Curved surface following control method for robot

A curved surface following control method for controlling a robot including a hand part to which a work tool is attached, an arm part connected to the hand part, and a controller for controlling operation of the hand part and the arm part, the curved surface following control method comprising:

• a normal direction identification process that includes, based on a formula for approximating a shape of a target workpiece including a curved surface, identifying a normal direction of a virtual shape which is a shape represented by the formula at a virtual position where the work tool attached to the hand part contacts the virtual shape;
• and
• a work tool posture control process that includes bringing the work tool attached to the hand part into contact with the target workpiece at a corresponding position which is a position corresponding to the virtual position on a surface of the target workpiece, in a posture along the normal direction identified in the normal direction identification process, wherein
• the robot or the work tool includes a force sensor,
• a traveling path of the work tool along a surface of the virtual shape represented by the formula is expressed as a group of work tool travel direction vectors that indicate a movement in a tangent plane oriented perpendicular to the normal direction, and
• in the work tool posture control process, moving the work tool in the posture along the normal direction along respective work tool travel direction vectors, and correcting a position of the work tool in a direction of advancing inward from the virtual shape or retreating outward from the virtual shape according to a detection value of the force sensor.