Hierarchical control for artificial hearts

This paper describes a hierarchical control structure to regulate the operation of turbo-hydrodynamic heart assist devices. The goal of the controller is to provide performance that satisfies as many clinical constraints as possible, consistent with the amount and validity of hemodynamic measurements available. Local control algorithms built into the devices maintain pump speed at a reference value, and the primary problem addressed by the hierarchical controller is to determine the desired reference. At the top of the hierarchy is a supervisor that maintains a model of the pump and the patient and continuously evaluates the available estimates of hemodynamic variables, reliability of the patient model, past history of the patient, and validity of the information available. Depending on this evaluation, the supervisor uses either heuristic criteria or a multi-objective optimization algorithm to determine the reference speed. It also evaluates the operating status of the device