Blood-glucose regulator design for diabetics based on LQIR-driven Sliding-Mode-Controller with self-adaptive reaching...

Area of Science:

• Biomedical Engineering
• Control Systems Engineering
• Endocrinology

Background:

• Type I Diabetes impairs the pancreas's ability to regulate blood glucose (BG).
• Existing control strategies like Linear-Quadratic-Integral-Regulator (LQIR) and Sliding-Mode-Controller (SMC) have limitations in resilience to noise and meal disruptions, or cause insulin infusion rate perturbations.
• A need exists for a control strategy that combines the optimality of LQIR with the robustness of SMC.

Purpose of the Study:

• To develop and evaluate a hybridized LQIR-driven SMC strategy for improved glycemic regulation in Type I Diabetes.
• To leverage the benefits of both LQIR and SMC while mitigating their individual drawbacks.
• To enhance BG regulation accuracy and disturbance rejection capabilities.

Main Methods:

• Formulation of a hybrid control approach combining a glycemic LQIR law with an innovative sign function sliding mode reaching law.
• Integration of a customized LQIR-driven sliding surface.
• Augmentation of the SMC reaching law with a nonlinear adaptation mechanism to minimize chattering and compensate for perturbations.
• Offline numerical optimization of controller parameters.
• Analysis via customized MATLAB simulations under measurement noise and meal disruptions.

Main Results:

• The hybridized control scheme successfully generated optimal control decisions from LQIR while maintaining SMC's robustness against disturbances.
• The nonlinear adaptation mechanism effectively compensated for external perturbations and minimized chattering.
• Simulations demonstrated improved BG regulation accuracy, normalizing BG levels to 80 mg/dL from a hyperglycemic state.
• The proposed method showed enhanced disturbance-rejection capabilities.

Conclusions:

• The proposed hybridized LQIR-driven SMC strategy offers a superior approach to BG regulation for Type I Diabetes compared to standalone LQIR or SMC.
• This novel control method effectively balances optimality and robustness, addressing key challenges in diabetes management.
• The findings support the potential clinical application of this advanced control strategy for Type I Diabetes patients.