摘要
温度是高温热处理工业中的重要热工参数。实时准确的温度场监测是提高产品质量、预防工业事故、节约能源、减少污染的有效手段。传统的高温测量技术多采用热电偶等接触式传感器,但其侵入式单点测量的方式已不能满足目前工业测量的需要。基于CCD图像传感器的非接触测温技术是集电子技术、传热学、图像处理技术于一体的高新技术,以其响应迅速、非接触测量、适用范围广等优点成为高温检测领域中的研究热点之一。目前直接利用CCD测温的方法还处于实验室研究和工厂试验阶段。测温精度低、动态测温范围窄,实时处理能力弱、便携性差是制约CCD测温技术应用的主要因素。
论文分析了CCD的基本工作原理与辐射测温方法,首先搭建了线阵CCD测温系统。采用高灵敏度黑白线阵CCD实现辐射体单点温度或均匀温度场测量。通过在CCD前加载滤光片获取单波长下的灰度输出,运用比色法获取辐射温度。结合实验讨论了波长选择对测温精度的影响,针对系统在不同波长组合下的温度输出具有多传感器关联特性,提出了自适应加权实时数据融合算法,在改善测量结果的基础上提高了系统的实时性。
研究了面阵CCD数字成像原理与图像测温的基本方法,建立了基于彩色面阵CCD的测温系统,用于全温度场监测。在分析传统测温系统的优势与不足的基础上,设计了基于面阵CCD的单镜头双色测温系统,采用一个分光滤光光路实现了单CCD对三色图像的同步获取,降低了系统误差。分析了系统中辐射体温度与辐射图像像点灰度之间的映射关系,利用比色原理推导出该系统的温度计算公式。根据人造黑体原理,设计了满足工程需要的实验室用黑体炉,用于标定公式中的系统修正因子并进行测温实验研究。
为提高系统测温精度且便于工程应用,对系统潜在的误差源进行了分析并提出了相应的解决方案。针对测温系统中CCD光谱响应带宽引起的误差,提出了基于CCD光谱响应曲线寻迹的数字滤光方法,利用曲线寻迹思想和数字离散化技术获得单波长下的灰度输出,以算法模拟滤光功能,使系统无需任何外置滤光光路即可实现辐射测温,减小了系统误差。此外,受周围环境和测温设备本身的影响,获取的辐射图像含有大量的未知噪声。针对该问题,提出了基于改进GCV准则的小波图像去噪方法。利用小波分析技术和改进的广义交叉验证算法对摄取后的含噪图像进行降噪处理,降低噪声信号对测温精度的影响。
研究了CCD测温系统的动态测温范围。针对CCD感光特性导致系统可测温区较窄的问题,提出了彩色图像灰度拟合算法。在黑体炉上建立灰度拟合关系式,估算饱和温区的虚拟灰度值,以增加可用灰度比来扩展测温区间。为提高拟合精度,通过分析灰度比曲线对算法进行了校正。
为便于测温系统的工程应用,设计开发了基于FPGA(Field Programmable Gate Array)的便携式实时测温系统和基于PC的全温度场实时监控系统。前者采用一块FPGA实现了数据采集、温度计算和显示,适用于对实时性要求较高的现场测温,为开发便携式测温仪打下了基础;后者可进行图像采集、算法处理、灰度分析和温度场显示等,适用于工业热处理过程的后台监控与后续分析,为全面监测热处理过程,改善燃烧状况、节能减排提供了技术支持。
Temperature is one of the important parameters in the high temperature heat treatment field. The real-time and accurate measurement of temperature field is an effective mean for improving product quality, preventing industrial accident, conserving energy and reducing environment pollution. The conventional contact sensor such as thermocouples would not meet the demands of industry development because of the drawback of single-point and intrusive measurement. The uncontact temperature measurement using a CCD image sensor is a new technique that integrates electronics, heat transfer theory and image processing technique, and attracts the attention of the researchers on account of its obvious advantages like quick response, uncontact measurement and wide available range. The method now is still in research and experimental stage. The main factors limiting the technology application include low measurement accuracy, narrow measurable temperature scope, weak real-time processing ability and poor portability.
