Electro-optical sensors integrated in arc welding workstation for process monitoring by means of fuzzy logic controller

摘要

In the arc welding process, the weld bead results from the formation of an electric arc between the filler wire and the specimen. A non-intrusive sensor aiming to monitor the process has been developed. It consists in four electro-optic modules capable of detecting infrared, visible, and ultraviolet radiation coming from the interaction zone. During the welding process five different signals (IR, UV, two visible regions and plasma electronic temperature) are simultaneously stored. The system is split into two modules, and the optical components for the collection of the radiation coming from the working zone are assembled in a telescope and integrated on the torch used by the operator for manual arc welding processes, in order to allow the sensor to be applied to a wide range of industries. Process data stored by the system are filtered by applying a continuous Kalman filter to reduce the SIN ratio. Numerical values are then analyzed considering blocks of 500 values. For each set of data information dealing with intensity, signal noise and behavior are evaluated. Based on this first analysis, monitoring rules have been pointed out for each signal. These rules are then implemented by a fuzzy supervisor, capable of supplying information regarding the quality of the weld bead.