US 12,533,799 B2Granted

Robot, gripping force control device, gripping force control method, and recording medium storing gripping force control program

AssigneeOMRON Corporation

InventorsChisato Nakashima, Misato Nabeto

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Abstract

This robot comprises: a finger that grips a workpiece; a motor that drives the finger; a driving current detection unit that detects a driving current of the motor; a gripper including a tactile sensor provided in the finger; a driving force calculation unit that calculates a driving force applied to the workpiece by the finger on the basis of a driving current value of the motor; a pressing force calculation unit that calculates a pressing force that the tactile sensor receives from the workpiece on the basis of a detection value of the tactile sensor; and a control unit that determines which of the driving force and the pressing force is to be used on the basis of a gripping force setting value that is a setting value of the gripping force applied to the workpiece by the finger and controls the gripping force using the value of the driving force or the pressing force which is determined to be used.

Claims16

Dependent claims

A robot, comprising:

a gripper including a plurality of fingers that grip a target object, a motor that drives at least one finger of the plurality of fingers as a drive finger, a drive current detection section that detects a drive current of the motor, and a tactile sensor that is provided at a tactile finger that is at least one finger of the plurality of fingers;
a drive force computation section that computes a drive force that the drive finger is imparting to the target object based on a drive current value of the motor detected by the drive current detection section;
a pressing force computation section that computes a pressing force that the tactile sensor is receiving from the target object based on a detection value of the tactile sensor;
and
a control section that determines which of the drive force or the pressing force to employ based on a gripping force set value that is a setting value of gripping force that the drive finger or the tactile finger is to impart to the target object, and that controls the gripping force employing a value of whichever of the drive force or the pressing force was determined to be employed, wherein:
a force anticipated as a force for the drive finger to impart to the target object, in a case in which an instructed current value of a given value has been issued and the motor driven, is taken as an instructed drive force, a magnitude of a difference between the drive force computed based on the detected drive current value and the instructed drive force is taken as a first error, and a magnitude of a difference between a reaction force corresponding to the computed pressing force and the instructed drive force is taken as a second error;
and
in order to control the gripping force, the control section determines to employ the drive force or the pressing force that corresponds to a smallest error among the first error or the second error when the instructed drive force is configured as the gripping force set value.

5 more elements

A gripping force control device connected to a gripper of a robot that includes a plurality of fingers that grip a target object, a motor that drives at least one finger of the plurality of fingers as a drive finger, a drive current detection section that detects a drive current of the motor, and a tactile sensor that is provided at a tactile finger that is at least one finger of the plurality of fingers, the gripping force control device controlling a gripping force imparted to the target object by the drive finger or the tactile finger and comprising:

a drive force computation section that computes a drive force being imparted to the target object by the drive finger based on a drive current value of the motor detected by the drive current detection section;
a pressing force computation section that computes a pressing force that the tactile sensor is receiving from the target object based on a detection value of the tactile sensor;
and
a control section that determines which of the drive force or the pressing force to employ based on a gripping force set value that is a setting value of the gripping force, and that controls the gripping force employing a value of whichever of the drive force or the pressing force was determined to be employed, wherein:
a force anticipated as a force for the drive finger to impart to the target object, in a case in which an instructed current value of a given value has been issued and the motor driven, is taken as an instructed drive force, a magnitude of a difference between the drive force computed based on the detected drive current value and the instructed drive force is taken as a first error, and a magnitude of a difference between a reaction force corresponding to the computed pressing force and the instructed drive force is taken as a second error;
and
in order to control the gripping force, the control section determines to employ the drive force or the pressing force that corresponds to a smallest error among the first error or the second error when the instructed drive force is configured as the gripping force set value.

4 more elements

A gripping force control method in a gripping force control device connected to a gripper of a robot that includes a plurality of fingers that grip a target object, a motor that drives at least one finger of the plurality of fingers as a drive finger, a drive current detection section that detects a drive current of the motor, and a tactile sensor that is provided at a tactile finger that is at least one finger of the plurality of fingers, and that controls a gripping force imparted to the target object by the drive finger or the tactile finger, the gripping force control method comprising:

computing a drive force that the drive finger is imparting to the target object based on a drive current value of the motor detected by the drive current detection section;
computing a pressing force that the tactile sensor is receiving from the target object based on a detection value of the tactile sensor;
determining which of the drive force or the pressing force to employ based on a gripping force set value that is a setting value of the gripping force;
and
controlling the gripping force employing a value of whichever of the drive force or the pressing force was determined to be employed, wherein:
a force anticipated as a force for the drive finger to impart to the target object, in a case in which an instructed current value of a given value has been issued and the motor driven, is taken as an instructed drive force, a magnitude of a difference between the drive force computed based on the detected drive current value and the instructed drive force is taken as a first error, and a magnitude of a difference between a reaction force corresponding to the computed pressing force and the instructed drive force is taken as a second error;
and
in order to control the gripping force, the control section determines to employ the drive force or the pressing force that corresponds to a smallest error among the first error or the second error when the instructed drive force is configured as the gripping force set value.

5 more elements

A non-transitory recording medium storing a gripping force control program in a gripping force control device connected to a gripper of a robot that includes a plurality of fingers that grip a target object, a motor that drives at least one finger of the plurality of fingers as a drive finger, a drive current detection section that detects a drive current of the motor, and a tactile sensor that is provided at a tactile finger that is at least one finger of the plurality of fingers, and that controls a gripping force imparted to the target object by the drive finger or the tactile finger, the gripping force control program causing a computer to execute processing comprising:

computing a drive force that the drive finger is imparting to the target object based on a drive current value of the motor detected by the drive current detection section;
computing a pressing force that the tactile sensor is receiving from the target object based on a detection value of the tactile sensor;
determining which of the drive force or the pressing force to employ based on a gripping force set value that is a setting value of the gripping force;
and
controlling the gripping force employing a value of whichever of the drive force or the pressing force was determined to be employed, wherein:
a force anticipated as a force for the drive finger to impart to the target object, in a case in which an instructed current value of a given value has been issued and the motor driven, is taken as an instructed drive force, a magnitude of a difference between the drive force computed based on the detected drive current value and the instructed drive force is taken as a first error, and a magnitude of a difference between a reaction force corresponding to the computed pressing force and the instructed drive force is taken as a second error;
and
in order to control the gripping force, the control section determines to employ the drive force or the pressing force that corresponds to a smallest error among the first error or the second error when the instructed drive force is configured as the gripping force set value.

5 more elements

Dependencies are inferred from the claim text.

Facts

Application: 18/039,961Filed 14 Sep 2021
Priority: JP 2020-2034818 Dec 2020
Published: US 2024/0001540 A14 Jan 2024
Granted: 27 Jan 2026
Term ends: Not estimatedThe source records don’t support an estimate.

Classification10 codes

B25J 9/1612
Program controls: characterised by the hand, wrist, grip control
B25J 9/1633
Characterised by the control loop: compliant, force, torque control, e.g. combined with position control
B25J 9/1653
Characterised by the control loop: parameters identification, estimation, stiffness, accuracy, error analysis
B25J 13/082
Touching devices, e.g. pressure-sensitive: grasping-force detectors