Research On The Control Problems Of Several Types Of Uncertain Nonlinear Systems Based On Observers

This paper introduces the related knowledge of the observer and the controller for nonlinear systems.Based on the previous research results,observer-based control methods suitable for several kinds of nonlinear systems with their own characteristics are designed,respectively.The main contents can be divided into the following three parts:1.Reduced-dimensional observer-based adaptive Backstepping control method for nonlinear systems with Lipschitz conditions and unknown functions of perturbations and output.In this section,the stabilization control problem of nonlinear systems with Lipschitz conditions is discussed.The affine system discussed in this chapter has the following characteristics:?i?the output cannot directly characterize all state informations,?ii?it contains unknown functions of perturbations and output.Based on Lemma 1.4.1-1.4.2 and the design ideas of reduced-dimensional observer for linear systems,we designed a reduced-order observer-based Backstepping adaptive controller.And we theoretically proved the effectiveness of the above observer-based control method to solve the state stabilization problem.2.Interconnencted Kalman adaptive observer-based Backstepping control method for the sensorless motor model.In this part,the current tracking control problem of the motor model with unmeasurable flux is studied.Based on the above Kalman adaptive observer^[1],a Kalman adaptive observer with internal links is proposed.Subsequently,combining the above interconnected Kalman adaptive observer with the control method of Backstepping,a interconnected Kalman adaptive observer-based Backstepping control method is proposed.Under the condition of observability,it is proved theoretically that the above observer-based control method not only can make the closed-loop system exponentially stable but also can effectively solve the tracking control problem.3.NDOB-based sliding mode control method and the direct adaptive fuzzy control method for Lorenz system.In this part,the stability control problem for equilibrium points of a class of nonlinear chaotic systems?Lorenz systems?is studied.Taking simplicity,convenience,and flexibility as the principles and basing on the characteristics of the Lorenz system,when the system has the unknown parameter?,we introduce the direct adaptive fuzzy controller and the NDOB-based SMC controller.In the SMC method,the nonlinear item of the controller can cause shaking.So,we have fuzzy processing for the gain k to eliminate the shaking of the sliding surface.We also theoretically analyzed the effectiveness of the proposed control method in this part to solve the equilibrium points stabilization problem.Simulation results more intuitively show the significance of the designed methods in this paper.