Accelerometer utilizing image-based movement tracking

• US 20070165907A1
• Filed: 01/17/2006
• Published: 07/19/2007
• Est. Priority Date: 01/17/2006
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Avago Technologies ECBU IP Singapore Pte Limited (Broadcom, Inc.)
• Inventors: Schroeder, Dale, Clifford, George
• Granted Patent: US 7,653,214 B2
• Time in Patent Office: Days
• US Class Current: 382/103
• CPC Class Codes: G01P 15/003 Kinematic accelerometers, i.e. measuring acceleration in relation to an external reference frame, e.g. Ferratis accelerometers G01P15/001, G01P15/16, G01P15/165 take precedence
• CPC Class Codes: G01P 15/093 by photoelectric pick-up
• CPC Class Codes: G06T 7/246 using feature-based methods, e.g. the tracking of corners or segments

Abstract

An accelerometer captures multiple frames of image information and uses the image information to generate acceleration data related to an object. In particular, multiple image frames are used to determine relative movement between a target and an image collection system. The relative movement between the target and the image collection system is tracked over time to generate acceleration data related to the object.

Claims

1. An accelerometer comprising:

a target;

an image collection system configured to capture image information related to the target;

a tracking engine configured to process the image information to track movement of the target relative to the image collection system and to output movement information; and

conversion logic configured to generate acceleration data related to an object in response to the movement information.

2. The accelerometer of claim 1 wherein the target and the image collection system are configured such that one of the target and the image collection system moves relative to the other in response to acceleration of an object and wherein the target includes a feature, which when moved relative to the image collection system, produces image information that is distinguishable in at least one direction.

3. The accelerometer of claim 2 further comprising a rigid connection between the object and one of the target and the image collection system, wherein the rigid connection is configured to cause the object and one of the target and the image collection system to move in unison in response to acceleration of the object.

4. The accelerometer of claim 2 further comprising an inertial connection between the object and one of the target and the image collection system, wherein the inertial connection is configured to allow movement between the object and one of the target and the image collection system in response to acceleration of the object.

5. The accelerometer of claim 2 further comprising:

a rigid connection between the object and one of the target and the image collection system, wherein the rigid connection is configured to cause the object and one of the target and the image collection system to move in unison in response to acceleration of the object; and

an inertial connection between the object and the other one of the target and the image collection system, wherein the inertial connection is configured to allow movement between the object and the other one of the target and the image collection system in response to acceleration of the object.

6. The accelerometer of claim 1 wherein the image collection system further comprises:

a light source configured to illuminate the target; and

an image sensor configured to capture image information related to the target in response to light that reflects off the illuminated target.

7. The accelerometer of claim 6 wherein the image sensor comprises an array of distinct photodetectors, wherein each distinct photodetector generates light intensity information.

8. The accelerometer of claim 7 wherein the image sensor captures the image information as image frames and wherein the tracking engine is configured to correlate common features in the image frames to determine the magnitude of movement of the common features.

9. The accelerometer of claim 6 wherein the image sensor captures the image information as image frames and wherein the tracking engine is configured to correlate common features in the image frames to determine the magnitude and direction of movement of the common features.

10. The accelerometer of claim 6 wherein the image sensor and tracking engine are located on a single integrated circuit device.

11. The accelerometer of claim 1 wherein the target comprises features that are rotationally unique.

12. The accelerometer of claim 11 wherein the movement information includes linear movement information and angular movement information and wherein the acceleration data includes linear acceleration data and angular acceleration data.

13. A method for obtaining acceleration data related to an object, the method comprising:

capturing image information from a target using an image collection system;

processing the image information to track movement of the target relative to the image collection system, wherein the movement is indicated by movement information; and

converting the movement information to acceleration data related to the object.

14. The method of claim 13 wherein the target and image collection system are configured such that one of the target and the image collection system moves relative to the other in response to acceleration of an object and wherein the target includes a feature, which when moved relative to the image collection system, produces image information that is distinguishable in at least one direction.

15. The method of claim 14 wherein one of the target element and the image collection system moves in unison with the object in response to acceleration of the object.

16. The method of claim 14 wherein one of the target element and the image collection system moves relative to the object in response to acceleration of the object.

17. The method of claim 14 wherein one of the target element and the image collection system moves in unison with the object in response to acceleration of the object and wherein the other one of the target element and the image collection system moves relative to the object in response to acceleration of the object.

18. The method of claim 13 wherein capturing the image information comprises capturing image frames.

19. The method of claim 18 wherein processing the image information to track movement of the target comprises correlating common features in the image frames to determine the magnitude and direction of movement of the common features.

20. The method of claim 14 wherein capturing the image information comprises illuminating the target and detecting light that reflects off of the illuminated target.

21. The method of claim 14 wherein the target comprises features that are rotationally unique.

22. The method of claim 21 wherein the movement information includes linear movement information and angular movement information and wherein the acceleration data includes linear acceleration data and angular acceleration data.

23. An accelerometer comprising:

a target;

an image collection system configured to capture image information related to the target;

wherein one of the target element and the image collection system is connected to an object by a rigid connection and wherein the other one of the target element and image collection system is connected to the object by an inertial connection and wherein the target includes a feature, which when moved relative to the image collection system, produces image information that is distinguishable in at least one direction;

a tracking engine configured to process the image information to track movement of the target relative to the image collection system and to output movement information; and

conversion logic configured to generate acceleration data related to an object in response to the movement information.

24. The accelerometer of claim 23 wherein the rigid connection is configured to cause the object and one of the target element or the image collection system to move in unison in response to acceleration of the object.

25. The accelerometer of claim 23 wherein the inertial connection is configured to allow movement between the object and one of the target element or the image collection system in response to acceleration of the object.

26. The accelerometer of claim 24 wherein the rigid connection is configured to cause the object and one of the target element or the image collection system to move in unison in response to acceleration of the object and wherein the inertial connection is configured to allow movement between the object and the other of the target element and the image collection system in response to acceleration of the object.