BIOENGINEERING, FOOD, AND NATURAL PRODUCTS Robust H Glucose Control in Diabetes Using a Physiological Model

A robust H controller was de®eloped to deli®er insulin ®ia a mechanical pump in Type I diabetic patients. A fundamental nonlinear diabetic patient model was linearized and then reduced to a third-order linear form for controller synthesis. Uncertainty in the nonlinear model was characterized by up to 40% ®ariation in eight physiological parameters. A sensiti®ity analysis identified the three-parameter set ha®ing the most significant effect on glucose and insulin dynamics o®er the frequency range of interest [ ] ( ) s 0.002, 0.2 radrmin . This uncertainty was represented in the frequency domain and incorporated in the controller design. Controller performance was assessed in terms ( ) of its ability to track a normoglycemic set point 81.1 mgrdL in response to a 50 g meal disturbance. In the nominal continuous-time case, the controller maintained glucose concentrations within 3.3 mgrdL of set point. A controller tuned to accommodate uncertainty yielded a maximum de®iation of 17.6 mgrdL for the worst-case parameter ®ariation.