ADAPTIVE STATE RECONSTRUCTION AND INFERENTIAL CONTROL

In this thesis modeling, state reconstruction and control of discrete systems are considered. First an arbitrarily fast identifier is proposed. The stability of the scheme has been established by applying both Lyapunov's direct method and Popov's hyperstability theorem. The performance of the proposed scheme has been compared with that of the least squares identifier by applying them to a distillation column model. Then based on the proposed identifier an arbitrarily fast adaptive observer has been designed. By choosing an appropriate canonical form the proposed identifier and adaptive observer have been extended to multivariable systems. Several classes of the adaptive control schemes in the literature have been reviewed and the performances of two well known self-tuning regulators (Astrom's and Clarke's schemes) have been compared by applying the schemes to a distillation column model. Based on the proposed identifier and adaptive observer two new adaptive pole-placement controllers have been proposed. The first scheme is developed in the frequency domain and the second scheme in the state space. Global asymptotic stability has been shown by Lyapunov's direct method. Finally the control of systems having outputs available at different sampling rates is considered. This can happen in practice due to limitations of the measurement devices. An adaptive control scheme which assigns all the closed-loop poles of such systems in the presence of asymptotically constant disturbances has been proposed. As an example of systems which have outputs available at different rates a distillation column is considered. An inferential control scheme which estimates the overhead composition from the tray temperature and uses the estimates for controlling the column has been proposed. The performance of the proposed scheme has been compared with several traditional control schemes. Through the simulation results it has been shown that the proposed inferential control scheme can be used effectively for both servo and regulation control.