International Journal of Engineering Research & Science (IJOER) ISSN: [2395-6992] [Vol-2, Issue-12, December- 2016] Page | 67 Synthesis of Discrete State Observer by One Measurable State Variable and Identification of Immeasurable Disturbing Influence Mariela Alexandrova Department of Automation, Technical University of Varna, Bulgaria Abstract – The entire research presents synthesis of discrete state observer by one measurable state variable and identification of immeasurable disturbing influence, aiming to suggest a procedure for reconstruction of the immeasurable disturbing influence. The suggested solution aims also optimization according to the time of completion of the reconstruction process. Keywords – discrete state observer, disturbing influence, immeasurable disturbing influence, measurable state variables, observer synthesis, state space, state space model, pole placement. I. INTRODUCTION For the aim of analysis and synthesis in state space, an option for direct measurement or reconstruction of the state variables is needed. If such information is hard to be obtained even in case of availability of methods for direct measuring, it is often considered the use of information needed received through other channels. For the purpose of collecting the needed information for the state variables of the system a wide use of observers of full and reduced order, steady-state error free or with steady-state error, is natural. Beside the number of methods and approaches every practical realization is still a matter of interest, especially when if immeasurable disturbing influence is to be taken into consideration for analysis and synthesis. II. FORMULATION OF THE PROBLEM The object considered for analysis is continuous linear time-invariant system with structure presented in Fig.1 [1,3]. FIGURE 1. STRUCTURE OF THE PLANT UNDER CONSIDERATION The continuous linear time-invariant system is considered in particular dual-mass DC electromechanical plant. For the purpose of the synthesis of state observer the plant will be described and analyzed in the state space. Considering eventual technical realization there is a set of state variables chosen, which elements corresponds to real physical variables as follows:   - armature current   ;   - rotor speed   ;   – engine elastic torque   and   – working/actuating machine speed   (plant output). As a result and with accordance with the structure of the plant, presented above the following system of equations describes the state variables of the plant:                                                        (1) In regards to the basis considered the plant can be described in the state space with the following equations:             (2)