In the paper, the basic principle of CCD is analyzed and a prototype system of temperature measurement using a linear CCD sensor is presented firstly. The system is able to get the radiation image gray-level at a single wavelength by loading the filter in front of the CCD and then calcuates point temperature or uniform temperature field of radiation object by applying the two-color theory. Then the method of wavelength selection and its effect on the measured results are discussed combined with the experimental. In view of the multi-sensor characteristic of temperature output at varity wavelength combinations, an algorithm of adaptive weighted real-time data fusion is presented. It improves the accuracy of temperature measurement and efficiency of system operation.
Combining the digital imaging processing technique and two-color temperature measurement method, a novel instrumentation system is built for whole temperature field monitoring using a color matrix CCD camera. On the basis of analyzing the advantages and the disadvantages of the conventional methods, a two-color temperature measurement system with a single camera is designed. The system can capture the three monochrome images synchronically by using a splitting/filtering optical path, which reduces the system error. The relationship is deduced between the radiation temperature and pixel gray-level, and then a temperature expression is given based on the two-color theory. To meet measurement needs, an industrial black-body furnace is made for system calibration and experimental research.
To improve the accuracy of temperature measurement and easy to be used in engineering application, the system’s potential error sources are analyzed and the corresponding solution are given. Aiming at the error aroused by CCD spectral response bandwidth, a digital filtering method is proposed to get gray-level output at single wavelength by applying the thought of CCD spectral responsed curve tracing and the digital image discretization technique. The system simulates the filter effect with an algorithm to accomplish the temperature measurement using CCD camera without any external filtering optical path. Besides, the radiation image captured by CCD camera involves much unknown noise from bug dust, environment light and optical device. For this problem, an algorithm of multiple wavelet images de-noising based on improved Generalized Cross Validation (GCV) law is adopted to purify the radiation image and reduce measuring error.
The issue on the dynamic temperature measurement scope is discussed. The CCD sensor’s photo-behavior results in measurable temperature range too narrow to show the whole temperature field accurately. For solving the problem, a gray-level fitting algorithm is presented to establish an expression about RG gray-level to estimate the virtual gray-level on the saturation pixel. Increased gray-level ratios will extend the range of temperature measurement. To decrease the fitting error, the algorithm mentioned above is corrected through analyzing the curve of gray-level ratio.
Two application tools have been developed for convinent to apply the temperature measurement system into industrial field. One is a FPGA(Field Programmable Gate Array)-based portable real-time temperature measurement system. The system, using a FPGA chip to implement data acquisition, temperature calculation and showing, is suitable for getting real-time results of simple point temperature or mean value of temperature zone. The other one is a PC-based monitoring system of temperature field, which is applied to monitor and analyze combustion temperature field with the powerful image processing function including image acquisition, algorithm processing, gray-level analysis and temperature field showing, etc. The two tools provide technique support for the over-all monitoring of heat-treatment processing, improving combustion efficiency, saving energy source and reducing pollution.
引文
1 B. Olika, B. Bo. Prediction of steel temperature in ladle through time/temperature simulation. Scand J metallurgy, 1993, 22:219-231
2李晶,毕其富.钢包精炼过程中钢水成分微调及温度预报.钢铁研究学报. 1999,11 (2):6-8
3张永乐.浅谈锅炉爆炸的原因、爆炸的能量及预防措施.电器工厂设计. 2005,33(2): 31-34
4王满家.锅炉炉膛安全保护装置应用状况分析.中国电力. 1993, 3:34-38
5中国能源消耗现状及其管理策略研究报告(2007)
6 K. Kyuma, S. Tai, T. Matsui, et al. Fiber-Optic instrument for temperature measurement. IEEE Transations on Microwave Theory and Techniques. 1982,82(4):522-525
7 V. Fernicola, L. Crovini. Digital optical fiber point sensor for high-temperature measurement. Journal of Lightwave Technology. 1995,13(7):1331-1334
8 M. Bramanti, E. A. Salerno, A. Tonazzini, S. Pasini, A. Gray. An acoustic pyrometer system for tomographic thermal imaging inpower plant boilers. IEEE Transations on Instrumentation and Measurement. 1996,45(1): 159-167
9 J. Lu, K. Wakai, S. Takahashi, S. Shimizu. Acoustic computer tomographic pyrometry for two-dimensional measurement of gases taking into account the effect of refraction of sound wave paths. Measurement Science and Technology. 2000, 11: 692-697
10 J. R. Gebhart, B .E. Kinchen, R. R. Strange. Optical pyrometer and technique for temperature measurement. US patent, Patent number: 4222663.
