影像測量儀是一-種“基于成像在光電耦合器件上的光學(xué)影像系統(tǒng)(簡稱影像系統(tǒng))，通過光電耦合器件采集,經(jīng)過軟件處理成像,顯示在計(jì)算機(jī)屏幕上，利用測量軟件進(jìn)行幾何運(yùn)算得出最終結(jié)果的非接觸式測量儀器”。測量軟件通過數(shù)字圖像處理技
術(shù)提取工件表面的坐標(biāo)點(diǎn),再利用坐標(biāo)變換和數(shù)據(jù)處理技術(shù)轉(zhuǎn)換成坐標(biāo)測量空間中的各種幾何要素，
從而得到被測工件幾何尺寸和形位公差等參數(shù)。
1、影像測量儀發(fā)展概述
20世紀(jì)70年代后期，尤其是在DavidMar教授建立“計(jì)算視覺(Computational Vision)”理論框架以來,圖像處理技術(shù)和圖像傳感器獲得了快速發(fā)展。
隨著坐標(biāo)測量技術(shù)的日趨發(fā)展與成熟，在以光學(xué)比較為基礎(chǔ)的光學(xué)測量領(lǐng)域里,坐標(biāo)測量方法的發(fā)展應(yīng)用有了更進(jìn)一步的實(shí)質(zhì)性進(jìn)展。.
1977年,美國View Engineering 公司發(fā)明了世界上第一臺由電機(jī)驅(qū)動XYZ軸的RB-1影像測量系統(tǒng)(見圖1),它是一臺控制終端整合了視頻檢測和軟件測量的自動影像測量儀。此外, Mechanical Technology公司的Boice Vista 系統(tǒng)則充分借鑒了坐
標(biāo)測量機(jī)的優(yōu)勢,在坐標(biāo)測量機(jī)的測頭上集成了一個視頻圖像測量系統(tǒng),該系統(tǒng)可以將測量數(shù)據(jù)與預(yù)先編制好的標(biāo)稱尺寸和公差進(jìn)行比較。
這兩臺儀器通過不同途徑借鑒了坐標(biāo)測量機(jī)的坐標(biāo)測量原理,將被測量物體的圖像投影到坐標(biāo)系中。其測量平臺繼承了坐標(biāo)測量機(jī)的形式，但其測頭與光學(xué)投影儀相似。這些儀器的出現(xiàn)開辟了一個重要的測量儀器行業(yè),即影像測量儀行業(yè)。上世紀(jì)80年代初,影像測量技術(shù)有了重要的發(fā)展。1981 年, ROI公司開發(fā)出光學(xué)影像探針(見圖2),可以替代坐標(biāo)測量機(jī)上的接觸式探針進(jìn)行非接觸式測量,從此這個光學(xué)配件就成了影像設(shè)備的基.礎(chǔ)部件之一。在80年代中期,市場上又出現(xiàn)了帶高放大倍率顯微鏡目鏡的影像測量儀。
進(jìn)入上世紀(jì)90年代，隨著CC)技術(shù)、計(jì)算機(jī)技術(shù)、數(shù)字圖像處理技術(shù)LED照明技術(shù).直流/交流伺服驅(qū)動技術(shù)的發(fā)展,影像測量儀產(chǎn)品獲得了巨大的發(fā)展。更多的廠商進(jìn)入到影像測量儀產(chǎn)品市場,共同推進(jìn)了影像測量儀產(chǎn)品的發(fā)展。
2000年以后,我國在該領(lǐng)域的技術(shù)水平不斷提高,有關(guān)影像測量技術(shù)研究的文獻(xiàn)也不斷出現(xiàn);國內(nèi)企業(yè)(如天準(zhǔn)、智泰怡信、賽克數(shù)碼、新天等公司)所開發(fā)的影像測量儀在生產(chǎn)規(guī)模、品種和質(zhì)量上也不斷有所提升和發(fā)展。2009年我國制定了國家標(biāo)準(zhǔn)
GB/T24762- 2009: 產(chǎn)品幾何技術(shù)規(guī)范( GPS)影像測量儀的驗(yàn)收檢測和復(fù)檢檢測,它適用于XY平面直角坐標(biāo)系的影像測量儀，包括在垂直于平面直角坐標(biāo)系Z方向上具有定位或測量功能的影像測量儀。
值得一.提的是天準(zhǔn)精密技術(shù)有限公司,該公司由一批風(fēng)華正茂、胸懷振興我國精密測量行業(yè)壯志的學(xué)子們所創(chuàng)建,在學(xué)習(xí)借鑒國外優(yōu)秀產(chǎn)品的基礎(chǔ)上開發(fā)創(chuàng)新,形成了自身的特色和優(yōu)勢。經(jīng)過多年不懈努力,天準(zhǔn)公司于2007年在國內(nèi)首次推出了具有完全自主知識產(chǎn)權(quán)的三維自動影像測量儀系列產(chǎn)品，填補(bǔ)了國內(nèi)空白，在國產(chǎn)的影像測量儀中處于技術(shù)領(lǐng)先地位。
2影像測量儀 的評估
本文嘗試從儀器結(jié)構(gòu)、關(guān)鍵技術(shù)指標(biāo)等方面對影像測量儀產(chǎn)品進(jìn)行評價,由于筆者影像測頭方面.的資料欠缺，故未與涉及。
(1)外觀與結(jié)構(gòu)
