Motor feedback physiological control for a continuous flow ventricular assist device

The response of a continuous flow magnetic bearing supported ventricular as sist device, the CFVAD3 (CF3) to human physiologic pressure and flow needs is varied by adjustment of the motor speed. This paper discusses a model of the automatic feedback controller designed to develop the required pump pe rformance. The major human circulatory, mechanical, and electrical systems were evaluated using experimental data from the CF3 and linearized models d eveloped. An open-loop model of the human circulatory system was constructe d with a human heart and a VAD included. A feedback loop was then closed to maintain a desired reference differential pressure across the system. A pr oportional-integral (PI) controller was developed to adjust the motor speed and maintain the system reference differential pressure when changes occur in the natural heart. The effects of natural heart pulsatility on the cont rol system show that the reference blood differential pressure is maintaine d without requiring CF3 motor pulsatility.