Integration of Fault Detection and Diagnosis with control for a Three-Tank System using Robust Residual Generator

Abstract

In this paper an algorithms is developed for fault diagnosis and fault tolerant control strategy for nonlinear systems subjected to an unknown time-varying fault in the presence of modeling error. In this paper, a design procedure for robust residual generators is developed using reference model and optimization criterion, based on robust H∞ filtering, used to synthesize the residual generator. The fault magnitude and time of occurrence of fault is obtained through a transformation of robust residuals in to structured residuals. The estimated magnitude of the disturbance variable is used by the feed-forward control algorithm to make appropriate changes in the manipulated variable to keep the controlled variable near its set value. The feed-forward controller acts along with feed-back controller to control the multi variable system. The performance of the proposed scheme is applied to a three- tank process for various types of disturbance inputs and modeling errors to show the effectiveness of the proposed approach