LIDAR Based 3-D Imaging With Varying Illumination Field Density

• US 20170269198A1
• Filed: 03/20/2017
• Published: 09/21/2017
• Est. Priority Date: 03/21/2016
• Status: Active Grant

• Current Assignee: Velodyne Lidar USA, Inc. (Ouster, Inc.)
• Original Assignee: Velodyne LiDAR, Inc. (Ouster, Inc.)
• Inventors: Hall, David S., Kerstens, Pieter J., Rekow, Mathew Noel, Nestinger, Stephen S.
• Granted Patent: US 9,983,297 B2
• Time in Patent Office: Days
• 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 7/4815 using multiple transmitters
• CPC Class Codes: G01S 7/4816 of receivers alone
• CPC Class Codes: G01S 7/484 Transmitters
• CPC Class Codes: G01S 7/4868 Controlling received signal intensity or exposure of sensor

Abstract

Methods and systems for performing three dimensional LIDAR measurements with varying illumination field density are described herein. A LIDAR device includes a plurality of pulse illumination sources and corresponding detectors. The current pulses supplied to the pulse illumination sources are varied to reduce total energy consumption and heat generated by the LIDAR system. In some embodiments, the number of active pulse illumination sources is varied based on the orientation of the LIDAR device, the distance between the LIDAR device and an object detected by the LIDAR device, an indication of an operating temperature of the LIDAR device, or a combination thereof. In some embodiments, the number of active pulse illumination sources is varied based on the presence of an object detected by the LIDAR device or another imaging system.

Claims

1. A light detection and ranging (LIDAR) device, comprising:

a plurality of pulsed illumination sources emitting pulses of illumination light from the LIDAR device into a three dimensional environment;

a plurality of photosensitive detectors, wherein each photosensitive detector detects an amount of light reflected from the three dimensional environment illuminated by the pulses of illumination light emitted by a corresponding pulsed illumination source of the plurality of pulsed illumination sources, and wherein each photosensitive detector generates an output signal indicative of the detected amount of light associated with the pulses of illumination light emitted by the corresponding pulsed illumination source; and

a computing system configured to;

receive the plurality of output signals indicative of the detected amounts of light;

determine a distance between the LIDAR device and an object in the three dimensional environment based on a difference between a time when each pulse of illumination light is emitted from the LIDAR device and a time when each corresponding photosensitive detector detects an amount of light reflected from the three dimensional environment illuminated by the pulse of illumination light; and

adjust a number of the plurality of illumination sources emitting pulses of illumination light from the LIDAR device during operation of the LIDAR device.

2. The LIDAR device of claim 1, wherein the adjustment of the number of the plurality of illumination sources emitting pulses of illumination light from the LIDAR device involves reducing a current supplied to a subset of the plurality of illumination sources emitting pulses of illumination light from the LIDAR device to a reduced value.

3. The LIDAR device of claim 2, wherein the reduced value is a negligible value.

4. The LIDAR device of claim 1, wherein each of the plurality of pulsed illumination sources and each of the plurality of photosensitive detectors are mounted to a rotating frame of the LIDAR device that rotates with respect to a base frame of the LIDAR device, and wherein the LIDAR device also includes:

an orientation sensor configured to detect an orientation of the rotating frame with respect to the base frame.

5. The LIDAR device of claim 4, wherein the adjustment of the number of the plurality of illumination sources emitting pulses of illumination light from the LIDAR device is based on the orientation of the rotating frame with respect to the base frame.

6. The LIDAR device of claim 1, wherein the adjustment of the number of the plurality of illumination sources emitting pulses of illumination light from the LIDAR device is based on the distance between the LIDAR device and an object in the three dimensional environment.

7. The LIDAR device of claim 6, wherein the adjustment of the number of the plurality of illumination sources emitting pulses of illumination light from the LIDAR device involves reducing a number of the plurality of illumination sources emitting pulses of illumination light from the LIDAR device when the distance between the LIDAR device and an object in the three dimensional environment is less than a predetermined threshold value.

8. The LIDAR device of claim 6, wherein the adjustment of the number of the plurality of illumination sources emitting pulses of illumination light from the LIDAR device involves reducing a number of the plurality of illumination sources emitting pulses of illumination light from the LIDAR device when one or more of the output signals is a negligible value for a first period of time.

9. The LIDAR device of claim 8, wherein the adjustment of the number of the plurality of illumination sources emitting pulses of illumination light from the LIDAR device involves increasing the number of the plurality of illumination sources emitting pulses of illumination light from the LIDAR device when the one or more output signals is a non-negligible value for a second period of time immediately after the first period of time.

