Lidar scanner calibration

• US 9,971,024 B2
• Filed: 06/20/2017
• Issued: 05/15/2018
• Est. Priority Date: 11/22/2013
• Status: Active Grant

• Current Assignee: Uatc, LLC (Uber Technologies, Inc.)
• Original Assignee: Uber Technologies, Inc.
• Inventors: Schwarz, Brent S., Haslim, James A., Iturraran, Nicholas M., Karasoff, Michael D.
• Primary Examiner(s): Geisel, Kara E
• Assistant Examiner(s): Smith, Maurice
• Application Number:
  US15/627,700
• Publication Number:
  US 20170307738A1
• Time in Patent Office: 329 Days
• CPC Class Codes: G01S 17/14 wherein a voltage or current pulse is initiated and terminated in accordance with the pulse transmission and echo reception respectively, e.g. using counters
• CPC Class Codes: G01S 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 7/4812 transmitted and received beams following a coaxial path
• CPC Class Codes: G01S 7/4818 using optical fibres
• CPC Class Codes: G01S 7/4861 Circuits for detection, sampling, integration or read-out
• CPC Class Codes: G01S 7/497 Means for monitoring or calibrating
• CPC Class Codes: G01S 7/4972 Alignment of sensor

Abstract

A LiDAR sensor can include a laser configured to output electromagnetic pulses and an optical splitter positioned to split each of the electromagnetic pulses into (i) at least one calibration pulse, and (ii) at least one external pulse directed toward an object external from the LiDAR sensor. The LiDAR sensor can further include a photodetector configured to detect the at least one calibration pulse and a reflected pulse based on the at least one external pulse reflecting from the object. The LiDAR sensor can further include a processor configured to adjust a bias voltage of the photodetector based on the at least one calibration pulse.

Claims

1. A LiDAR sensor comprising:

a laser configured to output electromagnetic pulses;

an optical splitter positioned to split each of the electromagnetic pulses into (i) at least one calibration pulse, and (ii) at least one external pulse directed toward an object external from the LiDAR sensor;

a photodetector configured to detect the at least one calibration pulse and a reflected pulse based on the at least one external pulse reflecting from the object; and

a processor configured to adjust a bias voltage of the photodetector based on the at least one calibration pulse.

2. The LiDAR sensor of claim 1, wherein the photodetector comprises an avalanche photodiode.

3. The LiDAR sensor of claim 2, wherein the processor adjusts the bias voltage of the avalanche photodiode based on the at least one calibration pulse prior to the avalanche photodiode detecting the reflected pulse to compensate for a temperature change of the avalanche photodiode.

4. The LiDAR sensor of claim 3, wherein the temperature change affects a gain of the avalanche photodiode, and wherein the processor adjusts the bias voltage to maintain the gain of the avalanche photodiode as substantially constant.

5. The LiDAR sensor of claim 1, wherein the photodetector generates a response pulse for each of the at least one detected calibration pulse and the reflected pulse, and wherein the processor adjusts the bias voltage of the photodetector based on the response pulse corresponding to the at least one detected calibration pulse.

6. The LiDAR sensor of claim 1, wherein the optical splitter comprises one or more beam-splitters.

7. The LiDAR sensor of claim 1, wherein the optical splitter comprises one or more fiber optic couplers.

8. The LiDAR sensor of claim 1, wherein the LiDAR sensor is mounted to a vehicle.

9. The LiDAR sensor of claim 1, wherein the laser comprises a fiber laser.

10. The LiDAR sensor of claim 1, wherein the processor is further configured to determine a time of flight of the reflected pulse to determine a distance from the LiDAR sensor to the object.

11. A method performed by a processor, the method comprising:

outputting a laser pulse using a laser of a LiDAR sensor, the laser pulse being split by an optical splitter into (i) at least one calibration pulse, and (ii) at least one external pulse directed toward an object external from the LiDAR sensor;

detecting the at least one calibration pulse from a photodetector of the LiDAR sensor;

based on the at least one calibration pulse, adjusting a bias voltage of the photodetector; and

detecting a reflected pulse from the photodetector, the reflected pulse being based on the at least one external pulse reflecting from the object.

12. The method of claim 11, wherein the photodetector comprises an avalanche photodiode.

13. The method of claim 12, wherein the processor adjusts the bias voltage of the avalanche photodiode based on the at least one calibration pulse prior to detecting the reflected pulse to compensate for a temperature change of the avalanche photodiode.

14. The method of claim 13, wherein the temperature change affects a gain of the avalanche photodiode, and wherein the processor adjusts the bias voltage to maintain the gain of the avalanche photodiode as substantially constant.

15. The method of claim 11, wherein the processor adjusts the bias voltage of the photodetector based on a response pulse from the photodetector, the response pulse corresponding to the at least one detected calibration pulse.

16. The method of claim 11, wherein the optical splitter comprises one or more beam-splitters.

17. The method of claim 11, wherein the optical splitter comprises one or more fiber optic couplers.

18. The method of claim 11, wherein the LiDAR sensor is mounted to a vehicle.

19. The method of claim 11, further comprising:

determining a time of flight of the reflected pulse; and

based on the time of flight, determining a distance from the LiDAR sensor to the object.

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

output a laser pulse using a laser of a LiDAR sensor, the laser pulse being split by an optical splitter into (i) at least one calibration pulse, and (ii) at least one external pulse directed toward an object external from the LiDAR sensor;

detect the at least one calibration pulse from a photodetector of the LiDAR sensor;

based on the at least one calibration pulse, adjust a bias voltage of the photodetector of the LiDAR sensor; and

detect a reflected pulse from the photodetector, the reflected pulse being based on the at least one external pulse reflecting from the object.