Method and system for encoding and decoding LiDAR

Patent metadata

Field	Value
Publication number	US-11947047-B2
Application number	US-202117210173-A
Country	US
Kind code	B2
Filing date	Mar 23, 2021
Priority date	Jan 5, 2017
Publication date	Apr 2, 2024
Grant date	Apr 2, 2024

Abstract

The present disclosure describes a system and method for encoding pulses of light for LiDAR scanning. The system includes a sequence generator, a light source, a modulator, a light detector, a correlator, and a microprocessor. The sequence generator generates a sequence code that the modulator encodes into a pulse of light from the light source. The encoded pulse of light illuminates a surface of an object, in which scattered light from the encoded light pulse is detected. The correlator correlates the scattered light with the sequence code that outputs a peak value associated with a time that the pulse of light is received. The microprocessor is configured to determine a time difference between transmission and reception of the pulse of light based on whether the amplitude of the peak exceeds the threshold value. The microprocessor calculates a distance to the surface of the object based on the time difference.

First claim

What is claimed is:

1. A method, comprising:
transmitting, with a light source, a pulse group signal, wherein the pulse group signal comprises a plurality of pulses having a characteristic;
receiving a returned pulse group signal, wherein the returned pulse group signal corresponds to the transmitted pulse group signal scattered from a surface;
correlating the returned pulse group signal with the transmitted pulse group signal based on the characteristic;
determining a time difference between (1) a time associated with the transmitted pulse group signal and (2) a time associated with the returned pulse group signal;
calculating a distance from the light source to the surface based on the time difference; and
determining a reflectivity of the surface based on a correlation of the characteristic of the pulse group signal with the characteristic of the returned pulse group signal wherein the characteristic includes an amplitude of a correlation peak.

2. The method of claim 1 , wherein the characteristic is a number of pulses in the transmitted pulse group signal.

3. The method of claim 1 , wherein the characteristic is a pulse width of the pulse group signal.

4. The method of claim 1 , wherein the characteristic is an amplitude of the pulse group signal.

5. The method of claim 1 , wherein the characteristic is a pulse shape of the pulse group signal.

6. The method of claim 1 , wherein the characteristic is a repetition period of the pulse group signal.

7. The method of claim 1 , wherein the characteristic is a pulse position in a given timing slot of the pulse group signal.

8. The method of claim 1 , wherein the characteristic is a frequency of each pulse.

9. The method of claim 1 , wherein the transmitted pulse group signal is a first pulse group signal, the method further comprising:
transmitting a second pulse group signal, wherein the second pulse group signal comprises a second plurality of pulses having a second characteristic;
receiving a second returned pulse group signal, wherein the returned pulse group signal corresponds to the second pulse group signal scattered from a second surface;
correlating the second returned pulse group signal with the second pulse group signal based on the second characteristic;
determining a second time difference between (1) a time associated with the second pulse group signal and (2) a time associated with the second returned pulse group signal;
calculating a second distance from the light source to the second surface based on the second time difference; and
determining a reflectivity of the second surface based on a correlation of the second characteristic of the second pulse group signal with the characteristic of the second returned pulse group signal.

10. The method of claim 9 , wherein a time between (1) the time associated with the first pulse group signal and (2) the time associated with the second pulse group signal is less than a round trip time of flight for a light pulse to reach a farthest object per design of the light source.

11. The method of claim 9 , wherein:
the second pulse group signal is transmitted after the first pulse group signal, and the first returned pulse group signal is correlated with the first pulse group signal regardless of when the first returned pulse group signal is received relative to receipt of the second returned pulse group signal.

12. The method of claim 1 , further comprising transmitting a first plurality of pulse group signals, wherein:
the first pulse group signal is part of the first plurality of pulse group signals, and
each pulse group signal of the plurality of the pulse group signals is transmitted periodically at a first time interval.

13. The method of claim 12 , further comprising transmitting a second plurality of pulse group signals, wherein:
each of the second plurality of the second pulse group signals is transmitted periodically at a second time interval.

14. The method of claim 13 , wherein a ratio between the first time interval and the second time interval is configured such that none of the first plurality of the first pulse group signal overlaps with any of the second plurality of pulses.

15. The method of claim 13 , wherein the second time interval is smaller than the first time interval.

16. The method of claim 1 , wherein the light source is placed on a vehicle.

17. A light detection and ranging (LiDAR) scanning system, comprising:
a light source, wherein the light source is configured to transmit a pulse group signal, wherein the pulse group signal comprises a plurality of pulses having a characteristic;
a light detector configured to receive a returned pulse group signal, wherein the returned pulse group signal corresponds to the transmitted pulse group signal scattered from a surface; and
a microprocessor electrically coupled to the light source and the light detector, wherein the microprocessor is configured to:
correlate the returned pulse group signal with the transmitted pulse group signal based on the characteristic;
determine a time difference between (1) a time associated with the transmitted pulse group signal and (2) a time associated with the returned pulse group signal;
calculate a distance from the light source to the surface based on the time difference; and
determine a reflectivity of the surface based on a correlation of the characteristic of the pulse group signal with the characteristic of the returned pulse group signal wherein the characteristic includes an amplitude of a correlation peak.

18. The system of claim 17 , wherein the characteristic is a number of pulses in the transmitted pulse group signal.

19. The system of claim 17 , wherein the characteristic is a frequency of each pulse.

20. The system of claim 17 , wherein the light source is placed on a vehicle.

Assignees

• Innovusion Ireland Ltd
• Seyond Inc

Inventors

• Li Yimin
• Bao Junwei
• Zhang Rui

Classifications

• G01S7/4865 Primary

  Time delay measurement, e.g. time-of-flight measurement, time of arrival measurement or determining the exact position of a peak (peak detection in noise, signal conditioning G01S7/487) · CPC title

• G01S7/484

  Transmitters · CPC title

• G01S17/10

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

• G01S7/4876

  by removing unwanted signals (G01S7/495 takes precedence) · CPC title

• G01S7/487 Primary

  Extracting wanted echo signals {, e.g. pulse detection} · CPC title