A nonlinear control method of multi-input multi-output nonlinear non-minimum phase system

Abstract

State feedback linearization control method for nonlinear systems based on differential geometry method is still an important area of research. In the process of linearizing the nonlinear system by differential homeomorphism transformation, the original nonlinear systems can be divided into two parts: the external dynamics described by linear subsystem and the internal dynamics (namely zero dynamics) described by nonlinear subsystem. For non-minimum phase systems whose zero dynamics are instable, the traditional controller is difficult to guarantee the stability of zero dynamics although it can make the external dynamics meet some performance requirements. Therefore, characters of non-minimum phase make the feedback linearization method based on differential geometry face enormous challenges. For this reason, a nonlinear control method for multi-input multi-output (MIMO) nonlinear non-minimum phase systems is provided in this paper, it can guarantee the stability of the zero dynamics while meeting the performance requirements of external dynamics. Finally, this method is applied to isothermal continuous stirred tank reactor (CSTR) non-minimum phase system, and the simulation results verify the effectiveness of the proposed method.