精密測量儀器類產(chǎn)品的外觀與結(jié)構(gòu)是用戶選擇的重要依據(jù)。好的產(chǎn)品外觀與結(jié)構(gòu)，給人以穩(wěn)重、可e靠、精密的感覺,往往是決定一款產(chǎn)品在市場獲得成敗的重要因素。
目前影像測量儀的結(jié)構(gòu)形式主要有立柱式結(jié)構(gòu)、固定橋式結(jié)構(gòu)與移動橋式結(jié)構(gòu)。立柱式結(jié)構(gòu)和固定橋式結(jié)構(gòu)在小量程的影像測量儀中應(yīng)用都很廣泛,各有優(yōu)勢。移動橋式結(jié)構(gòu)主要用在特大量程的影像測量儀中。立柱式結(jié)構(gòu)的優(yōu)勢在于結(jié)構(gòu)緊湊、
占用場地小、裝取工件方便;固定橋式結(jié)構(gòu)的特點(diǎn)是產(chǎn)品穩(wěn)重、大氣，但占用場地較大,裝取工件不太方便;移動橋式結(jié)構(gòu)則容易實(shí)現(xiàn)大量程測量,測量過程中工件固定不動。
(2)光源系統(tǒng)
光源系統(tǒng)在影像測量儀中起著至關(guān)重要的作用,直接決定著一-臺影像儀性能的好壞、功能的強(qiáng)弱。好的光源系統(tǒng)可幫助影像測頭獲取清晰、銳利、均勻-致的正確圖像,確保測量的精度與重復(fù)性。
為實(shí)現(xiàn)對不同材質(zhì)、不同形狀、不同種類的工件提供有效的照明,完成復(fù)雜的測量任務(wù),影像測量儀通常都會提供三種照明光源:表面光源、輪廓光源、同軸光源。
表面光源為工件上表面的測量提供照明。好的表面光源，要能提供不同入射角度和不同入射方向的照明,確保不同的工件獲得--致的照明效果。
輪廓光源為工件外輪廓、通孔等測量提供照明。輪廓光源通常安裝在影像測量儀的底座上，在工作時,圖像上被工件阻擋部分成像為黑色,無阻擋部分粕角幫助影像測頭獲得黑自分明、對比度高、邊界清晰的工件圖像。在輪廓光源照明下，儀器往往能達(dá)到最高的測量精度。
同軸光源沿著鏡頭光軸方向投射到工件表面,可為工件的高反射率表面和深孔部位的測量提供照明。
(3)多測頭集成
影像測頭在二維尺寸測量上具備無可比擬的速度優(yōu)勢,但影像測頭也有其不擅長的地方,在三維測量中,測量效率不夠高、工件側(cè)面特征無法測量等。
由此就出現(xiàn)了多測頭集成的需求,綜合使用影像測頭.接觸式測頭、激光測頭和白光測頭等,可針對不同的工件及不同的測量需求，選擇最合適的測量方式，以便提供最佳的測量精度以及最好的測量效率。在二維尺寸的大批量檢測時,可使用影像測
頭;在測量復(fù)雜工件側(cè)璧,而對效率要求又不高的情況下，可選擇接觸式測量;在復(fù)雜工件的三維測量中，如果對效率要求很高可使用白光測頭或激光測頭。
(4)測量性能
精度是測量儀器的根本,精度是用戶選擇儀器的最重要指標(biāo)之一。影像測量儀的測量精度主要取決于影像測頭的質(zhì)量.照明光源系統(tǒng)性能、儀器運(yùn)動及定位精度,數(shù)據(jù)處理測量軟、硬件的質(zhì)量和水平也是極其重要的影響因素。
作為自動化測量儀器,影像測量儀的測量效率是客戶最為看重的要素之一。高測量效率可以減少設(shè)備投入、提高生產(chǎn)效率、降低人工費(fèi)用等。
(5)測量功能
影像測量儀的基本測量功能通常包括:點(diǎn)線、圓、弧等多種基本幾何量的測量,在測量方式上，提供多種提取及構(gòu)建方式;提供多種形狀公差和位置公差的測量;提供多種坐標(biāo)系建立方式;提供手動測量與自動批量測量;批量測量程序可記錄測量基元、提取方式、機(jī)臺操控、光源控制、自動聚焦等過程;可導(dǎo)入導(dǎo)出CAD圖紙;測量數(shù)據(jù)輸出到指定格式的報表中。
除了這些基本測量功能外,儀器廠商通常還會提供SPC、圖紙比對、離線編程、定制輸出報表等擴(kuò)展功能。部分廠商還會針對特定用戶行業(yè)的測量需求,開發(fā)相應(yīng)的專用軟件或硬件,增加儀器測量功能,如小模數(shù)齒輪測量、試驗(yàn)篩校準(zhǔn)等。
(6)其他方面
產(chǎn)品易用性、對環(huán)境的適應(yīng)性、操作界面是否人性化等方面，也是判別儀器性能的重要因素。是否能方便建立測量任務(wù)、制定及輸出報表、機(jī)臺操控等,影響用戶對儀器的接受程度。儀器的長期穩(wěn)定性,測量方案的提供,客戶服務(wù)的響應(yīng)速度。交貨周期、定制化開發(fā)能力等等,都是影響客戶選擇影像測量儀產(chǎn)品的重要因素。
3、國內(nèi)外典型產(chǎn)品的點(diǎn)評
影像測:量儀可天致分為科學(xué)級和工業(yè)級兩大類。科學(xué)級產(chǎn)品精度非常高對工作環(huán)境和操作人員要求也非常高,目前世界上只有少數(shù)廠家有這類產(chǎn)品,其市場容量很小。
