Amelioration of digital PID controller performance for blood glucose level of diabetic patient

The background of this paper discusses the design of a digital PID (Proportional-integral derivative) controller for controlling the blood glucose level of a diabetic patient. The objective is to design a digital PID controller for external insulin injection, which can inject insulin to the patient accurately to sustain the blood glucose level of a diabetic patient. The patient's blood sugar level is considered as input variable & injected insulin level is considered as output variable, which is to be controlled. A dynamic model is constructed & a transfer function is defined for this system. The Proportional, Integral & Derivatives coefficients are found using various tuning rules. The conventional Ziegler Nicholas method produces a very high overshoot that can endanger a patient's life. Therefore, other efficient tuning techniques like Chien-Hrones-Reswick (set-point regulation) and Chien-Hrones-Reswick (distribution regulation) methods are used to find the Proportional, Integral & Derivative coefficient. The tuning responses are studied & parameters are compared. The best response given by the PID is converted into Digital PID. Different transformation methods are studied to convert the conventional PID into the digital PID controller.