Systems and methods for efficient multi-return light detectors

Patent metadata

Field	Value
Publication number	US-12449306-B2
Application number	US-202418595114-A
Country	US
Kind code	B2
Filing date	Mar 4, 2024
Priority date	Dec 7, 2017
Publication date	Oct 21, 2025
Grant date	Oct 21, 2025

Abstract

Described herein are systems and methods that may efficiently detect multi-return light signals. A light detection and ranging system, such as a LIDAR system, may fire a laser beam that may hit multiple objects with a different distance in one line, causing multi-return light signals to be received by the system. Multi-return detectors may be able to analyze the peak magnitude of a plurality of peaks in the return signals and determine a multitude of peaks, such as the first peak, the last peak and the maximum peak. One embodiment to detect the multi-return light signals may be a multi-return recursive matched filter detector. This detector comprises a matched filter, peak detector, centroid calculation and a zeroing out function. Other embodiments may be based on a maximum finder that algorithmically selects the highest magnitude peaks from samples of the return signal and buffers for regions of interests peaks.

First claim

What is claimed:

1. A multiple-return light signal detection method for a light detection and ranging (LIDAR) system, the method comprising:
receiving a multi-return signal having a plurality of peaks in a time period;
filtering the multi-return signal based at least in part, on a pulse shape of an emitted laser beam, to produce a filtered signal;
identifying a sequence of two or more peaks of the filtered signal in the time period;
selecting at least one peak from the sequence of two or more peaks;
identifying a number of samples centered around each of the at least one selected peak; and
determining, for each selected peak, a centroid of the selected peak based at least in part on the samples centered around the selected peak.

2. The method of claim 1 , wherein filtering the multi-return signal comprises convolving the multi-return signal with a signal having the pulse shape of the emitted laser beam.

3. The method of claim 1 , further comprising:
determining, for each selected peak, a time of arrival and an intensity saturation count based on a centroid of the selected peak.

4. The method of claim 1 , wherein identifying the sequence of two or more peaks of the filtered signal in the time period comprises identifying each peak of the filtered signal having a respective amplitude that exceeds a pre-set threshold value, and wherein a probability of false alarm depends on the pre-set threshold value.

5. The method of claim 1 , wherein filtering the multi-return signal is performed by a matched filter operating at a rate of 8 samples per clock.

6. The method of claim 1 , wherein the sequence of two or more peaks is identified based at least in part on mean and variance noise statistics.

7. The method of claim 1 , wherein the selected peak is at least one of a largest peak and a second largest peak.

8. The method of claim 1 , wherein the selected peak is at least one of a first arrived peak and a last arrived peak.

9. The method of claim 1 , wherein samples are identified around each of the two or more peaks in the sequence of two or more peaks.

10. A light detection and ranging (LIDAR) system, comprising:
a transmitter configured to emit a laser beam;
a light detector configured to receive a multi-return signal having a plurality of peaks in a time period;
a matched filter circuit configured to filter the multi-return signal based at least in part on a pulse shape of the emitted laser beam to produce a filtered signal; and
a peak filter circuit configured to:
identify a sequence of two or more peaks of the filtered signal in the time period;
select at least one peak from the sequence of two or more peaks; and
cause a buffer to store a number of samples centered around each of the at least one selected peaks; and
determine, for each selected peak, a centroid of the selected peak based at least in part on the samples centered around the selected peak.

11. The system of claim 10 , wherein filtering the multi-return signal comprises convolving the multi-return signal with a signal having the pulse shape of the emitted laser beam.

12. The system of claim 10 , wherein selecting at least one peak comprises:
determining a peak magnitude for each of the two or more peaks in the time period; and
selecting at least one peak from the two or more peaks based on a time of arrival.

13. The system of claim 10 , further configured to:
determine, for each selected peak, a time of arrival and an intensity saturation count based on a centroid of the selected peak.

14. The system of claim 13 , wherein the matched filter operates at a rate of 8 samples per clock.

15. The system of claim 10 , wherein the buffer stores 10 samples around the selected peak.

16. The system of claim 10 , wherein the sequence of two or more peaks is determined based at least in part on mean and variance noise statistics.

17. The system of claim 10 , wherein the selected peak is at least one of a largest peak and a second largest peak.

18. The system of claim 10 , wherein the selected peak is at least one of a first arrived peak and a last arrived peak.

19. The system of claim 10 , wherein, identifying the sequence of two or more peaks of the filtered signal in the time period comprises identifying each peak of the filtered signal having a respective amplitude that exceeds a pre-set threshold value, and wherein a probability of false alarm depends on the pre-set threshold value.

20. The system of claim 10 , wherein samples are stored around each of the two or more peaks in the sequence of two or more peaks.

Assignees

• Velodyne Lidar Usa Inc

Inventors

• Gunnam Kiran Kumar
• Gao Kanke
• Barot Nitinkumar Sagarbhai
• Gopalan Anand
• Hall David S

Classifications

• G01S17/931

  of land vehicles · CPC title

• G01S7/4816

  of receivers alone · CPC title

• G01S17/42 Primary

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

• G01S7/4861 Primary

  Circuits for detection, sampling, integration or read-out · CPC title

• G01S17/86

  Combinations of lidar systems with systems other than lidar, radar or sonar, e.g. with direction finders · CPC title