工業(yè)級產(chǎn)品占據(jù)了市場最大份額。在工業(yè)級產(chǎn)品中，精度高、性能穩(wěn)定.效率高、功能豐富的一線品牌主要有國外的蔡司、三豐、尼康、0GP、海克斯康及國內(nèi)的天準(zhǔn)精密技術(shù)等公司。它們各自開發(fā)的具有三維影像測量功能的品牌產(chǎn)品代表了當(dāng)今工業(yè)級影像測量儀的先進(jìn)水平，本文擬以這些公司相同規(guī)格的一個主導(dǎo)產(chǎn)品作為對象,進(jìn)行概略的介紹比較。
其他常見的進(jìn)口品牌及絕大部分國產(chǎn)品牌的產(chǎn)品，總體水平質(zhì)量上相比來看，還存在一些差距。
(1)蔡司
德國蔡司公司是工業(yè)測量領(lǐng)域的著名企業(yè)，具有豐富的產(chǎn)品線,其CMM更曾是高端CMM的代名詞。蔡司旗下最有代表性的影像測量儀產(chǎn)品為0-NSPECT(見圖3)。0- NSPECT 采用固定橋式結(jié)構(gòu),產(chǎn)品美觀、穩(wěn)重,具備影像式測頭和接觸式測頭、
兩種檢測手段。
(2)三豐
日本三豐公司作為泄界著名的精密測量儀器制造商,其影像測量儀產(chǎn)品線廣。 型號齊全,圖4為其代表性產(chǎn)品QV- ELF202PRO。 該產(chǎn)品采用固定橋式結(jié)構(gòu)。產(chǎn)品外觀穩(wěn)重,太氣。
(3)天準(zhǔn)
中國蘇州的天準(zhǔn)精密技術(shù)有限公司多年來專注于精密測量儀器的研發(fā),是中國技術(shù)領(lǐng)先的影像測量儀品牌,兩項(xiàng)國家校準(zhǔn)規(guī)范的起草單位。其代表性產(chǎn)品VMU322具有測量精度高、測量速度快、功能豐富等優(yōu)點(diǎn)(見圖5)。
(4)尼康
日本尼康在光學(xué)測量儀器領(lǐng)域技術(shù)實(shí)力雄厚、產(chǎn)品眾多。其典型產(chǎn)品VMR3020產(chǎn)品美觀、精致,測量精度高,功能全面，如圖6所示。
(5)0GP
美國0GP公司一直致力于影像測量儀產(chǎn)品的開發(fā)、生產(chǎn)與銷售,擁有影像測量儀的多項(xiàng)核心技術(shù),其典型產(chǎn)品ZIP250如圖7所示。它采用了固立柱式結(jié)構(gòu),儀器技術(shù)水平較高。
( 6)海克斯康
瑞典的海克斯康是全球知名的長度測量儀器廠商,2010年初推出了Optive系列影像測量儀,其中的Peformance222是其代表性產(chǎn)品(見圖8)。該產(chǎn)品源自Mahr技術(shù),采用立柱式結(jié)構(gòu),結(jié)構(gòu)穩(wěn)定、精度高,是一款優(yōu)秀的影像測量儀產(chǎn)品。
英斯特力儀器是一家集研發(fā)、生產(chǎn)及銷售于一體的 影像測量儀，拉力試驗(yàn)機(jī), 硬度計(jì) ,探傷儀, 粗糙度儀, 測厚儀, 金相設(shè)備廠家, 致力于為客戶提供更好的檢測儀器。
Image measuring instrument is a - "based on imaging optical image system on the optocoupler (referred to as the image system), through the optocoupler acquisition, after software processing imaging, displayed on the computer screen, using the measurement software geometric operation to obtain the final result of the non-contact measuring instrument". Measurement software through digital image processing technology
The coordinate points on the workpiece surface are extracted and converted into various geometric elements in the coordinate measurement space by coordinate transformation and data processing technology.
The parameters such as geometric dimension and shape and position tolerance are obtained.
1. Overview of image measuring instrument development
Image processing techniques and image sensors have advanced rapidly since the late 1970s, especially since professor DavidMar established the theoretical framework "Computational Vision".
