A NOVEL ON-LINE FAULT DETECTION SCHEME USING MULTIVARIABLE ZEROS AND ZERO DIRECTIONS

摘要

A new algorithm which generates a class of input signals corresponding to which the combination of plant outputs in the output zero direction is always zero irrespective of time, is proposed. Using this result and the results in MacFarlane and Karcanias (1976) we propose two tests to find the defective rows and the defective columns of a plant transfer function matrix. Our fault detection scheme is based on the following triple: the output zero direction of the plant, the transmission zero of the plant, and the input zero direction of the plant. Based on the faulty rows and columns we identify the faulty elements of the plant transfer function matrix. A system of four interconnected water tanks with two multivariable zeros and four stable poles was found ideal for illustrating the results obtained. The algorithm proposed is used to detect changes occurring in the four-tank setup. Each input channel is analyzed one at a time. In the latter part of the work we have analyzed the 4-tank system by measuring the new steady state output of the plant which is obtained after disturbing the plant from its previous equilibrium state by changing the inputs by a small quantity from their equilibrium values. The method helps in pin-pointing the defective elements of the plant transition matrix. The key advantage of this method lies in the fact that the changes can be found without having to restart the plant.