Abstract: A control system for a direct teaching/playback type robot, including a low spring constant member connected to a drive source for driving a robot element through a frictional coupling. The control system basically includes a first incremental position detector provided between the robot element and the frictional coupling for detecting the rotational position of the robot element, a second incremental position detector connected to the drive source for detecting the rotational position of the drive source, and a switch for selectively connecting the output terminals of the first and second position detectors to a drive source controller in teaching and playback modes of operation, respectively.

Abstract: A method for controlling a weaving path of a welding torch to trace a welding line in consumable electrode arc welding, including: detecting in a rightward weaving stroke of weaving motion a welding current level IL.sub.1 at the left end position of the weaving motion and a minimum current level IL.sub.2 during the period of the rightward weaving stroke and in a leftward weaving stroke of weaving a welding current level IR.sub.1 at the right end position of the weaving motion and a minimum current level IR.sub.2 during the period of the leftward weaving stroke; calculating the values of differential current (IL.sub.1 -IL.sub.2) and (IR.sub.1 -IR.sub.2) in the rightward and leftward weaving strokes, respectively; comparing and computing a disparity, if any, between the differential current values; and shifting the position of a median point of weaving motion according to the extent of the disparity in the differential current values.