An improved nonlinearity measure based on gap metric

An improved nonlinearity measure is proposed for quantifying the nonlinear degree of nonlinear systems. By gridding the operating space of a nonlinear system smartly, the measurement of nonlinearity is largely simplified and the computation load is significantly reduced. Unlike most of the current nonlinearity measures, the proposed nonlinearity measure is applicable to both integrating and unstable nonlinear systems. Besides, the proposed method is of great use when multimodel control is employed to design a controller. A benchmark continuous stirred tank reactor (CSTR) process is presented to illustrate to the effectiveness of the proposed method.