With the development and maturity of coordinate measurement technology, the development and application of coordinate measurement method has made further substantial progress in optical measurement field based on optical comparison. .
In 1977, American View Engineering company invented the world's first RB-1 image measurement system driven by a motor XYZ axis (see Figure 1). It is an automatic image measuring instrument with a control terminal integrating video detection and software measurement. Mechanical Technology's Boice Vista, meanwhile, borrows heavily from sitting
The advantage of the scale measuring machine is that a video image measuring system is integrated into the measuring head of the coordinate measuring machine, which can compare the measured data with pre-programmed nominal dimensions and tolerances.
These two instruments refer to the coordinate measuring principle of CMM in different ways and project the image of the measured object into the coordinate system. Its measuring platform inherits the form of coordinate measuring machine, but its probe is similar to the optical projector. The emergence of these instruments opened up an important measuring instrument industry, that is, image measuring instrument industry. In the early 1980s, there were important developments in image measurement technology. In 1981, ROI developed an optical imaging probe (figure 2) that could replace the contact probe on a CMM for non-contact measurements, and this optical accessory has been the basis of imaging equipment ever since. One of the base components. In the mid-1980s, image-measuring instruments with high magnification microscope eyepieces appeared on the market.
In the 1990s, with CC technology, computer technology, digital image processing technology, LED lighting technology. With the development of DC/AC servo drive technology, image measuring instrument products have achieved great development. More manufacturers enter the image measuring instrument product market, and jointly promote the development of image measuring instrument products.
