蒸发液滴空间实验研究的图像反馈控制系统

提出了一种利用图像反馈控制系统测量液滴蒸发速率的方法.该系统主要由图像采集、图像处理、反馈控制三个部分组成.其工作原理是对CCD采集到的液滴图像进行分析,得到液滴的物性参数,利用控制注液器动态注入来维持液滴的大小,由此得到单位时间内的注入量,即液滴蒸发速率.或通过对液滴图像几何尺寸的计算,得到单位时间内液滴的变化量,进而得到液滴的蒸发速率.为了从动态变化的图像中准确找到液滴的轮廓,简单介绍了基于拉普拉斯方程,运用牛顿法和龙格库塔法等数值方法,对图像轮廓进行拟合的算法理论.以拟合得到的液滴轮廓为基础,利用数值积分计算液滴的表面积和体积,从而由体积的变化量确定蒸发速率.介绍了图像反馈控制系统的软件结构和硬件结构.并给出了利用其进行液滴蒸发测量得到的实验结果.该系统是为我国SJ-10返回式卫星上蒸发与流体界面效应空间实验研究项目专门开发的. 

Image Feedback Control System in the Space Drop Evaporation Experiment

In this paper,a method to measure the drop evaporation velocity by image feedback control system is presented.The system is constituted of 3 parts:image acquisition,image processing, and feedback control.Analyzing drop pictures from the CCD camera,the physical features of the drop could be obtained,and evaporating volume could be calculated from the geometry differences between two pictures.To maintain the drop volume,drive the injector to inject dynamically.The evaporation velocity could be calculated by the evaporating volume per unit time.In order to determine the accurate contour of the dynamically changed drop,the contour approach principle is investigated and some numerical algorithms such as Laplace equation,Newton-Raphson method and Runge-Kutta method are introduced.Based on the drop contour determined from the contour approach,the volume and the surface area of drop could be calculated by numerical integral.The software structure and hardware structure of the system are described,an experiment result is given finally.The system is developed for the liquid experiment in SJ-10 recoverable satellite.