Browsing by Subject "Cardiovascular modeling"

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Hierarchical control of a two-piston toroidal blood pump
(2019-05-07) Gohean, Jeffrey Robert; Longoria, Raul G.; Beaman, Joseph; Rausch, Manuel; Chen, Dongmei
The two-piston toroidal pump (2PTP) is a new pulsatile pumping paradigm with potential physiological advantages compared to existing continuous flow blood pump technologies. The purpose of this research was to develop hierarchical control methods for this new pumping modality, including high-level physiological control and low-level piston control. First, geometric constraints were identified for this pump architecture and piston path-planning methods were developed to define pulsatile ejections. To develop high-level control, an open-loop lumped parameter model of the cardiovascular system was improved with a modified end-diastolic pressure-volume elastance curve and then used to study ventricular function curves with different types of blood pump support. It was determined that synchronous counterpulse support with the 2PTP provides a more physiological response to preload compared to continuous flow, which could prevent overpumping and ventricular suction at low preloads. To develop low-level piston control, a variable structure model of the 2PTP was developed and then used to test improved control techniques. An algorithmic approach to switched bond graph structures was developed for hydraulic networks to derive state equations for the variable structure model. Linear control and Kalman-filter-based estimation methods were developed with a reduced-order model of the pump. Improved control and estimation methods were tested and confirmed in preliminary experiments in mock circulatory loops. Estimation of pump flow and differential pump pressure were verified, which could be useful feedback to physiological control or as diagnostic tools for doctors.