基于DSP的航天器压力变化检漏仪的设计

Design of Spacecraft Pressure Change Leak Detector Based on DSP

航天器的密封性能是极其重要的指标之一,利用压力变化方法进行舱体密封性检漏是保障其密封性的重要技术手段;设计研制小型压力变化检漏仪对满足航天器检漏设备小型集成化、高精度的迫切需求是十分重要的;以DSP为数据的核心处理器,分析绝压和差压具有温度补偿方法,设计基于485通信接口实现数字绝压传感器的数据采集,采用250Ω的高精度电阻接入电流环的方法实现差压传感器的信号调理,通过ADS1247高精度24位数模转换器实现差压信号的采集;并采用恒流供电和电阻比测量原理实现对两路热敏电阻温度传感器的测量;各信号经DSP中固化的压力变化检漏算法集中处理,得到被测物体的漏率值,检测结果通过LCD显示;所研制集绝压、差压和温度多参量监测于一体的检漏仪,经过温度、压力、检漏试验等测试,验证了其精度和检漏能力满足要求;研究结果表明:所研制的检漏仪小巧,精度高,可靠性高,可实现压力、温度、漏率等多参量的同时监测,漏率检测的最大相对误差为19.3%,相对不确定度小于2%,可有效地解决航天器泄漏检测的问题。

Sealing performance is one of the key technical parameters for spacecraft in orbit.The pressure change leak detection method is the important technical way for protecting the spacecraft cabin from leak.For the mini-integration and high precision requirements of spacecraft leak testing equipment,a minitype pressure change leak detector is designed and developed.DSP was used as the core data processor,and the absolute pressure and the differential pressure leak testing methods were analyzed.The interface based on 485 was designed to sample the absolute pressure sensor signal and using 250Ω high precision resistance into the current loop,the differential pressure sensor signal was transformed and the signal was sampled by the ADS1247 with 24bit AD.And then two temperature sensor based on heat resistance were sampled with constant current supply and resistance comparing method.And these signals were processed by the DSP,and the leak rate value was gained and displayed on the LCD.The leak detector was designed,which could measure absolute pressure,difference pressure and temperature at the same time,and then the precision and leak testing ability were met the requirements.The study results show that the instrument has simple facilities,the high precision and high reliability.It can measure the pressure,temperature,leak rate parameters at the same time.The leak testing max relative error is 19.3%,and the relative uncertainty is less than 2%,it can be better applied to spacecraft leak detection.