Method and system for adaptive scanning with optical ranging systems

Patent metadata

Field	Value
Publication number	US-11624828-B2
Application number	US-201716464108-A
Country	US
Kind code	B2
Filing date	Nov 21, 2017
Priority date	Nov 30, 2016
Publication date	Apr 11, 2023
Grant date	Apr 11, 2023

Abstract

Techniques for adaptive scanning with a laser scanner include obtaining range measurements at a coarse angular resolution and determining a range gate subset and a characteristic range. A fine angular resolution is based on the characteristic range and a target spatial resolution. If the fine angular resolution is finer than the coarse angular resolution, then a minimum vertical angle and maximum vertical angle is determined for a horizontal slice of the subset of angular width based on the first angular resolution. The scanning laser ranging system is then operated to obtain second range measurements at the second angular resolution in the slice between the minimum vertical angle and the maximum vertical angle. In some embodiments, the scanning is repeated for each horizontal slice in the range gate subset using a minimum vertical angle and maximum vertical angle for that slice.

First claim

What is claimed is:

1. A method for operating a scanning laser ranging system, comprising:
operating the scanning laser ranging system, using a first angular resolution, to obtain a plurality of first range measurements in a field of view of the scanning laser ranging system;
assigning a second angular resolution to a particular range gate of a plurality of range gates using one or more first range measurements corresponding to the particular range gate of the plurality of range gates;
operating the scanning laser ranging system, using the second angular resolution assigned to the particular range gate of the plurality of range gates, to obtain a plurality of second range measurements; and
controlling an autonomous vehicle using the plurality of second range measurements.

2. The method of claim 1 , wherein assigning the second angular resolution to the particular range gate of the plurality of range gates comprises assigning the second angular resolution using a target spatial resolution for the particular range gate.

3. The method of claim 2 , wherein the first angular resolution is larger than the target spatial resolution.

4. The method of claim 2 , further comprising determining the target spatial resolution using at least one of a predetermined value or a predetermined fraction of a size of an object in the field of view, the predetermined value is less than or equal to ten centimeters.

5. The method of claim 1 , wherein operating the scanning laser ranging system to obtain at least one of the plurality of first range measurements or the plurality of second range measurements comprises operating the scanning laser ranging system to scan using a saw-tooth scan trajectory.

6. The method of claim 1 , wherein the first angular resolution is about ten to one hundred times the second angular resolution.

7. The method of claim 1 , further comprising determining, using a characteristic range of the particular range gate of the plurality of range gates, a reference path delay for obtaining the plurality of second range measurements, wherein operating the scanning laser ranging system comprises delaying a reference signal used by the scanning laser ranging system to obtain the plurality of second range measurements by the reference path delay.

8. The method of claim 1 , wherein operating the scanning laser system to obtain the plurality of second range measurements comprises operating the scanning laser system to avoid scanning angle spaces with no returns.

9. The method of claim 1 , wherein operating the scanning laser system to obtain the plurality of first range measurements comprises using the first angular resolution as a vertical angular resolution and a third angular resolution different than the first angular resolution as a horizontal angular resolution.

10. The method of claim 1 , wherein the particular range gate of the plurality of range gates is associated with a portion of an angular space of the field of view of the scanning laser ranging system, and the one or more first range measurements are greater than a minimum range assigned to the particular range gate and less than a maximum range assigned to the range gate.

11. A light detection and ranging (LIDAR) system, comprising:
a laser source configured to generate an optical signal;
a modulator configured to modulate at least one of a frequency or a phase of the optical signal;
one or more scanning optics configured to transmit the modulated optical signal; and
a processing circuit configured to:
operate the one or more scanning optics, using a first angular resolution, to obtain a plurality of first range measurements in a field of view of the one or more scanning optics;
assign a second angular resolution to a particular range gate of a plurality of range gates using one or more first range measurements corresponding to the particular range gate of the plurality of range gates;
operate the one or more scanning optics, using the second angular resolution assigned to each of the plurality of range gates, to obtain a plurality of second range measurements; and
control an autonomous vehicle using the plurality of second range measurements.

12. The LIDAR system of claim 11 , wherein the processing circuit is configured to assign the second angular resolution to the particular range gate of the plurality of range gates using a target spatial resolution for the particular range gate of the plurality of range gates.

13. The LIDAR system of claim 12 , wherein the first angular resolution is larger than the target angular resolution.

14. The LIDAR system of claim 11 , wherein the processing circuit is configured to operate the scanning optics to scan using a saw-tooth scan trajectory to obtain at least one of the plurality of first range measurements or the plurality of second range measurements.

15. The LIDAR system of claim 11 , wherein the first angular resolution is about ten to one hundred times the second angular resolution.

16. The LIDAR system of claim 11 , wherein the processing circuit is configured to determine a reference path delay for obtaining the plurality of second range measurements using a characteristic range of the particular range gate of the plurality of range gates and delay a reference signal used to obtain the plurality of second range measurements by the reference path delay.

17. The LIDAR system of claim 11 , wherein the processing circuit is configured to operate the one or more scanning optics to avoid scanning angle spaces with no returns to obtain the plurality of second range measurements.

18. The LIDAR system of claim 11 , further comprising a detector array configured to receive a return signal responsive to the modulated optical signal transmitted by the one or more scanning optics, wherein the processing circuit is configured to determine at least one second range measurement using the return signal.

19. A non-transitory computer-readable medium comprising processor-executable instructions that when executed by one or more processors, cause the one or more processors to:
control a scanning laser ranging system, using a first angular resolution, to obtain a plurality of first range measurements in a field of view of the scanning laser ranging system;
assign a second angular resolution to a particular range gate of a plurality of range gates using one or more first range measurements corresponding to the particular range gate of the plurality of range gates;
control the scanning laser ranging system, using the second angular resolution assigned to the particular of the plurality of range gates, to obtain a plurality of second range measurements; and
control an autonomous vehicle using the plurality of second range measurements.

20. The non-transitory computer-readable medium of claim 19 , comprising instructions that cause the one or more processors to control the autonomous vehicle to avoid a collision with an object.

Assignees

• Blackmore Sensors & Analytics Llc

Inventors

• Crouch Stephen C
• Reibel Randy R
• Curry James
• Berg Trenton

Classifications

• G01S17/34

  using transmission of continuous, frequency-modulated waves while heterodyning the received signal, or a signal derived therefrom, with a locally-generated signal related to the contemporaneously transmitted signal · CPC title

• G01S17/18

  wherein range gates are used · CPC title

• G01S17/89 Primary

  for mapping or imaging · CPC title

• G01S7/4817 Primary

  relating to scanning · CPC title

• G01S7/497

  Means for monitoring or calibrating · CPC title