Control by pulses under MPC schemes, with applications to artificial pancreas

In many applications - mainly coming from the biomedical field - the control actions cannot be continuously applied to the system under control. The most extreme case is the one that derives in the impulsive control: the control actions are instantaneously injected into the system (modeled as Dirac delta signal) at certain time instants and remain null the rest of the time in a given period. This representation is useful to account for input injections of enough short duration in comparison with the time period. However, in many other applications, this hypothesis is hard to approximate, since the input injection lasts a non-negligible short time into the period. This way, the inputs are pulses instead of impulses, but still remain null a considerable portion of the period. The main objective of this work is to properly model this kind of controlled systems and to propose an MPC strategy that appropriately exploits this representation. The benefits of both, the model and the control strategy are tested by means of the control of the commercially available (FDA approved) UVa/Padova Type 1 Diabetes Metabolic simulator.