Vehicle regional scanner

• US 6,661,524 B2
• Filed: 07/09/2001
• Issued: 12/09/2003
• Est. Priority Date: 07/09/2001
• Status: Expired due to Fees

• Current Assignee: United Defense LP (BAE Systems Plc)
• Original Assignee: United Defense LP (BAE Systems Plc)
• Inventors: Smith, Thomas D., Henry, Peter
• Primary Examiner(s): Lee, John R.
• Assistant Examiner(s): QUASH, ANTHONY G
• Application Number:
  US09/902,058
• Publication Number:
  US 20030007160A1
• Time in Patent Office: 883 Days
• Field of Search: 356/614, 356/3.01, 356/3.02, 56/102.F
• US Class Current: 356/614
• CPC Class Codes: F41H 11/24 the elements being ploughs
• CPC Class Codes: F41H 11/28 using brushing or sweeping means or dozers to push mines lying on a surface aside; using means for removing mines intact from a surface
• CPC Class Codes: G01S 17/08 for measuring distance only indirect measurement G01S17/46; active triangulation systems G01S17/48
• CPC Class Codes: G01S 17/88 Lidar systems specially adapted for specific applications

Abstract

A method and apparatus for measuring ground height in front of a vehicle, such as a vehicle for clearing buried land mines, in which a scanning pulsed laser to used to scan along one or more lines in front of the vehicle, with such scanning being executed more slowly in certain regions where data is collected and more quickly in intermediate regions where data is not collected. The time of flight along those lines is measured, and using that measurement, the ground height calculated and stored, with the higher elevations being discarded as the representing the tops of vegetation and the lower elevations being representative of the ground height or elevation in front of blade. A dozer blade on the vehicle is then adjusted in response to the calculated height to position the blade for the proper depth of cut in order to effectively uncover and remove the buried mines.

Claims

1. A method for detecting the height of the ground covered with vegetation in front of a vehicle having an adjustable dozer blade, comprising the steps of:

scanning a laser beam in front of the vehicle along a path essentially transverse to the motion of the vehicle, wherein the beam traverses said path at a speed sufficiently slow to allow the beam to penetrate the vegetation and be reflected from the ground at some points along said path;

sensing the reflected light of the laser beam at a plurality of discrete points along said path;

determining from the sensed reflected laser light the time of flight of the laser beam at each of the plurality of points; and

calculating the height of the ground based upon the longest time of flight.

2. The method according to claim 1, wherein the path includes at least one intermediate segment and further comprising the steps of:

moving said beam along said intermediate segment at a speed much higher than said slow speed; and

ignoring the time of flight for light reflected during the traverse of the intermediate segment.

3. The method according to claim 2 wherein the intermediate segment defines left and right end segments for said path and further comprising the steps of:

separately sensing the reflected light of the laser beam at a plurality of discrete points along each of the end segments of said path;

separately determining from the sensed reflected laser light the time of flight of the laser beam at each of the plurality of points along each end segment; and

separately calculating the height of the ground for each end segment based upon the longest time of flight associated with the respective end segment.

4. The method, as claimed in claim 3, further comprising the step of raising and lowering the ends of the dozer blade in front of the vehicle according to the determined ground height at each of said end segments so that the blade will maintain a relatively uniform depth of cut.

5. The method according to claim 1, comprising the steps of:

passing a second laser beam along a second line in front of the vehicle, wherein said second line has a first, second and third scan segments separated by a first and second intermediate segments;

moving said beam in said scan segments at speeds sufficiently slow to permit the light from said beam to penetrate to the ground and be reflected;

moving said beam in said intermediate segments at a speed higher than said slow speed;

sensing reflected second laser light from only along said scan segments of said second line;

determining from sensed reflected laser light the time of flight of the laser beam at a plurality of points in said scan segments; and

calculating the height of the ground from the determined time of flight.

6. The method according to claim 5, and further comprising the step of, comparing the heights along said second path with those along said first path to determine the change in height therebetween.

7. The method according to claim 6 further comprising the step of initiating the raising and lowering the blade in anticipation of said change in height.

8. A method for detecting the height of the ground covered with vegetation in front of a vehicle having an adjustable dozer blade, comprising the steps of:

scanning a plurality of laser beams in front of the vehicle, each of said beams following a path essentially transverse to the motion of the vehicle, wherein each beam traverses said its associated path at a speed sufficiently slow to allow the beam to penetrate the vegetation and be reflected from the ground at some points along said path;

sensing the reflected light of each laser beam at a plurality of discrete points along its associated path;

determining from the sensed reflected laser light the time of flight of each laser beam at each of the plurality of points; and

calculating the height of the ground along each path based upon the longest time of flight.

9. The method according to claim 8 wherein a single laser beam is split into said plurality of beams.

10. A vehicle comprising:

a dozer blade mounted on the vehicle and capable of being raised and lowered and tilted;

a propulsion system connected to move the vehicle in a forward direction;

a laser for creating a laser beam mounted on the vehicle;

a scanner for scanning the laser beam along a path in front of the vehicle at a speed slow enough to penetrate vegetation and be reflected by the ground;

a sensor for sensing reflected laser light mounted on the chassis adjacent to said scanner; and

a processor for determining from sensed reflected laser light the time of flight of the laser beam at a plurality of points along said path;

a memory device for storing the determined time of flight for each of said plurality of points;

and said processor calculating the height of the ground based on the longest of the determined times of flight.

11. The vehicle according to claim 10, and further comprising:

adjustable cylinders for raising, lowering and tilting the blade; and

said cylinders are adjusted responsive to the height calculated by said processor so that the blade maintains a substantially uniform depth of cut.

12. The vehicle according to claim 10, wherein said path has end segments separated by an intermediate segment and said scanner scans along the end segments at said slow speed and along said intermediate segment at a greater speed;

and

said memory device stores only the time of flight at points along said end segments.

13. The vehicle according to claim 12, wherein said processor is adapted to calculate the heights at each of the end segments to determine the transverse slope of the ground and said cylinders are adjusted to tilt said blade to conform to said slope.

14. The vehicle according to claim 10, where in said path has central and end segments with an intermediate segment between each end segment and the central segment,

said scanner scans along said central and end segments at said slow speed and along said intermediate segments at a greater speed;

and;

said memory device stores only the times of flight at points along said central and end segments.

15. The vehicle, as claimed in claim 10, further comprising:

means for providing a second laser beam for scanning along said blade;

a second sensor for sensing light reflected from said blade; and

said processor adapted to determine from said blade reflected light the present position of said blade.