The Research On Tracking Control Of State Constrained Nonlinear Systems Under Time Constraints

With the development of social demand and science and technology,the operating environment of systems is becoming increasingly complex,and people’s demand for system security and performance is increasing.In recent years,the tracking control problem of state constrained and time constrained nonlinear systems has attracted widespread attention and research.This type of tracking control needs to satisfy both state constraints and convergence time constraints to ensure the safe and fast operation of the system.This not only increases the difficulty of the controller design,but also increases the complexity of system stability analysis.In order to better meet practical application scenarios,this dissertation focuses on the design and analysis of tracking control for state constrained nonlinear systems under fixed-and predefined-time constraints.The main research content of this dissertation is given as follows:1.The fixed-time tracking control problem of fully state constrained pure-feedback nonlinear systems is studied.Firstly,by using the nonlinear transformation method,the constrained states are transformed into a series of unconstrained new state variables,transforming the tracking control problem of the original state constrained system into the target tracking control problem of the unconstrained system.Then,in order to improve the convergence speed of system tracking error,a fixed-time tracking controller is designed by using the adding a power integrator technology,which avoids the singularity problem of the fixed-time controller in the backstepping design process.This achieves the fixed-time tracking of the target output within a fixed time while ensuring the satisfaction of system state constraints to ensure the safety and fast performance of the system.2.The predefined-time tracking control of the high-order uncertain strict-feedback nonlinear systems with full state constraints is studied.Firstly,the original system is transformed into a new unconstrained system by using the nonlinear transformation method.Then,a smooth time base generator function suitable for any order system is constructed by using the time base generator method.A predefined-time tracking controller based on the time base generator is designed by using the adaptive neural network technology and the backstepping method.Thus the output tracking of the high-order uncertain nonlinear system is achieved within a predefined-time.3.The fixed-time consensus tracking control problem for uncertain nonlinear multiagent systems with hybrid state constraints is studied.Here,the hybrid state constraints include different situations such as full state constraints,partial state constraints,or non state constraint.Firstly,a unified nonlinear transformation function which can simultaneously handle both state constrained and state unconstrained situations is constructed,making the controller designed based on this transformation applicable to various state constrained systems.Then,in order to ensure that the followers can estimate the leader’s output signal within a fixed-time,a distributed fixed-time observer is designed.Furthermore,a distributed fixed-time tracking controller is designed to solve the output consensus tracking problem of the multi-agent systems with hybrid state constraints.4.The predefined-time tracking control problem of the uncertain nonlinear multiagent systems with hybrid stated constraints is studied.In order to improve the general applicability of control algorithms to practical applications,this section avoids the assumptions of positive upper and negative lower bounds in state constraints and constructs a unified nonlinear transformation for more general hybridly state constrained multi-agent systems.At the same time,to reduce the computational complexity of controller design,a predefined-time filter based on a time base generator function is proposed.Furthermore,by utilizing the adaptive technique and fuzzy logic systems to estimate the system uncertainties,a predefined-time fuzzy tracking controller is designed,and the convergence of the target tracking errors of agents is analyzed.