Tham khảo tài liệu 'recent advances in robust control – novel approaches and design methodse part 16', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 20 Identification of Linearized Models and Robust Control of Physical Systems Rajamani Doraiswami1 and Lahouari Cheded2 Department of Electrical and Computer Engineering University of New Brunswick Fredericton 2Department of Systems Engineering King Fahd University of Petroleum and Minerals Dhahran Canada 2Saudi Arabia 1. Introduction This chapter presents the design of a controller that ensures both the robust stability and robust performance of a physical plant using a linearized identified model . The structure of the plant and the statistics of the noise and disturbances affecting the plant are assumed to be unknown. As the design of the robust controller relies on the availability of a plant model the mathematical model of the plant is first identified and the identified model termed here the nominal model is then employed in the controller design. As an effective design of the robust controller relies heavily on an accurately identified model of the plant a reliable identification scheme is developed here to handle unknown model structures and statistics of the noise and disturbances. Using a mixed-sensitivity H optimization framework a robust controller is designed with the plant uncertainty modeled by additive perturbations in the numerator and denominator polynomials of the identified plant model. The proposed identification and robust controller design are evaluated extensively on simulated systems as well as on two laboratory-scale physical systems namely the magnetic levitation and two- tank liquid level systems. In order to appreciate the importance of the identification stage and the interplay between this stage and the robust controller design stage let us first consider a model of an electro-mechanical system formed of a DC motor relating the input voltage to the armature and the output angular velocity. Based on the physical laws it is a third-order closed-loop system formed of fast electrical and slow mechanical subsystems. It is very difficult to
