PID CONTROLLER TUNING FOR DESIRED CLOSED-LOOP RESPONSES FOR SI SO SYSTEMS/

Proportional, integral, and derivative (PID) parameters are obtained f or general process models by approximating the feedback form of an IMC controller with a Maclaurin series in the Laplace variable. These PID parameters yield closed-loop responses that are closer to the desired responses than those obtained by PID controllers tuned by other metho ds. The improvement in closed-loop control performance becomes more pr ominent as the dead time of the process model increases. A new design method for two degree of freedom controllers is also proposed. Such co ntrollers are essential for instable processes and provide significant ly improved dynamic performance over single degree of freedom controll ers for stable processes when the disturbances enter through the proce ss.