Wide-view LIDAR with areas of special attention

• US 9,383,753 B1
• Filed: 09/26/2012
• Issued: 07/05/2016
• Est. Priority Date: 09/26/2012
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Google Inc. (Alphabet Inc.)
• Inventors: Templeton, Bradley, Droz, Pierre-yves, Zhu, Jiajun
• Primary Examiner(s): Olszewski, John R
• Assistant Examiner(s): Cass, Jean-Paul
• Application Number:
  US13/627,623
• Time in Patent Office: 1,378 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G01S 17/10 using transmission of interrupted, pulse-modulated waves determination of distance by phase measurements G01S17/32
• CPC Class Codes: G01S 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 17/86 Combinations of lidar systems with systems other than lidar, radar or sonar, e.g. with direction finders
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 17/931 of land vehicles
• CPC Class Codes: G01S 7/4802 using analysis of echo signal for target characterisation; Target signature; Target cross-section
• CPC Class Codes: G01S 7/484 Transmitters
• CPC Class Codes: G01S 7/4865 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 Class Codes: G05D 1/0231 using optical position detecting means position-fixing by using electromagnetic waves other than radio waves, e.g. optical position detecting means G01S5/16
• CPC Class Codes: G05D 1/024 in combination with a laser lasers per se H01S
• CPC Class Codes: G05D 1/0246 using a video camera in combination with image processing means

Abstract

A light detection and ranging device with dynamically adjustable angular resolution for use as a sensor providing environmental information for navigating an autonomous vehicle is disclosed. A first region of a scanning zone is scanned while emitting light pulses at a first pulse rate, and a second region of the scanning zone is scanned while emitting light pulses at a second pulse rate different from the first pulse rate. Information from the LIDAR device indicative of the time delays between the emission of the light pulses and the reception of the corresponding returning light pulses is received. A three dimensional point map is generated where the resolution of the point map in the first region is based on the first pulse rate and is based on the second pulse rate in the second region.

Claims

1. A method comprising:

scanning a light detection and ranging (LIDAR) device through a first range of orientations directed to a first region of a scanning zone while emitting light pulses from the LIDAR device at a first pulse rate;

scanning the LIDAR device through a second range of orientations directed to a second region of the scanning zone while emitting light pulses from the LIDAR device at a second pulse rate that is different from the first pulse rate;

receiving returning light pulses corresponding to the light pulses emitted from the LIDAR device;

determining a three-dimensional (3-D) point map of the scanning zone based on time delays between emitting the light pulses and receiving the corresponding returning light pulses and the orientations of the LIDAR device, wherein the angular resolution of the 3-D point map, with respect to the LIDAR device, is based on the first pulse rate in the first region and is based on the second pulse rate in the second region;

adjusting the pulse rate of the LIDAR device throughout the scanning zone according to real-time analysis of the returning light pulses such that the angular resolution of a given region of the 3-D point map is based, at least in part, on an indication of a spatial or temporal frequency of the 3-D point map in the given region, such that a first region of the scanning zone that includes features organized with a higher spatial or temporal frequency than a second region is scanned with a greater angular resolution than the second region;

analyzing the 3-D point map to identify obstacles in the scanning zone interfering with a current path of an autonomous vehicle associated with the LIDAR device;

determining a modified path of the autonomous vehicle that avoids the identified obstacles than the current path; and

causing the autonomous vehicle to navigate along the modified path.

2. The method according to claim 1, wherein the scanning the LIDAR device through the first range of orientations and the second range of orientations is carried out at a substantially constant angular rate of change, such that the angular resolution of the 3-D point map in the first and second regions is proportionate to the first and second pulse rates, respectively.

3. The method according to claim 1, wherein the scanning the LIDAR device through the first range of orientations is carried out at a first angular rate of change, and the scanning the LIDAR device through the second range of orientations is carried out at a second angular rate of change, such that the angular resolution of the 3-D point map in the first and second regions is proportionate to the first and second pulse rates, respectively, and inversely proportionate to the first and second angular rates of change, respectively.

4. The method according to claim 1, wherein scanning the LIDAR device through the first region of the scanning zone while emitting light pulses from the LIDAR device at the first pulse rate and scanning the LIDAR device through the second region of the scanning zone while emitting light pulses from the LIDAR device at the second pulse rate are performed during a common scan of the LIDAR device through the scanning zone.

5. The method according to claim 4, wherein the scanning at the second pulse rate is initiated responsive to determining, based on real-time analysis of the 3-D point map, that the second region of the 3-D point map includes, or is proximate to, an edge of a reflective object indicated by a discontinuity in distances to the LIDAR device of points in the 3-D point map that are angularly adjacent, with respect to the LIDAR device.

