| In recent years,the Backstepping method has been widely applied in nonlinear control theory and practice.Dynamic surface control technology is an effective nonlinear control design method developed on the basis of classical Backstepping theory technology.Due to the advantages of the Backstepping method and the ability to solve its inherent "complexity explosion" problem,this technology has received significant attention in both theoretical and applied research.However,the control scheme proposed based on existing dynamic surface control technology can only ensure bounded tracking,meaning that the tracking error can only converge to a small neighborhood,but cannot achieve precise tracking with zero error.Based on this,this paper proposes a set of adaptive fuzzy dynamic surface asymptotic tracking control scheme for several typical uncertain nonlinear systems,combining Backstepping theory,dynamic surface technology and fuzzy logic,which realizes the accurate tracking of the reference signal of the system,and gives the theoretical proof of the stability,convergence and robustness of the closed-loop system.The main content includes the following three aspects:Firstly,the adaptive fuzzy dynamic surface asymptotic tracking control problem for a class of nonlinear fractional order systems with non strict feedback structures is considered.Because the nonlinear function in the non strict feedback system contains all the states,the problem of algebraic loop will arise in the process of controller design.First,fuzzy logic system is used to deal with unknown nonlinearity,and at the same time,the monotonicity of fuzzy basis function is used to successfully solve the algebraic ring problem.Furthermore,a dynamic surface control algorithm is designed,and the addition of a first-order filter in each step of the Backstepping method can greatly reduce computational complexity.The control scheme designed in this article can achieve asymptotic convergence of tracking error while ensuring the stability of the closed-loop system.Finally,the simulation results validate the effectiveness of the control scheme.Secondly,an adaptive fuzzy dynamic surface asymptotic tracking control scheme with event triggered mechanism is proposed for fractional order nonlinear large-scale systems with unknown strong interconnections.Due to the fact that the strongly interconnected term encompasses all states of the entire interconnected system,designing solutions is even more difficult.Using the properties of Gaussian function to deal with unknown interconnections and nonlinear functions can not only relax the additional assumptions about interconnections to a large extent,but also eliminate the impact of uncertainty.In addition,a new event triggering mechanism has been established,which can save communication resources more than traditional time triggering schemes.Finally,a simulation example shows that the control scheme designed in this paper can achieve asymptotic convergence of tracking error while ensuring the stability of the closed-loop system.Finally,for uncertain nonlinear systems with full state constraints,an adaptive fuzzy event triggered dynamic surface asymptotic tracking control algorithm is proposed when the control coefficient of the system is completely unknown.By introducing the lower bound of the unknown control coefficient,a new obstacle Lyapunov function is designed.This function can not only successfully eliminate the requirements for the lower bound of the control coefficient in the control law based on the boundary estimation method and the smooth function construction method,but also make the system state never violate the constraints.In addition,by introducing a positive integral function in the design process of the controller,and based on Barbarat Lemma,it is proven that the controller designed in this paper can achieve asymptotic convergence of tracking error.Finally,the effectiveness of this scheme was verified through two simulation examples. |
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