Improving Tuning Techniques of Digital Proportional Integral Derivative Controller for Blood Glucose Level of Diabetic Patient

Abstract

The closed-loop control algorithm for regulating the blood glucose concentration in diabetic patients is used. The digital Proportional-integral derivative (PID) controller is designed based on different tuning methods, Ziegler–Nichols method, Cohen-Coon method, and Chien-Hrones-Reswick (CHR) method, to control the blood glucose level for diabetic patient. The blood glucose level of the patient is considered as input variable & injected insulin level is considered as output variable which is to be manipulated. A dynamic model is constructed and transfer function is defined for this system. The tuning responses are studied and the parameters were compared. During the process the step responses given by the PID is converted into digital PID controller. The results show that Ziegler-Nichols method yields a very high overshoot where as Cohen-Coon method exhibits a low overshoot with a low settling time, Chien-Hrones-Reswick yields high settling time.