Control device, robot and control method

A robot comprising:

• a robot arm provided with a force detector;
• and
• a processor that is configured to execute computer-executable instructions so as to control the robot,
• wherein the processor is configured to:
• operate the robot arm to move a screw gauge which is disposed on a tip side of the force detector of the robot arm, used for an inspection of a screw hole in a workpiece, and provided with an external thread to make the external thread have contact with the screw hole;
• detect force applied to the screw gauge in an x-axis direction and a y-axis direction using the force detector to perform force control in a direction perpendicular to a direction of an axis of the screw hole based on detection information of the force detector;
• operate the robot arm to move the screw gauge in a direction so as to reduce the detected forces in the x-axis direction and the y-axis direction based on the force control to align the screw gauge with the screw hole;
• when the screw gauge is aligned with the screw hole, store a z-axis position of a distal end of the screw gauge as an initial position, the initial position being at an entrance to the screw hole and aligned with a plane on a surface of the workpiece;
• rotate the screw gauge and move the screw gauge from the initial position in a z-axis direction into the screw hole;
• stop rotation of the screw gauge based on detection of a force in the z-axis direction by the force detector;
• store the z-axis position of the distal end of the screw gauge as a stop position;
• and
• determine a depth of the screw hole based on a difference between the initial position and the stop position.

A method of controlling a robot including a robot arm provided with a force detector, the method comprising:

• operating the robot arm to move a screw gauge which is disposed on a tip side of the force detector of the robot arm, used for an inspection of a screw hole in a workpiece, and has an external thread, to make the external thread have contact with the screw hole;
• detecting force applied to the screw gauge in an x-axis direction and a y-axis direction using the force detector to perform force control in a direction perpendicular to a direction of an axis of the screw hole based on detection information of the force detector, and operating the robot arm to move the screw gauge in a direction so as to reduce the detected forces in the x-axis direction and the y-axis direction based on the force control to align the screw gauge with the screw hole;
• when the screw gauge is aligned with the screw hole, storing a z-axis position of a distal end of the screw gauge as an initial position, the initial position being at an entrance to the screw hole and aligned with a plane on a surface of the workpiece;
• rotating the screw gauge and move the screw gauge from the initial position in a z-axis direction into the screw hole;
• stopping rotation of the screw gauge based on detection of a force in the z-axis direction by the force detector;
• storing the z-axis position of the distal end of the screw gauge as a stop position;
• and
• determining a depth of the screw hole based on a difference between the initial position and the stop position.