Design of an impulsive offset-free MHE/ZMPC scheme for type 1 diabetes treatment

Abstract

Type 1 diabetes treatment can be modeled as an impulsive control system because insulin doses are administered to the patient as small pulses and not as a continuous or discrete input. Therefore, an impulsive scheme of estimation and control is needed. Here, an impulsive MHE is designed and it is coupled with a zone MPC which allows to include the system constraints in both estimation and control problems. In addition, an offset-free strategy is added to compensate the effects of the inherent plant-model mismatch given by the physiological changes of the patient. These variations can generate an inaccurate insulin administration that produces an offset in relation to the normoglycemia zone and leads to hypoglycemia or hyperglycemia events. The offset-free MHE/ZMPC formulation reestablishes the normoglycemia behavior by compensating parameter variations. Variations up to 30% were considered, as well as the sensor noise from the continuous glucose monitor.