System Identification and Feedback Control of an Aerosol Production Process

A method for determining the relationship between the input (generator output rate) and output (chamber aerosol concentration) of an aerosol generating system is discussed. This relationship is modeled in terms of discrete transfer functions that separate the input that results from the physical aspects of the generating system from the input that is a result of the noise inherent to the process. A computer-aided design (CAD) software package was used to estimate these transfer functions and simulate the response of the modeled system to step-changes in generator output rate. The estimated transfer functions were then used to design a feedback control system that incorporated a proportionalintegral- derivative (PID) control algorithm. This algorithm effectively established new concentration levels after step-changes in generator output rate of various magnitudes were made.