Device for teaching position and posture for robot to grasp workpiece, robot system, and method

A robot system comprising:

• a robot including a hand configured to grip a workpiece;
• a vision sensor configured to image the workpiece;
• and
• a device configured to teach a position and orientation at which the robot grips the workpiece with the hand in a control coordinate system for controlling the robot, the device comprising a processor configured to:
• acquire a plurality of pieces of image data obtained by repeatedly imaging the workpiece by a vision sensor arranged at a known position in the control coordinate system when the robot grips the workpiece with the hand;
• respectively acquire a plurality of pieces of workpiece position data, each of which indicates a position and orientation of the workpiece in the control coordinate system when the vision sensor images one of the plurality of pieces of image data, based on the plurality of pieces of image data, when the robot grips the workpiece with the hand;
• respectively acquire a plurality of pieces of hand position data, each of which indicates a position and orientation of the hand in the control coordinate system when the vision sensor images the one of the plurality of pieces of image data, when the robot grips the workpiece with the hand;
• respectively acquire a plurality of pieces of teaching position data, each of which indicates a positional relationship between the hand and the workpiece in the control coordinate system when the vision sensor images the one of the plurality of pieces of image data, based on the plurality of pieces of workpiece position data and on the plurality of pieces of hand position data, the teaching position data is represented as coordinates of the control coordinate system;
• and
• obtain new teaching position data by excluding the coordinates of the teaching position data, which are outside of a predetermined allowable range, among the coordinates of the plurality of pieces of the teaching position data,
• wherein the robot is controlled to grip the workpiece based on the acquired teaching position data.

A method of teaching a position and orientation at which a robot grips a workpiece with a hand in a control coordinate system for controlling the robot, the method comprising:

• acquiring, by a processor, a plurality of pieces of image data obtained by repeatedly imaging the workpiece by a vision sensor arranged at a known position in the control coordinate system when the robot grips the workpiece with the hand;
• respectively acquiring, by the processor, a plurality of pieces of workpiece position data, each of which indicates a position and orientation of the workpiece in the control coordinate system when the vision sensor images one of the plurality of pieces of image data, based on the plurality of pieces of image data, when the robot grips the workpiece with the hand;
• respectively acquiring, by the processor, a plurality of pieces of hand position data, each of which indicates a position and orientation of the hand in the control coordinate system when the vision sensor images the one of the plurality of pieces of image data, when the robot grips the workpiece with the hand;
• respectively acquiring, by the processor, a plurality of pieces of teaching position data, each of which indicates a positional relationship between the hand and the workpiece in the control coordinate system when the vision sensor images the one of the plurality of pieces of image data, based on the plurality of pieces of workpiece position data and on the plurality of pieces of hand position data, the teaching position data is represented as coordinates of the control coordinate system;
• obtaining new teaching position data by excluding the coordinates of the teaching position data, which are outside of a predetermined allowable range, among the coordinates of the plurality of pieces of the teaching position data;
• and
• controlling the robot to grip the workpiece based on the acquired teaching position data.