11 J. Mishin, M. Vardelle, J. Lesinski, P. Fauchais. Two-color pyrometer for the statistical measurement of the surface temperature of particles under thermal plasma conditions. Journal of Physics of E: Scientific Instruments. 1987,20(6): 620-625
12 A. Cezairliyan, A. P. Miiller. Melting temperature of nickel by a pulse heating technique. International Journal of Thermophysics. 1984,5(3):315-320
13原遵东,赵琪,段宇宁等.新型精密光电高温计.计量学报. 2003,24(4):241-247
14杨世铭.传热学(第二版).北京:高等教育出版社, 1991
15 J. Hahn, C. Rhee. Reference wavelength method for a two-color pyrometer. Applied Optics. 1987, 26(24): 5276~5279
16 B. Müller, U. Renz. Development of a fast fiber-optic two-color pyrometer for the temperaturemeasurement of surfaces with varying emissivities. Review of Scientific Instruments. 2001,72(8):3366-3374
17 M. shimoda, et al. Prediction method of unburnt carbon for coal fired utility boiler using imageprocessing technique of combustion flame. IEEE Transations On Energy Conversion. 1990, 5(1):640-650
18 A. Barducci, I. Pippi. Temperature and emissivity retrieval from remotelu sensed images usingthe“greybody emissivity”method. IEEE Transations on Geoscience and Remote Sensing.1996,34(3): 681-695
19須沢憲一,三浦和彦,野村太一,稲田憲治.発電プラントの総合監視制御システムを適用したH-25がスタービン制御装置「HIACS-MULTI」.電力エネルギー分野の最新開発技術. 2008,90(2):180-184
20舒子凯.三菱新型火焰检测装置OPTIS简介.热工自动化信息. 1993
21 Y. Tago, F. Akimoto, K. Kitagawa, N. Arai. Measurements of surface temperature and emissivityby two-dimensional four-color thermometry with narrow bandwidth. Energy. 2005,30:485-495
22 E. Renier, F. Meriaudeau, P. Suzeau, et al. CCD temperature imaging: application in steel industry.Proceedings of the 1996 IEEE IECON 22nd International Conference. 1996, 2: 1295-1300
23 G. Lu, Y. Yan, S. Cornwell, G. Riley. Temperature profiling of pulverised coal flames usingmulti-Colour pyrometer and digital imaging techniques. Proceedings of IEEE Instrumentationand Measurement Technology Conference. 2005, 1658-1662
24 P. M. Brisley, G. Lu, Y. Yan, et al. Three-Dimensional temperature measurement of combustionflames using a single monochromatic CCD camera. IEEE Transations on Instrumentation andMeasurement. 2005,54(4):1417-1421
25 S. Collins. Advanced flame monitors take on combustion control. Power, 1993,137(10):75-78
26蔡小舒,罗武德.光谱法测量煤粉火焰温度和黑度的研究.工程热物理学报. 2000,21(6):779-782
27季琨,蔡小舒,赵志军.不同种类燃料火焰的辐射光谱测量.工程热物理学报, 2004,25(1):171-173
28孙江,徐伟勇,余岳峰.根据煤粉火焰图像判断燃烧状况的计算机判断算法.热力发电.1999, 1: 14-18
29徐伟勇,余岳峰,张银桥,等.采用传像光纤和数字图像处理技术检测燃烧火焰.动力工程, 1999, 19(1): 45-48
30程晓舫,周洲.彩色三基色温度测量原理的研究.中国科学(E辑). 1997,27(4): 342-345
31符泰然,程晓舫,钟茂华,等.基于波段带宽的谱段测温法的测温范围分析.光谱学与光谱分析. 2008, 28(9): 1994-1997
32符泰然,杨臧健,程晓舫.基于彩色CCD测量火焰温度场的算法误差分析.中国电机工程学报. 2009,29(2):81-86
33孙晓刚,胡晓光,戴景民.可同时测量真温及光谱发射率的8波长高温计.光学技术. 2001,27(4):305-309
34戴景民,王新北.材料发射率测量技术及其应用.计量学报. 2007, 28(3): 232-236
35辛春锁,戴景民,王英力.光纤式20波长辐射高温计的研制.红外技术. 2008,30(1):47-50
36周怀春,韩才元.用于煤粉燃烧诊断的火焰颜色计测方法.光谱学与光谱分析. 1994,14(2):31-34
37姚斌,姜志伟,周怀春. W型火焰锅炉炉膛温度场的可视化试验研究.热能动力工程. 2006,21(1):35-38
38娄春,周怀春,姜志伟,等.炉膛内断面温度场与辐射参数同时重建实验研究.中国电机工程学报. 2006,26(14):98-103
