Control for Carbon Dioxide Exchange Process in a Membrane Oxygenator Using Online Self-Tuning Fuzzy-PID Controller

Abstract

Background and objectiveThe aim of this study is to evaluate the performance of conventional PID that is tuned using Zeigler-Nichols continuous cycling, Fuzzy Logic Controller (FLC) and self-tuning Fuzzy-PID (self-tuning FPID) methods to control the rate of CO2 removal from a membrane oxygenator during extracorporeal blood purification process. MethodsSweep gas flow rate is chosen as the manipulated variable of arterial CO2 partial pressure (pCO2) in blood. The performance of these controllers is evaluated based on their response in controlling task and also by the calculation of three performance indices, namely Integral Absolute Error (IAE), Integral Squared Error (ISE) and Integral Time Absolute Error (ITAE). The robustness of the controllers using these tuning methods is then assessed for set point tracking and load disturbance rejection tests. ResultsResults indicated that the self-tuning FPID is observed as the best controller compared to conventional PID and FLC with lower oscillation, overshoot and shorter settling time. As for quantitative measurement, self-tuning FPID outshines the other controllers with 0.854, 1.084 and 41.450 for IAE, ISE and ITAE, respectively in set point tracking task while 0.532 IAE, 0.016 ISE and 28.970 ITAE measured for load disturbance rejections. ConclusionIt can be concluded that self-tuning FPID is the best controller to be used in the automation of extracorporeal circulation control for both set point tracking and load disturbance rejection tests.