The invention relates to an arc welding robot having a welding gun (2) a welding power source (3), a robot controller (4), a current sensor (5) sensing the current supplied to the arc, a position measurement system (7) sensing the position of the welding gun (2) and processing means processing data related to the sensed current and the sensed position and delivering robot commands based on the processed data. According to the invention the processing means is the micro processor (8) of the robot controller (4). The invention also relates to a corresponding method for controlling an arc welding robot.