Observer-Based Event-Triggered Tracking Control for Discrete-Time Nonlinear Systems Using Adaptive Critic Design

In this article, a new output-feedback event-triggered (ET) tracking control strategy is investigated for discrete-time strict-feedback nonlinear systems based on the adaptive critic design (ACD). An effective state observer is designed to obtain current states information, which can remove the restriction that the system can be converted to the input-output model. Subsequently, dissimilar to the n-step forward predictor with multiple neural networks (NNs) and n-step delays, variable substitution technique is used to avoid time delays and calculation burden of multiple NNs. ACD structure is constructed to acquire the optimal control strategy by critic and action NNs. An effective iterative strategy is adopted to deal with the approximation error of action NN. In this way, the update law of the controller is constructed, which is more reasonable and easier to be implemented. Meanwhile, ET mechanism is placed between the senor and the controller. A novel ET condition is constructed to moderate the burden of network communications and realize the ideal control performance. All the state signals are guaranteed to be bounded. Numerical simulations are performed to display the feasibility of the presented approach.