首页 | 官方网站   微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 53 毫秒
1.
在相位测量型光学三维面形测量中,最终都要将相位信息转换成被测物体的高度分布信息,这个过程往往是通过对已知世界空间坐标的特征点事先标定,获得测量系统的内外特征参数后,完成被测物体的三维坐标转换.因此,标定是三维面形测量的关键环节.本文基于双向二次相位-高度映射方法和摄像机针孔模型线性无畸变标定技术,充分利用傅里叶变换的频谱方向特性,提出了对含有特征点的二维标定物表面变形条纹的频谱进行方向滤波操作,同时获取测量系统XYZ三个方向上的标定数据,对测量系统进行立体校准的系统标定方法.结合旋转风扇叶片形变的测量系统,给出了该方法的标定结果:在XY面内(230mm×230mm)的标准偏差小于0.27mm;在Z方向上小于0.022mm,位移测量灵敏度优于0.05mm.该方法为测量系统的实用化奠定了基础.  相似文献   

2.
3D测量系统中的高精度摄像机标定算法   总被引:4,自引:0,他引:4  
本文在分析完整的摄像机镜头畸变模型的基础上,提出了一种新的标定算法.该算法包括三个步骤,首先在不考虑镜头畸变的情况下利用标定块上的中间若干个点,采用线性优化方法求出除畸变系数以外的其他外部参数和主要的内部参数;然后固定上述已求得的参数,利用线性优化方法求解畸变系数;最后对所有内部参数和外部参数进行全局非线性优化.最后对本文的标定算法进行了标定实验,实验结果表明,本文算法的标定精度可以达到0.0367 mm,可以满足高精度三维测量及其他应用的要求.  相似文献   

3.
基于交比不变性的投影仪镜头畸变参数标定方法   总被引:1,自引:0,他引:1  
利用了透视投影中的交比不变的性质,针对由CCD和投影仪组成的测量系统,在CCD已经标定的情况下,仅考虑投影仪畸变模型为一阶径向畸变的情况,只需要投影仪投射共线的投影坐标已知的4个点,利用交比不变性,建立一元二次方程就可以标定投影仪镜头的畸变参数.该方法的特点是算法简单,易于实施,需要已知条件较少.  相似文献   

4.
王芃芃  周虎 《光电工程》2012,39(1):103-107
为了提高基于视觉引导的经纬仪测量系统的测量效率,提出了一种对空间平面上目标点坐标进行精确瞄准测量的方法。利用激光电子经纬仪对目标做单轴扫描,进一步获得像平面扫描轨迹的平行网格模型,通过该模型建立了扫描线长度与经纬仪单轴旋转角度的关系,并对镜头畸变进行校正,最后利用插值算法得到经纬仪瞄准目标点时的精确角度值。实验结果表明,在矫正畸变后在 10 m×10 m空间内精度可达到 3″,该方法可以有效提高测量效率,保证测量精度。  相似文献   

5.
在采用LED的光源步进法三维测量系统中,由于LED发散角大,在短距离内就达到较大的条纹投影面积,造成系统工作距离短.另外大功率LED发光面尺寸大导致条纹对比度低,投影高亮度、高对比度的条纹困难.为解决上述问题,提出在光源步进法投影装置中采用激光二极管(LD)作为光源,实现高亮度、高对比度相移条纹投影.采用该投影装置与双目摄像机设计了便携、高速的三维测量系统.首先利用改进的傅里叶变换轮廓术获取变形条纹相位及调制强度;接着利用激光散斑的随机性,在调制强度图中实现双目图像的粗匹配;然后在粗匹配的基础上进行条纹相位展开,利用相位实现精匹配;最后获得待测物体三维形貌.利用设计的系统进行了实验验证.系统的测量体积为360 mm×290 mm×100 mm,采集的三维数据最多为1280×1024点.实现了100 f/s的三维形貌测量速度,对平面的测量标准偏差为0.19 mm,对5个间隔距离为1.00 mm的平面进行了测量,测量距离的平均误差为0.05 mm.  相似文献   

6.
为减小结构光投影视觉测量系统中相位失真对测量结果的影响,基于最小二乘法和线性插值方法,建立实际光栅相位与理想光栅相位映射关系,并以此关系对投影条纹的相位误差进行校正。在校正过程中,为满足线性插值的单调性、有效性和唯一性,对所采集到的相位进行线性拉伸变换,使其覆盖全部投射相位值,并引入微调函数使其形成单调变化的相位序列。为验证该方法的有效性,搭建由摄像机、投影仪组成的光栅投影结构光三维测量系统。实验结果表明:该方法能够对投影仪生成的光栅条纹的非正弦畸变进行补偿和校正,并最终给出合理的相位测量结果。该方法简单可行,可用于实际结构光测量系统的校正。  相似文献   

