A Hybrid Control Approach to Nonlinear Plant Stabilization, Suppression of Disturbance, and Compensation of Deviation Errors

This brief proposes a hybrid control approach which can realize desired control performances of multiple objectives for a class of nonlinear plants, such as stability, suppression of disturbance, compensation of deviation errors, and so on. The proposed method is composed of two control schemes. One is a multiple-purpose pole control (MPPC) for the stabilization of an unstable nonlinear plant and the other is simulator-based foresight control (SFC) which aims the suppression of disturbance and the compensation of deviation errors. In MPPC, an unstable nonlinear plant can be stabilized by means of old fashioned pole assignment control method. The procedure of tuning of control parameters is performed with simulator-study assisted design by just observing the responses of state variables. In SFC, the suppression of disturbance can be realized by the insertion of servo filter in line of disturbance which can adjust the relative degree of disturbance. In addition, ideal convergence of errors of state variables can be realized by defining control target equation which describes an ideal convergence dynamics of deviation errors. The proposed SFC can be applied for the full range disturbance, and can predict output behavior of nonlinear plant at any load level. In this brief, the simulation results on the control of a stable nonlinear boiler with 50 width load change of a 14th order model as well as many unstable nonlinear system models are illustrated to demonstrate the effectiveness of the proposed method.