Measurement of Dynamic Process Nonlinearity

Abstract A new measure of dynamic process nonlinearity is proposed which builds on previous derivative-based methods for analyzing steady state nonlinearity. The proposed methodology is based on an operator description of nonlinear input-output systems. The contribution of second order derivative terms is evaluated relative to the L-norm of the process output signals. The important issue of scaling is addressed by defining a scaling operator, which also enables scaling relative to linear control structures. A procedure for calculating the measure for various model types is presented. The application of the measure is illustrated for bioreactor and CSTR process examples.