Apparatus for measuring velocity of a moving image or object

• US 4,580,894 A
• Filed: 06/30/1983
• Issued: 04/08/1986
• Est. Priority Date: 06/30/1983
• Status: Expired due to Fees

• Current Assignee: Itek Corp (Northrop Grumman Corporation)
• Original Assignee: Itek Corp (Northrop Grumman Corporation)
• Inventors: Wojcik, David R.
• Primary Examiner(s): Buczinski, Stephen C.
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US06/509,497
• Time in Patent Office: 1,013 Days
• Field of Search: 356/28, 356/152
• US Class Current: 356/28
• CPC Class Codes: G01P 3/36 Devices characterised by the use of optical means, e.g. using infrared, visible, or ultraviolet light G01P3/68 takes precedence; gyrometers using the Sagnac effect, i.e. rotation-induced shifts between counter-rotating electromagnetic beams G01C19/64

Abstract

Apparatus for measuring the velocity of a moving image or object including a first array of sensors extending in a first direction transverse to image motion for sensing a primary set of image elements; a second array of sensors extending generally in the first direction and spaced a known distance from the first array for sensing successive sets of image elements; a device for correlating the primary set of image elements with each of the successive sets of image elements and for producing a correlation level indicating the level of correlation of the primary set with each of the successive sets; means for selecting one of the correlation levels which indicates an optimal level of correlation; and means for determining the time interval between the sensing of the first array of the primary set and the sensing by the second array of the successive set corresponding to the selected correlation level; in addition, the means for correlating may include means for comparing with the primary set each successive set in a plurality of different positions along the first direction and for producing a comparison level indicating the level of comparison of the primary set with each of the successive sets in each of the different positions along the first direction; and means for determining the displacement between the position in which the successive set is sensed and the position corresponding to the indicated comparison level.

Claims

1. Apparatus for measuring the velocity of a moving image or object comprising:

a first array of sensors extending in a first direction transverse to image motion for sensing a primary set of image elements;

a second array of sensors extending generally in said first direction and spaced a known distance from said first array for sensing successive sets of image elements;

means for correlating said primary set of image elements with each of said successive sets of image elements and producing a correlation level indicating the level of correlation of said primary set with each of said successive sets, said means for correlating including means for comparing with said primary set each said successive set in a plurality of different positions along said first direction and for producing a comparison level indicating the level of comparison of said primary set with said successive set in each of said different positions;

means for selecting one of said correlation levels which indicates an optimum level of correlation; and

means for determining the time interval between the sensing by said first array of said primary set and the sensing by said second array of said successive set corresponding to said selected correlation level.

2. The apparatus of claim 1 further including means for calculating a forward image velocity component from said time interval and said known distance between said arrays.

3. The apparatus of claim 1 in which said means for correlating further includes means for indicating the one of said comparison levels which represents the best level of comparison produced for said successive set.

4. The apparatus of claim 3 further including means for determining the displacement between the position in which the successive set is sensed and the position corresponding to the indicated comparison level.

5. The apparatus of claim 4 further including means for calculating the lateral image velocity component from said time interval and said displacement.

6. The apparatus of claim 1 in which said first and second arrays are linear.

7. The apparatus of claim 1 in which at least one of said first and second arrays is a charge-coupled device.

8. The apparatus of claim 1 further including means for changing the distance between the first and second arrays.

9. The apparatus of claim 1 further including switching means for interchanging the inputs from said first and second arrays to said means for correlating, for enabling said primary set of image elements to be sensed by said second array and said successive sets of image elements to be sensed by said first array.

10. Apparatus for measuring the velocity of a moving image or object comprising:

a first array of sensors extending in a first direction transverse to image motion for sensing a primary set of image elements;

a second array of sensors extending generally in said first direction and spaced a known distance from said first array for sensing successive sets of image elements;

means for comparing with said primary set each said successive set in a plurality of different positions along said first direction and for producing a comparison level indicating the level of comparison of said primary set with said successive set in each of said different positions;

means for indicating the one of said comparison levels which indicates the best level of comparison produced for each said successive set and for indicating that comparison level as a correlation level indicating the level of correlation of said primary set with that successive set;

means for selecting one of said correlation levels which indicates an optimal level of correlation between said successive sets and said primary set; and

means for determining the time interval between the sensing by said first array of said primary set and the sensing by said second array of said successive set corresponding to said selected correlation level.

11. The apparatus of claim 10 further including means for calculating a forward image velocity component from said time interval and said known distance between said arrays.

12. The apparatus of claim 11 further including:

means for determining the displacement between the position in which the successive set corresponding to said selected correlation level is sensed and the position corresponding to the indicated comparison level selected as said selected correlation level; and

means for calculating a lateral image velocity component from said time interval and said displacement.

13. Apparatus for measuring the velocity of a moving image or object comprising:

a first array of sensors extending in a first direction transverse to image motion for sensing a primary set of image elements;

a second array of sensors extending generally in said first direction and spaced a known distance from said first array for sensing successive sets of image elements;

means for comparing with said primary set a successive set in a plurality of different positions along said first direction and for producing a comparison level indicating the level of comparison of said primary set with said successive set in each of said different positions;

means for indicating the one of said comparison levels which indicates the best level of comparison produced for said successive set; and

means for determining the displacement between the position in which said given successive set is sensed and the position corresponding to said indicated comparison level.

14. The apparatus of claim 13 further including means for determining the time interval between the sensing by said first array of said primary set and the sensing by said second array of said given successive set;

and means for calculating a lateral image velocity component from said time interval and said displacement.