Adaptive fuzzy sliding mode control design for laser metal deposition

This paper presents design and implementation of a novel adaptive fuzzy sliding mode control (AFSMC) scheme and its application to the height control of laser metal deposition process (LMD). Because of the uncertainties in modelling, and imperfections in switching devices or delays, the standard sliding mode control (SMC) cannot be used due to chattering. In order to eliminate the chattering, the control scheme proposed in this paper uses an adaptive fuzzy inverse dynamic model of the LMD process constructed from the input-output data, and an auxiliary continuous proportional-integral type control law constructed using the algebraic distance of trajectories from the switching surface. The simulation and experimental studies are presented to verify the performance and robustness of the controller and its ability in eliminating the chattering, and tracking the different trajectories. The overall performance, on-line learning capability and the disturbance attenuation property of the proposed control scheme makes it suitable for industrial applications.