| In today’s business,sophisticated controlled objects frequently have a lot of unknown variables,including actuator failure,input saturation restrictions,and unknown control direction.Any of these will deteriorate the system’s dynamic properties and even render it unstable.Studying the control issues of MIMO nonlinear systems with actuator defects,input saturation limitations,and uncertain control directions is therefore extremely important theoretically.In this paper,three practical event-triggered preset performance control strategies are proposed for several classes of MIMO nonlinear systems with actuator fault,input saturation constraint,and unknown control direction.These strategies are based on obstacle Lyapunov function,event-triggered mechanism,and preset performance control based on fuzzy system estimation of unknown continuous function vector.The main contents of the paper are as follows:First,the piecewise smooth function is used to approximate the saturated input in the system and the mean value theorem is used to transform the input for a class of MIMO nonlinear systems with input saturation limitations and actuator faults.To address the model’s unidentified nonlinear function,a fuzzy system is developed.Second,an adaptive controller based on the obstacle Lyapunov function is created to follow the target signal.This error transform is created using the inverse hyperbolic tangent function.Ultimately,the stability analysis establishes the uniform boundedness of all of the closed-loop system’s signals,and the simulation results validate the efficiency of the control strategy.Second,for a class of MIMO nonlinear systems with faulty actuators and outside interference.In order to approximate the unknown continuous function in the dynamic model,fuzzy logic is first applied.The tracking error and the state error are then coordinated using a new error transformation mechanism.The system output component is limited by applying the symmetric barrier Lyapunov function to each output component.Finally,the stability analysis establishes that all of the closed-loop system’s signals are uniformly bounded,and the success of the design strategy is tested using a simulated example.Third,for a class of MIMO nonlinear systems with unknown control direction,firstly,fuzzy logic system and parameter adaptive law are used to solve the unknown continuous functions and uncertain parameters in the system model.Secondly,Nussbaum type function is introduced to solve the problem of unknown control gain of input signal.Finally,the virtual control law and the actual input signal are designed based on the new error transformation to ensure that the tracking error can converge according to the preset performance function.At the end of this paper,it is proved that all the signals of the whole closed-loop system are uniformly bounded by Lyapunov stability theory and the effectiveness of the proposed scheme is verified by numerical simulation results. |
