Calibration for an autonomous vehicle LIDAR module

• US 10,746,858 B2
• Filed: 08/17/2017
• Issued: 08/18/2020
• Est. Priority Date: 08/17/2017
• Status: Active Grant

• Current Assignee: Uatc, LLC (Uber Technologies, Inc.)
• Original Assignee: Uatc, LLC (Uber Technologies, Inc.)
• Inventors: Bradley, David McAllister, Yang, Gehua
• Primary Examiner(s): Hellner, Mark
• Application Number:
  US15/679,338
• Publication Number:
  US 20190056484A1
• Time in Patent Office: 1,097 Days
• Field of Search: 356 501
• CPC Class Codes: G01S 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 17/66 Tracking systems using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 17/931 of land vehicles
• CPC Class Codes: G01S 7/4815 using multiple transmitters
• CPC Class Codes: G01S 7/4972 Alignment of sensor

Abstract

A LIDAR calibration system can detect a first set of return signals from a plurality of fiducial targets in a calibration facility for a lower set of laser scanners of the LIDAR module. The LIDAR calibration system can also detect a second set of return signals from one or more planar surfaces associated with a calibration trigger location on a road network for an upper set of laser scanners of the LIDAR module. Based on the first and second sets of return signals, the LIDAR calibration system can generate a set of calibration transforms to adjust a set of intrinsic parameters of the LIDAR module.

Claims

1. A light-detection and ranging (LIDAR) calibration system for an autonomous vehicle, the LIDAR calibration system comprising:

one or more processors; and

one or more memory resources storing instructions that, when executed by the one or more processors, cause the LIDAR calibration system to;

for a lower set of laser scanners of a LIDAR module, detect a first set of return signals from a plurality of fiducial targets in a calibration facility, the lower set of laser scanners each having an elevation angle below a threshold elevation angle;

for an upper set of laser scanners of the LIDAR module, detect a second set of return signals from one or more planar surfaces associated with a calibration trigger location on a road network;

the upper set of laser scanners each having an elevation angle above the threshold elevation angle; and

generate a set of calibration transforms to adjust a set of intrinsic parameters of the LIDAR module based on the first and second sets of return signals.

2. The LIDAR calibration system of claim 1, wherein the LIDAR calibration system is included on-board the autonomous vehicle.

3. The LIDAR calibration system of claim 1, wherein the LIDAR calibration system is remote to the autonomous vehicle, and wherein the executed instructions further cause the LIDAR calibration system to:

receive, from the autonomous vehicle over one or more networks, a log set comprising LIDAR data that includes the first and second sets of return signals from the LIDAR module.

4. The LIDAR calibration system of claim 1, wherein the calibration trigger location corresponds to a map trigger included in a given localization sub-map stored on-board the autonomous vehicle.

5. The LIDAR calibration system of claim 1, wherein the executed instructions further cause the LIDAR calibration system to:

track the autonomous vehicle as the autonomous vehicle operates throughout a given region; and

when the autonomous vehicle intersects the calibration trigger location, initiate a calibration check for the upper set of laser scanners.

6. The LIDAR calibration system of claim 5, wherein the calibration check comprises determining, for each laser scanner of the upper set of laser scanners, whether a current set of return signals from the laser scanner are within a nominal set of ranges corresponding to the set of intrinsic parameters.

7. The LIDAR calibration system of claim 1, wherein the set of intrinsic parameters of the LIDAR module comprises a plurality of offset angles for each laser scanner of the LIDAR module.

8. The LIDAR calibration system of claim 1, wherein the set of intrinsic parameters of the LIDAR module comprises the elevation angle for each laser scanner of the LIDAR module.

9. The LIDAR calibration system of claim 1, wherein the executed instructions further cause the LIDAR calibration system to:

determine range measurements to the plurality of fiducial targets and the one or more planar surfaces based on image data from at least one camera of the autonomous vehicle; and

correlate the range measurements with the first and second sets of return signals to determine variations in the intrinsic parameters of the LIDAR module;

wherein the executed instructions cause the LIDAR calibration system to generate the set of calibration transforms to adjust for the variations in the intrinsic parameters of the LIDAR module.

