Periodicity and Power Minimization in Maglev Artificial Hearts

左心室辅助装置(LVADs)是一种新兴的治疗成千上万的终末期心脏病患者的方法。这些“人造心脏”被植入体内，并与天然心脏配合泵血。目前的(第二代)泵是旋转泵，在液膜轴承中使用血液本身作为润滑剂。该项目是针对商业研究实验室正在开发的第三代泵，这些实验室使用反馈控制的磁悬浮泵叶轮。磁悬浮消除了对血液(红细胞、血小板和白细胞)的机械磨损和剪切损伤。由于磁悬浮的好处，匹兹堡大学该项目的成员于1998年在动物试验中植入了第一台磁悬浮泵。反馈控制、磁性材料的进步和受控对象的系统优化使这项技术成为可能。然而，来自自然心脏的小尺寸、短时间常数、非线性、不稳定和准周期扰动对我们这些向患者承诺这个工程系统将维持他们的生命的人来说是一个可怕的挑战。悬浮控制器设计中的基本权衡是功耗和稳健稳定性。此外，执行器、电力电子和控制设计的相互作用提供了显著节能的机会。这项工作的目的是提高效率，改善对来自自然心脏的准周期压力扰动的控制响应，并优化驱动电磁执行器的PWM波形。我们相信，从最优化、非线性内部模型、非线性学习控制等概念的扩展，以及对典型患者血压波形的关注，将导致用于磁悬浮LVAD的稳健的低功率悬浮控制器。一个成功的项目的结果将是医疗使用的安全控制器和便携式电池重量的显著减少。该项目的智力优势是电力和控制研究人员、心脏外科医生和生物工程师之间的跨学科合作；将非线性控制理论创新地扩展到准周期干扰抑制；以及我们提出的用于开发驱动波形和向医学和工程界交流我们的想法的实验设备。更广泛的影响将包括改善数千名心脏病专利的生活，培训介于控制理论和生物医学之间的博士生；出版被广泛引用的论文；开发一种仪器；在会议上展示我们的实验工作；以及继续国际机器人计划，有来自代表性不足群体的180名K-12学生参与。

Left Ventricular Assist Devices (LVADs) are an emerging treatment for the thousands of patients suffering from end-stage heart disease. These "artificial hearts" are implanted and cooperate with the natural heart in pumping blood. The current (second generation) pumps are rotary pumps that use the blood itself as a lubricant in fluid film bearings. This project is directed at the 3rd generation of pumps being developed in commercial research laboratories which employ feedback-controlled magnetically-levitated pump impellers. Magnetic levitation eliminates mechanical wear and shear-induced damage to the blood (red blood cells, platelets, and leucocytes). Motivated by the benefits of magnetic levitation, the first magnetically-levitated pump was implanted in an animal trial by members of this project at the University of Pittsburgh in 1998. The technology was enabled by feedback control, advances in magnetic materials and systematic optimization of the controlled plant. However, the small size, short time constants, nonlinearity, instability, and quasi-periodic disturbances from the natural heart pose an awesome challenge to those of us who promise patients that this engineered system will sustain their lives. The essential trade-off in the levitation controller design is power consumption versus robust stability. Moreover, interactions of actuator, power electronics, and control design offer opportunities for significant power savings. This work is directed at efficiency gains associated with improvements of control response to quasi-periodic pressure disturbances from the natural heart, and optimization of PWM waveforms driving the electromagnetic actuators. We believe that the extension of concepts from optimization, nonlinear internal models, nonlinear learning control, and attention to representative patient blood pressure waveforms will lead to a robust low-power levitation controller for maglev LVADs. The consequences of a successful project will be safe controllers for medical use and a significant reduction in portable battery weight.The intellectual merits of this project are the interdisciplinary collaboration amongst power and control researchers, cardiac surgeons, and bioengineers; the innovative extension of nonlinear control theory to quasiperiodic disturbance rejection; and the experimental apparatus we propose for developing drive waveforms and communicating our ideas to the medical and engineering communities. The broader impacts will include improving the lives of thousands of heart disease patents, the training of PhD students bridging control theory and biomedicine; the publication of well cited papers; the development of a apparatus; exhibiting our experimental work at conferences; and the continuation of the PI's robotics program involving 180 K-12 students from underrepresented groups.