This doctoral thesis treats three issues in control engineering related to relay feedback and multivariable control systems. Linear systems with relay feedback is the first topic. Such systems are shown to exhibit several interesting behaviors. It is proved that there exist multiple fast relay switches if and only if the sign of the first non-vanishing Markov parameter of the linear system is p...

this paper presents a robust controller design methodology for a class of linear uncertain multivariable systems with hard time-domain constraints on their outputs and control signals in response to step disturbance inputs. in this approach, the m×m mimo system is replaced by m2 siso systems and then, using the qft technique, desirable controllers are synthesized. the final controller will be d...

A 2-degree-of-freedom internal model control strategy based on U-model is presented for an unknown multivariable nonlinear systems. The proposed algorithm focuses the case where the noise is added at the input of the system and makes use of a local disturbance rejector. The unknown multivariable nonlinear system is identified by the control oriented U-model and the inverse controller is establi...

This paper concerns a study on the optimal control for nonlinear systems. An appropriate alternative in order to alleviate the nonlinearity of a system is the exact linearization approach. In this fashion, the nonlinear system has been linearized using input-output feedback linearization (IOFL). Then, by utilizing the well developed optimal control theory of linear systems, the compensated ...