Fuzzy adaptive process control of resistance spot welding with a current reference model

Abstract

This paper describes a fuzzy adaptive process control scheme for resistance spot welding and proposes a new method identifying dynamic welding resistance to estimate the spot welding process. An optimal current reference model is also founded, which would modify its output according to the stages in the spot welding process. Then a fuzzy adaptive real time process control system is developed with a fuzzy controller and the welding current reference model. The results of simulations and experiments show that the fuzzy adaptive process control has better transient performance for the welding process. Through simulation and numerical calculation it is shown that a bigger sound nugget could be obtained by the proposed scheme with the same welding time and input energy as the usual constant current control method. Simultaneously, it is also indicated that the welding current reference model is effective for reducing loss energy and realizing online process control for spot welding.