Abstract: The H infinity technique with pole placement constraints is used to design CH-47 helicopter controller. The benefits from this are that the system not only has satisfied H-infinity requirement but also can force the closed-loop poles into a suitable sub-region of left-half plan. It avoids over fast dynamic responses for digital implementation and has satisfactory damping. In this design, the following problems are considered: How to choose controller structure? How to design the weighting functions? Should uncertainty be defined in input or output? There are answers in the paper. The simulation results show that the system designed satisfies ADS-33 requirement and robustness stability.

Key words: H -infinit y contr ol, r obustness contr ol, helicopter, pole- placement