【作者】 李晨；

【导师】 郭旭红；

【作者基本信息】 苏州大学 ， 机械制造及其自动化， 2016， 硕士

【摘要】 无限远成像系统光学星敏感器装调时,其后方安装有CCD接收装置,为使CCD接收装置达到最清晰的成像,CCD接受像面位置需与星敏感器成像焦点位置重合。现有方法为在星敏感器法兰面与CCD接收装置法兰面间安装有一定厚度的修切圈,通过手动对多个尺寸的修切圈进行反复试装试测来寻找固定CCD接收像面位置,这种实现方式工作效率低且精度难以保证。为改变国内精密仪器装配检测中手动试装的现状,提高光学系统研制的生产效率和精度,开展自动调焦测量技术的研究具有十分重要的意义。为此,针对星敏感器装调过程中的实际需求,本文基于自动调焦技术与误差补偿技术,设计出一种精确测量星敏感器后工作距的星敏感器自动调焦系统(以下简称自动调焦系统),完成系统误差精度的分析与合理控制,运用误差耦合理论对系统进行精度分配;基于PID控制算法实现误差的实时补偿,使系统精度达到设计要求;可对星敏感器后工作距进行快速、准确地测量,从而得到装调所需修切圈厚度的精确尺寸,改进现有手动试装修切圈的方法,提升了效率和精度。主要研究内容如下:首先,设计了自动调焦系统,根据功能要求将该系统分为四个模块:目标及光源系统、无限远目标发生系统、自动调焦测量装置、自动调焦控制系统。重点设计了自动调焦系统测量装置,测量装置主要由直线导轨、精密位移台、检测支架、CCD相机等构成,实现CCD相机的三维精准运动及图像的采集与成像。完成测量装置直线导轨、电控精密位移台、手动精密位移台等选型,分析零部件具体选型依据并获得各部件的详细参数,直线导轨长500mm,精密电控位移台量程为100mm,负载力矩为6Nmm,利用绘图软件对自动调焦系统测量装置的机械结构部分进行设计,确定了机械结构的详细尺寸参数,设计了自动调焦控制系统,并完成自动调焦系统的装配工作。其次,基于静力学和动力学基本理论,建立自动调焦系统测量装置三维模型,利用MSC.Patran&Nastran分析软件对CCD支撑部件和被测星敏感器进行静力学分析及模态分析,静态分析得到CCD支撑部件最大变形量为7.98×10-5mm,CCD支撑部件所受最大应力为2.9×10-2Pa,说明CCD支撑部件具有较好的静态特性;通过动态分析得CCD支撑部件和星敏感器结构前6阶固有频率及振型,CCD支撑部件一阶固有频率为892.89Hz,星敏感器一阶固有频率为1674Hz,动态分析结果表明CCD支撑部件和星敏感器基频较高,动态性能较好。再次,基于ISO230-2定位精度标准,完成自动调焦系统的定位精度试验,测得自动调焦系统定位精度为±20.95μm,对影响自动调焦系统精度的主要因素进行误差分析,影响因素主要包括CCD相机、直线导轨、精密电控位移台、形位误差和装配误差。通过误差分析与控制可得直线导轨精度为±2μm,驱动电机精度为±6.75μm,丝杠精度为±5.28μm,形位精度为±2μm,装配精度为±2μm,运用误差耦合法得到自动调焦系统定位精度为±18.29μm;并基于PID算法在Labview开发环境下开发了系统的误差补偿软件,对自动调焦系统进行实时误差补偿,通过定位精度试验测得误差补偿后系统定位精度为±15.95μm,提高了24%,使系统精度达到设计要求。最后,利用自动调焦系统完成被测星敏感器后工作距的测量,测得星敏感器后工作距为5.21mm,试验结果表明自动调焦系统满足星敏感器后工作距测量的基本功能,并对今后工作的方向提出了一些建议。更多还原

【Abstract】 When the optical star sensor of infinite distance imaging system is assembled,the CCD receiving device is fixed after it.In order to achieve the most clear imaging of the CCD receiver.The image plane position of CCD needs to be coincident with the focus position of star sensor.The existing methods is installing a certain thickness of trim ring between the flange face of the star sensor and the flange face of CCD receiving device.The fixed CCD receiving image plane position can be found through the manual method to trial and test repeatedly.This implementation method is inefficient and the precision can not be guaranteed.In order to change the present situation of the manual test in the development of the optical system in China,improve the production efficiency and precision of the optical system development,it is important to carry out the research of auto focusing measurement technology.So aiming at the actual demand of the alignment process of star sensor,an automatic focusing system is designed to accurately measure the working distance of the sensor based on auto focusing technology and error compensation technology.The system realizes the reasonable control of the error precision based on the coupling error theory,real time compensation of error is done based on PID controller algorithm.And the positioning precision of the system is improved,fast and accurate measurement of the working distance of star sensor can be made.So the accurate size thickness of trim ring required can be gotten.And the system precision reaches the design requirements.The main research contents are as follows:Firstly,automatic focusing system is designed.According to the functional requirements,the system is divided into four modules: target and light source system,infinite distant target generation system,automatic focusing measuring device,automatic focusing control system.The design of automatic focusing system measuring device is focused,the measuring device mainly consists of linear guide rail,precision displacement stage,detection bracket,CCD camera and so on.Three dimensional precision motion of CCD camera and acquisition of imaging can be realized.Linear guide rail,electric control precision displacement stage,manual precision displacement stage and so on is selected.The specific selection basis and detailed parameters of parts are analyzed,the length of linear guide rail 500 mm,the measurement range of precision electronic displacement is 100 mm,and the load torque is 6Nmm.The design of the mechanical structure of the measuring device of the automatic focusing system is designed by using the drawing software.The detailed dimension parameters of the mechanical structure are determined.And the assembly process of the auto focusing system is completed.Secondly,the three-dimensional model of the automatic focusing system for measuring device is established based on statics and dynamics theory,static analysis and modal analysis of CCD support part and star sensor are completed by using MSC.Patran & Nastran analysis software,maximum deformation of CCD support member is 7.98×10-5 mm,the maximum stress is 2.9×10-2 Pa,CCD support member has a good static characteristics;The first 6 order natural frequency and vibration type of CCD support components and star sensor can be gotten through the dynamic analysis,the first order natural frequency of CCD support part of is 892.89 Hz,first-order natural frequency of star sensor is 1674 Hz.The dynamic analysis results show that the CCD support component and star sensor have high fundamental frequency,and the dynamic performance is good.Thirdly,the positioning precision test experiment of auto focusing system is completed,the positioning precision of automatic focusing system is ±20.95μm based on ISO230-2 positioning precision standard,,the main factors which affect the precision of auto focusing system are analyzed,and factors mainly include CCD camera,linear guide rail,precision electric displacement,shape error and assembly error.Through the error analysis and control,linear guide rail precision is ±2μm,driving motor precision is ±675μm,lead screw precision is ±5.28μm,position precision is ±2μm,assembly precision is ±2μm,the positioning precision of automatic focusing system is ±18.29μm by using coupling error theory and precision distribution.And based on PID algorithm,error compensation software is designed in the Labview development environment,real-time error compensation is realized.The positioning precision is ±15.95μm after error compensation,the precision is increased by 24%,and the final precision meets the design requirements.Lastly,the working distance of star sensor is measured by using auto focusing system,the working distance of star sensor is 5.21μm.The experimental results show that auto focusing system meets the basic function of star sensor working distance measurement,and a series of advice of improvement are the proposed.更多还原