No abstract

Left ventricular assist devices (LVADs) have become a viable alternative to heart transplantation in heart failure therapy. In clinical practice, rotary blood pumps used as LVADs are operated at a constant rotational speed and thus do not adapt to the varying demand of the patient. This paper presents a robust control approach for automatic adaptation of the blood pump speed to the blood flow demand of the patient’s body, which enables a defined load sharing between an LVAD and the native ventricle. Robust stability was checked using a detailed model of the human cardiovascular system with uncertainties that describe the most important native physiological control loops as well as a range of pathologies. The robust assistance controller was tested in an in vivo setup and was able to stabilize the cardiovascular system after myocardial infarction.

In this contribution, inertial and magnetic sensors are considered for real-time strapdown orientation tracking of human limb or robotic segment orientation. By using body sensor network integrated triaxial gyrometer, accelerometer, and magnetometer measurements, two orientation estimation filters are presented and subsequently designed for bias insensitive tracking of human gait. Both filters use quaternions for rotation representation, where preprocessing accelerometer and magnetometer data is conducted with the quaternion based estimation algorithm (QUEST) as a reference filter input. This results in a significant reduction of the complexity and calculation cost on the body sensor network. QUEST-based preprocessed attitude data is used for the designed extended Kalman filter (EKF) and a new complementary sliding mode observer. EKF-QUEST and complementary sliding mode observer are designed and tested in simulations and subsequently validated with a reference motion tracking system in treadmill tests.