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1. (WO2019027567) USE OF EXTENDED DETECTION PERIODS FOR RANGE ALIASING DETECTION AND MITIGATION IN A LIGHT DETECTION AND RANGING (LIDAR) SYSTEM
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CLAIMS

We 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 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 the corresponding detection periods comprise (i) one or more standard detection periods that establish a nominal detection range for the LIDAR device and (ii) one or more extended detection periods having respective durations that are longer than respective durations of the one or more standard detection periods;

making a determination, by the computing system, that the LIDAR device detected one or more return light pulses during one or more of the extended detection periods that correspond to one or more particular emitted light pulses;

in response to making the determination, determining, by the computing system, that the one or more detected return light pulses have detection times relative to corresponding emission times of the one or more particular emitted light pulses that are indicative of one or more ranges;

making a further determination, by the computing system, of whether or not the one or more ranges indicate that an object is positioned outside of the nominal detection range; and

engaging, by the computing system, in object detection in accordance with the further determination.

2. The method of claim 1, wherein the computing system has access to a fixed schedule that indicates timing to respectively initiate and end the one or more extended detection periods, and wherein operating the LIDAR device to detect return light pulses in accordance with the detection time sequence comprises operating the LIDAR device in accordance with the fixed schedule.

3. The method of claim 1, wherein operating the LIDAR device to detect return light pulses in accordance with the detection time sequence comprises operating the LIDAR device to respectively initiate the one or more extended detection periods in accordance with a periodic time sequence.

4. The method of claim 1, wherein the one or more extended detection periods correspond to one or more light pulses emitted by the LIDAR in one or more particular directions of travel.

5. The method of claim 4, wherein the one or more particular directions of travel comprise a direction of travel that is substantially parallel to a ground surface or is elevated away from the ground surface.

6. The method of claim 1, wherein making the further determination comprises: making a further determination of whether or not the nominal detection range comprises the one or more ranges;

if the further determination is that the nominal detection range comprises the one or more ranges, then, responsive to making the further determination, determining that the one or more ranges do not indicate that an object is positioned outside of the nominal detection range; and

if the further determination is that the nominal detection range does not comprise the one or more ranges, then, responsive to making the further determination, determining that the one or more ranges indicate that an object is positioned outside of the nominal detection range.

7. The method of claim 1, wherein engaging in object detection in accordance with the further determination comprises:

if the further determination is that the one or more ranges indicate an object positioned outside of the nominal detection range, then, responsive to making the further determination, using at least the one or more ranges as a basis for generating a representation of an object positioned outside of the nominal detection range; and

if the further determination is that the one or more ranges do not indicate an object positioned outside of the nominal detection range, then, responsive to making the further

determination, using at least the one or more ranges as a basis for generating a representation of an object positioned within the nominal detection range.

8. The method of claim 1, wherein engaging in object detection in accordance with the further determination comprises:

if the further determination is that the one or more ranges indicate an object positioned outside of the nominal detection range, then, responsive to making the further determination, using at least the one or more ranges as a basis for determining a distance between the LIDAR device and an object positioned outside of the nominal detection range; and

if the further determination is that the one or more ranges do not indicate an object positioned outside of the nominal detection range, then, responsive to making the further determination, using at least the one or more ranges as a basis for determining a distance between the LIDAR device and an object positioned within the nominal detection range.

9. The method of claim 1, wherein engaging in object detection in accordance with the further determination comprises:

if the further determination is that the one or more ranges indicate an object positioned outside of the nominal detection range, then, responsive to making the further determination, using at least the one or more ranges as a basis for identifying an object positioned outside of the nominal detection range; and

if the further determination is that the one or more ranges do not indicate an object positioned outside of the nominal detection range, then, responsive to making the further determination, using at least the one or more ranges as a basis for identifying an object positioned within the nominal detection range.

10. The method of claim 1, further comprising:

determining, by the computing system, that the LIDAR device detected other return light pulses during corresponding detection periods for each of two or more emitted light pulses; and

in response to determining that the LIDAR device detected other return light pulses, determining, by the computing system, that (i) the detected other 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 other 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,

wherein engaging in object detection in accordance with the further determination comprises:

based on the further determination, selecting 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 in object detection in accordance with the selecting.

