155 Sborník vědeckých prací Vysoké školy báňské - Technické univerzity Ostrava číslo 2, rok 2005, ročník LI, řada strojní článek č. 1486 Miluše VÍTEČKOVÁ * , Antonín VÍTEČEK ** EXPERIMENTAL PLANT IDENTIFICATION BY RELAY METHOD EXPERIMENTÁLNÍ IDENTIFIKACE METODOU RELÉ Abstract The paper deals with use of the relay method for the experimental plant identification. The two position symmetric relay without and with hysteresis, without the integrator and with the integrator in front of and behind the relay is considered. There are brought out the computational formulas for simple plants. Abstrakt Příspěvek se zabývá využitím metody relé pro identifikaci regulovaných soustav. Je uvažováno dvoupolohové symetrické relé s hysterezí nebo bez ní, bez integračního členu a s integračním členem zapojeným na výstupu nebo vstupu relé. Pro několik jednoduchých regulovaných soustav jsou odvozeny pro jejich parametry výpočetní vztahy. 1 INTRODUCTION The relay method was originally used for plant identification by Rotač [7] and lately also for controller autotuning, see reference [2, 1]. The aim of this paper is to show the basic modifications of the relay methods from the viewpoint of experimental plant identification. Two position symmetric relays without and with hysteresis and with the integrator in front of the relay and behind of the relay are considered. 2 RELAY METHOD WITHOUT INTEGRATOR In experimental plant identification using the relay method without the integrator it is assumed that the relay is plugged into the closed-loop system in lieu of a controller in accordance with Fig. 1, where: e, w, u and y are the control error, desired, manipulated and controlled variables, G S (s) – the plant transfer function, G N (a) – the describing function of the relay (Fig. 2), s – the complex variable in L-transform, a – the harmonic oscillation amplitude input at the relay input. w e u y ) ( a G N ) ( s G S Fig. 1 Closed-loop system with relay * doc. Ing., CSc., Department ATŘ-352, Faculty of Mechanical Engineering VŠB – Technical University of Ostrava, 17. listopadu 15, Ostrava - Poruba, 708 33, Czech Republic, (+420) 59 732 4493, e-mail miluse.viteckova@vsb.cz ** prof. Ing., CSc., Dr.h.c., Department ATŘ-352, Faculty of Mechanical Engineering VŠB – Technical University of Ostrava, 17. listopadu 15, Ostrava - Poruba, 708 33, Czech Republic, (+420) 59 732 3485, e- mail antonin.vitecek@vsb.cz, Faculty of Mechatronics and Machinery Design, Kielce University of Technology, Al. Tysiąclecia Państwa Polskiego 7, 25-314 Kielce, Poland