Time-division multiple access scanning for crosstalk mitigation in light detection and ranging (lidar) devices

Patent metadata

Field	Value
Publication number	US-12406507-B2
Application number	US-202217821535-A
Country	US
Kind code	B2
Filing date	Aug 23, 2022
Priority date	Aug 23, 2022
Publication date	Sep 2, 2025
Grant date	Sep 2, 2025

Abstract

Example embodiments relate to time-division multiple access scanning for crosstalk mitigation in light detection and ranging (lidar) devices. An example embodiment includes a method. The method includes emitting a first group of light signals into a surrounding environment. The first group of light signals corresponds to a first angular resolution. The method also includes detecting, during a first listening window, a first group of reflected light signals. Additionally, the method includes emitting a second group of light signals into the surrounding environment. The second group of light signals corresponds to a second angular resolution with respect to the surrounding environment. The second angular resolution is lower than the first angular resolution. Further, the method includes detecting a second group of reflected light signals from the surrounding environment. In addition, the method includes synthesizing, by a controller of the lidar device, a dataset usable to generate one or more point clouds.

First claim

What is claimed is:

1. A method comprising:
emitting, from a first group of light emitters of a light detection and ranging (lidar) device, a first group of light signals into a surrounding environment, wherein the first group of light signals corresponds to a first angular resolution with respect to the surrounding environment;
detecting, by a first group of light detectors of the lidar device during a first listening window, a first group of reflected light signals from the surrounding environment, wherein the first group of reflected light signals corresponds to reflections of the first group of light signals from objects in the surrounding environment;
emitting, from a second group of light emitters of the lidar device, a second group of light signals into the surrounding environment, wherein the second group of light emitters of the lidar device represents a subset of the first group of light emitters of the lidar device, wherein the second group of light signals corresponds to a second angular resolution with respect to the surrounding environment, and wherein the second angular resolution is lower than the first angular resolution;
detecting, by a second group of light detectors of the lidar device during a second listening window, a second group of reflected light signals from the surrounding environment, wherein the second group of light detectors of the lidar device represents a subset of the first group of light detectors of the lidar device, wherein the second group of reflected light signals corresponds to reflections of the second group of light signals from objects in the surrounding environment, and wherein a duration of the second listening window is shorter than a duration of the first listening window; and
synthesizing, by a controller of the lidar device, a dataset usable to generate one or more point clouds, wherein the dataset is based on the detected first group of reflected light signals and the detected second group of reflected light signals, and wherein synthesizing the dataset comprises, for each of the detected reflected light signals in the second group of detected reflected light signals:
determining a second target distance based on the respective detected reflected light signal;
determining a first target distance based on a corresponding detected reflected light signal in the first group of detected reflected light signals, wherein the corresponding detected reflected light signal in the first group of detected reflected light signals was detected by the same light detector within the lidar device;
determining a difference between the second target distance and the first target distance; and
including the second target distance or the first target distance in the dataset if the difference is less than a threshold difference value.

2. The method of claim 1 , further comprising:
emitting, from a third group of light emitters of the lidar device, a third group of light signals into the surrounding environment, wherein the third group of light emitters of the lidar device represents a different subset of the first group of light emitters of the lidar device than the second group of light emitters, wherein the third group of light signals corresponds to a third angular resolution with respect to the surrounding environment, and wherein the third angular resolution is the same as the second angular resolution; and
detecting, by a third group of light detectors of the lidar device during a third listening window, a third group of reflected light signals from the surrounding environment, wherein the third group of light detectors of the lidar device represents a different subset of the first group of light detectors of the lidar device than the second group of light detectors, wherein the third group of reflected light signals corresponds to reflections of the third group of light signals from objects in the surrounding environment, wherein a duration of the third listening window is the same as the duration of the second listening window, and
wherein the dataset is based on the detected third group of reflected light signals.

3. The method of claim 2 , wherein the third listening window does not overlap with the second listening window.

4. The method of claim 2 , wherein the second group of light signals comprises a plurality of light signals, wherein the third group of light signals comprises a plurality of light signals, and wherein the second group of light signals and the third group of light signals are interlaced with respect to the surrounding environment.

5. The method of claim 1 , wherein the second group of light detectors comprises a plurality of light detectors, and wherein the second group of light detectors is selected from the first group of light detectors so as to be uniformly distributed across the first group of light detectors.

6. The method of claim 1 , wherein the second group of light detectors is distributed across the first group of light detectors in space such that no crosstalk occurs between light detectors within the second group when illuminating a retroreflector located at a maximum detectable range with a light signal in the second group of light signals, and wherein the maximum detectable range is based on the duration of the second listening window.

7. The method of claim 1 , further comprising:
emitting, from each of the light emitters in the lidar device, a calibration light signal into the surrounding environment;
detecting, by each of the light detectors of the lidar device during a calibration listening window, a reflected calibration light signal from the surrounding environment, wherein each reflected calibration light signal corresponds to a reflection of one of the calibration light signals from an object in the surrounding environment;
identifying, based on the detected reflected calibration light signals, one or more light emitters within the lidar device for which the corresponding calibration light signal was reflected from a retroreflector in the surrounding environment; and
selecting the first group of light emitters of the lidar device from a set of all emitters in the lidar device, wherein the first group of light emitters corresponds to those light emitters that were not identified as the one or more light emitters within the lidar device for which the corresponding calibration light signal was reflected from a retroreflector in the surrounding environment.

8. The method of claim 7 , wherein the one or more light emitters within the lidar device for which the corresponding calibration light signal was reflected from a retroreflector in the surrounding environment are identified based on a detected intensity of the corresponding detected reflected calibration light signal from the surrounding environment.

9. The method of claim 1 , wherein emitting the first group of light signals into the surrounding environment comprises emitting the first group of light signals into the surrounding environment using a first emission power, wherein emitting the second group of light signals into the surrounding environment comprises emitting the second group of light signals into the surrounding environment using a second emission power, and wherein the second emission power is less than the first emission power.

10. The method of claim 9 , wherein the second emission power is less than 25% of the first emission power.

11. The method of claim 1 , wherein the dataset is usable to generate a first point cloud and a second point cloud, wherein the first point cloud comprises data relating to the first group of detected reflected light signals, and wherein the second point cloud comprises data relating to the second group of detected r

Assignees

• Waymo Llc

Inventors

• Goetz Georges
• Dunphy James
• Tazzoli Augusto
• Schleuning David

Classifications

• B60W2420/408

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

• B60W2554/4049

  Relationship among other objects, e.g. converging dynamic objects · CPC title

• B60W60/0015

  specially adapted for safety · CPC title

• G01S7/497

  Means for monitoring or calibrating · CPC title

• G01S7/4815

  using multiple transmitters · CPC title