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1

Robustness of closed-loop glucose control systems

Wyciślok Artur, Śmieja Jarosław

Archives of Control Sciences

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2023

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Vol. 33, No. 3

681--705

EN

The main purpose of this work is to provide an extensive, simulation-based comparison of robustness of PID and MPC algorithms in control of blood glucose levels in patients with type 1 diabetes and thus answer the question of their safety. Cohort testing, with 1000 simulated, randomized patients allowed to analyze specific control quality indicators, such as number of hypoglycemic events, and length of hypo- and hyperglycemia periods. Results show that both algorithms provide a reasonable safety level, taking into account natural changes of patients’ physiological parameters. At the same time, we point out drawbacks of each solution, as well as general problems arising in close-loop control of blood glucose level.

2

Maximizing performance of linear model predictive control of glycemia for T1DM subjects

Dodek Martin, Miklovicová Eva

Archives of Control Sciences

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2022

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Vol. 32, No. 2

305--333

EN

The primary objective of this paper is the custom design of an effective, yet relatively easy-to-implement, predictive control algorithm to maintain normoglycemia in patients with type 1 diabetes. The proposed patient-tailorable empirical model featuring the separated feedback dynamics to model the effect of insulin administration and carbohydrate intake was proven to be suitable for the synthesis of a high-performance predictive control algorithm for artificial pancreas. Within the introduced linear model predictive control law, the constraints were applied to the manipulated variable in order to reflect the technical limitations of insulin pumps and the typical nonnegative nature of the insulin administration. Similarly, inequalities constraints for the controlled variable were also assumed while anticipating suppression of hypoglycemia states during the automated insulin treatment. However, the problem of control infeasibility has emerged, especially if one uses too tight constraints of the manipulated and the controlled variable concurrently. To this end, exploiting the Farkas lemma, it was possible to formulate the helper linear programming problem based on the solution of which this infeasibility could be identified and the optimality of the control could be restored by adapting the constraints. This adaptation of constraints is asymmetrical, thus one can force to fully avoid hypoglycemia at the expense of mild hyperglycemia. Finally, a series of comprehensive in-silico experiments were carried out to validate the presented control algorithm and the proposed improvements. These simulations also addressed the control robustness in terms of the intersubject variability and the meal announcements uncertainty.

3

In silico testing of optimized Fuzzy P+D controller for artificial pancreas

Soylu S., Danisman K.

Biocybernetics and Biomedical Engineering

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2018

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Vol. 38, no. 2

399--408

EN

Background and objectives: Despite therapeutic advances, a complete cure has not been found yet for patients with type 1 diabetes (T1D). Artificial pancreas (AP) is a promising approach to cope with this disease. The controller part of the AP can compute the insulin infusion rate that keeps blood glucose concentration (BGC) in normoglycemic ranges. Most controllers rely on model-based controllers and use manual meal announcements or meal detection algorithms. For a fully automated AP, a controller only using the patient's BGC data is needed. Methods: An optimized Mamdani-type hybrid Fuzzy P+D controller was proposed. Using the University of Virginia/Padova Simulator, a 36 h scenario was tested in nine virtual adult patients. To take into account the effect of continuous glucose monitor noise, the scenario was repeated 25 times for each adult.The main outcomes were the percentage of time BGC levels in the euglycemic range, low blood glucose index (LBGI), and blood glucose risk index (BGRI), respectively. Results: The obtained BGC values were found to be in the euglycemic range for 82.6% of the time. Moreover, the BGC values were below 50 mg/dl, below 70 mg/dl and above 250 mg/dl for 0%, 0.35% and 0.74% of the time, respectively. The BGRI, LBGI, and high blood glucose index (HBGI) were also found as 3.75, 0.34 and 3.41, respectively. The proposed controller both increases the time the BGC levels in the euglycemic range and causes less hypoglycemia and hyperglycemia relative to the published techniques studied in a similar scenario and population.

4

Sztuczna trzustka - stan obecny i prognozy

Marcinkowska M., Wyrodek K., Żórawski P., Łagan S.

Aktualne Problemy Biomechaniki

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2010

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z. 4

131--136

PL

Cukrzyca jest chorobą cywilizacyjną spowodowaną nieprawidłowym funkcjonowaniem trzustki, dotykającą coraz większy procent społeczeństwa. Leczenie objawów tej groźnej choroby uzależnia pacjenta od regularnych pomiarów glukozy, zastrzyków insulinowych oraz ścisłej diety. Dlatego wiele ośrodków naukowych pracuje nad skutecznymi sposobami regulacji poziomu cukru we krwi. Szczególnie obiecujące wyniki dają tzw. sztuczne trzustki, czyli mechaniczne, biologiczne i biochemiczne obiekty, których głównym zadaniem jest zapewnienie pacjentowi przez długi czas lub na stałe odpowiedniej dawki insuliny. Dzięki trafnemu doborowi pomiaru poziomu glukozy i metod dozowania, które odgrywają ważną rolę w całym procesie leczenia, można ułatwić życie milionom ludzi.

EN

Diabetes is a lifestyle disease, caused by abnormal funcionality of pancreas, which afflict more and more people every year. Treatment of this dangerous diseases makes patients dependant on regular glucose measurement , insulin injections and strict diet. Because of that many research facilities is trying to develope an effective way of blood sugar regulation. Particulary propitious are so called “artifficial pancreases”. They are biological, biochemical and mechanical objects, which are suppoused to stabilise blood sugar concetration for longest possible period, ultimately for life. Thanks to apposite selection of glucose measurment and posology methods, which have main role in treatment, life of millions of people can be facilitated.

5

The design of an insulin pump concept of closing the loop

Hawłas H., Lewenstein K.

Journal of Automation Mobile Robotics and Intelligent Systems

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2009

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Vol. 3, No. 4

195-198

EN

This paper explains what insulin pump is and outlines basic requirements for such device. The material presented in this paper is an attempt to collect actual knowledge about closed loop insulin delivery systems. From scientific point of view we are going to propose the closed loop insulin-dispensing device with control built on the base of predictive neural network system. The blocks of such systems are listed, and main problems to overcome are defined.