Abstract: An off-line data teaching method for a robot in which a desired posture of the robot is maintained in passing the bending portion of the operation line by preparing off-line teaching data for an operation line on a workpiece which is subjected to an operation of a robot, and by performing an insertion of a circular arc. The indicators (A, L and C) representing air-cut points, terminal point of a linear segment, and intermediate and terminal points of a circular arc segment are assigned to each coordinate data of the operation line consisting of linear segments and circular arc segments on a plane. The circular arc J(1)i+1 of small radius is inserted by defining the new teaching points L(1)i+1, C"(1)i+1 and C'(1)i+1 and disqualify the bending point Li+1. The coordinate data after insertion of the circular arc and the indicators are used to determine the position and posture of the robot.

Abstract: When a deburring tool encounters a large burr near point P'.sub.1 in the process in which the tip of the tool moves from point P.sub.1 to point P.sub.2 on a workpiece, the cutting resistance increases suddenly until it exceeds the present threshold Xth, the robot retracts the deburring tool in the direction in which the cutting resistance is reduced and brings the tool tip from point P'.sub.1 to point Q.sub.1. After that, the robot controls the movement of the tool so that the tool tip moves from point Q.sub.1 to point P.sub.2 (pattern I). When the cutting resistance exceeds the threshold Xth during the movement of the tool tip from point Q.sub.1 to point P.sub.2, a similar retraction movement is executed (pattern II, III). As long as the tool does not encounter such a large burr, the moving speed is controlled to a value corresponding to the cutting resistance.