Laser aided direct metal/material deposition (DMD)process is a layered manufacturing process able toproduce a 3-D part directly from a CAD image. Aclosed-loop feedback control system is considered as arequirement to ensure dimensional accuracy. Forconventional control methods, the effectiveness ofprocess control strongly relies on accuracy of theanalytical model of the system behaviour. However,development of such an analytical model is quitedifficult and impractical, since coupled processvariables cause the complexity and nonlinearity ofDMD process. Fuzzy logic-based control, that nomodel but only knowledge of the process is requiredfor decision making using this control technique, isattempted to overcome the difficulty. A PID like fuzzylogic-based controller (FLC) was developed foradaptive deposition during DMD process. Thecontroller has the capability of continuously trackingthe reference height by varying the laser poweradaptively, thus depositing a clad line with varyingdeposition height and a layer with curved surface.This feature provides a potential of building 3-D partswith nonlinear geometry such as overhang, whilemaintaining the accuracy of surface curvature.Simulation was performed tuning up fuzzy controllerparameters with an experiment-based fuzzy logicmodel of the DMD process and simulated results werecompared with experimental results to verify theperformance of the controller.
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