Method and apparatus for measuring dimensions of objects on a conveyor

• US 6,137,577 A
• Filed: 11/03/1999
• Issued: 10/24/2000
• Est. Priority Date: 07/26/1995
• Status: Expired due to Term

• Current Assignee: SICK Incorporated (Sick)
• Original Assignee: PTO (Safe Fleet Holdings LLC)
• Inventors: Woodworth, Mark R.
• Primary Examiner(s): Font, Frank G.
• Assistant Examiner(s): Stafira, Michael P.
• Application Number:
  US09/432,597
• Time in Patent Office: 356 Days
• Field of Search: 356/385, 356/379, 356/376, 356/383, 356/384, 356/386, 356/387, 356/430, 356/431, 356/237, 356/373, 356/375, 356/380, 364/478, 414/21, 414/902, 414/934, 414/786, 250/221, 350/6.91, 350/6.8
• US Class Current: 356/623
• CPC Class Codes: G01B 11/00 Measuring arrangements characterised by the use of optical techniques
• CPC Class Codes: G01B 11/04 specially adapted for measuring length or width of objects while moving

Abstract

A method and apparatus for measuring the length, width, and height of rectangular solid objects moving on a conveyor. The apparatus includes a light curtain, two laser triangulation range finders, and a pulse tachometer mounted on a frame around a conveyor. As an object is conveyed through the frame, measurements from each of the sensors are correlated by a digital computer to estimate the length, width and height of the object. The method and apparatus does not require a break in the surface of the conveyor, and is insensitive to object placement and orientation on the conveyor.

Claims

1. An apparatus for determining a size of an object on a conveyor, the object having a substantially rectangular shape, the apparatus comprising:

first side determining means for determining a first locus of values corresponding to locations of a first side of the object as the object travels along the conveyor in a direction perpendicular to the first side determining means;

second side determining means for determining a second locus of values corresponding to locations of a second side of the object as the object travels along the conveyor in a direction perpendicular to the second side determining means;

third side determining means for determining a third locus of values corresponding to a height of the object;

a first capture buffer for receiving the first locus of values;

a second capture buffer for receiving the second locus of values;

a third capture buffer for receiving the third locus of values;

a processor configured to receive the first locus of values and to determine a first side of the object as having a first linear characteristics, the processor configured to receive the second locus of values and to determine a second side of the object as having a second linear characteristic, and the processor configured to receive the third locus of values and to determine the height of the object,

wherein the processor outputs data corresponding to a size of the object based on the determined first side, the determined second side, and the determined height of the object.

2. The apparatus according to claim 1, further comprising:

a first work buffer for storing data obtained from the first capture buffer that is used by the processor to determine the first side of a first object while information related to a first side of a second object is being stored into the first capture buffer;

a second work buffer for storing data obtained from the second capture buffer that is used by the processor to determine the second side of the first object while information related to a second side of the second object is being stored into the second capture buffer; and

a third work buffer for storing data obtained from the third capture buffer that is used by the processor to determine the height of the first object while information related to a height of the second object is being stored into the third capture buffer.

3. The apparatus according to claim 2, wherein the first through third capture buffers and the first through third work buffers provide for pipelined operation of the apparatus.

4. The apparatus according to claim 1, wherein the processor determines the first side of the object as having the first linear characteristic by using a linear least-squares fit.

5. The apparatus according to claim 4, wherein the processor determines the second side of the object as having the second linear characteristic by using the linear least-squares fit.

16. The apparatus according to claim 1, wherein the height of the object is determined based on an arithmetic average of the third locus of values.

6. An apparatus for determining a size of an object on a conveyor, the object having a substantially rectangular shape, the apparatus comprising:

a first side determining unit that determines a first locus of values corresponding to locations of a first side of the object as the object travels along the conveyor in a direction perpendicular to the first side determining unit;

a second side determining unit that determines a second locus of values corresponding to locations of a second side of the object as the object travels along the conveyor in a direction perpendicular to the second side determining unit;

a third side determining unit that determines a third locus of values corresponding to a height of the object;

a first capture buffer for receiving the first locus of values;

a second capture buffer for receiving the second locus of values;

a third capture buffer for receiving the third locus of values;

a processor configured to receive the first locus of values and to determine a first side of the object as having a first linear characteristic, the processor configured to receive the second locus of values and to determine a second side of the object as having a second linear characteristic, and the processor configured to receive the third locus of values and to determine the height of the object,

wherein the processor outputs data corresponding to a size of the object based on the determined first side, the determined second side, and the determined height of the object.

7. The apparatus according to claim 6, further comprising:

a first work buffer for storing data obtained from the first capture buffer that is used by the processor to determine the first side of a first object while information related to a first side of a second object is being stored into the first capture buffer;

a second work buffer for storing data obtained from the second capture buffer that is used by the processor to determine the second side of the first object while information related to a second side of the second object is being stored into the second capture buffer; and

a third work buffer for storing data obtained from the third capture buffer that is used by the processor to determine the height of the first object while information related to a height of the second object is being stored into the third capture buffer.

8. The apparatus according to claim 6, wherein the first through third capture buffers and the first through third work buffers provide for pipelined operation of the apparatus.

9. The apparatus according to claim 6, wherein the processor determines the first side of the object as having the first linear characteristic by using a linear least-squares fit.

10. The apparatus according to claim 9, wherein the processor determines the second side of the object as having the second linear characteristic by using the linear least-squares fit.

17. The apparatus according to claim 6, wherein the height of the object is determined based on an arithmetic average of the third locus of values.

11. A method of determining a size of an object on a conveyor, the object having a substantially rectangular shape, the method comprising:

determining a first locus of values corresponding to locations of a first side of the object as the object travels along the conveyor;

determining a second locus of values corresponding to locations of a second side of the object as the object travels along the conveyor;

determining a third locus of values corresponding to a height of the object;

receiving and storing the first locus of values in a first capture buffer;

receiving and storing the second locus of values in a second capture buffer;

receiving and storing the third locus of values in a third capture buffer;

receiving the first locus of values and determining a first side of the object as having a first linear characteristic;

receiving the second locus of values and determining a second side of the object as having a second linear characteristic;

receiving the third locus of values and determining the height of the object; and

outputting data corresponding to a size of the object based on the determined first side, the determined second side, and the determined height of the object.

12. The method according to claim 11, further comprising:

storing, in a first work buffer, data obtained from the first capture buffer that is used to determine the first side of a first object while information related to a first side of a second object is being stored into the first capture buffer;

storing, in a second work buffer, data obtained from the second capture buffer that is used to determine the second side of the first object while information related to a second side of the second object is being stored into the second capture buffer; and

storing in a third work buffer, data obtained from the third capture buffer that is used to determine the height of the first object while information related to a height of the second object is being stored into the third capture buffer.

13. The method according to claim 12, wherein the first through third capture buffers and the first through third work buffers provide for pipelined operation.

14. The method according to claim 11, wherein the first side of the object is determined as having the first linear characteristic by using a linear least-squares fit.

15. The method according to claim 14, wherein the second side of the object is determined as having the second linear characteristic by using the linear least-squares fit.

18. The apparatus according to claim 11, wherein the height of the object is determined based on an arithmetic average of the third locus of values.