Electro-optical range finding and speed detection system

• US 5,642,299 A
• Filed: 08/12/1996
• Issued: 06/24/1997
• Est. Priority Date: 09/01/1993
• Status: Expired due to Term

• Current Assignee: Larry C. Hardin
• Original Assignee: Larry C. Hardin
• Inventors: Nash, Larry V., Hardin, Larry C.
• Primary Examiner(s): Ramirez, Ellis B.
• Assistant Examiner(s): Stamber, Eric W.
• Application Number:
  US08/693,681
• Time in Patent Office: 316 Days
• Field of Search: 364/565, 364/560, 364/561, 364/426.04, 364/460, 364/461, 364/436, 382/100, 382/103, 382/106, 382/107, 324/160, 324/161, 340/936, 340/937, 340/942, 356/3, 356/4.01, 356/28, 356/28.5
• US Class Current: 702/142
• CPC Class Codes: G01C 3/10 using a parallactic triangle with variable angles and a base of fixed length in the observation station, e.g. in the instrument
• CPC Class Codes: G01P 3/38 using photographic means
• CPC Class Codes: G01P 3/68 using optical means, i.e. using infrared, visible, or ultraviolet light G01P3/80 takes precedence ; by reflection of waves G01S17/58

Abstract

A passive optical speed and distance measuring system includes a pair of camera lenses positioned along a common baseline a predetermined distance apart and controlled by an operator to capture images of a target at different times. The camera lenses are focused on light sensitive pixel arrays which capture target images at offset positions in the line scans of the pixel arrays. A video signal processor with a computer determines the location of the offset positions and calculates the range to the target by solving the trigonometry of the triangle formed by the two camera lenses and the target. Once the range to the target is known at two different times the speed of the target is calculated.

Claims

1. An electro-optical range finding system comprising:

(a) a pair of optical lenses, each lens in said pair of optical lenses oriented along a line of sight towards a target, said pair of optical lenses positioned a predetermined width apart along a common baseline;

(b) at least one light sensitive device responsive to light from each lens in said pair of optical lenses for forming first and second one-dimensional images of said target on first and second linear pixel arrays;

(c) a video correlator for comparing said first and second one-dimensional images on said first and second linear pixel arrays to find an offset pixel shift between said first and second one-dimensional images on said first and second linear pixel arrays, respectively; and

(d) a calculator for determining a range to the target as a trigonometric function of said offset pixel shift and said predetermined width between said pair of optical lenses.

2. The electro-optical system of claim 1 wherein there is a separate light sensitive device for each optical lens in said pair of optical lenses.

3. The electro-optical range finding system of claim 2 wherein said light sensitive devices are video cameras, each video camera containing a charge coupled device.

4. The electro-optical range finding system of claim 1 wherein said video correlator includes a computer programmed with a correlation algorithm for finding a global null of sums of differences between said first and second one-dimensional images to determine said offset pixel shift.

5. In an electro-optical ranging device, a method of determining a range to a target object comprising the steps of:

(a) providing first and second optical lenses spaced a predetermined distance apart along a common baseline, said optical lenses having overlapping fields of view;

(b) directing light from said first and second optical lenses onto at least one optically sensitive device;

(c) electronically scanning said light sensitive device in a region thereon responsive to said first optical lens to establish a one-dimensional template image along a predetermined scan line;

(d) successively electronically scanning said light sensitive device in a region thereon responsive to said second optical lens to determine a plurality of one-dimensional images;

(e) comparing each of said plurality of one-dimensional images with said one-dimensional template image to determine which of said plurality of one-dimensional images most closely correlates with said template image;

(f) determining a line distance between said template image and said one-dimensional image which most closely correlates with said template image; and

(g) calculating a range to said target object as a function of said line distance and said predetermined distance.

6. The method of claim 5 wherein said light sensitive device is electronically scanned in a direction perpendicular to said base line.

7. The method of claim 6 wherein said optical lenses are mounted a predetermined vertical distance apart along a vertical common baseline.