Computer aided design of decentralized PID controllers

Considers decentralized PID controllers formed by m elementary PIDs with one input and one output. A method is provided to calculate in closed form the polynomial of the closed loop poles as a function of the parameters of the various elementary PID units. This makes it easy to fix within preassigned values, for example using repeatedly the root locus technique or parameter optimization methods, the parameters of the individual PID units in order to confine the closed loop poles in some desired region of the complex plane or minimize some quality index of the closed loop control system. The authors also emphasize the appropriateness of inserting, whenever possible, a static decoupler in the direct chain