10. The LIDAR device of claim 1, further comprising:

an imaging device configured to generate an image of at least a portion of an illumination field of the LIDAR device.

11. The LIDAR device of claim 10, wherein the adjustment of the number of the plurality of illumination sources emitting pulses of illumination light from the LIDAR device involves reducing light emission from one or more of the plurality of illumination sources when there is no object detected in a portion of the image corresponding to the field of view of the one or more illumination sources, and wherein the adjustment of the number of the plurality of illumination sources emitting pulses of illumination light from the LIDAR device involves increasing light emission from one or more of the plurality of illumination sources when there is an object detected in the portion of the image corresponding to the field of view of the one or more illumination sources.

12. The LIDAR device of claim 11, wherein the imaging device is a camera that is communicately coupled to the LIDAR device.

13. The LIDAR device of claim 11, wherein the imaging device is an imaging module communicately coupled to the LIDAR device, wherein the imaging module generates the image based on a plurality of distance measurements generated by the LIDAR device.

14. A light detection and ranging (LIDAR) device, comprising:

a plurality of pulsed illumination sources emitting pulses of illumination light from the LIDAR device into a three dimensional environment;

a plurality of photosensitive detectors, wherein each photosensitive detector detects an amount of light reflected from the three dimensional environment illuminated by the pulses of illumination light emitted by a corresponding pulsed illumination source of the plurality of pulsed illumination sources, and wherein each photosensitive detector generates an output signal indicative of the detected amount of light associated with the pulses of illumination light emitted by the corresponding pulsed illumination source; and

a non-transient computer-readable medium comprising computer-readable instructions that when read by a computing system cause the computing system to;

receive the plurality of output signals indicative of the detected amounts of light;

determine a distance between the LIDAR device and an object in the three dimensional environment based on a difference between a time when each pulse of illumination light is emitted from the LIDAR device and a time when each corresponding photosensitive detector detects an amount of light reflected from the three dimensional environment illuminated by the pulse of illumination light; and

adjust a number of the plurality of illumination sources emitting pulses of illumination light from the LIDAR device during operation of the LIDAR device.

15. The LIDAR device of claim 14, wherein the adjustment of the number of the plurality of illumination sources emitting pulses of illumination light from the LIDAR device involves reducing a current supplied to a subset of the plurality of illumination sources emitting pulses of illumination light from the LIDAR device to a negligible value.

16. The LIDAR device of claim 14, wherein each of the plurality of pulsed illumination sources and each of the plurality of photosensitive detectors are mounted to a rotating frame of the LIDAR device that rotates with respect to a base frame of the LIDAR device, and wherein the LIDAR device also includes:

an orientation sensor configured to detect an orientation of the rotating frame with respect to the base frame, and wherein the adjustment of the number of the plurality of illumination sources emitting pulses of illumination light from the LIDAR device is based on the orientation of the rotating frame with respect to the base frame.

17. The LIDAR device of claim 14, wherein the adjustment of the number of the plurality of illumination sources emitting pulses of illumination light from the LIDAR device is based on the distance between the LIDAR device and the object in the three dimensional environment.

18. The LIDAR device of claim 14, wherein the adjustment of the number of the plurality of illumination sources emitting pulses of illumination light from the LIDAR device is based on an indication of an operating temperature of the LIDAR device.

19. A method comprising:

emitting pulses of illumination light from each of a plurality of pulsed illumination sources of a LIDAR device into a three dimensional environment;

detecting an amount of light reflected from the three dimensional environment illuminated by each of the pulses of illumination light emitted by the plurality of pulsed illumination sources;

generating a plurality of output signals each indicative of the detected amount of light associated with the pulses of illumination light emitted by each of the plurality of pulsed illumination sources; and

receiving the plurality of output signals indicative of the detected amounts of light;

determining a distance between the LIDAR device and an object in the three dimensional environment based on a difference between a time when each pulse is emitted from the LIDAR device and a time when a corresponding amount of light reflected from the three dimensional environment illuminated by the pulse of illumination light is detected; and

adjusting a number of the plurality of illumination sources emitting pulses of illumination light from the LIDAR device during operation of the LIDAR device.

20. The method of claim 19, further comprising:

imaging at least a portion of a field of view of the plurality of pulsed illumination sources, wherein the adjusting of the number of the plurality of illumination sources emitting pulses of illumination light from the LIDAR device involves reducing the number when there is no object detected in the image and increasing the number when there is an object detected in the image.