Automatic vehicle identification and classification (AVIC) system employing a tunnel-arrangement of PLIIM-based subsystems

• US 6,827,265 B2
• Filed: 06/06/2002
• Issued: 12/07/2004
• Est. Priority Date: 03/24/1998
• Status: Expired due to Fees

• Current Assignee: Metrologic Instruments Incorporated (Honeywell International Inc.)
• Original Assignee: Metrologic Instruments Incorporated (Honeywell International Inc.)
• Inventors: Zhu, Xiaoxun, Knowles, C. Harry, Schnee, Michael D.
• Primary Examiner(s): Le, Thien M.
• Application Number:
  US10/165,422
• Publication Number:
  US 20030042304A1
• Time in Patent Office: 915 Days
• Field of Search: 235/462-1-4, 235/472.01, 235/472.02, 235/472.03, 235/454, 235/455, 235/470
• US Class Current: 235/462.01
• CPC Class Codes: G02B 19/0014 at least one surface having optical power
• CPC Class Codes: G02B 19/0052 the light source comprising a laser diode coupling into light guides using intermediate optical elements G02B6/4204; semiconductor lasers having optical devices external to the laser cavity H01S5/005
• CPC Class Codes: G02B 19/0085 for use with both a detector and a source , e.g. in a transceiver, G02B19/009, G02B19/0095 take precedence
• CPC Class Codes: G02B 19/009 for use with infrared radiation
• CPC Class Codes: G02B 19/0095 for use with ultraviolet radiation
• CPC Class Codes: G02B 26/10 Scanning systems
• CPC Class Codes: G02B 27/095 Refractive optical elements
• CPC Class Codes: G02B 27/48 Laser speckle optics
• CPC Class Codes: G06K 7/10 by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation
• CPC Class Codes: G06K 7/10594 Beam path
• CPC Class Codes: G06K 7/10722 Photodetector array or CCD scanning
• CPC Class Codes: G06K 7/10732 Light sources
• CPC Class Codes: G06K 7/146 the method including quality enhancement steps
• CPC Class Codes: G06Q 10/00 Administration; Management
• CPC Class Codes: G06Q 30/00 Commerce
• CPC Class Codes: G06V 20/62 Text, e.g. of license plates, overlay texts or captions on TV images
• CPC Class Codes: G06V 30/144 using a slot moved over the image; using discrete sensing elements at predetermined points; using automatic curve following means
• CPC Class Codes: H01S 5/005 Optical components external to the laser cavity, specially adapted therefor, e.g. for homogenisation or merging of the beams or for manipulating laser pulses, e.g. pulse shaping H01S5/026, H01S5/18388 take precedence
• CPC Class Codes: H01S 5/02325 Mechanically integrated components on mount members or optical micro-benches
• CPC Class Codes: H01S 5/4025 Array arrangements, e.g. constituted by discrete laser diodes or laser bar H01S5/42 takes precedence

Abstract

An automatic vehicle classification and identification (AVIC) system for installation along a roadway. The system comprises first and second planar light illumination and imaging (PLIIM) based imaging and profiling subsystems mounted above and along side of the roadway. The function of these subsystems is to profile the geometry of top and side surfaces of each vehicle travelling under the subsystem and generate vehicle profile data for each such vehicle, and also, to capture digital images of both the front and rear license plates mounted on each vehicle, and generate vehicle image data representative of each captured digital image thereof. A computer system is provided for receiving vehicle image and profile data generated by first and second PLIIM based profiling systems, and processing the vehicle image and profile data so as to automatically identify and classify each vehicle travelling along said roadway. By virtue of the present invention, it is now possible to identify and classify vehicles by reading their license plates using planar laser illumination beams and linear image detection arrays with coplanar fields of view, thereby avoiding the need for large and expensive high-intensity lighting equipment required by conventional digital cameras employing 2-D electronic image detectors.

Claims

1. An automatic vehicle classification and identification (AVIC) system for installation along a roadway, comprising:

a first planar light illumination and imaging (PLIIM) based imaging and profiling subsystem mounted above said roadway, and arranged for (1) profiling the geometry of the top surface of each vehicle traveling under said first PLIIM-based profiling and imaging subsystem and generating vehicle profile data, for each vehicle profiled by said first PLIIM-based imaging and profiling subsystem, and also for (2) capturing digital images of both the front and rear license plates mounted on each said vehicle traveling under said first PLIIM-based profiling and imaging subsystem, and generating vehicle image data representative of each captured digital image;

a second planar light illumination and imaging (PLIIM) based imaging and profiling subsystem mounted above said roadway, and arranged for (1) profiling the geometry of the side surface of each vehicle traveling under said second PLIIM-based imaging and profiling subsystem and generating vehicle profile data, for each vehicle profiled by said second PLIIM-based Imaging and profiling subsystem, and also (2) capturing digital images of both the front and rear license plates mounted on each said vehicle traveling under said second PLIIM-based profiling and imaging subsystem, and generating vehicle image data representative of each captured digital image; and

a computer system for receiving vehicle image and profile data generated by said first and second PLIIM-based imaging and profiling systems, and processing said vehicle image and profile data so as to automatically identify and classify each vehicle traveling along said roadway.

