Method and system for laser phase tracking for internal reflection subtraction in phase-encoded LIDAR

Patent metadata

Field	Value
Publication number	US-10768282-B2
Application number	US-201916681663-A
Country	US
Kind code	B2
Filing date	Nov 12, 2019
Priority date	Nov 13, 2018
Publication date	Sep 8, 2020
Grant date	Sep 8, 2020

Abstract

A system and method for optical detection in autonomous vehicles includes modulating an optical signal from a laser to generate a modulated optical signal and transmitting the modulated optical signal toward an object. The system and method include receiving, responsive to transmitting the modulated optical signal, a returned optical signal and mixing the returned optical signal with a reference optical signal associated with the optical signal from the laser to generate a mixed optical signal and detecting the mixed optical signal to generate an electrical signal. Based on the electrical signal and the modulated optical signal, a parameter of an internal reflection of the returned optical signal from one or more optical components is determined, which may be used to operate a vehicle.

First claim

What is claimed is:

1. A system comprising:
a laser that provides a plurality of optical signals;
a modulator that modulates the plurality of optical signals from the laser to generate a plurality of modulated optical signals;
an optical coupler that generates a plurality of reference optical signals, each associated with a respective optical signal of the plurality of optical signals from the laser, transmits the plurality of modulated optical signals into free space, and receives a plurality of returned optical signals responsive to transmitting the plurality of modulated optical signals into the free space;
an optical mixer that mixes each of the plurality of returned optical signals with a respective reference optical signal of the plurality of reference optical signals to generate a respective mixed optical signal of a plurality of mixed optical signals;
an optical detector that detects each mixed optical signal of the plurality of mixed optical signals to generate a respective electrical signal of a plurality of electrical signals; and
a processor that:
determines a first signal by adjusting a parameter of a first electrical signal of the plurality of electrical signals;
determines a second signal by adjusting a parameter of a second electrical signal of the plurality of electrical signals;
determines an internal reflection signal indicative of an internal reflection of one or more optical components based on the first signal and the second signal;
determines a third signal by adjusting a third electrical signal of the plurality of electrical signals using the internal reflection signal; and
operates a vehicle based on the third signal.

2. The system of claim 1 , wherein the parameter of the first electrical signal and the parameter of the second electrical signal are each selected from at least one of a phase, an amplitude, a frequency, or an angular frequency.

3. The system of claim 1 , wherein the modulator modulates the plurality of reference optical signals prior to mixing each of the returned optical signals with the respective reference optical signal of the plurality of reference optical signals.

4. The system of claim 1 , wherein the plurality of optical signals are modulated based on a sequence of phases of each respective optical signal.

5. The system of claim 4 , wherein the optical coupler transmits the plurality of modulated optical signals into free space for each of a first plurality of measurements, and receives each of the returned optical signals for each of the first plurality of measurements.

6. The system of claim 5 , wherein the optical mixer generates the plurality of mixed optical signals for each of the first plurality of measurements, wherein the optical detector generates the respective electrical signal of the plurality of electrical signals for each of the first plurality of measurements.

7. The system of claim 6 , wherein the parameter of the first electrical signal and the second electrical signal each comprise a phase of the internal reflection signal for each of the first plurality of measurements.

8. The system of claim 7 , wherein the processor determines a parameter of the internal reflection signal based on a dot product measurement.

9. The system of claim 7 , wherein the processor determines the parameter of the internal reflection signal by:
determining an average over a second plurality of measurements including one or more measurements of the first plurality of measurements of the electrical signal, wherein the average is determined based at least in part on the phase of the internal reflection signal for each of the second plurality of measurements; and
determining a corrected return signal based at least in part on (i) the average over the second plurality of measurements and (ii) the electrical signal for at least one of the first plurality of measurements.

10. The system of claim 9 , wherein the processor operates the vehicle based on the corrected return signal.

11. The method of claim 1 , wherein the plurality of optical signals are modulated based on a sequence of phases of each respective optical signal.

12. The method of claim 11 , wherein transmitting the modulated optical signal toward the object comprises transmitting the plurality of modulated optical signals for each of a first plurality of measurements, wherein receiving the plurality of returned optical signals comprises receiving each of the returned optical signals for each of the first plurality of measurements.

13. The method of claim 12 , wherein the plurality of mixed optical signals are generated for each of the first plurality of measurements, wherein the respective electrical signal of the plurality of electrical signals is generated for each of the first plurality of measurements.

14. The method of claim 13 , wherein the parameter of the first electrical signal and the second electrical signal each comprises a phase of the internal reflection signal for each of the first plurality of measurements.

15. The method of claim 14 , wherein determining a parameter of the internal reflection signal further comprises determining the parameter of the internal reflection signal based on a dot product measurement.

16. The method of claim 14 , wherein determining the parameter of the internal reflection signal comprises:
determining an average over a second plurality of including one or more measurements of the first plurality of measurements of the electrical signal, wherein the average is determined based at least in part on the phase of the internal reflection for each of the second plurality of measurements; and
determining a corrected return signal based at least in part on (i) the average over the second plurality of measurements and (ii) the electrical signal for at least one of the first plurality of measurements.

17. The method of claim 16 , wherein operating the vehicle comprises operating the vehicle based on the corrected return signal.

18. A method comprising:
modulating a plurality of optical signals from a laser to generate a plurality of modulated optical signals;
transmitting the plurality of modulated optical signals into free space;
receiving, responsive to transmitting the plurality of modulated optical signals, a plurality of returned optical signals;
mixing each of the returned optical signals with a respective reference optical signal of the plurality of reference optical signals to generate a respective mixed optical signal of a plurality of mixed optical signals;
detecting each mixed optical signal of the plurality of mixed optical signals to generate a respective electrical signal of the plurality of electrical signals;
determining a first signal by adjusting a parameter of a first electrical signal of the plurality of electrical signals;
determining a second signal by adjusting a parameter of a second electrical signal of the plurality of electrical signals;
determining an internal reflection signal indicative of an internal reflection of one or more optical components based on the first signal and the second signal;
determining a third signal by adjusting a third electrical signal of the plurality of electrical signals using the internal reflection signal; and
operating, based on the third signal, a vehicle.

19. The method of claim 1 , wherein the parameter of the first electrical signal and the parameter of the second electrical signal are each selected from at least one of a phase, an amplitude, a frequency, or an angular frequency.

20. The method of

Assignees

• Blackmore Sensors & Analytics Llc

Inventors

• Crouch Stephen C
• Kadlec Emil
• Rupavatharam Krishna

Classifications

• G01S17/931

  of land vehicles · CPC title

• G01S17/66

  Tracking systems using electromagnetic waves other than radio waves · CPC title

• G01S17/26

  wherein the transmitted pulses use a frequency-modulated or phase-modulated carrier wave, e.g. for pulse compression of received signals · CPC title

• G01S7/495

  Counter-measures or counter-counter-measures {using electronic or electro-optical means} · CPC title

• G01S7/487

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