Measuring method and apparatus

• US 5,105,392 A
• Filed: 03/18/1991
• Issued: 04/14/1992
• Est. Priority Date: 09/01/1989
• Status: Expired due to Term

• Current Assignee: Quantronix Incorporated (Schneider Electric SE)
• Original Assignee: Quantronix Incorporated (Schneider Electric SE)
• Inventors: Kennington, Robert L., Smith, Brian H., Stringer, Bradley J.
• Primary Examiner(s): Pihulic, Daniel T.
• Application Number:
  US07/671,256
• Time in Patent Office: 393 Days
• Field of Search: 367/96, 367/99, 367/902, 367/103, 364/564, 364/567
• US Class Current: 367/99
• CPC Class Codes: G01B 11/002 for measuring two or more coordinates
• CPC Class Codes: G01B 11/04 specially adapted for measuring length or width of objects while moving
• CPC Class Codes: G01B 17/00 Measuring arrangements characterised by the use of infrasonic, sonic or ultrasonic vibrations
• CPC Class Codes: G07B 2017/00685 Measuring the dimensions of mailpieces

Abstract

The present invention relates to methods and apparatus for measuring the linear dimensions and determining the three-dimensional, spatial volume of objects. In the preferred embodiments, ultrasonic sensing is employed, alone or in combination with other measuring methods such as light curtains and the timing of moving objects, to ascertain linear dimensions. The preferred embodiments are particularly adapted to the measurement of large and irregularly configured objects, such as palletized loads, and to the measurement of moving, rectangular objects of random orientation with respect to the direction of travel.

Claims

1. An apparatus for measuring a load, comprising:

a target field;

a first plurality of downwardly facing ultrasonic sensors at a common distance above said target field and in laterally spaced mutual relationship;

a second plurality of ultrasonic sensors in laterally spaced mutual relationship facing and disposed at a common distance from a first side of said target field;

a third plurality of ultrasonic sensors in laterally spaced mutual relationship facing and disposed at a common distance from a second side of said target field parallel to said first side of said target field;

a fourth plurality of ultrasonic sensors in laterally spaced mutual relationship facing and disposed at a common distance from a third side of said target field perpendicular to said first and second sides of said target field;

through beam sensor means comprising a linearly extending beam emitter substantially parallel to said first side in alignment with a linearly extending receiver across said target field therefrom and substantially parallel to said second side of said therefor, said beam emitter and said receiver extending inwardly from the fourth side of said target field toward the third side thereof.

2. The apparatus of claim 1 further including weighing means under said target field.

3. The apparatus of claim 2 wherein said weighing means includes a deck, and said deck defines said target field.

4. The apparatus of claim 1 wherein each sensor in said first, second, third, and fourth plurality of sensors is adapted to fire substantially simultaneously with the other sensors in that plurality, and said apparatus is adapted to select and retain only the first returning ultrasonic signal from each of said first, second, third, and fourth pluralities of sensors reflected from said load.

5. The apparatus of claim 1 wherein said sensors in said second, third, and fourth pluralities of sensors are disposed at a common height above said target field.

6. A method of measuring a load on a horizontal surface comprising:

ultrasonically determining the distance between a first sensor above said load and subtracting said distance from the height of said first sensor above said surface;

ultrasonically determining the distances between second and third sensors on opposing first and second sides of said load and said load and subtracting said distances from the distance between said second and third sensors;

ultrasonically determining the distance between a fourth sensor and a third side of said load perpendicular to said opposing sides;

determining the distance between a known point and a fourth side of said load opposite said third side;

adding said distance between said fourth sensor and said third side to said distance between said point and said fourth side and subtracting the resulting sum from the distance between said fourth sensor and said point.

7. The method of claim 6 wherein said step of determining the distance between said fourth side of said load and said point is effected by interruption of a light curtain.

8. The method of claim 6 wherein said step of determining the distance between said fourth side of said load and said point is effected ultrasonically.

9. The method of claim 6 further including the step of weighing said load concurrently with said measuring.

10. The method of claim 6 wherein each of said first, second, third, and fourth sensors is arranged in a bank of sensors;

each sensor in a said bank including said first sensor being the same distance from said horizontal surface;

each sensor in said banks including said second and third sensors being in respective parallel and facing linear arrays;

each sensor in said bank including said fourth sensor being in a linear array perpendicular to said banks including said second and third sensors; and

said first, second, third, and fourth sensors are selected from their respective banks as being the closest in their respective banks to said load.

11. The method of claim 10 wherein said selection of said first, second, third, and fourth sensors is based on a comparison of travel times of all ultrasonic waves from sensors in each respective bank to and from said load.

12. A method of determining the actual dimensions of linearly moving, rectangular object, the sides of which are in non-parallel relationship to the direction of object travel, comprising:

linearly moving said object at a constant speed;

determining the apparent length of said object by measuring the travel time thereof past a point on the line of object travel;

determining the apparent width of said object by detecting the distances between said object and first and second sensors on each side of said moving object and subtracting the sum of said distances from the distance between said first and second sensors;

determining a distance taken in the path of object travel between a corner of said object facing the side of said direction of travel and the trailing edge of said object by measuring the travel time between the passage of said corner and that of said trailing edge past a common point; and

calculating the actual length and width of said object utilizing said determined apparent length, apparent width, and said object corner to trailing edge distance.

13. The method of claim 12 wherein said point is defined by a photocell beam.

14. The method of claim 12 wherein said first and second sensors comprise ultrasonic sensors.

15. The method of claim 12 wherein said point and said common point are the same.

16. An apparatus for determining the actual dimensions of a rectangular object, the sides of which are in non-parallel relationship to the direction at object movement, comprising:

conveying means for linearly moving said object at a constant speed on a path past a point;

detecting means for sensing and signalling the passage of the leading edge of said object and the trailing edge of said object past said point;

first and second sensing means disposed at a fixed mutual distance, with the path of object movement extending perpendicularly therebetween, for sensing and signalling the minimum distance between said object and each said sensing means and the instant of passage of a corner of said object facing said sensing means;

timing means for timing a first duration of passage of said object past said point responsive to said signals from said detecting means and for timing a second duration between passage of an object corner and passage of said trailing edge past said point responsive to a said sensing means signal and said trailing edge signal from said detecting means;

conversion means for converting said first duration to the apparent length of said object using said constant speed and for converting said second duration to a distance taken in the direction of object movement between a said corner and said trailing edge of said object using said constant speed; and

computation means for adding said sensed minimum distances and subtracting the resulting sum from said fixed mutual distance to obtain the apparent width of said object and for calculating the actual length and width of said object from said apparent length, apparent width, and said corner to trailing edge distance.

17. The apparatus of claim 16 wherein said detecting means comprises a through-beam photocell.

18. The apparatus of claim 16 wherein said first and second sensing means each comprise an ultrasonic sensor.

19. The apparatus of claim 18 wherein said detecting means comprises a through-beam photocell.

20. The apparatus of claim 16 wherein said first and second sensing means are disposed on a line perpendicular to said path of object movement and passing through said point.