Method and System for Ladar Pulse Deconfliction Using Delay Code Selection

• US 20180239000A1
• Filed: 02/14/2018
• Published: 08/23/2018
• Est. Priority Date: 02/17/2017
• Status: Active Grant

• Current Assignee: AEye, Inc.
• Original Assignee: AEye, Inc.
• Inventors: Dussan, Luis Carlos, Steinhardt, Allan
• Granted Patent: US 10,185,028 B2
• Time in Patent Office: Days
• CPC Class Codes: G01S 17/06 Systems determining position data of a target
• CPC Class Codes: G01S 17/10 using transmission of interrupted, pulse-modulated waves determination of distance by phase measurements G01S17/32
• CPC Class Codes: G01S 17/66 Tracking systems using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 17/86 Combinations of lidar systems with systems other than lidar, radar or sonar, e.g. with direction finders
• CPC Class Codes: G01S 17/931 of land vehicles
• CPC Class Codes: G01S 2013/9316 combined with communication equipment with other vehicles or with base stations
• CPC Class Codes: G01S 7/006 using shared front-end circuitry, e.g. antennas G01S13/765, G01S13/825 take precedence
• CPC Class Codes: G01S 7/4816 of receivers alone
• CPC Class Codes: G01S 7/484 Transmitters
• CPC Class Codes: G01S 7/4861 Circuits for detection, sampling, integration or read-out
• CPC Class Codes: G01S 7/4865 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 Class Codes: G01S 7/487 Extracting wanted echo signals , e.g. pulse detection
• CPC Class Codes: G01S 7/4873 by deriving and controlling a threshold value
• CPC Class Codes: G01S 7/4876 by removing unwanted signals G01S7/495 takes precedence

Abstract

Disclosed herein are a number of example embodiments that employ controllable delays between successive ladar pulses in order to discriminate between “own” ladar pulse reflections and “interfering” ladar pulses reflections by a receiver. Example embodiments include designs where a sparse delay sum circuit is used at the receiver and where a funnel filter is used at the receiver. Also, disclosed are techniques for selecting codes to use for the controllable delays as well as techniques for identifying and tracking interfering ladar pulses and their corresponding delay codes. The use of a ladar system with pulse deconfliction is also disclosed as part of an optical data communication system.

Claims

1. A method comprising:

selecting a delay code for use by a ladar system, the ladar system comprising a ladar transmitter and a ladar receiver;

the ladar transmitter transmitting a plurality of ladar pulses that are separated by a delay value corresponding to the selected delay code, wherein the transmitted ladar pulses separated by the delay value serve as an own ladar signal; and

the ladar receiver processing a received light signal based on the selected delay code to detect whether a reflection of the own ladar signal is present in the received light signal.

2. The method of claim 1 wherein the selecting step comprises selecting the delay code based on a hashing operation.

3. The method of claim 2 wherein the selecting step comprises:

generating a random number within a range of permitted numbers, wherein a maximum of the permitted numbers corresponds to a maximum permitted delay value; and

using the generated random number as the selected delay code.

4. The method of claim 3 wherein a minimum of the permitted numbers corresponds to a minimum permitted delay value.

5. The method of claim 1 wherein the selecting step comprises selecting the delay code based on a location of the ladar system.

6. The method of claim 5 the selecting step comprises:

tracking the location of the ladar system as the ladar system moves through a space; and

changing the delay code based on the tracked location as the ladar system moves through the space.

7. The method of claim 6 further comprising the ladar transmitter and the ladar receiver repeating the transmitting and processing steps using the changed delay code.

8. The method of claim 1 wherein the selecting step comprises selecting the delay code based on a posting by an electronic billboard.

9. The method of claim 8 further comprising:

the electronic billboard posting different delay codes for use by different ladar systems.

10. The method of claim 1 wherein the selecting step comprises selecting the delay code based on a collaboration with a plurality of other ladar systems.

