Automated method of and system for dimensioning objects over a conveyor belt structure by applying contouring tracing, vertice detection, corner point detection, and corner point reduction methods to two-dimensional range data maps of the space above the conveyor belt captured by an amplitude modulated laser scanning beam

• US 7,344,082 B2
• Filed: 12/05/2005
• Issued: 03/18/2008
• Est. Priority Date: 01/02/2002
• Status: Expired due to Fees

• Current Assignee: Metrologic Instruments Incorporated (Honeywell International Inc.)
• Original Assignee: Metrologic Instruments Incorporated (Honeywell International Inc.)
• Inventors: Zhu, Xiaoxun, Scott, Ian, Groot, John, Good, Timothy A., Au, Ka Man, Wilz, David M. Sr., Blake, Robert E., Germaine, Gennady, Dickson, LeRoy, Rockstein, George B., Knowles, Carl Harry, Schnee, Michael
• Primary Examiner(s): Le; Thien Minh
• Application Number:
  US11/294,890
• Publication Number:
  US 20060151604A1
• Time in Patent Office: 834 Days
• Field of Search: 23546201-46245, 235/472.01, 235/472.02, 235/472.03, 235/454, 235/470
• US Class Current: 235/462.14
• CPC Class Codes: G06K 7/14 using light without selection of wavelength, e.g. sensing reflected white light G06K7/10831 - G06K7/1097 take precedence

Abstract

A fully automated package identification and measuring system, in which an omni-directional holographic scanning tunnel is used to read bar codes on packages entering the tunnel, while a package dimensioning subsystem is used to capture information about the package prior to entry into the tunnel. Mathematical models are created on a real-time basis for the geometry of the package and the position of the laser scanning beam used to read the bar code symbol thereon. The mathematical models are analyzed to determine if collected and queued package identification data is spatially and/or temporally correlated with package measurement data using vector-based ray-tracing methods, homogeneous transformations, and object-oriented decision logic so as to enable simultaneous tracking of multiple packages being transported through the scanning tunnel.

Claims

1. An automated object dimensioning system for measuring dimension-related parameters of a scanned object transported along a conveyor belt structure, comprising:

a system housing having a light transmission aperture, supportable above a conveyor belt structure;

an optical bench, disposed within said system housing;

a laser beam production module disposed within said system housing, for generating an amplitude modulated laser beam;

a scanning mechanism, mounted on said optical bench, for projecting and said amplitude modulated laser beam through said light transmission aperture, and repeatedly scanning said amplitude modulated laser beam across the width of said conveyor belt structure;

a light collecting mechanism, mounted within said system housing, for collecting laser light reflected off said scanned object and focusing said reflected laser light;

a photodetector, mounted on said optical bench, for detecting said focused laser light and producing an electrical signal corresponding thereto;

signal processing circuitry, disposed within said system housing, for processing said produced electrical signal and, during each scan of said amplitude modulated laser beam across said scanned object, generating a row of raw digital range data representative of the distance from said scanning element to sampled points along said scanned object, measured with respect to a polar-type coordinate system symbolically-embedded within said automatic object dimensioning system;

a preprocessing data buffer, disposed within said system housing, for storing rows of raw digital range data produced by said signal processing circuitry; and

a programmed digital image processor, disposed within said system housing, for

(i) receiving rows of raw range data from said preprocessing data buffer,

(ii) processing data, including said rows of raw digital range data buffered in said preprocessing data buffer, so as to automatically produce a range data map representative of the space above said conveyor belt structure and buffer said range data map, and trace contours within said buffered range data map, and

(iii) computing dimension-related parameters of the object represented by said image contours traced within said buffered range data map.

2. The automated object dimensioning system of claim 1, wherein said programmed digital image processor comprises:

a first data processing stage for automatically processing said rows of raw digital range data in said preprocessing data buffer so as to produce said range data map representative of the space above said conveyor belt structure, and

a second data processing stage for automatically tracing said contours within said buffered range data map, wherein said traced contours are represented by a first set of indices (m,n) indicative of objects being transported along said conveyor belt structure.

3. The automated object dimensioning system of claim 2, wherein said programmed digital image processor comprises:

a third data processing stage for automatically processing said first set of indices (m,n) associated with said traced contours so as to detect vertices associated with polygonal-shaped objects extracted from said range data map, said detected vertices being represented by a second set of indices (m,n) and indicative of polygonal-shaped objects corresponding to objects being transported along said conveyor belt structure.

4. The automated object dimensioning system of claim 3, wherein said programmed digital image processor comprises:

a fourth data processing stage for automatically processing said second set of indices (m,n) associated with said detected vertices so as to detect a set of candidate corner points associated with the corners of a particular object being transported along said conveyor belt structure, said candidate corner points being represented by a third set of indices (m,n) and indicative of the corners of a particular object being transported along said conveyor belt structure.

5. The automated object dimensioning system of claim 4, wherein said programmed digital image processor comprises:

a fifth data processing stage for automatically processing said third set of indices (m,n) associated with detected corner point candidates so as to reduce said set of candidate corner points down to a set of corner points most likely to correspond to the corner points of a regular-shaped polygonal object, said most likely set of candidate corner points being represented by a fourth set of indices (m,n) and indicative of the corners of a regular-shaped polygonal object which most likely corresponds to the particular object being transported along said conveyor belt structure; and

a sixth data processing stage for automatically processing said fourth set of indices (m,n) associated with the corner points of a regular-shaped polygonal object so as to compute said dimension-related parameters of the object represented by said image contours traced within said buffered range data map.

6. The automated object dimensioning system of claim 5, wherein said sixth data processing stage further comprises:

a first data processing substage for automatically processing said fourth set of indices (m,n) associated with the corner points of a regular-shaped polygonal object so as to compute the surface area of the object represented by said traced contours within said buffered range data map; and

a second data processing substage for automatically processing said fourth set of indices (m,n) associated with the corner points of said regular-shaped polygonal object so as to compute the average height of the object represented by said traced contours in said buffered range data map, referenced relative to a global Cartesian-type coordinate reference system symbolically embedded within said system housing.

7. The automated object dimensioning system of claim 6, wherein said sixth data processing stage further comprises:

a third data processing substage for automatically processing said fourth set of indices (m,n) associated with the corner points of said regular-shaped polygonal object so as to compute the x, y, z coordinates corresponding to the corners of the object represented by said traced contours in said buffered range data map, referenced relative to said global Cartesian-type coordinate reference system.

8. The automated object dimensioning system of claim 2, wherein said first data processing stage employs window-type convolution kernals that smooth and edge-detect the raw range data and thus improve its quality for subsequent dimension data extraction operations.

9. The automated object dimensioning system of claim 2, wherein said first data processing stage includes means for subtracting detected background information (including noise) from the continuously updated range data map as to accommodate for changing background lighting conditions.

10. The automated object dimensioning system of claim 1, wherein said scanning mechanism comprises a polygonal-type laser scanning mechanism for scanning said amplitude modulated laser beam across the width of said conveyor belt structure.

12. The automated object dimensioning system of claim 1, wherein said photodetector comprises an avalanche-type photodetector mounted on said optical bench.

13. The automated object dimensioning system of claim 1, wherein said object is a package.

11. The automated object dimensioning system of 1, wherein said scanning mechanism comprises a holographic-type laser scanning mechanism for scanning said amplitude modulated laser beam across the width of said conveyor belt structure.