11. The method of claim 10, wherein determining that the LIDAR device detected other return light pulses during corresponding detection periods for each of two or more emitted light pulses comprises determining that the LIDAR device detected the other return light pulses during corresponding detection periods for each of the plurality of first emitted light pulses, and wherein selecting based on the further determination comprises:

if the further determination is that the one or more ranges indicate an object positioned outside of the nominal detection range, then, responsive to making the further determination, selecting use of the second set of ranges as a basis for object detection; and if the further determination is that the one or more ranges do not indicate an object positioned outside of the nominal detection range, then, responsive to making the further determination, selecting use of the first set of ranges as a basis for object detection

12. The method of claim 1, wherein engaging in object detection in accordance with the further determination comprises:

if the further determination is that the one or more ranges do not indicate an object positioned outside of the nominal detection range, then, responsive to making the further determination, using at least the one or more ranges as a basis for object detection; and

if the further determination is that the one or more ranges indicate an object positioned outside of the nominal detection range, then, responsive to making the further determination, engaging in an additional process to verify whether or not an object is positioned outside of the nominal detection range.

13. The method of claim 12, wherein the one or more particular emitted light pulses are emitted by the LIDAR in a particular direction of travel, and wherein engaging in the additional process comprises engaging in the additional process to verify whether or not an object is positioned (i) outside of the nominal detection range and (ii) along the particular direction of travel of the one or more particular emitted light pulses.

14. The method of claim 12, further comprising:

determining, by the computing system, that the LIDAR device detected other return light pulses during corresponding detection periods for each of two or more emitted light pulses; and

in response to determining that the LIDAR device detected other return light pulses, determining, by the computing system, that (i) the detected other 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 other 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,

wherein engaging in the additional process comprises:

determining whether or not the first set of ranges is representative of at least one known object;

based on the determining of whether or not the first set of ranges is representative of at least one known object, selecting 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 in object detection in accordance with the selecting.

15. The method of claim 12, further comprising:

determining, by the computing system, that the LIDAR device detected other return light pulses during corresponding detection periods for each of two or more emitted light pulses; and

in response to determining that the LIDAR device detected other return light pulses, determining, by the computing system, that (i) the detected other 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 other 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,

wherein engaging in the additional process comprises:

determining whether or not ranges of the first set are substantially similar to one another;

based on the determining of whether or not ranges of the first set are substantially similar to one another, selecting 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 in object detection in accordance with the selecting.

16. The method of claim 1, 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 further determination, engaging in detection of objects positioned in an environment around the vehicle, and wherein the computing system is configured to operate the vehicle based at least on scans by the LIDAR device of the environment around the vehicle.

17. A computing system for a self-driving vehicle 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 standard time period after a majority of emissions in the sequence and an extended time period after at least one of the emissions in the sequence, wherein the standard time period is associated with a nominal detection range for the LIDAR device.

18. The computing system of claim 17, wherein the extended time period occurs after an emission emitted in a direction of travel of the vehicle.

19. A vehicle comprising:

a Light Detection and Ranging (LIDAR) device; and

a computing system configured to:

operate the LIDAR device to emit light pulses at emission times in accordance with an emission time sequence 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 the corresponding detection periods comprise (i) one or more standard detection periods that establish a nominal detection range for the LIDAR device and (ii) one or more extended detection periods having respective durations that are longer than respective durations of the one or more standard detection periods;

make a determination that the LIDAR device detected one or more return light pulses during one or more of the extended detection periods that correspond to one or more particular emitted light pulses;

in response to making the determination, determine that the one or more detected return light pulses have detection times relative to corresponding emission times of the one or more particular emitted light pulses that are indicative of one or more ranges;

make a further determination of whether or not the one or more ranges indicate that an object is positioned outside of the nominal detection range; and

engage in object detection in accordance with the further determination.

20. The vehicle of claim 19, wherein engaging in object detection in accordance with the further determination comprises, in accordance with the further determination, engaging in detection of objects positioned in an environment around the vehicle, and wherein the computing system is further configured to:

operate the vehicle based at least on the detection, in accordance with the further determination, of objects positioned in the environment around the vehicle.