Method of measuring the dimensions of moving objects

• US 5,325,178 A
• Filed: 04/03/1992
• Issued: 06/28/1994
• Est. Priority Date: 04/18/1991
• Status: Expired due to Fees

• Current Assignee: Isover Saint-Gobain
• Original Assignee: Isover Saint-Gobain
• Inventors: Bichot, Bernard, Louis, Bernard
• Primary Examiner(s): EVANS, FANNIE L
• Application Number:
  US07/863,073
• Time in Patent Office: 816 Days
• Field of Search: 356/372, 356/381, 356/383, 356/384, 356/385, 250/560
• US Class Current: 356/630
• CPC Class Codes: G01B 11/04 specially adapted for measuring length or width of objects while moving

Abstract

An optical method continuously monitors the dimensions of a body having a parallelogram cross-section and supported on a moving conveyor. A first angular measurement of a first dimension of a first face of the body in a first direction is first performed, the first angular measurement being made with respect to a first reference angle at an apex of a first triangular plane having the first dimension as one side thereof. Substantially simultaneously with the step of determining the first angular measurement, a second angular measurement of a second dimension of a second face of the body in a second direction perpendicular to the first direction is determined, the second face intersecting the first face and the second angular measurement being made with respect to a second reference angle at an apex of a second triangular plane coplanar with the first triangular plane and having a second dimension as one side thereof. The first and second dimensions thus have a common point at a line of intersection of the first and second faces. The position of the common point with respect to one of the first and second directions is then estimated and an iterative process is used to determine the position of the common point. The iterative process is continued until the position of the common point is determined to within a required accuracy in both of the first and second directions.

Claims

1. An optical method of continuously monitoring the dimensions of a body having a parallelogram cross-section and supported on a movable conveyor in a line for producing insulating mats, comprising the steps of:

determining a first angular measurement of a first dimension of a first face of the body in a first direction, said first angular measurement being made with respect to a first reference angle at an apex of a first triangular plane having said first dimension as one side thereof;

substantially simultaneously with the step of determining the first angular measurement, determining a second angular measurement of a second dimension of a second face of the body in a second direction perpendicular to said first direction, said second face intersecting said first face and said second angular measurement being made with respect to a second reference angle at an apex of a second triangular plane coplanar with said first triangular plane and having said second dimension as one side thereof whereby said first and second dimensions have a common point at a line of intersection of said first and second faces;

estimating the position of said common point with respect to one of said first and second directions;

using an iterative process to determine the position of said common point;

continuing said iterative process until the position of said common point is determined to within a required accuracy in both of said first and second directions, wherein each of said steps of determining said first and second angular measurements comprises positioning a lens of a linear CCD camera at a respective said apex,

wherein said first and second directions are perpendicular to the direction of the movement, including the subsequent steps of;

cutting said body in a plane perpendicular to the direction of movement to form at least one panel; and

determining the length of said panel in the direction of movement, as a third angular measurement made with respect to a third reference angle at an apex of a third triangular plane having said length as one side thereof.

2. The method of claim 1 wherein said body is substantially a rectangular parallelepiped.

3. The method of claim 2 wherein each of said first and second triangles is a right triangle having a right angular apex at said common point.

4. The method of claim 1 wherein said steps are repeated at a frequency of 100 Hz.

5. The method of claim 1 including the subsequent steps of:

repeating said determining, estimating, using and continuing steps to produce plural determinations of the position of said common point;

determining a statistical value of said position of the common point from said plural determinations; and

disregarding produced values of the position of the common point which diverge from the statistical value by more than a predetermined amount.

