![]() ![]() ![]() The objectives of the controller are (1) to facilitate fully-automated active temperature control during the entire welding process, (2) to minimize the rise time, the settling time, the percentage maximum post-rise error (overshoot calculated as a percentage of the settling band half-width), and the post-settled root-mean-square (RMS) of the temperature error, and (3) to maintain the steady state performance of previous control methods.For welds performed in 6.35 mm plates of 7075-T651 Aluminum with controller gains identified through a manual tuning process, the mean controller performance is a rise time of 10.82 seconds, a settling time of 11.35 seconds, a percentage maximum post-rise error of 69.86% (as a percentage of the 3◦C settling band half-width), and a post-settled RMS error of 0.92◦C.Tuning of the start-up controller for operator-specified behavior can be guided through construction of regression models of the weld settling time, rise time, percent maximum post-rise error, and post-settled RMS error. The FSW temperature controller presented in this thesis, a Position-Velocity-Acceleration (PVA) controller implemented with gain-scheduling, is capable of active control during the start-up portion of a weld. The start-up portion of a weld is an obstacle for these types of active control.To date, only minimal exploratory research has been done to develop an active temperature controller for the start-up portion of the weld. Two types of active temperature control have been previously implemented for steady-state friction stir welding conditions: PID Feedback Control and Model Predictive Control. Temperature control in friction stir welding (FSW) is of interest because of the potential to improve the mechanical and microstructure characteristics of a weld. ![]()
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