6. The method according to claim 4, wherein the scanning at the second pulse rate is initiated responsive to determining, based on real-time analysis of the 3-D point map, that the second region of the 3-D point map includes, or is proximate to, a reflective object in motion.

7. The method according to claim 6, further comprising:

predicting, based on one or more previous 3-D point maps indicating previous positions of the reflective object in motion, a position of the reflective object during the scanning at the second pulse rate, and wherein the second region of the 3-D point map includes the predicted position of the reflective object.

8. The method according to claim 4, wherein the scanning at the second pulse rate is initiated responsive to determining, based on real-time analysis of the 3-D point map, that the second region of the 3-D point map includes, or is proximate to, a reflective object at a distance exceeding a threshold distance.

9. The method according to claim 4, further comprising:

comparing the determined 3-D point map with a baseline 3-D point map of the scanning zone, and identifying differences, if any, between the two 3-D point maps; and

wherein the scanning at the second pulse rate is initiated responsive to determining that the second region includes, or is proximate to, a reflective object not present in the baseline 3-D point map based on the identified differences.

10. The method according to claim 4, further comprising:

prior to the scanning, analyzing a baseline 3-D point map of the scanning zone to identify a portion of the baseline 3-D point map for high resolution scanning; and

setting the second region to correspond to the identified portion of the baseline 3-D point map.

11. The method according to claim 1, wherein the LIDAR device is configured to complete a scan of the entire scanning zone during a scanning interval, and wherein the scanning at the second pulse rate is initiated during the scanning interval based on information indicative of returning light pulses received during the scanning interval.

12. The method according to claim 1, wherein the LIDAR device is configured to complete a scan of the entire scanning zone during a scanning interval, and wherein the second pulse rate exceeds a maximum sustained pulse rate, the method further comprising:

scanning a third region of the scanning zone at a third pulse rate, wherein the third pulse rate is less than both the first and second pulse rates and is sufficient to provide a time-averaged pulse rate during the scanning interval that does not exceed the maximum sustained pulse rate.

13. A method comprising:

scanning a light detection and ranging (LIDAR) device through a range of orientations directed to at least a portion of a scanning zone at a first angular rate of change while emitting light pulses from the LIDAR device;

receiving returning light pulses corresponding to the light pulses emitted from the LIDAR device while scanned at the first angular rate of change;

determining a three-dimensional (3-D) point map of the scanning zone based on time delays between emitting the light pulses and receiving the corresponding returning light pulses and the orientations of the LIDAR device;

analyzing the determined 3-D point map to identify a region of the scanning zone indicated to include features organized with relatively high spatial or temporal frequencies;

scanning the LIDAR device through orientations directed to the identified region of the scanning zone at a second angular rate of change different from the first angular rate of change while emitting light pulses from the LIDAR device;

receiving returning light pulses corresponding to the light pulses emitted from the LIDAR device while scanned at the second angular rate of change;

determining a mixed resolution 3-D point map of the scanning zone based on time delays between emitting the light pulses and receiving the corresponding returning light pulses and the orientations of the LIDAR device such that the angular resolution of the mixed resolution 3-D point map, with respect to the LIDAR device, is based on the second angular rate of change in the identified region and is based on the first angular rate of change in one or more regions of the scanning zone other than the identified region;

analyzing the mixed resolution 3-D point map to identify obstacles in the scanning zone interfering with a current path of an autonomous vehicle associated with the LIDAR device;

determining a modified path of the autonomous vehicle that avoids the identified obstacles than the current path; and

causing the autonomous vehicle to navigate along the modified path.

14. The method according to claim 13, wherein the analyzing includes:

determining, based on real-time analysis of the 3-D point map, that the identified region of the 3-D point map includes, or is proximate to, an edge of a reflective object indicated by a discontinuity in distances to the LIDAR device of points in the 3-D point map that are angularly adjacent, with respect to the LIDAR device.

15. The method according to claim 13, wherein the analyzing includes:

determining, based on real-time analysis of the 3-D point map, that the identified region of the 3-D point map includes, or is proximate to, a reflective object in motion.

16. The method according to claim 15, wherein the analyzing further includes:

predicting, based on one or more previous 3-D point maps indicating previous positions of the reflective object in motion, a position of the reflective object during the scanning the identified region; and

setting the identified region to include the predicted position of the reflective object.

17. The method according to claim 13, wherein the analyzing includes:

comparing the determined 3-D point map with a baseline 3-D point map of the scanning zone, and identifying differences, if any, between the two 3-D point maps; and

determining that the identified region includes, or is proximate to, a reflective object not present in the baseline 3-D point map based on the identified differences.

