基于小孔投影面积的平面栅极间距测量方法

Measurement Method of Plane Grid Gap Based on Hole Projection Area

关键词:  离子推力器  栅极间距  机器视觉  间距测量  非接触式测量

Key words:  Ion thruster  Grid gap  Machine vision  Spacing measurement  Non-contact measurement

摘要:

栅极间距是影响推力器离子束流的发散角、推力大小的关键参数，为了解决栅极组件在装配过程中栅极间距自动检测的技术难题，针对栅极孔径的特殊结构和光线传播的特性，建立了栅极间距和小孔面积的数学模型，提出了基于机器视觉的非接触式平面栅极间距检测方法并搭建试验平台。选取栅极中心孔位进行35次重复试验，该方法的标准差为12μm，具有较高的重复精度。精度验证试验结果表明，该系统精度高于±20μm，满足离子推力器装配过程中的栅极间距测量要求，在实际应用中有望替代现有人工检测方法。

Abstract:

The grid gap is a key parameter affecting the dispersion angle and power of the thruster. In order to solve the technical problem of automatic grid gap detection in the grid assembly process， the mathematical model of grid gap and small aperture area was established for the special structure of grid aperture and the characteristics of light propagation. The non-contact plane grid gap detection method based on machine vision was proposed and a test platform was built. The center hole of grid was selected for 35 repeated tests. The standard deviation of the method is 12μm， which has a high repeatability. The accuracy verification test results show that the accuracy of the system is higher than ±20μm， which meets the requirements of grid gap measurement during the assembly of ion thrusters and is expected to replace the existing manual inspection methods in practical applications.