14. The non-transitory computer-readable medium of claim 1, wherein the executed instructions further cause the one or more processors to:

track the autonomous vehicle as the autonomous vehicle operates throughout a given region; and

when the autonomous vehicle intersects the calibration trigger location, initiate a calibration check for the upper set of laser scanners.

15. The non-transitory computer-readable medium of claim 14, wherein the calibration check comprises determining, for each laser scanner of the upper set of laser scanners, whether a current set of return signals from the laser scanner are within a nominal set of ranges corresponding to the set of intrinsic parameters.

18. The non-transitory computer-readable medium of claim 1, wherein the executed instructions further cause the one or more processors to:

determine range measurements to the plurality of fiducial targets and the one or more planar surfaces based on image data from at least one camera of the autonomous vehicle; and

correlate the range measurements with the first and second sets of return signals to determine variations in the intrinsic parameters of the LIDAR module;

wherein the executed instructions cause the one or more processors to generate the set of calibration transforms to adjust for the variations in the intrinsic parameters of the LIDAR module.

10. A non-transitory computer-readable medium storing instructions that, when executed by one or more processors, cause the one or more processors to:

for a lower set of laser scanners of a LIDAR module of an autonomous vehicle, detect a first set of return signals from a plurality of fiducial targets in a calibration facility, the lower set of laser scanners each having an elevation angle below a threshold elevation angle;

for an upper set of laser scanners of the LIDAR module, detect a second set of return signals from one or more planar surfaces associated with a calibration trigger location on a road network, the upper set of laser scanners each having an elevation angle above the threshold elevation angle; and

generate a set of calibration transforms to adjust a set of intrinsic parameters of the LIDAR module based on the first and second sets of return signals.

11. The non-transitory computer-readable medium of claim 10, wherein the one or more processors are included on-board the autonomous vehicle.

12. The non-transitory computer-readable medium of claim 10, wherein the one or more processors are remote to the autonomous vehicle, and wherein the executed instructions further cause the one or more processors to:

receive, from the autonomous vehicle over one or more networks, a log set comprising LIDAR data that includes the first and second sets of return signals from the LIDAR module.

13. The non-transitory computer-readable medium of claim 10, wherein the calibration trigger location corresponds to a map trigger included in a given localization sub-map stored on-board the autonomous vehicle.

16. The non-transitory computer-readable medium of claim 10, wherein the set of intrinsic parameters of the LIDAR module comprises a plurality of offset angles for each laser scanner of the LIDAR module.

17. The non-transitory computer-readable medium of claim 10, wherein the set of intrinsic parameters of the LIDAR module comprises the elevation angle for each laser scanner of the LIDAR module.

19. A computer-implemented method of calibrating a LIDAR module of an autonomous vehicle, the method comprising:

for a lower set of laser scanners of the LIDAR module, detecting a first set of return signals from a plurality of fiducial targets in a calibration facility, the lower set of laser scanners each having an elevation angle below a threshold elevation angle;

for an upper set of laser scanners of the LIDAR module, detect a second set of return signals from one or more planar surfaces associated with a calibration trigger location on a road network;

the upper set of laser scanners each having an elevation angle above the threshold elevation angle; and

generate a set of calibration transforms to adjust a set of intrinsic parameters of the LIDAR module based on the first and second sets of return signals.

20. The method of claim 19, further comprising:

determining range measurements to the plurality of fiducial targets and the one or more planar surfaces based on image data from at least one camera of the autonomous vehicle; and

correlating the range measurements with the first and second sets of return signals to determine variations in the intrinsic parameters of the LIDAR module;

wherein the executed instructions cause the one or more processors to generate the set of calibration transforms to adjust for the variations in the intrinsic parameters of the LIDAR module.