Disturbance observer design for nonlinear systems represented by input-output models

A new approach to the design of nonlinear disturbance observers for a class of nonlinear systems described by inputoutput differential equations is presented in this paper. In contrast with established forms of nonlinear disturbance observers, the most important feature of this new type of disturbance observer is that only measurement of the output variable is required, rather than the state variables. An inverse simulation model is first constructed based on knowledge of the structure and parameters of a conventional model of the system. The disturbance can then be estimated by comparing the output of the inverse model and the input of the original nonlinear system. Mathematical analysis demonstrates the convergence of this new form of nonlinear disturbance observer. The approach has been applied to disturbance estimation for a linear system and a new form of linear disturbance observer has been developed. The differences between the proposed linear disturbance observer and the conventional form of frequency-domain disturbance observer are discussed through a numerical example. Finally, the nonlinear disturbance observer design method is illustrated through an application involving a simulation of a jacketed continuous stirred tank reactor syste

A Flexible Terminal Approach to Sampled-Data Exponentially Synchronization of Markovian Neural Networks With Time-Varying Delayed Signals

This paper investigates the problem of sampled-data (SD) exponentially synchronization for a class of Markovian neural networks with time-varying delayed signals. Based on the tunable parameter and convex combination computational method, a new approach named flexible terminal approach is proposed to reduce the conservatism of delay-dependent synchronization criteria. The SD subject to stochastic sampling period is introduced to exhibit the general phenomena of reality. Novel exponential synchronization criterion are derived by utilizing uniform Lyapunov-Krasovskii functional and suitable integral inequality. Finally, numerical examples are provided to show the usefulness and advantages of the proposed design procedure