Research Of Iterative Identification And Control Design Method Based On PE Model

System identification, as a important method of system modeling, is a very important part of modern control theory. The identification methods approximate the real model by looking for a deterministic model, the results of control usually depend on the accurate mathematical models of controlled objects. Generally speaking, the model identification and controller design are independent from each other, which both depend on their own independent optimal criterion respectively, this affects controller normal performance. However, iterative identification can combine controller design with system model identification, and the quality of identified model is evaluated by control performance. Iterative closed-loop identification and controller design are achieved, and then the combination of model identification and controller design is solved. Therefore, the excitation signal optimal design and iterative controller design methods were improved under the conditions of the closed-loop based on the research of iterative identification and control design methods. Flexible transmission system low order iterative controller is designed based on iterative controller design method mentioned above, this thesis contains the following main sections.Excitation signal optimal design methods for closed-loop system is investigated for selecting optimal excitation signal which only consider inputs or outputs. Excitation signal selection is transferred into an optimization problem to find the optimal signal spectrum. Its objective function is defined as the joint approximation of input and output. The constraints of this optimal problem include two parts, the one is the robust stability of closed-loop identification, and the other is the power restrictions of excitation signal which will ensure that the identified model is stabilize and solvability. Based on these, optimal excitation signal spectrum model is formulated, and iterative method is proposed to deal with problem that optimal excitation signal spectrum typically depends on unknown system model, finally, its convergence is analyzed. Simulation result shows that identified model accuracy will be improved by using the excitation signal optimal method.The iterative controller design method is investigated for the combination of the iterative identification and controller design. The PE uncertainty model structure of the plant is expressed by prediction error identification method, the uncertainty model set is described by the Vinncombe distance. Finally, according to the stability margin concept, the closed-loop stability condition and condition of closed-loop system performance improvement of the uncertainty model are proposed. This ensures the closed-loop system stability and a better close-loop system performance during the iterative procedure. In view of the above two conditions, the iterative controller design method and the whole algorithm procedure are developed. This method will improve the stability and convergence of plant model when iterative controller is designed. Simulation results show the proposed method has the good performance.The low order iterative controller of the flexible transmission system is designed by the iterative controller design methods mentioned above and the research of flexible transmission system. Simulation results show the stability and convergence of system are improved by using the proposed method, and the performance of system is improved.