Lidar with smart safety-conscious laser intensity

• US 10,185,027 B2
• Filed: 11/29/2017
• Issued: 01/22/2019
• Est. Priority Date: 08/29/2016
• Status: Active Grant

• Current Assignee: O'Keeffe, James Thomas
• Original Assignee: O'Keeffe, James Thomas
• Inventors: O'Keeffe, James Thomas
• Primary Examiner(s): Abraham, Samantha K
• Application Number:
  US15/826,643
• Publication Number:
  US 20180088214A1
• Time in Patent Office: 419 Days
• CPC Class Codes: G01S 17/003 Bistatic lidar systems; Multistatic lidar systems
• CPC Class Codes: G01S 17/04 Systems determining the presence 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 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 17/66 Tracking systems using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 17/88 Lidar systems specially adapted for specific applications
• CPC Class Codes: G01S 17/931 of land vehicles
• CPC Class Codes: G01S 7/4802 using analysis of echo signal for target characterisation; Target signature; Target cross-section
• CPC Class Codes: G01S 7/4815 using multiple transmitters
• CPC Class Codes: G01S 7/4817 relating to scanning
• CPC Class Codes: G01S 7/484 Transmitters
• CPC Class Codes: G01S 7/489 Gain of receiver varied automatically during pulse-recurrence period
• CPC Class Codes: G01S 7/497 Means for monitoring or calibrating

Abstract

In one embodiment a laser range finder generates high-intensity laser pulses with intensities above a threshold intensity (e.g. above an eye-safe intensity) in an adaptive-intensity region of the field of view. The laser range finder further generates lower intensity (e.g. eye-safe) laser pulses in a protective guard region (e.g. a guard ring) that surrounds the high-intensity laser pulses. The guard region is located in the FOV such that ingress paths to the adaptive-intensity region must first traverse the lower-intensity guard region. The laser range finder analyzes laser reflections from the guard region to improve timely prediction of object intrusion into the adaptive-intensity region, thereby providing time to determine object trajectory or object classification. Upon determination that an object is likely to intersect the high-intensity laser pulses the laser range finder can discontinue the high-intensity laser pulses and instead generate laser pulses below the threshold intensity (e.g. eye-safe intensity laser pulses).

Claims

1. A method comprising:

generating with a laser range finder, having a field of view;

a first set of laser pulses in an adaptive-intensity region of the field of view, each with an intensity at the laser range finder above a threshold intensity; and

a guard set of laser pulses in a guard region of the field of view, each with an intensity at the laser range finder at or below the threshold intensity;

detecting with a detector in the laser range finder a set of laser reflections from the guard set of laser pulses;

sensing a trajectory of an object using the set of laser reflections and determining if the trajectory of the object is directed into the adaptive-intensity region; and

in response to sensing the trajectory of the object, discontinuing the first set of laser pulses and generating a second set of laser pulses in the adaptive-intensity region each with an intensity at the laser range finder at or below the threshold intensity when the trajectory of the object is directed into the adaptive-intensity region.

2. The method of claim 1 wherein the guard region is located relative to the adaptive-intensity region in the field of view such that a plurality of straight line paths, from an edge of the field of view to a perimeter of the adaptive-intensity region, traverse the guard region of the field of view before reaching the perimeter of the adaptive-intensity region.

3. The method of claim 1 wherein the laser range finder is attached to a vehicle and wherein the threshold intensity is based at least in part on a speed of the vehicle.

4. The method claim 1 further comprising the step of generating an object classification for the object using the set of laser reflections;

and

wherein the step of generating the second set of laser pulses in the adaptive-intensity region each with the intensity below the threshold intensity is performed at least in part in response to the object classification.

5. The method of claim 1 wherein the guard region encompasses at least some of a perimeter of the adaptive-intensity region in the field of view.

6. The method of claim 1 wherein the guard region and the adaptive intensity region of the field of view are mutually exclusive regions of the field of view.

7. The method of claim 1 wherein the adaptive-intensity region has a perimeter in the field of view and wherein the guard region encompasses the perimeter of the adaptive-intensity region.

8. The method of claim 1 wherein the first set of laser pulses and the guard set of laser pulses are generated in a single scan of the field of view.

9. The method of claim 1 further comprising the steps of:

receiving at a steerable laser assembly in the laser range finder a set of laser steering parameters;

dynamically steering with the steerable laser assembly at least one laser beam using the set of laser steering parameters; and

thereby generating the first set of laser pulses.

10. The method of claim 1 further comprising the steps of:

receiving at a steerable laser assembly a set of laser steering parameters; and

dynamically steering with the steerable laser assembly at least one laser beam;

to thereby generate the guard set of laser pulses and the first set of laser pulses in a single scan of the field of view.

11. The method of claim 1 wherein the second set of laser pulses in the adaptive-intensity region each with an intensity below the threshold intensity are generated in response to sensing, using at least some of the set of laser reflections, that the object in the guard region of the field of view is located within a threshold distance of the laser range finder.

12. The method of claim 1, wherein the threshold intensity is an eye-safe intensity.

13. The method of claim 1 wherein the laser range finder is attached to a vehicle;

wherein the set of guard pulses are generated in a range of directions; and

wherein the range of directions for the set of guard pulses is based at least in part on a speed of the vehicle.