39娄春;周怀春;吕传新,等.电站锅炉炉内三维温度场在线检测与分析.热能动力工程. 2005,20(1):61-64
40卫成业,王飞,马增益,等.运用彩色CCD测量火焰温度场的校正算法.中国电机工程学报. 2000,20(1):70-72
41黄群星,刘冬,王飞,等.非对称碳氢扩散火焰内烟黑浓度与温度联合重建模型研究.物理学报. 2008,57(12):7928-7936
42李汉舟,潘敏贵,潘泉,等.基于面阵CCD图像的温度场测量研究.仪器仪表学报. 2003,24(6): 653-656
43李汉舟,潘泉,张洪才,等.基于数字图像处理的温度检测算法研究.中国电机工程学报. 2003,23(6):195-199
44 R.S. Chouhan, K. Vivek Babu, M.A. Kumar, et al. Detection of methyl parathion using immuno-chemiluminescence based image analysis using charge coupled device 2006,21(7):1264-1271
45 J. Yuan, X. W. Long. CCD-area-based autocollimator for precision small-angle measurement. Review of Scientific Instruments. 2003,74(3):1362-1365
46 A. Ito, Y. Aoki, S. Hashimoto. Accurate extraction and measurement offine cracks from concrete block surface image. 28th Annual Conference of the IEEE Industrial Electronics Society. 2002, 3: 2202-2207
47王庆友. CCD应用技术.天津:天津大学出版社,2000
48米本和也[日],陈榕庭.. CCD/COMS图像传感器基础与应用.北京:科学出版社,2006
49杨经国, S. R. P. Smith.双色高温测量中的最佳化参数选择.计量学报. 1991,12(4): 274-279.
50康耀红.数据融合理论与应用.西安:西安电子科技大学出版社,2006
51 D. L. Hall, J. Llinas. An introduction to multisensor data fusion. Proceedings of the IEEE. 1997, 85(1): 6-23
52 F. Caron, M. Davy, E. Duflos, et al. Particle filtering for multisensor data fusion with switching observation models: application to land vehicle positioning. IEEE Transactions on Signal Processing. 2007,55(6):2703-2719
53 P. K. Varshney. Multisensor data fusion. Electronics & Communication Engineering Journal. 1997, 9(6): 245-253
54 R.C Luo, Chih-chen Yih, Kuo Lan Su. Multisensor fusion and integration: approaches, applications, and future research directions. Sensor Journal. 2002, 2(2):107-119
55 Gunho Sohn, Ian Dowman. Data fusion of high-resolution satellite imagery and LiDAR data for automatic building extraction. ISPRS Journal of Photogrammetry and Remote Sensing. 2007,62(1):43-63
56 Tim Bass. Intrusion detection systems and multisensor data fusion. Communications of The ACM. 2000,43(4):99-105
57 T. Toi, M. Ohita. A subband coding technique for image compression in single CCD cameras with bayer color filter arrays. IEEE Transations on Consumer Electronics. 1999,45(1):176-180
58赵春晖,潘泉.数字图像温度测量系统的建立.计算机应用. 2004,6(24):414- 416
59 Black-Body Furnace, US Patent 3,263,016, 1966
60 Mark J. Ballico, Trebor P. Jones. Novel experimental technique for measuring high-temperature spectral emissivities.Applied Spectroscopy. 1995,49(3): 335- 340
61 J. L. Pan, H. K. Choy, C. G. Fonstad. Very large radiative transfer over small distances from ablack body for themophotovoltaic. IEEE Transations on Electron Devices. 2000,47(1):241-249
62许秀贞,李自田,薛利军. CCD噪声分析及处理技术.红外与激光工程. 2004,33 (4):343-346
63 G. R. Hopkinson et al. Noise reduction techniques for CCD image sensors. Journal of Physics E: Scientific Instrumment. 1982,15:1214-1222
64 A. Frenkel, M. A. Sartor, M. S. Wlodawski. Photon-noise-limited operation of intensified CCD cameras. Applied Optics. 1997,36(22):5288-5297
