Characterization of a pediatric rotary blood pump

Abstract Introduction A ventricular assist device (VAD) is an electromechanical pump used to treat heart failures. For designing the physiological control system for a VAD, one needs a mathematical model and its related parameters. This paper presents a characterization procedure for determining the model parameter values of the electrical, mechanical, and hydraulic subsystems of a pediatric Rotary Blood Pump (pRBP). Methods An in vitro test setup consisting of a pRBP prototype, a motor driver module, an acrylic reservoir, mechanical resistance and tubings, pressure and fluid flow sensors, and data acquisition, processing, and visualization system. The proposed procedure requires a set of experimental tests, and a parameter estimation algorithm for determining the model parameters values. Results The operating limits of the pRBP were identified from the steady-state data. The relationship between the pressure head, flow rate, and the rotational speed of the pRBP was found from the static tests. For the electrical and mechanical subsystems, the dc motor model has a viscous friction coefficient that varies nonlinearly with the flow. For the hydraulic subsystem, the pressure head is assumed to be a sum of terms related to the resistance, the inertance, the friction coefficient, and the pump speed. Conclusion The proposed methodology was successfully applied to the characterization of the pRBP. The combined use of static and dynamic tests provided a precise lumped parameter model for representing the pRBP dynamics. The agreement, regarding mean squared deviation, between experimental and simulated results demonstrates the correctness and feasibility of the characterization procedure.

摘要 引言
心室辅助装置（Ventricular Assist Device, VAD）是用于治疗心力衰竭的机电式泵。为设计VAD的生理控制系统，需建立其数学模型并确定相关参数。本文针对儿童旋转血泵（pediatric Rotary Blood Pump, pRBP）的电气、机械与液压子系统，提出了一套用于确定其模型参数值的表征流程。
方法
本研究所用体外实验装置（In Vitro Test Setup）由pRBP原型机、电机驱动模块、丙烯酸储液罐、机械阻力组件与管路、压力与流体流量传感器，以及数据采集、处理及可视化系统组成。所提出的表征流程需开展一系列实验测试，并结合参数估计算法（Parameter Estimation Algorithm）以确定模型参数值。
结果
基于稳态实验数据确定了pRBP的工作限值；通过静态实验明确了该泵的压头（Pressure Head）、流量与转速间的关联关系。针对电气与机械子系统，直流电机（DC Motor）模型的粘性摩擦系数（Viscous Friction Coefficient）随流量呈非线性变化；对于液压子系统，压头被假定为与阻力、流感（Inertance）、摩擦系数及泵转速相关项的总和。
结论
所提出的表征方法已成功应用于pRBP的参数表征工作。通过静态与动态实验的联合应用，得到了可精准描述pRBP动力学特性的集总参数模型（Lumped Parameter Model）。实验与仿真结果在均方偏差（Mean Squared Deviation）指标上的一致性，验证了该表征流程的正确性与可行性。