Observer-based Controller Design for Blood Glucose Regulation for Type 1 Diabetic Patients

Document Type : Research Article

Author

Mechanical Engineering department- Fasa University-Fasa-Iran.

Abstract

In this paper, an observer-based nonlinear controller for regulating blood glucose concentrations (BGC) in type 1 diabetes mellitus (T1DM) is proposed. The virtual patient model considered is the extended Bergmann minimal model, which is augmented by a meal disturbance and adapted to represent the insulin-glucose homeostasis of T1DM. The backstepping (BS) technique is used to design a closed-loop feedback controller. The proposed controller does not need to measure insulin, plasma concentrations, while improving control performance and robustness against uncertainty. Insulin concentration and plasma levels are estimated using state observers. These estimations are used as feedback to the controller. The asymptotic stability of the observer-based controller is proved using the Lyapunov theorem. Moreover, it is proved that the system is bounded input-bounded output (BIBO) stable in the presence of uncertainties generated by uncertain parameters and external disturbances. For realistic situations, we consider only the BGC to be available for measurement, and additionally, inter-and intra-patient variability of system parameters is considered. The results confirm that the proposed controller can asymptotically regulate BGC by appropriate injection of insulin under meal disturbance and of variations in system parameters.

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