14. The method of claim 1 further comprising the steps of

generating with a steerable laser assembly,

a preliminary set of laser pulses in the guard region of the field of view, each with an intensity below the threshold intensity;

detecting with the detector a preliminary set of laser reflections corresponding to the preliminary set of laser pulses and thereby generating preliminary reflection data;

evaluating a safety criterion using at least some of the preliminary reflection data to generate a result; and

generating the first set of laser pulses in response to the result.

15. The method of claim 1 further comprising the step of in response to sensing the object, ceasing to generate laser pulses above the threshold intensity and wherein the second set of laser pulses are operable to replace the first set of laser pulses in the adaptive-intensity region of the field of view.

16. The method of claim 1 further comprising the steps of computing a distance to the object;

determining whether the distance is less than a threshold distance; and

generated the second set of laser pulses in the adaptive-intensity region, based at least in part on whether the distance to the object is less than the threshold distance.

17. A method comprising:

generating with a laser range finder, having a field of view and a detector, a first set of laser pulses in an adaptive-intensity region of the field of view, each with an intensity at the laser range finder above a threshold intensity, and a guard set of laser pulses in a guard region of the field of view, each with an intensity at the laser range finder at or below the threshold intensity;

detecting with the detector a set of laser reflections corresponding to the guard set of laser pulses and thereby generating reflection data;

sensing a trajectory of an object using the set of laser reflections comprising;

processing at least some of the reflection data to identify one or more aspects of the object in the guard region including the trajectory, and determining if the trajectory of the object is directed into the adaptive-intensity region; and

in response to identifying the one or more aspects of the object, discontinuing the first set of laser pulses and generating a second set of laser pulses in the adaptive-intensity region each with an intensity at the laser range finder at or below the threshold intensity before the object enters the adaptive-intensity region when the trajectory of the object is directed into the adaptive-intensity region.

18. The method of claim 17 wherein the guard region is located relative to the adaptive-intensity region such that a plurality of straight line paths, from an edge of the field of view to a perimeter of the adaptive-intensity region, traverse the guard region before reaching the perimeter of the adaptive-intensity region.

19. The method of claim 17 further comprising the steps of performing a safety test using the reflection data and thereby generate a result;

and in response to the result, generating the second set of laser pulses in the adaptive-intensity region, each with the intensity below the threshold intensity.

20. The method of claim 17 further comprising the step of processing the at least some of the reflection data comprises the step of measuring a distance to the object;

and

wherein the step of identifying the one or more aspects of the object comprises identifying whether the object is within a threshold distance of the laser range finder.

21. The method of claim 17 wherein the step of processing the at least some of the reflection data to identify the one or more aspects of the object comprises measuring a distance to the object using the at least some of the reflection data.

22. The method of claim 17 wherein the one or more aspects of the object comprises a location of the object within the guard region of the field of view.

23. A laser range finder comprising:

a steerable laser assembly comprising one or more laser generators;

to generate a first set of laser pulses in an adaptive-intensity region of a field of view, each with an intensity at the laser range finder above a threshold intensity; and

to generate a guard set of laser pulses in a guard region of the field of view, each with an intensity at the laser range finder at or below the threshold intensity;

a detector to detect a set of laser reflections from the guard region, corresponding to the guard set of laser pulses; and

electronic circuitry operably coupled to the detector;

to sense, using the set of laser reflections, at least one aspect of an object in the guard region including a trajectory, and to determine if the trajectory of the object is directed into the adaptive-intensity region; and

in response to sensing the at least one aspect of the object in the guard region, to instruct the steerable laser assembly to discontinue the first set of laser pulses and to generate a second set of laser pulses in the adaptive-intensity region, each with an intensity at the laser range finder at or below the threshold intensity before the object enters the adaptive-intensity region when the trajectory of the object is directed into the adaptive-intensity region.

24. The laser range finder of claim 23 wherein the guard region is defined as a region of the field of view that encompasses the guard set of laser pulses;

where the steerable laser assembly is configured to generate the guard set of laser pulses such that the guard region is located relative to the adaptive-intensity region such that a plurality of straight line paths, from an edge of the field of view to a perimeter of the adaptive-intensity region, traverse the guard region before reaching the perimeter of the adaptive-intensity region.

25. The laser range finder of claim 23 wherein the one or more laser generators comprises a first laser generator to generate the first set of laser pulses and a second laser generator to generate the guard set of laser pulses.

26. The laser range finder of claim 23 wherein the steerable laser assembly comprises

a first laser generator, with variable intensity, to generate at least some of the first and second sets of laser pulses in the adaptive-intensity region and

a second laser generator exclusive from the first laser generator, to generate the guard set of laser pulses.

27. The laser range finder of claim 23, wherein the steerable laser assembly rotates about an axis with a direction of rotation;

wherein the steerable laser assembly comprises a guard laser generator to generates the guard set of laser pulses and an adaptive intensity laser generator to generate the first set of laser pulses; and

wherein the guard laser generator is positioned relative to the adaptive intensity laser generator such that the guard set of laser pulses leads the first set of laser pulses in the direction of rotation.

28. The laser range finder of claim 23 wherein the electronic circuitry is configured

to calculate a distance from the object to the laser range finder using the set of laser reflections from the guard region;

and

wherein the electronic circuitry is configured to select the intensity below the threshold intensity of the second set of laser pulses, based at least in part on the distance from the object to the laser range finder.