Lidar sensor window configuration for improved data integrity

• US 10,641,877 B2
• Filed: 11/09/2018
• Issued: 05/05/2020
• Est. Priority Date: 01/27/2017
• Status: Active Grant

• Current Assignee: Waymo LLC (Alphabet Inc.)
• Original Assignee: Waymo LLC (Alphabet Inc.)
• Inventors: Lombrozo, Peter Craig, Rivera, Felix Jose Alvarez
• Primary Examiner(s): Ismail, Mahmoud S
• Application Number:
  US16/185,636
• Publication Number:
  US 20190178997A1
• Time in Patent Office: 543 Days
• Field of Search: 701 28, 356409, 356246, 356 501, 25027725, 235454
• CPC Class Codes: G01S 17/931 of land vehicles
• CPC Class Codes: G01S 2007/4975 of sensor obstruction by, e.g. dirt- or ice-coating, e.g. by reflection measurement on front-screen
• CPC Class Codes: G01S 2007/4977 including means to prevent or remove the obstruction
• CPC Class Codes: G01S 7/4811 common to transmitter and receiver
• CPC Class Codes: G01S 7/4813 Housing arrangements
• CPC Class Codes: G01S 7/497 Means for monitoring or calibrating
• CPC Class Codes: G05D 1/024 in combination with a laser lasers per se H01S
• CPC Class Codes: G06T 7/00 Image analysis

Abstract

The disclosure relates to determining whether an optical interferent is located on a sensor window and providing a way to identify and discard erroneous sensor data. An example system includes a housing, having a first sensor window and a second sensor window, a laser light source, and an optical sensor. The first window has a first property for deflecting water, and the second window has a second property for deflecting water different from the first property. The source is configured to generate a beam of light through the first window. One or more processors are configured to receive sensor data from the optical sensor and determine that an optical interferent is located on a surface of at least one of the first window and the sensor window based on a comparison between sensor data corresponding to the first window and sensor data corresponding to the second window.

Claims

1. A method for controlling a vehicle in an autonomous driving mode, the method comprising:

receiving, by one or more processors, sensor data generated by a sensor and identifying distances from the sensor to an object in an external environment of the sensor, the sensor having a housing including a first sensor window and a second sensor window, the first sensor window having a first external surface property and the second sensor window having a second external surface property different from the first external surface property;

determining, by the one or more processors, that a surface of the first sensor window includes an optical interferant based on a comparison between a first portion of the sensor data from the first sensor window corresponding to the object and a second portion of the sensor data from the second sensor window corresponding to the object; and

when the comparison indicates that the surface of the first sensor window includes the optical interferant, controlling, by the one or more processors, the vehicle in an autonomous driving mode based on the comparison.

2. The method of claim 1, wherein the first external surface property corresponds to an external surface of the first sensor window being more hydrophobic than an external surface of the second sensor window.

3. The method of claim 1, wherein the first external surface property corresponds to an external surface of the first sensor window being more hydrophilic than an external surface of the second sensor window.

4. The method of claim 1, wherein the first external surface property corresponds to a first coating applied to the first sensor window.

5. The method of claim 4, wherein the second external surface property corresponds to a second coating applied to the second sensor window, wherein the first coating and the second coating have different properties for deflecting water.

6. The method of claim 5, wherein the first external surface property corresponds to a first material of the first sensor window.

7. The method of claim 6, wherein the second external surface property corresponds to a second material of the second sensor window, wherein the first material and the second material have different properties for deflecting water.

8. The method of claim 1, wherein the comparison includes a comparison of a first distance to an object determined from the first portion of the sensor data from the first sensor window and a second distance to the object determined from the second portion of the sensor data from the second sensor window.

9. The method of claim 8, wherein the first distance and the second distance correspond to different locations of an object detected within a predetermined period of time.

10. The method of claim 1, wherein the first sensor window and the second sensor window comprise different portions of a single window.

11. The method of claim 1, wherein the optical interferent is water.

12. The method of claim 1, wherein the housing is attached to the vehicle.

13. The method of claim 1, wherein the sensor includes a semiconductor waveguide laser, a fiber laser or an excimer laser.

14. The method of claim 1, further comprising, when the comparison indicates that the first sensor window includes the optical interferant, temporarily ignoring sensor data generated via the first sensor window when controlling the vehicle in the autonomous driving mode.

15. The method of claim 1, further comprising, determining when sensor data generated via the first sensor window should no longer be ignored when controlling the vehicle in the autonomous driving mode.

16. The method of claim 1, further comprising, generating, using the sensor, the sensor data including the first portion and the second portion.

17. The method of claim 16, wherein the housing is configured to rotate such that the sensor is configured to generate a beam of light through both the first sensor window and the second sensor window at different times while the housing is rotating in order to generate the first portion and the second portion.

18. The method of claim 17, further comprising a mirror element configured to rotate and reflect the beam of light through both the first sensor window and the second sensor window at different times while the housing is rotating to generate the first portion and the second portion.

19. The method of claim 16, wherein the sensor includes a first laser and a second laser, the first laser being configured to generate a beam of light through the second sensor window while the second laser generates a beam of light through the first sensor window, and generating the sensor data includes using the first laser and the second laser.

20. The method of claim 19, wherein the second laser is fixed relative to the second sensor window and the first laser is fixed relative to the first sensor window, and the method further comprises rotating the second laser and the first laser with the housing in order to generate the sensor data.