Methods and systems for dithering active sensor pulse emissions

Patent metadata

Field	Value
Publication number	US-11237256-B2
Application number	US-201816134985-A
Country	US
Kind code	B2
Filing date	Sep 19, 2018
Priority date	Sep 19, 2018
Publication date	Feb 1, 2022
Grant date	Feb 1, 2022

Abstract

One example device comprises a plurality of emitters including at least a first emitter and a second emitter. The first emitter emits light that illuminates a first portion of a field-of-view (FOV) of the device. The second emitter emits light that illuminates a second portion of the FOV. The device also comprises a controller that obtains a scan of the FOV. The controller causes each emitter of the plurality of emitters to emit a respective light pulse during an emission time period associated with the scan. The controller causes the first emitter to emit a first-emitter light pulse at a first-emitter time offset from a start time of the emission time period. The controller causes the second emitter to emit a second-emitter light pulse at a second-emitter time offset from the start time of the emission time period.

First claim

What is claimed is:

1. A device comprising:
a plurality of emitters including at least a first emitter and a second emitter, wherein the first emitter emits light that illuminates a first portion of a field-of-view (FOV) of the device, and wherein the second emitter emits light that illuminates a second portion of the FOV; and
a controller that obtains a scan of the FOV, wherein the controller obtaining the scan of the FOV comprises the controller causing each emitter of the plurality of emitters to emit a respective light pulse during an emission time period associated with the scan, wherein the emission time period has a start time and an end time, and wherein the controller causing each emitter to emit the respective light pulse comprises the controller:
causing the first emitter to emit a first-emitter light pulse at a first-emitter time offset from the start time of the emission time period, and
causing the second emitter to emit a second-emitter light pulse at a second-emitter time offset from the start time of the emission time period; and

a plurality of detectors, wherein the controller obtaining the scan of the FOV comprises the controller operating the plurality of detectors to measure light from the FOV incident on the plurality of detectors during a detection time period that begins after the end time of the emission time period.

2. The device of claim 1 , further comprising:
a lens that focuses the light from the FOV for receipt by the plurality of detectors, wherein a first detector of the plurality of detectors is arranged to intercept a first portion of the focused light that includes a reflection of the light emitted by the first emitter, and wherein a second detector of the plurality of detectors is arranged to intercept a second portion of the focused light that includes a reflection of the light emitted by the second emitter.

3. The device of claim 1 , wherein a difference between the first-emitter time offset and the second-emitter time offset is at least 2.5 nanoseconds.

4. The device of claim 1 , wherein the scan obtained by the controller is a first scan, wherein the controller obtains a sequence of scans of the FOV including at least the first scan and a second scan subsequent to the first scan.

5. The device of claim 4 , wherein the controller obtaining the second scan comprises the controller modifying the first-emitter time offset.

6. The device of claim 5 , wherein the controller obtaining the second scan further comprises the controller modifying the second-emitter time offset.

7. The device of claim 6 , wherein the emission time period of the first scan is a first emission time period, and wherein the controller obtaining the second scan comprises the controller:
causing the first emitter to emit another first-emitter light pulse at the modified first-emitter time offset from a start time of a second emission time period associated with the second scan; and
causing the second emitter to emit another second-emitter light pulse at the modified second-emitter time offset from the start time of the second emission time period.

8. The device of claim 4 , wherein the controller determines a pseudo-random time offset sequence, and wherein the controller adjusts the first-emitter time offset for one or more scans of the sequence of scans according to the determined pseudo-random time offset sequence.

9. The device of claim 8 , wherein the sequence of scans is a first sequence of scans, wherein the controller obtains a second sequence of scans of the FOV after the first sequence of scans, and wherein the controller adjusts the second-emitter time offset for one or more scans of the second sequence of scans according to the determined pseudo-random time offset sequence.

10. The device of claim 1 , further comprising:
a transmitter that includes the plurality of emitters, wherein the transmitter transmits, during the emission time period of the scan, a plurality of light beams in a spatial arrangement that defines the FOV of the device,
wherein the light emitted by the first emitter includes at least a first light beam of the plurality of light beams, and wherein the light emitted by the second emitter includes at least a second light beam of the plurality of light beams.

11. The device of claim 10 , wherein the light emitted by the first emitter also includes a third light beam of the plurality of light beams.

12. The device of claim 11 , further comprising one or more optical elements that direct: a first portion of the light emitted by the first emitter toward a first position of the first light beam in the spatial arrangement, and a second portion of the light emitted by the first emitter toward a second position of the third light beam in the spatial arrangement.

13. A method comprising:
causing a plurality of emitters to emit a plurality of light pulses during a first emission time period associated with a first scan of a field-of-view (FOV), wherein a first emitter of the plurality of emitters is configured to illuminate a first portion of the FOV, wherein a second emitter of the plurality of emitters is configured to illuminate a second portion of the FOV, and wherein causing the plurality of emitters to emit the plurality of light pulses comprises:
causing the first emitter to emit a first-emitter light pulse at a first-emitter time offset from an end time of the first emission time period, and
causing the second emitter to emit a second-emitter light pulse at a second-emitter time offset from the end time of the first emission time period; and

obtaining the first scan based on measurements of light from the FOV received by a plurality of detectors during a first detection time period that begins after the end time of the first emission time period.

14. The method of claim 13 , further comprising:
obtaining a sequence of scans of the FOV including at least the first scan and a second scan subsequent to the first scan; and
modifying the first-emitter time offset for the second scan, wherein obtaining the second scan comprises causing the first emitter to emit another first-emitter light pulse at the modified first-emitter time offset from an end time of a second emission time period associated with the second scan, and
wherein obtaining the second scan is based on measurements of light from the FOV received by the plurality of detectors during a second detection time period that begins after the end time of the second emission time period.

15. The method of claim 14 , further comprising:
modifying, for the second scan, the second-emitter time offset, wherein obtaining the second scan comprises causing the second emitter to emit another second-emitter light pulse at the modified second-emitter time offset from the end time of the second emission time period.

16. The method of claim 13 , further comprising:
determining a pseudo-random time offset sequence;
obtaining a sequence of scans of the FOV including the first scan; and
selecting, for each scan of the sequence of scans, the first-emitter time offset from the pseudo-random time offset sequence based on an order of the scan in the sequence of scans.

17. The method of claim 13 , wherein a first detector of the plurality of detectors is arranged to receive light from the first portion of the FOV illuminated by the first emitter, the method further comprising:
detecting, via the first detector, a first-detector light pulse at a first detection time during the first detection time period; and
associating the first-detector light pulse with presence of a retroreflector in the f

Assignees

• Waymo Llc

Inventors

• Marx Michael
• Droz Pierre-Yves

Classifications

• G01S7/484 Primary

  Transmitters · CPC title

• G01S7/481

  Constructional features, e.g. arrangements of optical elements · CPC title

• G01S17/10 Primary

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

• G01S7/491

  Details of non-pulse systems · CPC title

• G01S7/4815 Primary

  using multiple transmitters · CPC title