Design of robust PID controller for flexible transmission system using quantitative feedback theory (QFT)

Abstract

Many practical systems are characterized by high uncertainty which makes it difficult to maintain good stability margins and performance properties for closed loop system. In case of conventional control, if plant parameter changes we can not assure about the system performance hence it is necessary to design robust control for uncertain plant. Among the various strategies proposed to tackle this problem, Quantitative Feedback Theory (QFT) has proved its superiority especially in the face of significant parametric uncertainty. The feature of QFT is that it can take care of large parametric uncertainty along with phase information. For the purpose of QFT, the feedback system is normally described by the two-degrees-of freedom structure. A PID controller is a generic control loop feedback mechanism widely used in industrial control systems. A flexible transmission system that has uncertainties in the frictional losses, stiffness of spring and inertial constant is presented using robust PID controller. © 2011 Springer-Verlag Berlin Heidelberg.