PHYSIOLOGICAL CONTROLLER DESIGN OF THE NCKU ELECTRO-HYDRAULIC TOTAL ARTIFICIAL HEART

Abstract

This work aims at developing a control logic that can support the electro-hydraulic total artificial heart (EHTAH) operating autonomously in accordance with the cardiac physiology. In the development of the control law, a set of system dynamic equations were used as the platform. A Starling-like cardiac control for a volumetrically-coupled, alternate left and right pumping is developed. In this Starling-like auto-regulation, cardiac output increases in response to the elevation of the blood return pressure. A reference model was constructed with the right ventricle diastolic or venous return mean pressure considered as the input, and the heart rate as well as the desired aortic and pulmonary arterial pressure waveforms generated as the output. Physiologically compatible EHTAH actuation is achieved by regulating the switching and the torque motor speeds subject to the control logic and the reference model constructed. In the pressure tracking control design, the method of neural adaptive model reference control was employed. General and specialized training procedures have been enforced to determine the connection weights associated with the neural controller. The trained neural controller shows a fast response in the pressure tracking control. Two Starling-like control logics, namely, error proportional and gain scheduling were proposed and examined. Both logics can lead to Starling-like blood regulation, though differing in transient behaviors. Gain scheduling logic is found more appealing for it can regulate the cardiac output change in a rapid and monotonically converging manner.