Analysing the effects of open-loop multiplicity on controllability of nonlinear systems

Abstract

We present in this paper a bifurcation based approach for the study of the controllability of a nonlinear system with multiplicity in the parameter space. The analysis is independent of detailed controller designs. The method is conducted by investigating the open-loop steady-state multiplicity behaviour and the singularity of the process gain matrix of nonlinear systems simultaneously. It can be applied to sizeable nonIinear processes to examine the controllability of the processes at the process design stages. The application of this method is demonstrated for an exothermic polymerization CSTR used by previous researchers to show the poor closed-loop performance of the S1S0 control strategy. It shows how this poor performance can be predicted and eliminated or minimised, and how the parameters affect the steady-state multiplicity of the process and behaviour of the process gains by using this approach.