Application And Research Of A Class Of Nonlinear System Adaptive Controller

Along with advancement of industrial control demand, various real requests can't be met by traditional feedback control of linear system. Because of the essential nonlinear characteristics of the control system and the complexity of various phenomena, a great deal of nonlinear phenomena can't be described by the dynamic characteristics of the linear system. Then the research and application of nonlinear control theories has attracted common great attentions of cybernetics field. Adaptive control algorithm is a new computer control algorithm with good efficiency and strong robustness that makes it suitable for complicated industrial processes whose accurate mathematics model is uneasily established.In this paper, minimum variance automatic correction is designed for a class of nonlinear system firstly. An adaptive control is implemented by using differential coefficient geometry algorithm to substitute the original nonlinear system with a time-varying linear system and recursive least-squares is used to identify the invariable coefficients. Then by using the Lyapunov synthesize method, two robust adaptive fuzzy controllers, one is for state feedback and the other is for output feedback, are designed for the tracking problem of a class of single input and single output unknown nonlinear system. A kind of fuzzy logic system is used to approximate the unknown nonlinearities. At the same time, this paper considers the existence of the approximation error and the system's external disturbance. Provide the approximation error and the system's external disturbance has an unknown boundary, an adaptive estimation boundary is designed. The final controller guarantees that the closed-loop system is robust stable and tracking error converges to a neighborhood of zero. In the design process of the output feedback controller, a high-gain observation is applied to make the performance of the output feedback controller achieves that of the state feedback controller. At last the performance of two adaptive schemes are demonstrated through the simulation studies of nonlinear power system containing TCSC.