ALTIMETER USING IMAGING CAPABILITY

• US 20160286141A1
• Filed: 03/23/2015
• Published: 09/29/2016
• Est. Priority Date: 03/23/2015
• Status: Abandoned Application

• Current Assignee: Rosemount Aerospace, Inc. (Rtx Corporation)
• Original Assignee: Rosemount Aerospace, Inc. (Rtx Corporation)
• Inventors: Ell, Todd A.
• Application Number:
  US14/665,294
• Publication Number:
  US 20160286141A1
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01C 3/08 Use of electric radiation detectors
• CPC Class Codes: G01C 3/26 using a parallactic triangle with fixed angles and a base of variable length, at, near, or formed by the object
• CPC Class Codes: G01C 5/00 Measuring height; Measuring distances transverse to line of sight; Levelling between separated points; Surveyors' levels G01C3/20, G01C3/30 take precedence
• CPC Class Codes: G01C 5/005 altimeters for aircraft G01C5/02, G01C5/06 take precedence
• CPC Class Codes: G01S 17/46 Indirect determination of position data
• CPC Class Codes: H04N 23/20 for generating image signals from infrared radiation only
• CPC Class Codes: H04N 23/56 provided with illuminating means
• CPC Class Codes: H04N 5/33 Transforming infrared radiation cameras or camera modules for generating image signals from infrared radiation H04N23/20; circuitry of SSIS for transforming infrared radiation into image signals H04N25/20

Abstract

An altimeter includes a laser projector for projecting a pattern onto a surface and a camera for viewing the projected pattern. An image processor is operatively connected to the laser projector and camera for determining distance to the surface based on cross-correlation of the projected and imaged patterns. The camera can be a short wave infrared (SWIR) camera. The projected pattern can be a pseudo-random, fixed pattern.

Claims

1. An altimeter comprising:

a laser projector for projecting a pattern onto a surface;

a camera for viewing the projected pattern; and

an image processor operatively connected to the laser projector and camera for determining distance to the surface based on cross-correlation of the projected and imaged patterns.

2. The altimeter of claim 1, wherein the camera is a SWIR camera.

3. The altimeter of claim 1, wherein the pattern is a pseudo-random, fixed pattern.

4. The altimeter of claim 1, wherein the image processor is configured to determine correlation peaks between the imaged pattern and the expected pattern indicating when the patterns align.

5. The altimeter of claim 4, wherein the image processor is configured to define a peak distance between a center of the projected pattern and a center of the imaged pattern.

6. The altimeter of claim 5, wherein the image processor is configured to determine height above the surface as a function of a distance between the laser projector and the camera and the peak distance.

7. The altimeter of claim 1, wherein the laser projector and camera are fixedly attached and co-boresighted such that resolution of the imaged pattern is scaleable to a resolution of the projected pattern.

8. The altimeter of claim 1, wherein the image processor is configured to control timing and repetition of the pattern emitted from the laser projector.

9. The altimeter of claim 8, wherein the image processor interfaces to a readout integrated circuit of the camera to control the exposure time and frame rate of the camera.

10. A method for determining distance to a surface, the steps comprising:

projecting a pattern onto a surface from a laser projector;

viewing the projected pattern using a camera and storing an imaged pattern; and

cross-correlating the imaged pattern with an expected pattern using an image processor operatively connected to the laser projector and camera.

11. The method of claim 10, further comprising determining correlation peaks of the imaged pattern and expected pattern such that a peak distance is defined between a center of the projected pattern and a center of the imaged pattern.

12. The method of claim 11, further comprising calculating a height above the surface as a function of a distance between the laser projector and the camera and the peak distance.

13. The method of claim 10, further comprising controlling the repetition rate of the projected pattern and exposure of the camera with the image processor.

14. The method of claim 10, wherein the camera is a SWIR.