DOURABLE SENSOR BASED CONTROL OF WELD POOL SURFACE

摘要

Practical welding control systems require durable/compact sensors to sense the welding process and appropriate control algorithms to produce smooth welds. A novel arc welding sensor, referred to as non-transferred plasma charge sensor, requires no additional attachment to the torch and is proved reliable for weld pool surface sensing. Aiming at eliminating the sensor's intrinsic uncertainties and achieving better accuracy and application independency, this paper proposes a simple yet effective method to improve the sensor's capability in measuring the weld pool under possible process variations. Specifically, reference signals are sampled from the top surface of the work-piece and used to define relative signals which can measure the depth of the weld pool with better accuracy. Because of possible large process variations, an interval model control algorithm with adaptively updated intervals is adopted. Closed-loop experiments showed that the developed control system is capable of achieving quality welds and is robust with respect to different variations.