Abstract :
In 1976, Youla, Bongiorno and Jabr published two, now classical, papers in which a complete parameterization of a set of stabilizing compensators for a multivariate feedback system was obtained. In the ensuing years, this work, which is often termed the YBJ theory, has led to the development of an entirely new approach to the feedback system design problem. Indeed, their stabilization theory has been extended to include: i) The tracking and disturbance rejection problem. ii) Robust design algorithms. iii) Design with a proper or stable compensator. iv) Transfer function design. v) Pole placement. vi) Simultaneous stabilization. The key to our theory is a three step design philosophy. i) Stabilization. ii) Achievement of Design Constraints. iii) Optimization of system performance.