Light detection and ranging (LIDAR) device range aliasing resilience by multiple hypotheses

Patent metadata

Field	Value
Publication number	US-10754033-B2
Application number	US-201715638607-A
Country	US
Kind code	B2
Filing date	Jun 30, 2017
Priority date	Jun 30, 2017
Publication date	Aug 25, 2020
Grant date	Aug 25, 2020

Abstract

A computing system may operate a LIDAR device to emit light pulses in accordance with a time sequence including a time-varying dither. The system may then determine that the LIDAR detected return light pulses during corresponding detection periods for each of two or more emitted light pulses. Responsively, the system may determine that the detected return light pulses have (i) detection times relative to corresponding emission times of a plurality of first emitted light pulses that are indicative of a first set of ranges and (ii) detection times relative to corresponding emission times of a plurality of second emitted light pulses that are indicative of a second set of ranges. Given this, the system may select between using the first set of ranges as a basis for object detection and using the second set of ranges as a basis for object detection, and may then engage in object detection accordingly.

First claim

I claim:

1. A method comprising:
operating, by a computing system, a Light Detection and Ranging (LIDAR) device to emit light pulses at emission times in accordance with an emission time sequence, wherein the emission time sequence includes a time-varying dither, and to detect return light pulses in accordance with a detection time sequence, wherein the detection time sequence includes, for each emitted light pulse, a corresponding detection period for detection of a corresponding return light pulse, and wherein a detection time of a return light pulse relative to a corresponding emission time of a corresponding emitted light pulse is indicative of a range to an object that reflected the corresponding emitted light pulse;
making a determination, by the computing system, that the LIDAR device detected return light pulses during corresponding detection periods for each of two or more emitted light pulses;
in response to making the determination, determining, by the computing system, that (i) the detected return light pulses have detection times relative to corresponding emission times of a plurality of first emitted light pulses that are indicative of a first set of ranges and (ii) the detected return light pulses have detection times relative to corresponding emission times of a plurality of second emitted light pulses that are indicative of a second set of ranges;
selecting, by the computing system, between using the first set of ranges as a basis for object detection and using the second set of ranges as a basis for object detection; and
engaging, by the computing system, in object detection in accordance with the selecting.

2. The method of claim 1 , wherein making a determination that the LIDAR device detected return light pulses during corresponding detection periods for each of two or more emitted light pulses comprises making a determination that the LIDAR device detected return light pulses during corresponding detection periods for each of the plurality of first emitted light pulses.

3. The method of claim 2 ,
wherein the LIDAR device has a nominal unambiguous detection range,
wherein ranges of the first set are within the nominal unambiguous detection range of the LIDAR device, and
wherein ranges of the second set are outside the nominal unambiguous detection range of the LIDAR device.

4. The method of claim 2 , wherein ranges of the second set are greater than ranges of the first set.

5. The method of claim 1 , further comprising:
determining, by the computing system, that the second set of ranges is representative of at least one known object,
wherein the selecting comprises, in response to determining that the second set of ranges is representative of at least one known object, selecting use of the second set of ranges as a basis for object detection.

6. The method of claim 1 , further comprising:
determining, by the computing system, that the second set of ranges is not representative of at least one known object,
wherein the selecting comprises, in response to determining that the second set of ranges is not representative of at least one known object, selecting use of the first set of ranges as a basis for object detection.

7. The method of claim 1 , further comprising:
determining, by the computing system, that ranges of the second set are substantially similar to one another,
wherein the selecting comprises, in response to determining that ranges of the second set are substantially similar to one another, selecting use of the second set of ranges as a basis for object detection.

8. The method of claim 1 , further comprising:
determining, by the computing system, that ranges of the second set are not substantially similar to one another,
wherein the selecting comprises, in response to determining that ranges of the second set are not substantially similar to one another, selecting use of the first set of ranges as a basis for object detection.

9. The method of claim 1 , wherein the LIDAR device is positioned on a vehicle, and wherein engaging in object detection in accordance with the selecting comprises, in accordance with the selecting, engaging in detection of objects positioned in an environment around the vehicle.

10. The method of claim 1 , wherein the LIDAR device is positioned on a vehicle, and wherein the computing system is configured to operate the vehicle based at least on scans by the LIDAR device of an environment around the vehicle.

11. A computing system comprising:
one or more processors;
a non-transitory computer readable medium; and
program instructions stored on the non-transitory computer readable medium and executable by the one or more processors to:
operate a Light Detection and Ranging (LIDAR) device to emit light pulses at emission times in accordance with an emission time sequence, wherein the emission time sequence includes a time-varying dither, and to detect return light pulses in accordance with a detection time sequence, wherein the detection time sequence includes, for each emitted light pulse, a corresponding detection period for detection of a corresponding return light pulse, and wherein a detection time of a return light pulse relative to a corresponding emission time of a corresponding emitted light pulse is indicative of a range to an object that reflected the corresponding emitted light pulse;
make a determination that the LIDAR device detected return light pulses during corresponding detection periods for each of two or more emitted light pulses;
in response to making the determination, determine that (i) the detected return light pulses have detection times relative to corresponding emission times of a plurality of first emitted light pulses that are indicative of a first set of ranges and (ii) the detected return light pulses have detection times relative to corresponding emission times of a plurality of second emitted light pulses that are indicative of a second set of ranges;
select between using the first set of ranges as a basis for object detection and using the second set of ranges as a basis for object detection; and
engage in object detection in accordance with the selecting.

12. The computing system of claim 11 , wherein the program instruction are further executable to:
determine that the second set of ranges is representative of at least one known object,
wherein the selecting comprises, in response to determining that the second set of ranges is representative of at least one known object, selecting use of the second set of ranges as a basis for object detection.

13. The computing system of claim 11 , wherein the program instruction are further executable to:
determine that ranges of the second set are substantially similar to one another,
wherein the selecting comprises, in response to determining that ranges of the second set are substantially similar to one another, selecting use of the second set of ranges as a basis for object detection.

14. The computing system of claim 11 , wherein the LIDAR device is positioned on a vehicle, wherein engaging in object detection in accordance with the further determination comprises, in accordance with the selecting, engaging in detection of objects positioned in an environment around the vehicle, and wherein the program instruction are further executable to operate the vehicle based at least on the detection of objects positioned in the environment around the vehicle.

15. A method comprising:
operating, by a computing system, a Light Detection and Ranging (LIDAR) device to emit light pulses at emission times in accordance with an emission time sequence, wherein the emissi

Assignees

• Waymo Llc

Inventors

• Shand Mark Alexander

Classifications

• B60W2420/408

  Radar; Laser, e.g. lidar · CPC title

• G01S7/4861 Primary

  Circuits for detection, sampling, integration or read-out · CPC title

• G01S17/10 Primary

  using transmission of interrupted, pulse-modulated waves (determination of distance by phase measurements G01S17/32) · CPC title

• G01S7/4865

  Time delay measurement, e.g. time-of-flight measurement, time of arrival measurement or determining the exact position of a peak (peak detection in noise, signal conditioning G01S7/487) · CPC title

• G01S17/42

  Simultaneous measurement of distance and other co-ordinates (indirect measurement G01S17/46) · CPC title