Adjustable scan patterns for lidar system

Patent metadata

Field	Value
Publication number	US-2019107623-A1
Application number	US-201816155243-A
Country	US
Kind code	A1
Filing date	Oct 9, 2018
Priority date	Oct 9, 2017
Publication date	Apr 11, 2019
Grant date	—

Abstract

In one embodiment, a lidar system includes a light source configured to emit pulses of light and a scanner configured to scan at least a portion of the emitted pulses of light along a scan pattern contained within an adjustable field of regard. The scanner includes a first scanning mirror configured to scan the portion of the emitted pulses of light substantially parallel to a first scan axis to produce multiple scan lines of the scan pattern, where each scan line is oriented substantially parallel to the first scan axis. The scanner also includes a second scanning mirror configured to distribute the scan lines along a second scan axis that is substantially orthogonal to the first scan axis, where the scan lines are distributed within the adjustable field of regard according to an adjustable second-axis scan profile.

First claim

What is claimed is:

1 . A lidar system comprising:
a light source configured to emit pulses of light; a scanner configured to scan at least a portion of the emitted pulses of light along a scan pattern contained within an adjustable field of regard, wherein the scanner comprises:
a first scanning mirror configured to scan the portion of the emitted pulses of light substantially parallel to a first scan axis to produce a plurality of scan lines of the scan pattern, wherein each scan line is oriented substantially parallel to the first scan axis; and
a second scanning mirror configured to distribute the scan lines along a second scan axis that is substantially orthogonal to the first scan axis, wherein the scan lines are distributed within the adjustable field of regard according to an adjustable second-axis scan profile that comprises a minimum scan angle along the second scan axis, a maximum scan angle along the second scan axis, and a scan-line distribution, wherein:
the scan lines are located between the minimum scan angle and the maximum scan angle; and
the scan-line distribution represents a distribution of scan lines between the minimum and maximum scan angles and corresponds to one or more positions or one or more scanning speeds of the second scanning mirror;

a receiver configured to detect at least a portion of the scanned pulses of light scattered by a target located a distance from the lidar system; and a processor configured to adjust the second-axis scan profile comprising adjusting the minimum scan angle, maximum scan angle, or scan-line distribution.

2 . The lidar system of claim 1 , wherein the one or more scanning speeds of the second scanning mirror comprise a substantially constant scanning speed, and the corresponding scan-line distribution comprises scan lines that are spaced apart substantially uniformly along the second scan axis.

3 . The lidar system of claim 1 , wherein the one or more scanning speeds of the second scanning mirror comprise a lower scanning speed and a higher scanning speed, and the corresponding scan-line distribution comprises:
a higher density of scan lines corresponding to the lower scanning speed; and a lower density of scan lines corresponding to the higher scanning speed.

4 . The lidar system of claim 1 , wherein the one or more positions of the second scanning mirror comprise a beginning position and an ending position, wherein:
the beginning position of the second scanning mirror corresponds to a scan line located at the maximum scan angle; and the ending position of the second scanning mirror corresponds to a scan line located at the minimum scan angle.

5 . The lidar system of claim 1 , wherein adjusting the second-axis scan profile comprises adjusting the minimum and maximum scan angles to reduce an angular range of the adjustable field of regard along the second scan axis so that the lidar system scans a particular region of interest with an increased density of scan lines or the lidar system scans the particular region of interest with an increased frame rate.

6 . The lidar system of claim 1 , wherein adjusting the second-axis scan profile comprises adding an angular-offset value to each of the minimum and maximum scan angles to shift the adjustable field of regard along the second scan axis by the angular-offset value.

7 . The lidar system of claim 1 , wherein adjusting the second-axis scan profile comprises adjusting the scan-line distribution to produce an increased density of scan lines for a particular region of interest.

8 . The lidar system of claim 1 , wherein the processor is configured to adjust the second- axis scan profile after the lidar system captures a first frame, wherein the adjusted second-axis scan profile is applied to a second frame that is captured after the first frame.

9 . The lidar system of claim 1 , wherein:
the processor is configured to adjust the second-axis scan profile in response to detecting the pulses of light scattered by the target; and the second-axis scan profile is adjusted to provide a scan of the target that has a higher resolution or a higher frame rate than a previous scan.

10 . The lidar system of claim 1 , wherein the processor is configured to adjust the second-axis scan profile based at least in part on a driving condition of a vehicle in which the lidar system is operating, wherein the driving condition comprises:
detection of the target within the adjustable field of regard of the lidar system; a grade of a road on which the vehicle is operating; or a change in the grade of the road on which the vehicle is operating.

11 . The lidar system of claim 1 , wherein the scan lines are distributed temporally based at least in part on a scanning speed of the first scanning mirror.

12 . The lidar system of claim 1 , wherein:
the first scanning mirror is driven repeatedly in a back-and-forth motion by a galvanometer scanner; and each scan line corresponds to a single forward or backward motion of the galvanometer scanner.

13 . The lidar system of claim 1 , wherein the first scanning mirror is a polygon mirror comprising two or more reflective surfaces, wherein:
the polygon mirror is configured to continuously rotate in one direction about a rotation axis of the polygon mirror; and the portion of the emitted pulses of light are reflected sequentially from the reflective surfaces as the polygon mirror is rotated, resulting in the portion of the emitted pulses of light being scanned substantially parallel to the first scan axis to produce the plurality of scan lines, wherein each scan line corresponds to a reflection from one of the reflective surfaces.

14 . The lidar system of claim 1 , wherein each scan line extends from one edge of the adjustable field of regard to an opposite edge of the adjustable field of regard.

15 . The lidar system of claim 1 , wherein the scan pattern comprises approximately 10 to approximately 1,000 scan lines.

16 . The lidar system of claim 1 , wherein each scan line being oriented substantially parallel to the first scan axis comprises each scan line being oriented to within approximately 5 degrees of the first scan axis.

17 . The lidar system of claim 1 , wherein:
the first scan axis is substantially horizontal; the second scan axis is substantially vertical; and the adjustable minimum scan angle and the adjustable maximum scan angle each corresponds to an elevation angle.

18 . The lidar system of claim 1 , wherein:
the first scan axis is substantially vertical; the second scan axis is substantially horizontal; and the adjustable minimum scan angle and the adjustable maximum scan angle each corresponds to an azimuth angle.

19 . The lidar system of claim 1 , wherein the adjustable field of regard comprises:
a field of regard along the first scan axis greater than or equal to 40 degrees; and a field of regard along the second scan axis that is between approximately 1 degree and approximately 40 degrees.

20 . The lidar system of claim 1 , wherein the processor is further configured to determine the distance from the lidar system to the target based at least in part on a round-trip time of flight for an emitted pulse of light to travel from the lidar system to the target and back to the lidar system.

21 . The lidar system of claim 1 , wherein:
the light source has an operating wavelength between approximately 1400 nm and approximately 1600 nm; and the lidar system operates in an eye-safe manner.

Assignees

• Luminar Tech Inc

Inventors

• Campbell Scott R
• Weed Matthew D
• Martin Lane A
• Eichenholz Jason M
• Russell Austin K

Classifications

• G01S7/4802

  using analysis of echo signal for target characterisation; Target signature; Target cross-section · CPC title

• G01S17/42

  Simultaneous measurement of distance and other co-ordinates (indirect measurement G01S17/46) · CPC title

• G01S17/931

  of land vehicles · CPC title

• G01S17/10 Primary

  using transmission of interrupted, pulse-modulated waves (determination of distance by phase measurements G01S17/32) · CPC title

• G02B26/10

  Scanning systems · CPC title