A Direct Synthesis Control Strategy for Single-Input, Single-Output Nonlinear System

Abstract

This paper describes the strategy to design and modify a conventional controller by direct synthesis and the internal model control (IMC) methods for a single-input, single-output (SISO) process system. Both of these methods are the most widely used approaches, both in their simplicity and in their generality. The design of a direct synthesis controller based on a linear inversion of the non-linear process model about a steady-state was first considered. The particular linear design technique adopted resulted in a Proportional -Integral (PI) controller whose parameters are easily computed as a function of the parameters of the linear invertible model and the controller tuning parameter. The internal model control (IMC) methods were also considered to determine the fault from external disturbance. From this study, it was observed that under certain conditions both direct synthesis and internal model control methods are equal. Their use in the design of analog and digital controllers is presented by the method of the required model.