Welding robot

A welding robot for welding an objective workpiece, comprising:

• a robot arm having a distal end defining the origin of a first coordinate system;
• a noncontact distance sensor attached to the distal end of said robot arm, for measuring a distance to the objective workpiece and delivering distance data;
• a rotating and sweeping means connected to said robot arm and having a rotating center axis corresponding to the first coordinate system, for rotating and sweeping said noncontact distance sensor;
• a rotating phase detecting means for detecting a rotating phase of said noncontact distance sensor and delivering rotating angle phase data;
• a signal waveform processing means operatively connected to said noncontact distance sensor and said rotating phase detecting means for forming a signal waveform obtained by the distance data and the rotating angle phase data, extracting an extreme feature point from the signal waveform, and delivering distance data and rotating angle phase data per feature point;
• a relationship calculating means operatively connected to said signal waveform processing means for calculating an actual relationship between the first coordinate system, and a second coordinate system having an origin defined on the objective workpiece, from the distance data and the rotating angle phase data delivered from said signal waveform processing means;
• a relationship setting and storing means for presetting and pre-storing a reference relationship between the first coordinate system and the second coordinate system;
• and
• a robot control means operatively connected to said relationship calculating means and said relationship setting and storing means for moving said robot arm so that the actual relationship between the first coordinate system and the second coordinate system, calculated by said relationship calculating means, coincides with the reference relationship between the first coordinate system and the second coordinate system.