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.