65 M. Gross, P. Goy, M. Al-Koussa. Shot-noise detection of ultrasound-tagged photons in ultrasound-modulated optical imaging. Optics Letters. 2003,28(24): 2482-2484
66 K. Irie, A. E. McKinnon, K. A. Unsworth, et al. Technique for evaluation of CCD video-camera Noise. IEEE Transactions on Circuits and Systems for Video Technology. 2008,18(2):280-284
67 J. Hynecek. Spectral analysis of reset noise observed in CCD charge detection circuits. IEEE Transactions on Electron Devices. 1990,37(3): 640-647
68 S. Donati, V. Svelto. Theory of CCD transfer noise from a circuit model. IEEE Transactions on Electron Devices. 1997,24(9):1184-1186
69 K. Irie, A. E. McKinnon, K. A. Unsworth, et al. A model for measurement of noise in CCD digital-video cameras. Measurement Science and Technology. 2008,19(4):045207
70李云飞,李敏杰,司国良,等. TDI-CCD图像传感器的噪声分析与处理.光学精密工程. 2007,15(8):1196-1202
71 W. C. McColgin, J. P. Lavine, J. Kyan, et al. Dark current quantization in CCD image sensors. International Electron Devices Meeting. San Francisco. 1992
72 Woon Bo Baek, Sung Jin Lee, Seung Yeob Baeg, et al. Flame image processing and analysis for optimal coal firing ofthermal power plant. IEEE International Symposium on Industrial Electronics. 2001,2:928-931
73甄成刚,韩璞,牛玉广.炉膛火焰图像处理技术及温度场重构.动力工程. 2003,23(4): 2548-2551
74卫成业,王飞,马增益,等.运用彩色CCD测量火焰温度场的校正算法.中国电机工程学报. 2000,20(1):70-72
75范立南,韩晓微,张广渊.图像处理与模式识别.北京:科学出版社,2007
76 H. Faraji, W. J. MacLean. CCD noise removal in digital images. IEEE Transations on Image Processing. 2006,15(9):2676-2685
77 J. Cao, M. Ahmadi, M. Shridhar. Recognition of handwritten numerals with multiple feature and multistage classifier. Pattern Recognition. 1995,28(2):153- 160
78 S. M. Lai, X. Li, W. F. Biscof. On techniques for detecting circumscribed masses in mammograms. IEEE Transations on Medical Imaging. 1989,8(4): 377-386
79 Rafael C. Gonzalez[美]著,阮秋琦等译.数字图像处理(第二版).北京:电子工业出版社,2003
80 J-S. LEE. Digital image smoothing and the sigma filter. Computer Vision, Graphics and Image Processing. 1983,24:255-269
81 Xing Wang. On the gradient inverse weighted filter. IEEE Transations on signal processing. 1992,40(2):482-484
82 A. Baraldi, F. Parmiggiani. An alternative form of the lee filter for speckle suppression in SAR images. Graphical Models and Image Processing. 1995,(1): 75-78
83陈传峰,朱长仁,宋洪芹.基于巴特沃斯低通滤波器的图像增强.现代电子技术. 2007, 30(24): 163-165
84 S. Castan, J. Zhao, J. Shen. New edge detection methods based on exponential filter. Proceedings of 10th International Conference on Pattern Recognition. 1990,5(1): 709-711
85 Matthew S. Crouse, Robert D. Nowak, Richard G. Baraniuk. Waveletbased statistical signal processing using hidden markov models. IEEE Transations on Signal Processing. 1998,46(4):886-902
86李旭超,朱善安,朱胜利.基于小波域层次Markov模型的图像分割.中国图象图形学报. 2007, 12(2): 308-314
87 G. Aubert, P. Kornprobst. Mathematical problems in image processing: partial differential equations and the calculus of Variations. US: Springer,2006
88王正明,谢美华.偏微分方程在图像去噪中的应用.应用数学. 2005,18(2): 219-224
