Sampled-data control of arc length and torch height using ITV image processing device.

Abstract

The problem for measuring and controlling the arc length and the torch height is important as a basis of research in automatic arc welding systems. Improvement of welding quality requires to keep constant optimum values of the length and current of the arc. In this paper, we discuss the stability and adaptability of the arc length in the MIG pulse arc welding system with a constant feeding speed of the electrode wire. Consequently, it is necessary to control the height of welding torch so as to keep the electrode extension constant for controlling both the current and length of the arc. We construct a basic visual robot which measures and controls the arc length and the torch height, using the personal computer, image processing device, and ITV camera as a sensor. Furthermore, we describe how to determine the characteristic of the digital controller, which controls the welding current and the digital servo motor for controlling the arc length and the torch height. We also introduce a basis of the electric techniques which incorporate the personal computer, image processing device, digital-analog converter, programmable current source, and digital servo motor.