Reduced-Order Observer-Based Dynamic Event-Triggered Adaptive NN Control for Stochastic Nonlinear Systems Subject to Unknown Input Saturation

• Published in: IEEE transaction on neural networks and learning systems Vol. 32; no. 4; pp. 1678 - 1690
• Main Authors: Wang, Lijie, Chen, C. L. Philip
• Format: Journal Article
• Language: English
• Published: United States IEEE 01.04.2021; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Actuators; Adaptive control; Artificial neural networks; Control methods; Dynamic event-triggered mechanism (DEM); improved neural network (NN); input saturation; Multi-agent systems; Neural networks; Nonlinear control; Nonlinear dynamical systems; Nonlinear systems; Observers; Parameters; reduced-order observer; Saturation; Ships; stochastic nonlinear systems; Stochastic systems; Stochasticity
• DOI: 10.1109/TNNLS.2020.2986281
• ISSN: 2162-237X; 2162-2388

In this article, a dynamic event-triggered control scheme for a class of stochastic nonlinear systems with unknown input saturation and partially unmeasured states is presented. First, a dynamic event-triggered mechanism (DEM) is designed to reduce some unnecessary transmissions from controller to actuator so as to achieve better resource efficiency. Unlike most existing event-triggered mechanisms, in which the threshold parameters are always fixed, the threshold parameter in the developed event-triggered condition is dynamically adjusted according to a dynamic rule. Second, an improved neural network that considers the reconstructed error is introduced to approximate the unknown nonlinear terms existed in the considered systems. Third, an auxiliary system with the same order as the considered system is constructed to deal with the influence of asymmetric input saturation, which is distinct from most existing methods for nonlinear systems with input saturation. Assuming that the partial state is unavailable in the system, a reduced-order observer is presented to estimate them. Furthermore, it is theoretically proven that the obtained control scheme can achieve the desired objects. Finally, a one-link manipulator system and a three-degree-of-freedom ship maneuvering system are presented to illustrate the effectiveness of the proposed control method.