Plasma arc cutting torch tracking control

The present paper is concerned with a tracking si-stem for cutting torch he ight in the plasma arc process. The computer based control system consists of the sensing and detection unit, controller, and servo actuator. The use qt arc and laser sensors to detect the torch height is presented, and their applied characteristics are investi gated in detail. A feedforward compens ation of work-piece position is introduced to improve tracking properties. Moreover, to address the non-linear characteristics of the arc sensor, devi ation classification and adaptive control approaches are also proposed. Tra cking experimental results show acceptable tracking-precision and strong no ise restraining capability for the system. These demonstrate the effectiven ess of the sensing and detection, and the proposed control algorithms. It i s also shown that the are sensing approach is more attractive, owing to its merits of synchronous sensing, high reliability, and low cost. (C) 2000 IE EE.