2. The AVIC system of claim 1, wherein each said PLIIM-based imaging and profiling subsystem comprises:

a system housing;

a linear imaging subsystem, mounted within said system housing, for producing a series of linear 2-D images of said moving vehicle surface as said vehicle surface moves past said linear imaging subsystem; and

an object profiling subsystem, mounted within said system housing, for profiling the surface of said vehicle as said vehicle moves past said object profiling subsystem, and producing a series of linear 3-D surface profile maps of said moving vehicle surface as said vehicle surface moves past said object profiling subsystem, wherein each said linear 3-D surface profile map comprises a set of 3-D coordinates specifying the location of sampled points along said moving vehicle surface.

3. The AVIC system of claim 2, wherein said system housing has first, second and third light transmission apertures linearly aligned with and optically isolated from each other, and said third light transmission aperture being disposed between said first and second light transmission apertures.

4. The AVIC system of claim 3, wherein said hear imaging subsystem comprises:

a linear image formation and detection module disposed in system housing, and having image forming optics with a field of view projectable through said third light transmission aperture and onto said vehicle moving relative to said first, second and third light transmission apertures during vehicle illumination and imaging operations; and

a pair of planar laser illumination ways (PLIAs) disposed on said system housing, and each said planar laser array (PLIA) including a plurality of laser diodes arranged together in a linear manner and said planar laser illumination arrays being arranged in relation to said linear image formation and detection module, and for producing a pair of planar laser illumination beams (PLIBs), and projecting said pair of planar laser illumination beams through said first and second light transmission apertures and oriented such that the planes of said planar laser illumination beams are coplanar with the field of view of said linear image formation and detection module so that the vehicle can be simultaneously illuminated by said planar laser illumination beams and imaged within said field of view of said linear image formation and detection module,

whereby a series of linear images of said vehicle are sequentially detected by said linear image formation and detection module as said vehicle moves past first, second and third light transmission apertures, so that said series of linear images can be grabbed and buffered for subsequent use in constructing two-dimensional images of said vehicle.

5. The AVIC system of claim 4, which further comprises:

an image frame grabber for grabbing images formed and detected by said image formation and detection module,

an image data buffer for buffering said grabbed images;

an image processing computer operably associated with said image data buffer, for processing said buffered images; and

a camera control computer for controlling said linear image formation and said detection module, and said pair of planar laser illumination arrays.

6. The AVIC system of claim 5, wherein said image forming optics have a variable focal distance and a variable focal length providing a variable field of view.

7. The AVIC system of claim 3, wherein said object profiling subsystem comprises a mechanism for producing and projecting a laser beam across the surface of each said vehicle as each said vehicle moves past said object profiling subsystem.

8. The AVIC system of claim 3, wherein said object profiling subsystem comprises a mechanism for producing and projecting an amplitude modulated (AM) laser beam across the surface of each said vehicle as each said vehicle moves past said object profiling subsystem.

9. The AVIC system of claim 3, wherein said linear imaging subsystem comprises:

a linear image formation and detection module disposed in said system housing, and having image forming optics with a field of view projectable through said third light transmission aperture and onto said vehicle moving relative to said first, second and third light transmission apertures during vehicle illumination and imaging operations; and

a pair of planar light illumination arrays (PLIAs) disposed on said system housing, and each said planar light illumination array (PLIA) including a plurality of light emitting diodes (LEDs) arranged together in a linear manner and said planar light illumination arrays being arrange in relation to said linear image formation and detection module, and for producing a pair of planar light illumination beams (PLIBs), and projecting said pair of planar light illumination beams through said first and second light transmission apertures and oriented such that the planes of said planar light illumination beams are coplanar with the field of view of said linear image formation and detection module so that the vehicle can be simultaneously illuminated by said planar light illumination beams and imaged within said field of view of said linear image formation and detection module,

whereby a series of linear images of said vehicle are sequentially detected by said linear image formation and detection module as said vehicle moves past first, second and third light transmission apertures, so that said series of linear images can be grabbed and buffered for subsequent use in constructing two-dimensional images of said vehicle.

10. The AVIC system of claim 9, which further comprises:

an image frame grabber for grabbing images formed and detected by said image formation and detection module,

an image data buffer for buffering said grabbed images;

an image processing computer operably associated with said image data buffer, for processing said buffered images; and

a camera control computer for controlling said linear image formation and said detection module, and said pair of planar laser illumination arrays.

11. The AVIC system of claim 9, wherein said image forming optics have a variable focal distance and a variable focal length providing a variable field of view.

12. The AVIC system of claim 9, wherein said object profiling subsystem comprises a mechanism for producing and projecting a laser beam across the surface of each said vehicle as each said vehicle moves past said object profiling subsystem.

13. The AVIC system of claim 9, wherein said object profiling subsystem comprises a mechanism for producing and projecting an amplitude modulated (AM) laser beam across the surface of each said vehicle as each said vehicle moves past said object profiling subsystem.