Since 2000, the technical level in this field has been continuously improved in Our country. The image measuring instrument developed by domestic enterprises (such as Tianjun, Zhitai Yixin, Secco Digital, Xintian etc.) has also been improved and developed in terms of production scale, variety and quality. China set a national standard in 2009
GB/ T24762-2009: Acceptance inspection and reinspection inspection of PRODUCT Geometric Technical Specification (GPS) image measuring instruments, which are suitable for image measuring instruments in XY plane rectangular coordinate system, including image measuring instruments with positioning or measurement function perpendicular to the plane rectangular coordinate system in the Z direction.
It is worth mentioning that Tianzhun Precision Technology Co., LTD., which was founded by a group of young students with the ambition to revitalize China's precision measurement industry, developed and innovated on the basis of learning from foreign excellent products and formed its own characteristics and advantages. After years of unremitting efforts, Tianzhon company launched in 2007 for the first time in China with fully independent intellectual property rights of 3d automatic image measuring instrument series products, to fill the domestic gap, in the domestic image measuring instrument technology leading position.
2. Evaluation of image measuring instrument
This paper attempts to evaluate the image measuring instrument products from the instrument structure, key technical indicators and other aspects, due to the author's image probe. Is not covered because of lack of information.
(1) Appearance and structure
The appearance and structure of precision measuring instruments are the important basis for users to choose. Good product appearance and structure, give people a stable, reliable, precise feeling, is often an important factor to determine the success or failure of a product in the market.
At present, the structure of image measuring instrument mainly includes column structure, fixed bridge structure and moving bridge structure. Both the column structure and the fixed bridge structure are widely used in the small range image measuring instrument, each has its own advantages. The moving bridge structure is mainly used in the image measuring instrument with large range. The advantage of the column structure lies in its compact structure,
Small occupation site, easy to install the workpiece; Fixed bridge structure is characterized by stable, atmospheric products, but occupy a large site, installation of the workpiece is not very convenient; Moving bridge structure is easy to achieve large range measurement, the workpiece is fixed during the measurement process.
(2) Light source system
Light source system plays an important role in image measuring instrument, which directly determines the performance and function of an image measuring instrument. Good light source system can help image probe to obtain clear, sharp, uniform - correct image, ensure the accuracy and repeatability of measurement.
In order to achieve the realization of different materials, different shapes, different types of workpiece to provide effective lighting, complete complex measurement tasks, image measuring instrument usually provides three lighting sources: surface light source, contour light source, coaxial light source.
The surface light source provides illumination for measuring the upper surface of the workpiece. A good surface light source should be able to provide illumination from different incident angles and different incident directions to ensure that different workpieces get the lighting effect.
Contour light source provides illumination for measuring workpiece contour and through hole. Contour light source is usually installed on the base of the image measuring instrument, at work, the image is blocked by the part of the workpiece imaging black, no blocking part of the workpiece Angle to help the image probe to obtain black from clear, high contrast, clear boundary of the workpiece image. The instrument usually achieves the highest measurement accuracy under the illumination of contour light source.
The coaxial light source is projected to the workpiece surface along the optical axis of the lens, which can provide illumination for the measurement of the high reflectivity surface and deep hole parts of the workpiece.
(3) Multi-probe integration
The image probe has incomparable speed advantage in two-dimensional size measurement, but the image probe also has its disadvantages, in three-dimensional measurement, the measurement efficiency is not high enough, the side features of the workpiece can not be measured.
Therefore, there is a need for multi-probe integration, integrated use of image probe. Contact probe, laser probe and white light probe can select the most suitable measurement method for different workpiece and different measurement requirements, in order to provide the best measurement accuracy and the best measurement efficiency. Image measurement can be used for mass inspection of two-dimensional dimensions
Head; In the case of measuring the side wall of complex workpiece, but the efficiency requirement is not high, contact measurement can be selected; In 3d measurement of complex workpiece, white light probe or laser probe can be used if high efficiency is required.
