Fuzzy PID control of anaesthesia

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This work is about the automatic drug administration for the regulation of bispectral (BIS) index in the anesthesia process during the clinical surgery by controlling the concentration target of two drugs, namely, propofol and remifentanil. To realize the automatic drug administration, real clinical data are collected for 42 patients for the construction of patients' models consisting of pharmacokinetic and pharmacodynamic models describing the dynamics reacting to the input drugs. A nominal anesthesia model is obtained by taking the average of 42 patients' models for the design of control scheme. Three PID controllers are employed, namely linear PID controller, type-1 (T1) fuzzy PID controller and interval type-2 (IT2) fuzzy PID controller, to regulate the BIS index using the nominal patient's model. The PID gains and membership functions are obtained using genetic algorithm (GA) by minimizing a cost function measuring the control performance. The best trained PID controllers are tested under different scenarios and compared in terms of control performance. Simulation results show that the IT2 fuzzy PID controller offers the best control strategy regulating the BIS index while the T1 fuzzy PID controller comes the second.

 

The results were summarised in the following paper:

 

Hugo Araujo, Bo Xiao, Chuang Liu, Yanbin Zhao, and H.K. Lam, “Design of type-1 and interval type-2 fuzzy PID control for anesthesia using genetic algorithms,” Journal of Intelligent Learning Systems and Applications, vol. 6, no. 2, pp. 70-93, May 2014.

 

which can be downloaded from http://dx.doi.org/10.4236/jilsa.2014.62007

 

The following video shows the regulation of BIS index using PID (red), T1 fuzzy PID (green) and IT2 fuzzy PID (blue) controllers.  The upper-left panel shows the transient response of the regulation of BIS index where the regions bounded by dash lines in magenta are an acceptable range the BIS index should stay.  The upper-right panel shows the firing strength of the rules corresponding to the membership functions N, Z and P.  The bottom-left panel shows the cost at time t. The smaller the cost, the better the performance is.  The bottom-right panel shows proportional, integral and derivative gains at time t.

 

Regulation of BIS index using PID, Fuzzy PID and Interval Type-2 Fuzzy PID Controllers.  GUI and video were prepared by Chuang Liu.