ROBOT HAVING WORKPIECE MASS MEASUREMENT FUNCTION

• US 20130061695A1
• Filed: 08/14/2012
• Published: 03/14/2013
• Est. Priority Date: 09/09/2011
• Status: Active Grant

• Current Assignee: Fanuc Corporation
• Original Assignee: Fanuc Corporation
• Inventors: SATO, Takashi
• Granted Patent: US 8,775,129 B2
• Time in Patent Office: Days
• US Class Current: 73/865
• CPC Class Codes: B25J 13/085 Force or torque sensors B25J13/082, B25J13/084 take precedence
• CPC Class Codes: B25J 19/02 Sensing devices
• CPC Class Codes: B25J 9/1633 compliant, force, torque control, e.g. combined with position control
• CPC Class Codes: G01G 19/086 wherein the vehicle mass is dynamically estimated
• CPC Class Codes: G01G 21/00 Details of weighing apparatus
• CPC Class Codes: G01G 9/00 Methods of, or apparatus for, the determination of weight, not provided for in groups G01G1/00 - G01G7/00
• CPC Class Codes: G01L 5/009 Force sensors associated with material gripping devices
• CPC Class Codes: G01L 5/16 for measuring several components of force
• CPC Class Codes: G05B 2219/37357 Force, pressure, weight or deflection
• CPC Class Codes: G05B 2219/40549 Acceleration of end effector
• CPC Class Codes: G05B 2219/40606 Force, torque sensor in finger
• CPC Class Codes: Y10S 901/46 Sensing device

Abstract

A robot (1) having a workpiece mass measurement function for measuring the mass of a workpiece that is held, includes a force measurement unit (5) that measures the force that is applied to the tip part (2) of the mechanism part of the robot (1), and a mass estimation unit (11) that estimates the mass of the workpiece that is held by the robot (1), based on information about the force acquired by the force measurement unit (5) while the robot (1) is moving.

Claims

1. A robot having a workpiece mass measurement function for measuring a mass of a workpiece that is held, the robot comprising:

a force measurement unit that measures a force that is applied to a tip part of a mechanism part of the robot; and

a mass estimation unit that estimates the mass of the workpiece that is held by the robot, based on the force acquired by the force measurement unit while the robot is moving.

2. The robot as defined in claim 1, wherein the force measurement unit estimates the mass of the workpiece based on a force measurement value measured when the workpiece is held and a force measurement value that is measured when the workpiece is not held.

3. The robot as defined in claim 1, wherein a posture of the tip part of the mechanism part is not changed while the robot is moving.

4. The robot as defined in claim 1, wherein an average value of a plurality of masses of the workpiece estimated by the mass estimation unit at a plurality of times while the robot is moving, is made a mass estimation value.

5. The robot as defined in claim 1, wherein

the mass estimation unit comprises an acceleration acquiring unit that measures or estimates acceleration that applies to the tip part of the mechanism part of the robot, and

the mass estimation unit estimates the mass of the workpiece that is held by the robot, based on the force measured by the force measurement unit while the robot is moving and the acceleration acquired by the acceleration acquiring unit.

6. The robot as defined in claim 5, wherein the acceleration acquiring unit calculates the acceleration by a dynamics equation.

7. The robot as defined in claim 5, wherein the acceleration acquiring unit acquires the acceleration measured by an acceleration sensor that is attached to the robot.

8. The robot as defined in claim 1, wherein

the force measurement unit measures the force in a plurality of directions,

the acceleration acquiring unit acquires the acceleration in the plurality of directions, and

the mass estimation unit estimates the mass with respect to the plurality of directions, so that an average value of a plurality of masses is made a mass estimation value.

9. The robot as defined in claim 1, wherein

the force measurement unit measures the force in a plurality of directions,

the acceleration acquiring unit acquires the acerbation in the plurality of directions, and

the mass estimation unit estimates the mass with respect to the plurality of directions, so that the mass corresponding to a direction where an absolute value of the acceleration is greatest, among the plurality of directions, is made a mass estimation value.

10. The robot as defined in claim 1, wherein the mass estimation unit estimates the mass of the workpiece that is held by the robot, based on the force acquired by the force measurement unit while the tip part of the mechanism part is moving on a surface that is perpendicular to a direction of a gravitational force that applies to the tip part of the mechanism part of the robot.

11. The robot as defined in claim 1, wherein the mass estimation unit estimates the mass of the workpiece that is held by the robot, based on the force that is acquired by the force measurement unit while the tip part of the mechanism part of the robot is moving on a linear path at constant speed.

12. The robot as defined in claim 10, further comprising a posture acquiring unit that acquires a posture of the tip part of the mechanism part of the robot,

wherein the mass estimation unit estimates the mass of the workpiece that is held by the robot, based on the forces in one or more directions measured by the force measurement unit and the posture acquired by the posture acquiring unit.

13. The robot as defined in claim 11, further comprising a posture acquiring unit that acquires a posture of the tip part of the mechanism part of the robot,

wherein the mass estimation unit estimates the mass of the workpiece that is held by the robot, based on the forces in one or more directions measured by the force measurement unit and the posture acquired by the posture acquiring unit.