Electric cylinder system

Patent metadata

Field	Value
Publication number	US-12117358-B2
Application number	US-202017763699-A
Country	US
Kind code	B2
Filing date	Aug 27, 2020
Priority date	Sep 30, 2019
Publication date	Oct 15, 2024
Grant date	Oct 15, 2024

Abstract

An electric cylinder system includes: an electric cylinder including a rod and a strain detector; an output unit configured to output, on the basis of a reference load value in accordance with an output value of a strain detector for calibration obtained when the rod presses the strain detector for calibration and a measurement load value in accordance with an output value of the strain detector obtained when the rod presses the strain detector for calibration, a gain and an offset for causing the measurement load value to approach the reference load value; a storage unit configured to store the gain and the offset as a calibration parameter; and a calibration unit configured to calibrate a load value in accordance with an output value detected by the strain detector on the basis of the calibration parameter wherein the gain and the offset satisfy a preset relationship.

First claim

The invention claimed is:

1. An electric cylinder system comprising:
an electric cylinder including a rod configured to press a workpiece, and a strain detector configured to output a value in accordance with a load applied to the rod;
a computer configured to output, on a basis of a reference load value in accordance with an output value of the strain detector for calibration obtained when the rod presses the strain detector for calibration and a measurement load value in accordance with an output value of the strain detector obtained when the rod presses the strain detector for calibration, a gain value and an offset value for causing the measurement load value to approach the reference load value;
a storage configured to store the gain value and the offset value output by the computer as a calibration parameter; and
a controller configured to calibrate a load value in accordance with an output value detected by the strain detector on a basis of the calibration parameter stored in the storage,
wherein the gain value and the offset value output by the computer satisfy a relationship of Expression (1):

a
=

s
xy

s
x
2

,

b
=

Y
-

a
×
X

(
1
)

where a represents the gain value, b represents the offset value, s x represents a variance value of the measurement load value, s xy represents a covariance value of the measurement load value and the reference load value, X represents an average value of the measurement load value, and Y represents an average value of the reference load value,
the computer further determines whether a difference between the reference load value and the measurement load value after calibration is equal to or less than a threshold value,
the computer outputs, when it is determined that the difference is not equal to or less than the threshold value, a correction value for correcting the load value corresponding to the measurement load value for which it is determined that the difference is not equal to or less than the threshold value,
the storage stores the correction value output by the computer,
the controller corrects the load value in accordance with the output value detected by the strain detector on a basis of the correction value stored in the storage, and
the correction value output by the computer satisfies a relationship of Expression (2):

C
d

=

y
d

-

x
d

=

(

y
2

-

y
1

)

×

(

x
d

-

x
1

)

(

x
2

-

x
1

)

+

y
1

-

x
d

(
2
)

where C d represents the correction value, x d represents the load value that is a subject of correction, y d is the reference load value corresponding to the load value x d , x 1 and x 2 are measurement load values of two neighboring points of the load value x d , and y 1 and y 2 are reference load values corresponding to the measurement load values x 1 and x 2 .

Assignees

• Sintokogio Ltd

Inventors

• Nakai Takuma
• Ishida Yuu

Classifications

• G01L5/0076

  Force sensors associated with manufacturing machines (G01L5/0066, G01L5/0071 and B23Q17/09 take precedence; for the specific machine or operation involved see relevant class, e.g. B21 - B42) · CPC title

• B30B15/281 Primary

  overload limiting devices (in general F16H35/10) · CPC title

• G01L25/00

  Testing or calibrating of apparatus for measuring force, torque, work, mechanical power, or mechanical efficiency · CPC title

• B30B15/148

  Electrical control arrangements · CPC title

• B30B1/186

  Control arrangements · CPC title