Linear-Rotary Position Control System With Enhanced Disturbance Rejection for a Novel Total Artificial Heart

A novel implantable total artificial heart, hereinafter referred to as theShuttlePump, is currently under development in a research collaboration between the Medical University of Vienna, the Power Electronic Systems Laboratory of ETH Zurich and Charite Berlin. Its novel, low-complexity, pulsatile pumping principle requires a specially-shaped piston performing a controlled, synchronized linear-rotary motion while providing the necessary hydraulic force and torque. The machine design of the PMSM-based linear-rotary actuator was conducted in previous work of the authors, leading to the construction of a hardware prototype satisfying the application requirements in terms of electromechanical force, torque, power losses and volume. This paper provides the details of the closed-loop linear-rotary position control system required to operate theShuttlePump. The design of the position control system targets tight reference tracking (±8mm linear stroke and continuous rotation) up to an operational frequency of 5Hz, under the heavy disturbance introduced by the axial hydraulic load force, as high as 45N. The experimental measurements show successful linear-rotary position tracking under the specified axial load, with a maximum error of 1mm and5∘.