Abstract: A robot controller for keeping the posture of a tool in a task coordinate system by a simple processing and allowing a robot to perform flexible translational motion. A robot controller for controlling a motor for driving a joint by a control circuit having a position/speed state feedback loop, has a mechanism for measuring the angle of a joint of a robot, a mechanism for storing the initial posture of a tool attached to the end of a hand of the robot, a mechanism for setting the position or speed gain of a specific joint axis smaller than the position or speed gains of the other joint axes, and a mechanism for calculating the correction of a position or speed command to keep the tool posture with respect to the robot base on the basis of the angle of the joint and the initial posture of the tool.

Abstract: A robot controller for keeping the posture of a tool in a task coordinate system by a simple processing and allowing a robot to perform flexible translational motion. A robot controller for controlling a motor for driving a joint by means of a control circuit having a position/speed state feedback loop, comprising means for measuring the angle of a joint of a robot, means (11) for storing the initial posture of a tool attached to the end of a hand of the robot, means (10) for setting the position or speed gain of a specific joint axis smaller than the position or speed gains of the other joint axes, and means (12) for calculating the correction of a position or speed command to keep the tool posture with respect to the robot base on the basis of the angle of the joint and the initial posture of the tool.

Abstract: When a welding teaching program employing a plurality of robots is completed, if a robot does not operate properly it may be preferably to make the robot retreat and operate in accordance with a different teaching program, urgently and at an optional timing. In the invention, when the operation of a program being executed is suspended, the program addresses are memorized and a different prestored teaching program is executed. Upon the termination of the different teaching program, the execution of the suspended program is resumed, referring to the memorized addresses.