Grip tool, grip system, slip detection device, slip detection program, and slip detection method

Patent metadata

Field	Value
Publication number	US-12426981-B2
Application number	US-202017766255-A
Country	US
Kind code	B2
Filing date	Oct 2, 2020
Priority date	Oct 4, 2019
Publication date	Sep 30, 2025
Grant date	Sep 30, 2025

Abstract

Provided is a grip tool that allows detecting a slip of an object. The grip tool includes a pair of grip portions that sandwiches to grip an object; an opening/closing mechanism that opens and closes the pair of grip portions; and at least one sensor unit disposed in one or both of the pair of grip portions. The sensor unit includes a plurality of force sensors disposed in a predetermined distribution. The plurality of force sensors each have a function of measuring forces in triaxial directions received from the object. The sensor unit can measure a load distribution received from the object. The slip of the object is detectable based on the load distribution.

First claim

The invention claimed is:

1. A grip system comprising:
a grip tool; and
a slip detection device, wherein the grip tool includes:
a pair of grip portions that sandwiches to grip an object;
an opening/closing mechanism that opens and closes the pair of grip portions; and
at least one sensor unit disposed in one or both of the grip portions of the pair of grip portions, wherein
the at least one sensor unit includes a plurality of force sensors disposed in a predetermined distribution, the plurality of force sensors each have a function of measuring forces in triaxial directions received from the object,
the slip detection device is configured to detect a slip of the object by using a distribution of a combined load as a load distribution, wherein the combined load is obtained by combining the forces measured in triaxial directions measured by the force sensors, using the following formula
F =√{square root over ( f x 2 +f y 2 +f z 2 )}  (1),

where F is the combined load, f x is the force in an x-axis direction of the triaxial directions, f y is the force in a y-axis direction of the triaxial directions, and f z is the force in a Z-axis direction of the triaxial directions.

2. The grip system according to claim 1 , wherein the slip detection device is configured to obtain a center position of the load distribution and detect the slip of the object based on a temporal change of the center position.

3. The grip system according to claim 1 , wherein the slip detection device is configured to obtain a peak position of the load distribution and detect the slip of the object based on a temporal change of the peak position.

4. The grip system according to claim 1 , wherein the slip detection device is configured to detect the slip of the object based on a parallel movement of the load distribution.

5. The grip system according to claim 1 , wherein
the slip detection device is configured to obtain a static friction coefficient of the object from a perpendicular load measurement value and a frictional force measurement value measured by the at least one sensor unit immediately before the object starts to slip, and
the slip detection device is configured to obtain a maximum static frictional force from the static friction coefficient and a current perpendicular load measurement value and predict a start of slipping of the object based on a relation between a current frictional force measurement value and the maximum static frictional force.

6. The grip system according to claim 1 , wherein a prediction of a start of slipping of the object is reflected to control an actuator of the grip tool.

7. A slip detection device for detecting a slip of an object gripped by a grip tool including a grip portion having a sensor unit with a plurality of force sensors, wherein
the slip detection device is configured to detect the slip of the object by using a distribution of a combined load as a load distribution, the combined load obtained by combining forces in triaxial directions measured by the force sensors, using the following formula
F =√{square root over ( f x 2 +f y 2 +f z 2 )}  (1),

where F is the combined load, f x is the force in an x-axis direction of the triaxial directions, f y is the force in a y-axis direction of the triaxial directions, and f z is the force in a Z-axis direction of the triaxial directions;
wherein a prediction of a start of slipping of the object is reflected to control an actuator of the grip tool.

8. The slip detection device according to claim 7 , wherein the slip detection device is configured to obtain a center position of the load distribution and detect the slip of the object based on a temporal change of the center position.

9. The slip detection device according to claim 7 , wherein the slip detection device is configured to obtain a peak position of the load distribution and detect the slip of the object based on a temporal change of the peak position.

10. The slip detection device according to claim 7 , wherein the slip detection device is configured to detect the slip of the object based on a parallel movement of the load distribution.

11. The slip detection device according to claim 7 , wherein
the slip detection device is configured to obtain a static friction coefficient of the object from a perpendicular load measurement value and a frictional force measurement value measured by the sensor unit immediately before the object starts to slip, and
the slip detection device is configured to obtain a maximum static frictional force from the static friction coefficient and a current perpendicular load measurement value and predict a start of slipping of the object based on a relation between a current frictional force measurement value and the maximum static frictional force.

12. A non-transitory, computer-readable storage medium storing a slip detection program for causing a computer to execute a process for detecting a slip of an object gripped by a grip tool including a grip portion having a sensor unit with a plurality of force sensors, wherein the process includes:
detecting a slip of the object by using a distribution of a combined load as a load distribution, the combined load obtained by combining forces in triaxial directions measured by the force sensors, using the following formula
F =√{square root over ( f x 2 +f y 2 +f z 2 )}  (1),

where F is the combined load, f x is the force in an x-axis direction of the triaxial directions, f y is the force in a y-axis direction of the triaxial directions, and f z is the force in a Z-axis direction of the triaxial directions;
wherein a prediction of a start of slipping of the object is reflected to control an actuator of the grip tool.

13. The non-transitory, computer-readable storage medium storing the slip detection program according to claim 12 , wherein the process includes:
obtaining a center position of the load distribution; and
detecting the slip of the object based on a temporal change of the center position.

14. The non-transitory, computer-readable storage medium storing the slip detection program according to claim 12 , wherein the process includes:
obtaining a peak position of the load distribution; and
detecting the slip of the object based on a temporal change of the peak position.

15. The non-transitory, computer-readable storage medium storing the slip detection program according to claim 12 , wherein the process includes
detecting the slip of the object based on a parallel movement of the load distribution.

16. The non-transitory, computer-readable storage medium storing the slip detection program according to claim 12 , wherein the process further includes:
obtaining a static friction coefficient of the object from a perpendicular load measurement value and a frictional force measurement value measured by the sensor unit immediately before the object starts to slip;
obtaining a maximum static frictional force from the static friction coefficient and a current perpendicular load measurement value; and
predicting a start of slipping of the object based on a relation between a current frictional force measurement value and the maximum static frictional force.

17. A slip detection method for detecting a slip of an object gripped by a grip tool including a grip portion having a sensor unit with a plurality of force sensors, the slip detection method comprising:
detecting a slip of the object by using a distribution of a combined load as a load distribution, the combined load obtained by com

Assignees

• Univ Kagawa Nat Univ Corp

Inventors

• Takao Hidekuni
• Fujiwara Masao

Classifications

• G01L5/162

  of piezoresistors · CPC title

• B25J15/08 Primary

  having finger members (B25J15/02, B25J15/04 take precedence) · CPC title

• A61B2562/043

  in a linear array · CPC title

• A61B17/29 Primary

  Forceps for use in minimally invasive surgery · CPC title

• A61B2090/064

  for measuring force, pressure or mechanical tension · CPC title