Methods and apparatus for object detection and identification in a multiple detector lidar array

• US 9,360,554 B2
• Filed: 04/11/2014
• Issued: 06/07/2016
• Est. Priority Date: 04/11/2014
• Status: Active Grant

• Current Assignee: Big Sky Financial Corporation
• Original Assignee: Facet Technology Corp.
• Inventors: Retterath, James E., Laumeyer, Robert A.
• Primary Examiner(s): RATCLIFFE, LUKE D
• Application Number:
  US14/251,254
• Publication Number:
  US 20150293228A1
• Time in Patent Office: 788 Days
• Field of Search: 356 301- 515, 356 6- 22, 356/28, 356/28.5
• US Class Current: 1/1
• 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 17/26 wherein the transmitted pulses use a frequency-modulated or phase-modulated carrier wave, e.g. for pulse compression of received signals
• CPC Class Codes: G01S 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 17/931 of land vehicles
• CPC Class Codes: G01S 7/481 Constructional features, e.g. arrangements of optical elements
• CPC Class Codes: G01S 7/4815 using multiple transmitters
• CPC Class Codes: G01S 7/4817 relating to scanning
• CPC Class Codes: G01S 7/4863 Detector arrays, e.g. charge-transfer gates
• 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 7/497 Means for monitoring or calibrating

Abstract

LiDAR (light detection and ranging) systems use one or more emitters and a detector array to cover a given field of view where the emitters each emit a single pulse or a multi-pulse packet of light that is sampled by the detector array. On each emitter cycle the detector array will sample the incoming signal intensity at the pre-determined sampling frequency that generates two or more samples per emitted light packet to allow for volumetric analysis of the retroreflected signal portion of each emitted light packet as reflected by one or more objects in the field of view and then received by each detector.

Claims

1. A LiDAR (light detection and ranging) system comprising:

an emitter that emits a series of emitted light packets over a field of view, each emitted light packet emitted for a cycle duration;

a detector array having an array of detectors configured to cover the field of view and sample an incoming retroreflected signal portion of an emitted light packet at a pre-determined sampling frequency that generates at least two samples corresponding to the cycle duration of the emitted light packet;

a processing system configured to analyze the samples from the detector array and detect an object within the field of view using at least a volumetric analysis of the at least two samples from each detector in the array of detectors corresponding to an intensity of the incoming retroreflected signal portion of each emitted light packet

wherein the processing system includes at least one graphics processing unit (GPU) configured to process the samples to produce multiple output points for each emitted light packet corresponding to a pre-defined grid of points for the field of view of the emitter

wherein the detector array includes a plurality of frame buffers corresponding to the pre-defined grid of points, each frame buffer corresponding to a different portion of the cycle duration associated with the emitted light packet.

2. The LiDAR system of claim 1 wherein the GPU is configured to utilize a segmentation analysis to differentiate between multiple objects in a single field of view.

3. The LiDAR system of claim 1 wherein the GPU is configured to utilize an edge-detection process to define an edge feature describing an edge of an object in the field of view.

4. The LiDAR system of claim 1 wherein the GPU is configured to utilize a corner-detection process to define a corner feature describing a corner of an object in the field of view.

5. The LiDAR system of claim 1 wherein the detector array includes a leading-edge frame buffer, a steady-state-frame buffer and a trailing-edge frame buffer that are collectively analyzed by the GPU to compare relative intensity ratios among detectors in the detector array.

6. The LiDAR system of claim 1 wherein the detector array includes a leading-edge frame buffer, a steady-state-frame buffer and a trailing-edge frame buffer that are collectively analyzed by the GPU using a time domain analysis to determine a direction and a rate of a slope of objects detected within the field of view.

7. The LiDAR system of claim 1 wherein the detector array includes a ramp-up frame buffer, a steady-state frame buffer and a ramp-down frame buffer that are collectively analyzed by the GPU to compare relative intensities among detectors in the detector array.

8. The LiDAR system of claim 1 wherein the GPU analyzes neighboring detectors in the detector array to facilitate determination of angles of the retroreflected signal portion of the emitted light packet.

9. The LiDAR system of claim 1 wherein the emitter generates an emitted beam that is characterized to determine an intensity of the emitted beam throughout an entire cross section of the emitted beam and wherein the processing system utilizes the intensity of the emitted beam to differentiate light energy patterns and resolve between emitted and reflected light energy patterns.

10. The LiDAR system of claim 1 wherein the emitter is configured for in situ calibration by emitting pre-determined calibration patterns of emitted light energy and measuring an intensity, a location and an angle of the reflected portion of the emitted light energy.

11. The LiDAR system of claim 1 wherein each detector in the detector array has a unique angle through which the retroreflected signal portion of each emitted light packet is received.

12. The LiDAR system of claim 1 wherein the emitter emits light energy as coherent electromagnetic laser energy.

13. A method for detecting and identifying an object within a field of view comprising:

providing a LiDAR system, the LiDAR system comprising an emitter and a detector array;

activating the emitter to emit a series of light pulses over a field of view for a cycle duration;

sampling a portion of the emitted light pulses utilizing the detector array at a sampling frequency that is faster than a frequency of the cycle duration;

deriving a signal corresponding to an intensity value associated with the sampled portion of the emitted light pulses; and

analyzing the signal to identify and detect an object within the field of view.