This is robust controller desing example. The controller is designed by pole-placement with sensitivity shaping using toolbox "Pole-placement master". For details on controller design see:

H. Prochazka and I.D. Landau, "Pole placement with sensitivity function shaping using 2nd   order digital notch filters", Automatica, 2003, (39)6, pages 1103-1107.

I.D. Landau, "Commande des systmes", Hermes, Paris, 2002