(4) Measurement performance
Precision is the fundamental of measuring instrument, precision is one of the most important indicators for users to choose instruments. The measuring precision of image measuring instrument mainly depends on the quality of image probe. The performance of lighting source system, the precision of instrument motion and positioning, and the quality and level of data processing and measurement software and hardware are also very important factors.
As an automatic measuring instrument, the measurement efficiency of image measuring instrument is one of the most important factors for customers. High measurement efficiency can reduce equipment input, improve production efficiency, reduce labor costs, etc.
(5) Measurement function
The basic measurement function of the image measuring instrument usually includes: point line, circle, arc and other basic geometric measurement, in the measurement method, provide a variety of extraction and construction methods; Provide a variety of shape tolerance and position tolerance measurement; Provide a variety of coordinate system establishment methods; Provide manual measurement and automatic batch measurement; The batch measurement program can record the measurement elements, extraction methods, machine control, light source control, automatic focusing and other processes; Can import and export CAD drawings; The measurement data is output to a report in the specified format.
In addition to these basic measurement functions, instrument manufacturers often provide extended functions such as SPC, drawing comparison, off-line programming, and customized output reports. Some manufacturers will also develop corresponding special software or hardware for the measurement needs of specific user industries, and increase instrument measurement functions, such as small module gear measurement, test screen calibration, etc.
(6) Other aspects
The usability of the product, adaptability to the environment and humanization of the operating interface are also important factors to judge the performance of the instrument. Whether it is convenient to establish measurement tasks, formulate and output statements, machine control, etc., will affect users' acceptance of the instrument. Long-term instrument stability, measurement solution delivery, customer service response speed. Delivery cycle, customized development ability and so on are important factors that affect customers' choice of image measuring instrument products.
3. Comments on typical products at home and abroad
Image measurement: measuring instrument can be divided into scientific and industrial two categories. Scientific products have very high precision and very high requirements for the working environment and operators. At present, only a few manufacturers in the world have such products, and their market capacity is very small.
Industrial grade products occupy the largest share of the market. In industrial grade products, high precision, stable performance. The first-line brands with high efficiency and rich functions mainly include foreign Zeiss, Santoyo, Nikon, 0GP, Hexagon and domestic Tianjun Precision Technology companies. The brand products with 3d image measurement function developed by each of them represent the advanced level of industrial image measurement instrument. This paper intends to take a leading product of the same specification of these companies as the object to make a brief introduction and comparison.
Compared with other common imported brands and most domestic brands, there are still some gaps in overall quality.
(1) the Zeiss
Zeiss is a famous company in the field of industrial measurement, with a rich product line, and its CMM was once synonymous with high-end CMM. The most representative Zeiss imaging instrument is 0-NSPECT(see Figure 3). 0-NSPECT adopts fixed bridge structure, the product is beautiful and stable, with image probe and contact probe,
Two methods of detection.
(2) sanfeng
As a famous manufacturer of precision measuring instruments, Santoyo has a wide product line of image measuring instruments. Various models are available. Figure 4 shows its representative product QV-ELF202Pro. The product adopts fixed bridge structure. Product appearance is stable, too gas.
(3) days
Suzhou Tianzhon Precision Technology Co., Ltd. has been focusing on the research and development of precision measuring instruments for many years. It is the leading image measuring instrument brand in China and the drafting unit of two national calibration specifications. Its representative product VMU322 has the advantages of high measurement accuracy, fast measurement speed and rich functions (see Figure 5).
(4) the nikon
Nikon has strong technical strength and numerous products in the field of optical measurement instruments. Its typical product, VMR3020, is beautiful and delicate, with high measurement accuracy and comprehensive functions, as shown in FIG. 6.
(5)0GP
American 0GP Company has been committed to the development, production and sales of image measuring instrument products. It owns a number of core technologies of image measuring instrument, and its typical product ZIP250 is shown in Figure 7. It adopts a fixed column structure and has a high level of instrument technology.
(6) Hex
Sweden hexcom is a world-renowned manufacturer of length measuring instruments. At the beginning of 2010, it launched Optive series of image measuring instruments, among which Peformance222 is its representative product (see figure 8). This product is derived from Mahr technology, using column structure, stable structure, high precision, is an excellent image measuring instrument products.
客服1 