LIDAR Based 3-D Imaging With Varying Illumination Intensity

• US 20170269197A1
• 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., Cui, Yupeng, Rekow, Mathew Noel, Nestinger, Stephen S.
• Granted Patent: US 10,197,669 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 7/4813 Housing arrangements
• CPC Class Codes: G01S 7/4815 using multiple transmitters
• 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 different illumination intensity patterns are described herein. Repetitive sequences of measurement pulses each having different illumination intensity patterns are emitted from a LIDAR system. One or more pulses of each repetitive sequence have a different illumination intensity than another pulse within the sequence. The illumination intensity patterns are varied to reduce total energy consumption and heat generated by the LIDAR system. In some examples, the illumination intensity pattern is varied based on the orientation of the LIDAR device. In some examples, the illumination intensity pattern is varied based on the distance between a detected object and the LIDAR device. In some examples, the illumination intensity pattern 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 pulsed illumination source emitting a sequence of pulses of illumination light from the LIDAR device into a three dimensional environment having a first repetition pattern of pulse intensities, wherein one or more pulses of illumination light of the first repetition pattern has a different illumination intensity than another pulse of illumination light of the first repetition pattern;

a photosensitive detector that detects an amount of light reflected from the three dimensional environment illuminated by each of the sequence of pulses of illumination light and generates an output signal indicative of the detected amount of light associated with each of the sequence of pulses of illumination light; and

a computing system configured to;

receive the output signal indicative of the detected amount 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 a pulse is emitted from the LIDAR device and a time when the photosensitive detector detects an amount of light reflected from the object illuminated by the pulse of illumination light; and

generate a command signal that causes the pulsed illumination source to change the sequence of pulses of illumination light to a second repetition pattern having a different pattern of pulse intensities than the first repetition pattern.

2. The LIDAR device of claim 1, wherein the changing of the sequence of pulses to the different pattern of pulse intensities is pseudorandom.

3. The LIDAR device of claim 1, wherein one or more of the sequence of pulses of illumination light of the second repetition pattern has a zero value.

4. The LIDAR device of claim 1, wherein the pulsed illumination source and the photosensitive detector 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 changing of the sequence of pulses to the different pattern of pulse intensities is based on the orientation.

5. The LIDAR device of claim 1, wherein the changing of the sequence of pulses to the different pattern of pulse intensities is based on the distance between the LIDAR device and an object in the three dimensional environment.

6. The LIDAR device of claim 5, wherein the changing of the sequence of pulses to the different pattern of pulse intensities involves reducing an average intensity of pulses for a given period of time when the distance between the LIDAR device and an object in the three dimensional environment is less than a predetermined threshold value.

7. The LIDAR device of claim 5, wherein the changing of the sequence of pulses to the different pattern of pulse intensities involves reducing an average intensity of pulses for a given period of time when the output signal is a negligible value for a first period of time.

8. The LIDAR device of claim 7, wherein the changing of the sequence of pulses to the different pattern of pulse intensities involves increasing the average intensity for the given period of time when the output signal is a non-negligible value for a second period of time immediately after the first period of time.

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

an imaging device configured to generate an image of at least a portion of a field of view of the pulsed illumination source, wherein the changing of the sequence of pulses to the different pattern of pulse intensities involves decreasing an average intensity of the pulses for a given period of time when there is no object detected in the image of the field of view of the pulsed illumination source, and wherein the changing of the sequence of pulses to the different pattern of pulse intensities involves increasing the average intensity for the given period of time when there is an object detected in the image of the field of view of the pulsed illumination source.

10. The LIDAR device of claim 9, wherein the imaging device is a camera that is communicately coupled to the LIDAR device.

11. The LIDAR device of claim 9, wherein the imaging device is an imaging module communicatively coupled to the LIDAR device, wherein the imaging module generates the image of the portion of the surrounding three dimensional environment based on a plurality of distance measurements generated by the LIDAR device.

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

a pulsed illumination source emitting a sequence of pulses of illumination light from the LIDAR device into a three dimensional environment having a first repetition pattern of pulse intensities, wherein one or more pulses of illumination light of the first repetition pattern has a different illumination intensity than another pulse of illumination light of the first repetition pattern;

a photosensitive detector that detects an amount of light reflected from the three dimensional environment illuminated by each of the sequence of pulses of illumination light and generates an output signal indicative of the detected amount of light associated with each of the sequence of pulses of illumination light; 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 output signal indicative of the detected amount 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 a pulse is emitted from the LIDAR device and a time when the photosensitive detector detects an amount of light reflected from the object illuminated by the pulse of illumination light; and

generate a command signal that causes the pulsed illumination source to change the sequence of pulses of illumination light to a second repetition pattern having a different pattern of pulse intensities than the first repetition pattern.

13. The LIDAR device of claim 12, wherein one or more of the sequence of pulses of illumination light of the second repetition pattern has a zero value.

14. The LIDAR device of claim 12, wherein the pulsed illumination source and the photosensitive detector 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 changing of the sequence of pulses to the different pattern of pulse intensities is based on the orientation.

15. The LIDAR device of claim 12, wherein the changing of the sequence of pulses to the different pattern of pulse intensities is based on the distance between the LIDAR device and an object in the three dimensional environment.

16. The LIDAR device of claim 15, wherein the changing of the sequence of pulses to the different pattern of pulse intensities involves reducing an average intensity of pulses for a given period of time when the distance between the LIDAR device and an object in the three dimensional environment is less than a predetermined threshold value.

17. The LIDAR device of claim 12, further comprising:

an imaging device configured to generate an image of at least a portion of a field of view of the pulsed illumination source, wherein the changing of the sequence of pulses to the different pattern of pulse intensities involves decreasing an average intensity of the pulses for a given period of time when there is no object detected in the image of the field of view of the pulsed illumination source, and wherein the changing of the sequence of pulses to the different pattern of pulse intensities involves increasing the average intensity for the given period of time when there is an object detected in the image of the field of view of the pulsed illumination source.

18. A method comprising:

emitting a sequence of pulses of illumination light from a LIDAR device into a three dimensional environment having a first repetition pattern of pulse intensities, wherein one or more pulses of illumination light of the first repetition pattern has a different illumination intensity than another pulse of illumination light of the first repetition pattern;

detecting an amount of light reflected from the three dimensional environment illuminated by each of the sequence of pulses of illumination light;

generating an output signal indicative of the detected amount of light associated with each of the sequence of pulses of illumination light;

receiving the output signal indicative of the detected amount 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 a pulse is emitted from the LIDAR device and a time when the photosensitive detector detects an amount of light reflected from the object illuminated by the pulse of illumination light; and

generating a command signal that causes the pulsed illumination source to change the sequence of pulses of illumination light to a second repetition pattern having a different pattern of pulse intensities than the first repetition pattern.

19. The method of claim 18, wherein the changing of the sequence of pulses to the different pattern of pulse intensities is based on the distance between the LIDAR device and an object in the three dimensional environment.

20. The method of claim 18, further comprising:

imaging at least a portion of a field of view of the pulsed illumination source, wherein the changing of the sequence of pulses to the different pattern of pulse intensities involves decreasing an average intensity of the pulses for a given period of time when there is no object detected in the image of the field of view of the pulsed illumination source, and wherein the changing of the sequence of pulses to the different pattern of pulse intensities involves increasing the average intensity for the given period of time when there is an object detected in the image of the field of view of the pulsed illumination source.