6. The method of claim 5 wherein said statistical value is determined at a frequency of 1 Hz.

7. The method of claim 1 wherein α

and β

are said first and second angular measurements, Y and Z are said first and second directions, A is the common point and Y_O is an estimate of the position of said common point with respect to the Y direction, wherein said step of using an iterative process to determine the position of said common point comprises the steps of;

initializing the iterative process of a point A_n for Y_n, where n=0 and Z_n =f(Y_n, α

);

performing a series of iterations while incrementing n by one unit, wherein for each A_n, Y_n =g(Z_n-1,β

) and Z_n =Z_n-1, and for each A_n+1, Y_n+1 =Y_n and Z_n+1 =f(Y_n, α

);

and wherein said continuing step comprises, for each iteration, testing |Y_n -Y_n-1 | and |A_n+1 -Z_n | against Δ

Ymin and Δ

Zmin, respectively, wherein Δ

Ymin and Δ

Zmin are said required accuracies in said first and second directions.

8. The method of claim 7 wherein a ratio between one of Δ

Ymin and Δ

Zmin and a respective dimension of the body in the Y and Z directions is between 0.5/1000 and 1/1000.

9. The method of claim 1 wherein said conveyor is stationary.

10. An optical method of continuously monitoring the dimensions of a body having a parallelogram cross-section and supported on a movable conveyor in a line for producing insulating mats, comprising the steps of:

determining a first angular measurement of a first dimension of a first face of the body in a first direction, said first angular measurement being made with respect to a first reference angle at an apex of a first triangular plane having said first dimension as one side thereof;

substantially simultaneously with the step of determining the first angular measurement, determining a second angular measurement of a second dimension of a second face of the body in a second direction perpendicular to said first direction, said second face intersecting said first face and said second angular measurement being made with respect to a second reference angle at an apex of a second triangular plane coplanar with said first triangular plane and having said second dimension as one side thereof, whereby said first and second dimensions have a common point at a line of intersection of said first and second faces;

estimating the position of said common point with respect to one of said first and second directions;

using an iterative process to determine the position of said common point;

continuing said iterative process until the position of said common point is determined to within a required accuracy in both of said first and second directions,

wherein said first and second directions are perpendicular to the direction of movement, including the subsequent steps of;

cutting said body in a plane perpendicular to the direction of movement to form at least one panel; and

determining the length of said panel in the direction of movement, as a third angular measurement made with respect to a third reference angle at an apex of a third triangular plane having said length as one side thereof.

11. The method of claim 10 wherein α

and β

are said first and second angular measurements, Y and Z are said first and second directions, A is the common point and Y_O is an estimate of the position of said common point with respect to the Y direction, wherein said step of suing an iterative process to determined the position of said common point comprises the steps of;

initializing the iterative process of a point A_n for Y_n, where n=0 and A_n =F(Y_n, α

);

performing a series of iterations while incrementing n by one unit, wherein for each A_n Y_n =g(X_n-1, β

) and Z_n =A_n-1, and for each A_n+1, Y_n+1 =Y_n and Z_n+1 =F(Y_n, α

);

and wherein said continuing step comprises, for each iteration, testing |Y_n =Y_n-1 | and |Z_N+1 -A_n | against Δ

Ymin and Δ

Zmin, respectively, wherein Δ

Ymin and Δ

Zmin are said required accuracies in said first and second directions.

12. The method of claim 10 including the step of controlling said cutting step as a function of the measured length of the panel.

13. An optical method of continuously monitoring the dimensions of a body having a parallelogram cross-section and supported on a movable conveyor in a line for producing insulating mats, comprising the steps of:

determining a first angular measurement of a first dimension of a first face of the body in a first direction, said first angular measurement being made with respect to a first reference angle at an apex of a first triangular plane having said first dimension as one side thereof;

substantially simultaneously with the step of determining the first angular measurement, determining a second angular measurement of a second dimension of a second face of the body in a second direction perpendicular to said first direction, said second face intersection said first face and said second angular measurement being made with respect to a second reference angle at an apex of a second triangular plane coplanar with said first triangular plane and having said second dimension as one side thereof, whereby said first and second dimensions have a common point at a line of intersection of said first and second faces;

estimating the position of said common point with respect to one of said first and second directions;

using an iterative process to determined the position of said common point;

continuing said iterative process until the position of said common point is determined to within a required accuracy in both of said first and second directions; and

cutting the body to form a panel.