Research And Improved Design Of Output Feedback Control Algorithm Based On State Observation

In practical engineering control systems such as industrial process control,robot control,and drone control,most of them are complex nonlinear control systems.They usually have high dimensionality,complex structure,strong nonlinearity and strong coupling.The control design of such complex nonlinear control systems is a difficult problem in the field of control.If the control method is not correct,it will be difficult to achieve the control requirements of the controlled system,there will be no good control effect,and even the controlled system will not be stable.Therefore,the study of adaptive output feedback control for complex nonlinear systems with inaccurate mathematical models,time-delay phenomena,unmeasurable states and unknown nonlinear disturbances has very important theoretical significance and practical application value.Aiming at the problem of adaptive output feedback control for nonlinear systems,this paper designs several control schemes based on existing nonlinear system control algorithms such as active disturbance rejection control,sliding mode control and backstepping.Based on the characteristics and advantages of these different control methods,combined with fuzzy logic systems or neural networks and high-order sliding mode differentiators,the drawbacks of existing control methods are improved.At the same time,the stability of the whole closed-loop system is verified by Lyapunov stability theory.The boundedness of all signals is guaranteed.The specific research contents and work are as follows:(1)For a class of uncertain nonlinear systems,a new adaptive output feedback control method combining backstepping method and active disturbance rejection control is studied.The extended state observer is used to estimate the unknown state of the controlled system in real time,and the extended state observer is used to realize the online approximation and compensation of uncertainties in the system.The virtual control signal in the design of the backstepping method is deduced by the nonlinear command filter,which avoids the problem of complex explosion in the design of traditional backstepping method,and the adaptive output feedback controller is designed.The stability of this control method is proved by the Lyapunov function,which verifies that all signals in the closed-loop system are bounded.Numerical simulation examples further verify the effectiveness of the proposed method.(2)A new type of adaptive backstepping sliding mode controller is designed for a class of switched nonlinear systems with unmeasurable system states,unknown nonlinear terms and disturbances.The fuzzy logic system(FLS)is used to construct the fuzzy state observer,and the fuzzy logic system is used to realize the variable gain control.In addition,a high-order sliding mode differentiator is introduced to construct a precise perturbation observer,and the second-order form of the high-order sliding mode nonlinear differentiator is used as a filter.Finally,based on fuzzy state observer and estimated compensation for disturbance,combined with adaptive backstepping design method and sliding mode control method,a new adaptive backstepping sliding mode controller is designed for this kind of switching system.The newly proposed method realizes the real-time online approximation of the unknown nonlinear function of the system and the acquisition of the unknown state of the system,and realizes the accurate estimation and compensation for the unknown disturbance of the system.In the traditional backstepping design process,the problem of the complexity of the control parameters caused by the repeated derivation of the virtual control signal is effectively avoided,and the chattering phenomenon in the traditional sliding mode control also has a good suppression effect.The stability of the system is proved by the Lyapunov function.The effectiveness of the control method is verified by simulation examples,and the simulation results further verify the system stability and signal boundedness.(3)A mathematical dynamic model was established for the continuous stirred tank reactor(CSTR)commonly used in industry,and a kind of adaptive integral sliding mode controller was designed for the CSTR mathematical model.Firstly,a finite-time state observer is designed for this complex nonlinear system based on sliding mode control.At the same time,a nonlinear disturbance observer is designed.Thus,the unmeasurable state variables and unknown disturbances in this nonlinear system are observed.Based on the estimation results,an integral sliding mode surface is designed and an adaptive proportional variable gain approach law is introduced.Finally,an adaptive integral sliding mode controller is constructed,which realizes fast tracking of the controlled system and has very good robustness.The boundedness of all signals in the closed-loop system and the stability of the closed-loop system are proved by Lyapunov stability theory.The effectiveness of the designed control scheme is verified by numerical simulation and experiment.