On Characteristic Modeling of a Class of High-order MIMO Nonlinear Systems

This paper investigates the characteristic modeling problem of a class of high-order MIMO nonlinear dynamical systems with zero dynamics and subjected to strong nonlinearities. The characteristic model is established by introducing a constructive discretization modeling method. We prove that the characteristic model can be represented by some multi-variable second-order time-varying difference equation, and the corresponding modeling error can be arbitrarily small by taking the sampling rate appropriately. Also, taking the flexible spacecraft attitude control system as a typical plant, we provide the derivative of its characteristic model. Compared with the existing characteristic modeling methods, what we developed is more convenient to analyze the modeling error, and provides a new perspective for understanding characteristic models.