Method and system for enhanced velocity resolution and signal to noise ratio in optical phase-encoded range detection

Patent metadata

Field	Value
Publication number	US-12241978-B2
Application number	US-202318320821-A
Country	US
Kind code	B2
Filing date	May 19, 2023
Priority date	Jul 16, 2019
Publication date	Mar 4, 2025
Grant date	Mar 4, 2025

Abstract

An autonomous vehicle control system may include one or more processors configured to receive an electrical signal generated based on a returned optical signal that is reflected from an object. The one or more processors may determine a Doppler frequency shift of the returned optical signal over a first duration of the electrical signal. The one or more processors may generate a corrected electrical signal based on the Doppler frequency shift. The one or more processors may determine a range to the object based on the corrected electrical signal over a second duration that is shorter than the first duration. The one or more processors may control at least one of a steering system or a braking system based on the range.

First claim

What is claimed is:

1. An autonomous vehicle control system comprising: one or more processors; and one or more computer-readable storage mediums storing instructions which, when executed by the one or more processors, cause the one or more processors to:
receive an electrical signal generated based on a returned optical signal that is reflected from an object;
determine a Doppler frequency shift of the returned optical signal over a first duration of the electrical signal;
generate a corrected electrical signal based on the Doppler frequency shift;
determine a range to the object based on the corrected electrical signal over a second duration that is shorter than the first duration; and
control at least one of a steering system or a braking system based on the range.

2. The autonomous vehicle control system as recited in claim 1 , wherein the one or more processors are further configured to:
generate a first optical signal by modulating a code that indicates a sequence of phases for a phase encoded signal with reference to an optical signal; and
transmit the first optical signal to the object.

3. The autonomous vehicle control system as recited in claim 2 , wherein the first duration is an integer multiple greater than 1 of a duration of the code.

4. The autonomous vehicle control system as recited in claim 2 , wherein the second duration is equal to or substantially equal to a duration of the code.

5. The autonomous vehicle control system as recited in claim 2 , wherein the one or more processors are further configured to:
determine the range to the object based on a cross correlation, over the second duration, between the corrected electrical signal and a radio frequency (RF) signal that is associated with the first optical signal.

6. The autonomous vehicle control system as recited in claim 5 , wherein the one or more processors are further configured to:
determine the cross correlation, over the second duration, between (i) a first Fourier transform of the RF signal that is associated with the first optical signal and (ii) a second Fourier transform of the corrected electrical signal.

7. The autonomous vehicle control system as recited in claim 1 , wherein the one or more processors are further configured to:
determine a spectrum over the first duration of the electrical signal; and
determine the Doppler frequency shift based on the spectrum.

8. The autonomous vehicle control system as recited in claim 1 , wherein the spectrum is a cross spectrum of an in-phase component of the electrical signal and a quadrature component of the electrical signal.

9. The autonomous vehicle control system as recited in claim 1 , wherein the one or more processors are further configured to:
determine the first duration based on at least one of a speed of a vehicle relative to a surface external to the vehicle, a location of the vehicle relative to the surface external to the vehicle, and a scan angle relative to the surface external to the vehicle.

10. The autonomous vehicle control system as recited in claim 1 , wherein the one or more processors are further configured to:
control the at least one of the steering system or the braking system based on the range and a sign of the Doppler frequency shift.

11. The autonomous vehicle as recited in claim 1 , wherein the one or more processors are further configured to:
generate a first optical signal by modulating a code that indicates a sequence of phases for a phase encoded signal with reference to an optical signal; and
transmit the first optical signal to the object.

12. The autonomous vehicle as recited in claim 11 , wherein the first duration is an integer multiple greater than 1 of a duration of the code.

13. The autonomous vehicle as recited in claim 11 , wherein the second duration is equal to or substantially equal to a duration of the code.

14. The autonomous vehicle as recited in claim 11 , wherein the one or more processors are further configured to:
determine the range to the object based on a cross correlation, over the second duration, between the corrected electrical signal and a radio frequency (RF) signal that is associated with the first optical signal.

15. The autonomous vehicle as recited in claim 14 , wherein the one or more processors are further configured to:
determine the cross correlation, over the second duration, between (i) a first Fourier transform of the RF signal that is associated with the first optical signal and (ii) a second Fourier transform of the corrected electrical signal.

16. A light detection and ranging (LIDAR) system, the LIDAR system comprising:
one or more processors; and one or more computer-readable storage mediums storing instructions which, when executed by the one or more processors, cause the one or more processors to:
receive an electrical signal generated based on a returned optical signal that is reflected from an object;
determine a Doppler frequency shift of the returned optical signal over a first duration of the electrical signal;
generate a corrected electrical signal based on the Doppler frequency shift; and
determine a range to the object based on the corrected electrical signal over a second duration that is shorter than the first duration.

17. An autonomous vehicle comprising:
at least one of a steering system or a braking system; and
a vehicle controller comprising one or more processors configured to:
receive an electrical signal generated based on a returned optical signal that is reflected from an object;
determine a Doppler frequency shift of the returned optical signal over a first duration of the electrical signal;
generate a corrected electrical signal based on the Doppler frequency shift;
determine a range to the object based on the corrected electrical signal over a second duration that is shorter than the first duration; and
control the at least one of the steering system or the braking system based on the range.

18. The autonomous vehicle as recited in claim 17 , wherein the one or more processors are further configured to:
determine a spectrum over the first duration of the electrical signal; and
determine the Doppler frequency shift based on the spectrum.

19. The autonomous vehicle as recited in claim 17 , wherein the one or more processors are further configured to: determine the first duration based on at least one of a speed of a vehicle relative to a surface external to the vehicle, a location of the vehicle relative to the surface external to the vehicle, and a scan angle relative to the surface external to the vehicle.

20. The autonomous vehicle as recited in claim 17 , wherein the one or more processors are further configured to:
control the at least one of the steering system or the braking system based on the range and a sign of the Doppler frequency shift.

Assignees

• Aurora Operations Inc

Inventors

• Crouch Stephen C
• Barber Zeb William
• Kadlec Emil
• Rupavatharam Krishna

Classifications

• G05D1/43

  Control of position or course in two dimensions [2D] · CPC title

• G05D2111/10

  Optical signals · CPC title

• G01S17/931 Primary

  of land vehicles · CPC title

• G01S17/32 Primary

  using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated · CPC title

• G05D1/0088

  characterized by the autonomous decision making process, e.g. artificial intelligence, predefined behaviours (using knowledge based models G06N5/00) · CPC title