Lowering Orders of Derivatives in Non-linear Residual Generation

Consistency relations are often used to design residual generatorsbased on non-linear process models. A main difficulty is that theygenerally include time differentiated versions of knownsignals which are difficult to estimate in a noisy environment. Themain results of this paper show how to lower, or if possible avoid,the need to estimate derivatives of known signals in order to computea residual. This is achieved by rewriting the problem into anintegrability problem using state-space realization theory. Anattractive feature of the approach is that general differentialalgebraic system descriptions can be handled in the same way as forexample ordinary differential equations and also that stability of theresidual generator is always guaranteed.