A Closed-Loop Artificial Pancreas Using a Proportional Integral Derivative with Double Phase Lead Controller Based on a New Nonlinear Model of Glucose Metabolism
Résumé
Background: Most closed-loop insulin delivery systems rely on model-based controllers to control the blood glucose level. Simple models of glucose metabolism, allowing easy design of the control law, are limited in their parametric identification from raw data. New control models and controllers issued from them are needed. Methods: A proportional integral with double phase lead (PIDD) controller was proposed. Its design was based on a linearization of a new nonlinear control model of the glucose-insulin system in type 1 diabetic patients validated with the "UVa/Padova T1DM Metabolic Simulator". A 36-hours scenario including 6 unannounced meals was tested in 9 virtual adults. The same trial database than Cameron et al (2011)1 has been used to compare the performance of our controller with their results. The scenario was repeated 25 times for each adult in order to take the CGM noise into account. The primary outcome was the time blood glucose levels were in target (70-180 mg/dl). Results: Blood glucose values were in target range for 77% of the time, below 50 mg/dl and above 250 mg/dl for 0.8% and 0.3% of the time respectively. The Low Blood Glucose Index (LBGI) and High Blood Glucose Index (HBGI) were 1.65 and 3.33 respectively. Conclusion: The linear controller presented, based on the linearization of a new easily identifiable nonlinear model, achieves good glucose control with low exposure to hypoglycemia and hyperglycemia.