Abdessattar CHAARI, obtained the doctorate thesis on February 1984 in the field of electric genius from the ENSET of Tunis, Tunisia. He works as an associate professor in the electrical department of the National Engineering school of Sfax, Tunisia. He is member of the research group on automatic control in the UCA of ENIS, Sfax. His research focus on Automatic Control: Phase Locked Loop PLL in industrial regulation and servo-systems, modeling, identification and control of systems (thermal systems, DC motor, induction motor), synthesis of linear observers and nonlinear ones: application to the regulation and control of nonlinear systems.