provide a graphical output that indicates a location based at least in part on the approximated angular velocity and a known starting point.

9. A method of approximating angular velocity comprising:

receiving linear acceleration information from a plurality of accelerometers;

calculating a relative acceleration for at least one pair of the plurality of accelerometers;

obtaining a distance value for the at least one pair of the plurality of accelerometers; and

approximating the angular velocity by multiplying the distance value by the relative acceleration to obtain.

10. The method of claim 9 further comprising:

determining a starting point; and

determining a current location using the approximation of angular velocity and the starting point.

11. The method of claim 9 further comprising calculating a plurality of relative accelerations.

12. The method of claim 11 further comprising determining if one or more of the plurality of relative accelerations provide meaningful information.

13. The method of claim 12 wherein approximating the angular velocity comprises calculating an average of the one or more of the plurality of relative accelerations that provide meaningful information.

14. The method of claim 12 further comprising:

determining if one of the plurality of accelerometers has provided unusable information for multiple iterations; and

omitting information from the one of the plurality of accelerometers that has provided unusable information.

15. The method of claim 13 wherein determining if one or more of the plurality of relative accelerations provide meaningful information comprises comparing the plurality of relative accelerations to a threshold.

16. The method of claim 13 wherein determining if one or more of the plurality of relative accelerations provide meaningful information comprises comparing the plurality of relative accelerations to each other.

17. A method for determining a position of a device comprising:

obtaining linear acceleration data from a plurality of accelerometers associated with the device;

computing a relative acceleration value for each axis of at least one pair of the plurality of accelerometers;

obtaining a distance value representing the distance between the at least one pair of the plurality of accelerometers;

multiplying the distance value with the relative acceleration values to approximate angular acceleration; and

using the approximated angular acceleration to determine a movement of the device.

18. The method of claim 17 further comprising:

obtaining a first position and orientation of the device; and

determining a current position of the device by adding the determined movement of the device to the first position.

19. The method of claim 17 further comprising determining if the device is traveling in a straight line.

20. The method claim 19 further comprising using the linear acceleration data to determine a speed and direction of travel of the device if it is determined that the device is traveling in a straight line.