Tuning advanced PID controllers via direct H∞-norm mimimization

The tuning of advanced PID control structures for multi-variable plants is an important problem in industry. This paper discusses the parameterization of such control structures with a direct minimization of the H
∞
-norm. Control designs for a distillation column and a helicopter at hover demonstrate the convergence properties of the algorithm as well as the performance limitation imposed by the fixed control structure. The heuristic algorithm achieves good results, although it cannot guarantee the global optimum.