Methods of real time image enhancement of flash LIDAR data and navigating a vehicle using flash LIDAR data

• US 8,655,513 B2
• Filed: 03/11/2011
• Issued: 02/18/2014
• Est. Priority Date: 03/12/2010
• Status: Active Grant

• Current Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Original Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Inventors: Vanek, Michael D.
• Primary Examiner(s): Trammell, James P
• Assistant Examiner(s): MELTON, TODD M
• Application Number:
  US13/046,030
• Publication Number:
  US 20110224840A1
• Time in Patent Office: 1,075 Days
• Field of Search: None
• US Class Current: 701/16
• CPC Class Codes: G01S 17/58 Velocity or trajectory determination systems; Sense-of-movement determination systems
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 7/4808 Evaluating distance, position or velocity data

Abstract

A method for creating a digital elevation map (“DEM”) from frames of flash LIDAR data includes generating a first distance R_i from a first detector i to a first point on a surface S_i. After defining a map with a mesh Θ having cells k, a first array S(k), a second array M(k), and a third array D(k) are initialized. The first array corresponds to the surface, the second array corresponds to the elevation map, and the third array D(k) receives an output for the DEM. The surface is projected onto the mesh Θ, so that a second distance R_k from a second point on the mesh Θ to the detector can be found. From this, a height may be calculated, which permits the generation of a digital elevation map. Also, using sequential frames of flash LIDAR data, vehicle control is possible using an offset between successive frames.

Claims

1. A non-transitory computer-readable medium comprising computer-executable instructions that when executed by a processor, cause the processor to perform:

emitting a first emitted laser light from a flash LIDAR apparatus to a first surface;

capturing a first reflected light reflected from the first surface by an array of detectors of the flash LIDAR apparatus;

generating a first frame of flash LIDAR data from the first reflected light, the first frame of flash LIDAR comprising a first array of range data, wherein the first array of range data corresponds to a first array of distances from the array of detectors to a corresponding first set of surface coordinates;

selecting an elevation map with a mesh defining a plurality of cells;

projecting the first array of range data onto the mesh, thereby generating a first projection array;

emitting a second emitted laser light from the flash LIDAR apparatus to a second surface after a predetermined time interval;

capturing a second reflected light reflected from the second surface by the array of detectors of the flash LIDAR apparatus;

generating a second frame of flash LIDAR data from the second reflected light, the second frame of flash LIDAR data comprising an second array of range data, wherein the second array of range data corresponds to a second array of distances from the array of detectors to a corresponding second set of surface coordinates;

projecting the second array of range data onto the mesh, thereby generating a second projection array;

calculating a previously unknown optical offset by correlating the first projection array with the second projection array using at least the predetermined time interval; and

based upon the optical offset, calculating a change in position of a vehicle, wherein the change in position is configured to be provided to a navigation apparatus as input for navigational control of the vehicle.

2. The non-transitory computer-readable medium of claim 1, wherein an operational frequency of the flash LIDAR apparatus is 30 Hz and the predetermined time interval is inversely proportional to the operational frequency and 1/30^th of a second.

3. The non-transitory computer-readable medium of claim 1, further comprising:

calculating a variable for the navigation control of the vehicle.

4. The non-transitory computer-readable medium of claim 3, wherein the variable comprises the vehicle'"'"'s attitude.

5. The non-transitory computer-readable medium of claim 3, wherein the variable comprises the vehicle'"'"'s speed.

6. The non-transitory computer-readable medium of claim 3, wherein the variable comprises the vehicle'"'"'s acceleration.

7. The non-transitory computer-readable medium of claim 3, the vehicle having an attitude, a speed and an acceleration, and wherein the variable comprises the attitude, speed and acceleration.

8. The non-transitory computer-readable medium of claim 3, further comprising:

providing a visualization processor; and

generating a visual representation with the visualization processor from the optical offset.

9. The non-transitory computer-readable medium of claim 1, wherein the vehicle comprises a spacecraft, a robot, or a robotic arm.

10. A non-transitory computer-readable medium comprising computer-executable instructions that when executed by a processor, cause the processor to perform:

(a) emitting a laser light from a flash LIDAR apparatus to a surface at a predetermined time interval, wherein the flash LIDAR apparatus comprises a plurality of detectors;

(b) capturing a reflected light reflected from the surface by the plurality of detectors of the flash LIDAR apparatus;

(c) generating an array of range data points from the reflected light, wherein a range data point is calculated as an average of the distances from the plurality of points on the surface to the corresponding plurality of detectors of the LIDAR apparatus;

(d) selecting an elevation map with a mesh defining a plurality of cells corresponding to the plurality of points on the surface;

(e) generating a projection array of range data points by projecting the array of range data points onto the mesh;

(f) calculating an array of height data based on the array of range data points and the projection array of range data points; and

(g) correlating the array of height data with a prior array of height data to produce a third array of height data corresponding to the elevation map.

11. The non-transitory computer-readable medium of claim 10, wherein, if there is no prior array of height data, initializing the prior array of height data to zero.

12. The non-transitory computer-readable medium of claim 10, further comprising:

enhancing the resolution of the third height array by repeating steps (a) through (e) for a predetermined number of frames of flash LIDAR data.

13. The non-transitory computer-readable medium of claim 12, wherein the predetermined number of frames is 10.

14. The non-transitory computer-readable medium of claim 12, wherein enhancing the resolution of the third height array includes normalizing the third height array for each of the predetermined number of frames of flash LIDAR data.

15. The non-transitory computer-readable medium of claim 12, wherein enhancing the resolution is determined by an asymptotic relationship between a convergence of the third array of height data and the predetermined number of frames of flash LIDAR data.

16. The non-transitory computer-readable medium of claim 15, wherein the predetermined number of frames is 10.

17. A non-transitory computer-readable medium comprising computer-executable instructions that when executed by a processor, cause the processor to perform:

(a) generating an array of range data points from a laser light reflected from a plurality of points on a surface to a plurality of detectors of a LIDAR apparatus, wherein a range data point is calculated as an average of the distances from the plurality of points on the surface to the plurality of detectors of the LIDAR apparatus;

(b) selecting an elevation map with a mesh defining a plurality of cells corresponding to the plurality of points on the surface;

(c) generating a projection array of range data points by projecting the array of range data onto the mesh;

(d) calculating an array of height data based on the array of range data points and the projection array of range data points;

(e) correlating the array of height data with a prior array of height data to produce a third array of height data corresponding the elevation map;

enhancing the resolution of the third height array by repeating steps (a) through (e) for a predetermined number of frames of flash LIDAR data, wherein the predetermined number of frames of 10.

18. The non-transitory computer-readable medium of claim 17, wherein enhancing the resolution is determined by an asymptotic relationship between a convergence of the third array of height data and the predetermined number of frames of flash LIDAR data.