18. An autonomous vehicle system comprising:

a light detection and ranging (LIDAR) device including;

a light source configured to be scanned through a range of orientations directed to a scanning zone while emitting light pulses; and

a light detector configured to receive returning light pulses reflected from features in the scanning zone, if any, each of the returning light pulses corresponding to an emitted light pulse; and

a controller configured to;

cause the LIDAR device to scan a first region of the scanning zone while emitting light pulses at a first pulse rate and scan a second region of the scanning zone while emitting light pulses at a second pulse rate different from the first pulse rate;

receive information from the LIDAR device indicative of the time delays between the emission of the light pulses and the reception of the corresponding returning light pulses;

determine, based on the time delays and orientations of the LIDAR device associated with each time delay, a three dimensional (3-D) point map, wherein the angular resolution of the 3-D point map, with respect to the LIDAR device, is based on the first pulse rate in the first region and is based on the second pulse rate in the second region;

adjust the pulse rate of the LIDAR device throughout the scanning zone according to real-time analysis of the returning light pulses such that the angular resolution of a given region of the 3-D point map is based, at least in part, on an indication of a spatial or temporal frequency of the 3-D point map in the given region, and such that a first region of the scanning zone that includes features organized with a higher spatial or temporal frequency than a second region is scanned with a greater angular resolution than the second region;

analyze the 3-D point map to identify obstacles in the scanning zone interfering with a current path of the autonomous vehicle;

determine a modified path of the autonomous vehicle that avoids the identified obstacles than the current path; and

cause the autonomous vehicle to navigate along the modified path.

19. The autonomous vehicle system according to claim 18, wherein the controller is further configured to:

determine, based on real-time analysis of the 3-D point map, that the second region of the 3-D point map includes, or is proximate to, an edge of a reflective object indicated by a discontinuity in distances to the LIDAR device of points in the 3-D point map that are angularly adjacent, with respect to the LIDAR device.

20. The autonomous vehicle system according to claim 18, wherein the controller is further configured to:

determine, based on real-time analysis of the 3-D point map, that the second region of the 3-D point map includes, or is proximate to, a reflective object in motion.

21. The autonomous vehicle system according to claim 20, wherein the controller is further configured to:

predict, based on one or more previous 3-D point maps indicating previous positions of the reflective object in motion, a position of the reflective object during the scan of the second region, wherein the second region includes the predicted position of the reflective object.

22. The autonomous vehicle system according to claim 18, wherein the controller is further configured to:

compare the determined 3-D point map with a baseline 3-D point map of the scanning zone, and identifying a difference between the two 3-D point maps; and

initiate the scan at the second pulse rate in response to determining that the second region includes, or is proximate to, the identified difference.

23. The autonomous vehicle system according to claim 18, wherein the LIDAR device is configured to complete a scan of the entire scanning zone during a scanning interval, and wherein the second pulse rate exceeds a maximum sustained pulse rate, and wherein the controller is further configured to:

cause the LIDAR device to scan a third region of the scanning zone at a third pulse rate less than both the first and second pulse rates and sufficient to provide a time-averaged pulse rate during the scanning interval that does not exceed the maximum sustained pulse rate.

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

cause a light detection and ranging (LIDAR) device to scan a first region of a scanning zone while emitting light pulses at a first pulse rate and scan a second region of the scanning zone while emitting light pulses at a second pulse rate different from the first pulse rate;

receive information from the LIDAR device indicative of the time delays between the emission of the light pulses and the reception of the corresponding returning light pulses;

determine, based on the time delays and orientations of the LIDAR device associated with each time delay, a three dimensional (3-D) point map, wherein the angular resolution of the 3-D point map, with respect to the LIDAR device, is based on the first pulse rate in the first region and is based on the second pulse rate in the second region;

cause the LIDAR device to adjust the pulse rate of the LIDAR device throughout the scanning zone according to real-time analysis of the returning light pulses such that the angular resolution of a given region of the 3-D point map is based, at least in part, on an indication of a spatial or temporal frequency of the 3-D point map in the given region, such that a first region of the scanning zone that includes features organized with a higher spatial or temporal frequency than a second region is scanned with a greater angular resolution than the second region;

analyzing the 3-D point map to identify obstacles in the scanning zone interfering with a current path of an autonomous vehicle associated with the LIDAR device;

determining a modified path of the autonomous vehicle that avoids the identified obstacles than the current path; and

causing the autonomous vehicle to navigate along the modified path.