11. The method of claim 10 wherein the other ladar systems are in an environment with the ladar system, the method further comprising:

the ladar system collaborating with the other ladar systems in the environment so that the ladar system and the other ladar systems in the environment each use different delay codes.

12. The method of claim 11 wherein the collaborating step comprises the ladar system exchanging delay codes with the other ladar systems in the environment;

and

wherein the selecting step comprises selecting the delay code based on the exchanged delay codes such that the selected delay code is a delay code that is not currently being used by the other ladar systems in the environment.

13. The method of claim 1 wherein the selecting step comprises selecting the delay code based on an analysis of characteristics of the received light signal over time.

14. The method of claim 1 wherein the selecting step comprises selecting a plurality n of delay codes;

wherein the transmitting step comprises the ladar transmitter transmitting an n-tuple of ladar pulses separated by n delay values corresponding to the n delay codes, wherein the transmitted n-tuple of ladar pulses separated by the delay values serve as the own ladar signal; and

wherein the processing step comprises the ladar receiver processing the received light signal based on the selected delay codes to detect whether a reflection of the own ladar signal is present in the received light signal.

15. The method of claim 14 further comprising:

repeating the method steps for each of a plurality of transmissions of the own ladar signal.

16. A ladar system comprising:

a processor configured to select a delay code;

a ladar transmitter configured to transmit a plurality of ladar pulses that are separated by a delay value corresponding to the selected delay code, wherein the transmitted ladar pulses separated by the delay value serve as an own ladar signal; and

a ladar receiver configured to process a received light signal based on the selected delay code to detect whether a reflection of the own ladar signal is present in the received light signal.

17. The system of claim 16 wherein the processor is further configured to select the delay code based on a hashing operation.

18. The system of claim 17 wherein the processor is further configured to:

generate a random number within a range of permitted numbers, wherein a maximum of the permitted numbers corresponds to a maximum permitted delay value; and

use the generated random number as the selected delay code.

19. The system of claim 18 wherein a minimum of the permitted numbers corresponds to a minimum permitted delay value.

20. The system of claim 16 wherein the processor is further configured to select the delay code based on a location of the ladar system.

21. The system of claim 20 wherein the ladar system is part of a moving vehicle, and wherein the processor is further configured to (1) track the location of the ladar system as the vehicle moves through a space, and (2) change the delay code based on the tracked location as the ladar system moves through the space.

22. The system of claim 21 wherein the ladar transmitter and the ladar receiver are configured to repeat the transmission and processing operations using the changed delay code.

23. The system of claim 16 wherein the processor is further configured to select the delay code based on a posting by an electronic billboard.

24. The system of claim 23 further comprising:

the electronic billboard, wherein the electronic billboard is configured to post different delay codes for use by different ladar systems.

25. The system of claim 16 wherein the processor is further configured to select the delay code based on a collaboration with a plurality of other ladar systems.

26. The system of claim 25 wherein the other ladar systems are in an environment with the ladar system, and wherein the processor is further configured to collaborate with the other ladar systems in the environment so that the ladar system and the other ladar systems in the environment each use different delay codes.

27. The system of claim 26 wherein the processor is further configured to (1) collaborate with the other ladar systems in the environment by exchanging delay codes with the other ladar systems in the environment, (2) select the delay code based on the exchanged delay codes such that the selected delay code is a delay code that is not currently being used by the other ladar systems in the environment.

28. The system of claim 16 wherein the processor is further configured to select the delay code based on an analysis of characteristics of the received light signal over time.

29. The system of claim 16 wherein the processor is further configured to select a plurality n of delay codes;

wherein the ladar transmitter is further configured to transmit an n-tuple of ladar pulses separated by n delay values corresponding to the n delay codes, wherein the transmitted n-tuple of ladar pulses separated by the delay values serve as the own ladar signal; and

wherein the ladar receiver is further configured to process the received light signal based on the selected delay codes to detect whether a reflection of the own ladar signal is present in the received light signal.

30. The system of claim 29 wherein the processor is further configured to select a new delay code for each of a plurality of new own ladar signal transmissions.