Center of gravity offset detection method and platform scale

Patent metadata

Field	Value
Publication number	US-10782201-B2
Application number	US-201815989682-A
Country	US
Kind code	B2
Filing date	May 25, 2018
Priority date	May 26, 2017
Publication date	Sep 22, 2020
Grant date	Sep 22, 2020

Abstract

A platform scale uses a method of detecting a center-of-gravity (COG) offset. A weight value of a load on a weighing platform is calculated. The weighing platform is allowed to reach a steady state. When the weight value exceeds a COG offset threshold, then a position of a load COG is calculated using a load COG position algorithm. Whether the calculated position is in a valid region of the weighing platform is determined. The weight value is displayed if the position is within the valid region; otherwise, the position of the COG is displayed. A display apparatus of the scale displays the weight value or the position of COG of the load. The platform scale alerts a user about a possible invalid weighing event by displaying an image indicative of the COG offset condition, ensuring effective and precise weighing.

First claim

What is claimed is:

1. A method for detecting a center-of-gravity (“COG”) offset in a platform scale having a load placed on a weighing platform thereof, the method comprising the steps of:
measuring a weight vale of the load from each of a plurality of 2n weighing sensors, with n sensors arranged on a first edge of the weighing platform and n sensors arranged on an opposing edge;
calculating a weight value of the load from the measured weight value;
allowing the weighing platform to reach a steady state;
determining whether the weight value meets or exceeds a COG offset threshold;
calculating, using an algorithm implemented on the platform scale, a load COG position on the weighing platform of a COG of the load, the algorithm comprising the steps of:
establishing a coordinate system for the plurality of 2n weighing sensors, such that the sensors on the first edge have the coordinates (k1, 0), (k2, 0), . . . (ki, 0) . . . (kn, 0), where n≥2, kn=a and k1=0, and the sensors on the opposing edge have the coordinates (g1, b), (g2, b), . . . (gj, b) . . . (gn, b), where gn=a, and g1=0, wherein a and b are, respectively, the distances between two farthest apart weighing sensors on two adjacent edges of the weighing platform;
calculating the value X of the COG in the coordinate system using the formula:

X
=

(

∑

j
=
1

n

⁢

W
j

⁢

g
j

+

∑

i
=
1

n

⁢

W
i

⁢

k
i

)

/

(

∑

i
=
1

n

⁢

W
i

+

∑

j
=
1

n

⁢

W
j

)

and
calculating the value Y of the COG in the coordinate system using the formula:

Y
=

b
⁢

∑

j
=
1

n

⁢

W
j

/

(

∑

i
=
1

n

⁢

W
i

+

∑

j
=
1

n

⁢

W
j

)

where Wj is a weight value generated by the weighing sensor at the coordinates (gj, b), and Wi is a weight value generated by the weighing sensor at the coordinates (ki, 0);
determining whether the calculated load COG position is in a valid region of the weighing platform; and
if the calculated load COG position is within the valid region, then displaying the calculated weight value; otherwise, displaying the calculated load COG position.

2. The method of claim 1 , wherein the valid region of the weighing platform is adjustable.

3. The method of claim 2 , wherein the valid region of the weighing platform is adjustable as a percentage of the length, the width or both the length and the width of the weighing platform.

4. The method of claim 3 , wherein the center-of-gravity offset threshold is adjustable.

5. The method of claim 1 , wherein the step of displaying the calculated load COG position comprises the substeps of:
generating an image representative of the calculated load COG; and
displaying the image on a display apparatus of the of the platform scale.

6. The method of claim 1 , wherein:
the plurality of weighing sensors is arranged in a square or rectangular pattern on the weighing platform.

7. The method of claim 1 , wherein:
the weighing platform is in a square or rectangular shape.

8. The method of claim 1 , wherein:
the plurality of weighing sensors is arranged uniformly on corners or along edges of the weighing platform.

9. The method of claim 1 , wherein:
at least one of the plurality of weighing sensors is arranged in each of the corners of the weighing platform.

10. The method of claim 1 , wherein:
the plurality of weighing sensors arranged on the first edge of the weighing platform are spaced apart uniformly, and
the plurality of weighing sensors arranged on the opposing edge of the weighing platform are spaced apart uniformly.

11. The method of claim 1 , wherein the step of determining wh

Assignees

• Mettler Toledo Changzhou Measurement Tech Co Ltd
• Mettler Toledo Changzhou Prec Instrument Co Ltd
• Mettler Toledo Int Trading Shanghai Co Ltd

Inventors

• Wang Zhiqiang
• Ge Yiwen
• Ji Genjun
• Zheng Shaowen
• Bliss Douglas

Classifications

• G01M1/12

  Static balancing; Determining position of centre of gravity (by determining imbalance G01M1/14) · CPC title

• G01G23/002 Primary

  Means for correcting for obliquity of mounting (for pendulum-weight apparatus G01G1/16) · CPC title

• G01G21/22

  Weigh pans or other weighing receptacles; Weighing platforms · CPC title

• G01G23/01

  Testing or calibrating of weighing apparatus · CPC title

• G01G23/18

  Indicating devices, e.g. for remote indication; Recording devices; Scales, e.g. graduated · CPC title