Grip tool, grip system, slip detection device, slip detection program, and slip detection method
View Patent ↗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.
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 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, fx is the force in an x-axis direction of the triaxial directions, fy is the force in a y-axis direction of the triaxial directions, and fz 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.
18. The slip detection method according to claim 17 , wherein the detecting 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.
19. The slip detection method according to claim 17 , wherein the detecting 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.
20. The slip detection method according to claim 17 , wherein the detecting includes detecting the slip of the object based on a parallel movement of the load distribution.
21. The slip detection method according to claim 17 , further comprising:
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.