89 Ingrid Daubechies. Where do wavelets come from?-a personal point of view. Proceedings of IEEE. 1996,84(4):510-513
90张智,夏德深.结合复小波的倒易晶胞图像复原方法.电子学报. 2008,36(10): 1979-1985
91孙伟峰,何俊华.基于多小波变换的图像去噪新方法.光子学报. 2008, 37(11): 2360-2364
92武东生,刘秉琦.小波变换在CCD图像边缘检测中的应用.应用光学. 2004,25(2): 48-50
93 S. G. Mallat. A theory for multi-resolution signal decomposition: the wavelet representation. IEEE Transactions on Pattern Analysis and Machine Intelligence. 1989,11(7):674-693
94 David L. Donoho. Denoising by soft-thresholding. IEEE Transactions on Information Theory. 1995, 41(3): 613-627
95崔锦泰[美],程正兴[译].小波分析导论.西安:西安交通大学出版社,1997
96 L. Donoho David, M. Jhonstone lain. Threshold selection for wavelet shrinkage of noisy data. Proceedings of the 16th Annual International Conference of IEEE, Engineering in Medicine and Biology Society. 1994, 1:A24-A25
97 D. L. Donoho, I. M. Johnstone. Adapting to unknown smoothness via wavelet shrinkage. Journal of American Statistical Association. 1995,90(432):1200-1224
98 S. Sardy. Minimax threshold for denoising complex signals with waveshrink. IEEE Transations on Signal Processing. 2000,48(4):1023-1028
99 S. Grace Chang, Bin Yu, M. Vattereli. Adaptive wavelet thresholding for image denoising and compression. IEEE Transations on Image Processing. 2000, 9:1532-1546
100 G. P. Nason. Wavelet shrinkage using cross-validation. Journal of the Royal Statistical Society: Series B. 1996,58(2):463-479
101 N. Weyrich, G. T. Warhola. Wavelet shrinkage and generalized cross validation for image denoising. IEEE Transations on Image Processing. 1998,7(1):82-90
102 Maarten Jansen, Maurits Malfait, Adhemar Bltheel. Generalized cross validation for wavelet thresholding. Signal Processing. 1997,56(1):33-44
103 M. Jansen, A. Bultheel. Multiple wavelet threshold estimation by generalized crossvalidation for images with correlated noise. IEEE Transations on Image Processing. 1999,8(7): 947-953
104胡良梅,高隽,何柯峰.图像融合质量评价方法的研究.电子学报. 2004, 32(12A): 218-22.
105张华,潘际銮,廖宝剑.以ICCD为传感器的温度场实时检测(I):温度场分区处理的原则及方法.中国科学(E辑). 1997,27(5):418-423
106朱明程. FPGA原理及应用设计.北京:电子工业出版社,1994
107 S. Karimi, P. Poure. FPGA-based fully digital fast power switch fault detection and compensation for three-phase shunt active filters. Electric Power Systems Research. 2008,78(11):265-268
108 Akila Gothandaraman, Gregory D. Peterson, et al. FPGA acceleration of a quantum Monte Carlo application. Parallel Computing. 2008,34(4-5):278-291
109 B. A. Draper, J. R. Beveridge, A. P. W. Bohm, et al. Accelerated image processing on FPGAs.IEEE Transations on Image Processing. 2003,12(12):1543- 1551
110 E. Motuk, R. Woods, S. Bilbao. FPGA-based hardware for physical modelling sound synthesis by finite difference schemes. Proceedings of IEEE International Conference on Field-Programmable Technology. 2005: 103-110
111 Priyadarshan Kolte, Roger Smith, Wen Su. A fast median filter using altiVec. IEEE International Conference on Computer Design (ICCD’99). 1999: 384-391
112张华,潘际銮,廖宝剑.基于ICCD双色热图像的温度场实时检测传感系统.仪器仪表学报. 1998, 19(1):94-97