Hyper temporal lidar using multiple matched filters to orient a lidar system to a frame of reference

Patent metadata

Field	Value
Publication number	US-11822016-B2
Application number	US-202117525034-A
Country	US
Kind code	B2
Filing date	Nov 12, 2021
Priority date	Mar 26, 2021
Publication date	Nov 21, 2023
Grant date	Nov 21, 2023

Abstract

A lidar system comprises (1) an array of pixels for sensing incident light and (2) a circuit for processing a signal representative of the sensed incident light to detect a reflection of a laser pulse from a target within a field of view. The circuit can comprise a plurality of matched filters that are tuned to different reflected pulse shapes for detecting pulse reflections within the incident light, and wherein the circuit (1) applies the signal to the matched filters to determine an obliquity for the target based how the matched filters respond to the applied signal and (2) determines a correction angle based on the determined target obliquity, the correction angle for orienting the field of view to a frame of reference in response to a tilting of the lidar system. In an example embodiment, the circuit can comprise a signal processing circuit that performs the signal application and correction angle determination operations. In another example embodiment, the circuit can comprise (1) a signal processing circuit that performs the signal application operation and (2) a receiver controller circuit that performs the correction angle determination operation.

First claim

What is claimed is:

1. A lidar system comprising:
an array of pixels for sensing incident light; and
a circuit for processing a signal representative of the sensed incident light to detect a reflection of a laser pulse from a target within a field of view, wherein the circuit comprises a plurality of matched filters that are tuned to different reflected pulse shapes for detecting pulse reflections within the incident light, and wherein the circuit (1) applies the signal to the matched filters to generate filter response data from the matched filters, wherein the generated filter response data is indicative of an obliquity for the target and (2) determines a correction angle based on the generated filter response data from the matched filters, wherein the correction angle orients the field of view to a frame of reference in response to a tilting of the lidar system.

2. The system of claim 1 further comprising:
a lidar transmitter that fires a laser pulse shot at a ground plane to produce a pulse reflection from which the correction angle is determined.

3. The system of claim 2 wherein the ground plane comprises a road surface.

4. The system of claim 1 further comprising:
a lidar transmitter that fires a laser pulse shot at a target with a known orientation relative to the frame of reference to produce a pulse reflection from which the correction angle is determined.

5. The system of claim 4 wherein the target with the known orientation comprises a street sign.

6. The system of claim 1 wherein the frame of reference is a horizon for the lidar system.

7. The system of claim 1 further comprising:
a control circuit that adjusts a plurality of angles for a plurality of range point returns in a point cloud based on the determined correction angle.

8. The system of claim 1 further comprising:
a control circuit that adjusts a shot angle for a scheduled laser pulse shot based on the determined correction angle.

9. The system of claim 8 wherein the control circuit (1) predicts a change in orientation for the lidar system based on a current trajectory for the tilting of the lidar system and (2) adjusts the shot angle for the scheduled laser pulse shot based on the determined correction angle and the predicted change in orientation.

10. The system of claim 9 wherein the circuit operates to determine a plurality of correction angles over time in response to the tilting of the lidar system over time; and
wherein the control circuit adjusts a plurality of shot angles for a plurality of scheduled laser pulse shots based on the determined correction angles.

11. The system of claim 1 wherein the circuit comprises a signal processing circuit, wherein the signal processing circuit (1) applies the signal to the matched filters to generate the filter response data that is indicative of the obliquity for the target and (2) determines the correction angle based on the generated filter response data from the matched filters.

12. The system of claim 1 wherein the circuit comprises a signal processing circuit and a receiver controller circuit, wherein the signal processing circuit applies the signal to the matched filters to generate the filter response data that is indicative of the obliquity for the target, and wherein the receiver controller circuit determines the correction angle based on the generated filter response data from the matched filters.

13. The system of claim 1 wherein the matched filters include a plurality of matched filters corresponding to different degrees of obliquity for the target that are tuned to different reflected pulse shapes for reflections from the target at different degrees of obliquity.

14. The system of claim 13 wherein the circuit determines a degree of obliquity for the target based on which of the matched filters produces a largest response to the applied signal, and wherein the correction angle is based on the determined degree of obliquity for the target.

15. The system of claim 13 wherein the different degrees of obliquity include non-obliquity.

16. The system of claim 13 wherein the matched filters include:
a first matched filter tuned to a reflected pulse shape for a reflection from a non-oblique target; and
a second matched filter tuned to a reflected pulse shape for a reflection from an oblique target.

17. The system of claim 16 wherein the circuit classifies the target as oblique or non-oblique based on which of the first and second matched filters produces a larger response to the applied signal.

18. The system of claim 13 wherein the matched filters include:
a first matched filter tuned to a reflected pulse shape for a reflection from a non-oblique target;
a second matched filter tuned to a reflected pulse shape for a reflection from an oblique target at a first amount of non-zero obliquity; and
a third matched filter tuned to a reflected pulse shape for a reflection from an oblique target at a second amount of non-zero obliquity.

19. The system of claim 18 wherein the circuit determines whether the target exhibits non-obliquity, the first amount of non-zero obliquity, or the second amount of non-zero obliquity based on which of the first, second, and third filters produces a largest response to the applied signal.

20. The system of claim 1 wherein the matched filters include a matched filter corresponding to an oblique target that is tuned to a reflected pulse shape that exhibits a stretching relative to a transmitted pulse shape for the laser pulse that is indicative of the oblique target.

21. The system of claim 1 wherein the circuit applies the signal to the matched filters in parallel.

22. The system of claim 1 wherein the circuit comprises an application-specific integrated circuit (ASIC) on which the matched filters are deployed.

23. The system of claim 1 wherein the circuit comprises a field programmable gate array (FPGA) on which the matched filters are deployed.

24. The system of claim 1 wherein the laser pulse exhibits a transmitted laser pulse shape that is Gaussian.

25. The system of claim 1 further comprising:
a laser source;
a lidar transmitter, wherein the lidar transmitter comprises a plurality of scannable mirrors, and wherein the lidar transmitter transmits a plurality of laser pulses from the laser source toward a plurality of targets in the field of view via the scannable mirrors according to a shot list; and
a control circuit that schedules laser pulses in the shot list for targeting defined range points in the field of view based on (1) a laser energy model that models energy available for laser pulses from the laser source over time and (2) a mirror motion model that models motion for at least one of the scannable mirrors over time.

26. The system of claim 25 wherein the lidar transmitter (1) scans a first scannable mirror in a resonant mode and (2) scans a second scannable mirror in a point-to-point mode according to a step function that varies as a function of the range points targeted by the shot list.

27. The system of claim 1 further comprising:
a lidar transmitter that fires a plurality of laser pulse shots toward a plurality of targeted range points in the field of view according to a shot list, wherein the shot list defines an order of shot angles in the field of view for the range points to be targeted with the laser pulse shots; and
wherein the circuit (1) selects a plurality of

Assignees

• Aeye Inc

Inventors

• Dussan Luis
• Steinhardt Allan
• Benscoter Joel
• Gustavson Todd

Classifications

• G01S7/4863 Primary

  Detector arrays, e.g. charge-transfer gates · CPC title

• G01S7/484

  Transmitters · CPC title

• G01S7/4814 Primary

  of transmitters alone · CPC title

• G01S7/4816

  of receivers alone · CPC title

• G01S7/4817

  relating to scanning · CPC title