摘要
近红外波段(NIR,波长范围:780~2500 nm)在线光谱分析技术具有小型化、快速检测、结果稳定可靠等优点,在工业现场检测领域有着广泛的应用。由于近红外光谱分析系统受温度影响较大,传统的光栅分光在线光谱分析系统所采用的光谱仪通常仅对探测器制冷,光路部分仍然会受到温度影响产生波长漂移等测量误差。此外,系统也多采用PC计算机来进行数据采集和控制,并通过配备独立的工业通讯模块实现光谱分析系统与产线总控系统的通讯,不仅增加了设备成本与体积,也显著降低了系统的稳定性。针对这些问题,基于STM32单片机开展了在线恒温光谱分析系统研制与测试。系统采用STM32单片机来控制近红外光谱仪,通过设定和修改采集间隔时间并采集光谱数据,对光谱数据进行预处理,来计算得到目标样品的理化指标。对于温度控制,开发了在STM32单片机上运行的基于比例-积分-微分(PID)控制算法的恒温控制系统,对光谱仪整体(包含光路和电路部分)实现了闭环恒温控制。同时,开发了基于STM32单片机的工业通讯接口(包含Modbus协议通讯和4~20 mA电流信号通讯)。系统实验测试结果表明,该设计能够长时间稳定运行,并有效降低了环境温度变化对光谱数据带来的干扰。在长达48小时的系统运行过程中,光谱仪温度稳定控制在5℃左右,温控精度优于0.25℃。相对于未恒温控制的运行模式,恒温控制条件下的平均吸收光谱强度相对标准差显著减小,并实现了数据采集、预处理、样品理化指标计算、工业信号通讯及温度控制的一体化设计,以满足工业现场在线检测需求。
Near-Infrared(NIR,wavelength range:780~2500 nm)on-line spectral analysis technique has the advantages of miniaturization,rapid detection,and stable and reliable results.Therefore,this technique is widely used in the field of industrial detection.Because the spectroscopic system is significantly affected by ambient temperature,the detector is always cooled in traditional on-line spectroscopic systems.However,measurement errors,such as wavelength drift,are still generated from the optical components when temperature changes.In addition,PCs are always used for system control and spectra acquisition,which significantly increase system instability.In order to solve these problems,this paper proposes an on-line thermostatic control spectroscopic system based on an STM32 single-chip microcomputer.Firstly,STM32 single-chip microcomputer is used to control the near-infrared spectroscopy for spectra data acquisition,configuration setting,preprocessing of the spectral data,and calculation of the physical and chemical parameters of the sample.Secondly,a constant temperature control system has been developed based onthe STM32 single-chip microcomputer,in which the proportional-integral-differential(PID)control algorithm is used.The closed-loop thermostatic control has been realized for the whole spectrometer,including the optical and the circuit part.At last,an industrial communication interface including Modbus protocol communication and 4~20 mA current signal communication has also been developed based on the STM32 single-chip microcomputer.The system test results show that the whole system can be operated stably without PC for a long time.The measure errors originating from the changing of ambient temperature also reduce obviously.During a test of 48-hour system operation,the temperature of the spectrometer is controlled stably at around(5±0.25)℃.A much smaller relative standard deviation of absorption spectra is obtained when the thermostatic control is applied.The system integrates spectra acquisition,pretreatment,calculation of physical and chemical parameters,industrial communication and thermostatic control,which can satisfy the requirements of industrial on-line detection.
作者
黄超
赵宇红
张洪明
吕波
尹相辉
沈永才
符佳
李建康
HUANG Chao;ZHAO Yu-hong;ZHANG Hong-ming;L Bo;YIN Xiang-hui;SHEN Yong-cai;FU Jia;LI Jian-kang(School of Electrical Engineering,University of South China,Hengyang 421001,China;Institute of Plasma Physics,HFIPS,Chinese Academy of Sciences,Hefei 230031,China;Science Island Branch Graduate School,University of Science and Technology of China,Hefei 230031,China;School of Physics and Materials Engineering,Hefei Normal University,Hefei 230601,China;Institute of Energy,Hefei Comprehensive National Science Center,Hefei 230031,China;School of Nuclear Science and Technology,University of South China,Hengyang 421001,China)
出处
《光谱学与光谱分析》
SCIE
EI
CAS
CSCD
北大核心
2023年第9期2734-2739,共6页
Spectroscopy and Spectral Analysis
基金
安徽省重点研究与开发计划项目(202104a06020021),中国科学院等离子体物理研究所科学基金项目(DSJJ-202002),安徽高校协同创新项目(GXXT-2021-029)资助。
关键词
在线光谱分析系
STM32单片机
比例-积分-微分控制
数据采集控制
On-line spectroscopic system
STM32 single-chip microcomputer
Proportional-integral-differential(PID)control
Pctra data acquisition