7.
数字图像相关测量中镜头成像畸变的估计和校正   总被引:3,自引:0,他引:3  
提出一种用于高精度数字图像相关测量的镜头成像畸变估计和校正方法.通过对由刚体平移实验得到的畸变位移场进行分析获得镜头的畸变系数,并根据畸变系数对畸变位移场进行校正.对一25mm固定焦距镜头的成像畸变进行估计,并进一步讨论了该镜头成像畸变对位移测量误差的影响.结果显示,可有效消除由镜头成像畸变引起的位移测量误差,达到高精度测量的目的.  相似文献   

8.
基于信标的摄影测量定位技术,提出了一种用于光电助降系统的双摄影测量算法.利用两台CCD 摄像机探测直升机两侧各四个信标,建立目标坐标系、摄像机坐标系和图像坐标系,根据信标、镜头中心和信标像点的共线性得到关于旋转矩阵和平移矢量的线性方程组,由此计算出直升机相对于着降点的位姿.设计了一套直升机光电助降实验系统,使用高性能DSP 系统进行实时图像处理,运用双摄影测量算法实时计算直升机着降引导信息.模拟实验结果表明,在两摄像机距离着降点8~13 m 范围内,光电助降实验系统的距离测量精度达到±5 cm,而角度测量精度达到±3°.  相似文献   

9.
针对面结构光三维测量中投影盲区导致出现无效相位区域的问题,提出了一种无效相位区域补偿方法.根据光栅投影法重建原理可知,无效区域的主值相位为参考平面对应的主值相位值.首先,由投影仪投射一幅具有均匀光强的白光图到被测钢板表面,使用CCD相机采集钢板表面背景图;其次,对其进行二值化,得到无效相位区域位置;然后,通过背景相位图替换,得到无效相位的真实相位,完成无效相位区域的补偿;最后,对一块带孔洞的钢板进行三维重建,对比分析无效相位区域补偿前后的孔洞直径测量结果.实验证明,无效相位区域补偿后孔洞测量精度为0.1 mm,补偿前孔洞测量精度结果为0.3 mm,因此该方法改善了阴影盲区导致的孔洞直径测量误差较大的缺点,在一定程度上提高了孔洞直径的测量精度.  相似文献   

10.
《中国测试》2017,(12):69-74
为适应精密元器件微小结构测量的需求,建立一种基于线结构光扫描的影像测量系统。系统采用自行研制的低畸变(优于0.02%)、大景深(大于5 mm)双远心光学镜头,在景深范围内,物像映射矩阵呈现良好的线性关系。对测量图像噪声抑制方法及结构光图像中线提取算法进行研究,用线性映射算法还原工件轮廓,实现微小结构的快捷测量。为保证测量的稳定,系统选择线激光光源并引入窄带滤光片,有效抑制背景噪声,在5 mm量程内,一阶误差补偿后的测量误差控制在-10~10μm内。测量系统对工件定位要求低,适用于精密零件台阶、倾角及微小异型面的常规测量,可满足基本的工业及计量检测要求。  相似文献   

11.
In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.  相似文献   

12.
13.
A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.  相似文献   

14.
On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……  相似文献   

15.
Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……  相似文献   

16.
In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M2(B,C), (W,Mo)2(B,C), M3(B,C), M23(B,C)6 type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm2. The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K1 mill housing of bar mill.  相似文献   

17.
A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.  相似文献   

18.
The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...  相似文献   

19.
Several researches have been reported about the characteristic of β-Ga2O3 nanowires which was synthesized on nickel oxide particle. But indeed, recent researches about synthesis of β-Ga2O3 nanowires on oxide-assisted transition metal are limited to nickel or cobalt oxide catalyst. In this work, Gallium oxide (β-Ga2O3 ) nanowires were synthesized by a simple thermal evaporation method from gallium powder in the range of 700 - 1000℃ using the iron, nickel, copper, cobalt and zinc oxide as a catalyst, respectively. The β-Ga2O3 nanowires with single crystalline without defects were successfully synthesized at the reaction temperature of 850, 900 and 950℃ in all the catalysts. But optimum experimental condition in synthesis of nanowires varied with the kind of catalyst. As increasing synthesis temperature,the morphology of gallium oxide nanowires changed from nanowires to nanorods, and its diameter increased. From these results, we could be proposed that the growth mechanism of β-Ga2O3 nanowires was changed with synthesis temperature of nanowires. Microstructure and morphology of Synthesized nanowire was characterized by HR-TEM, FE-SEM, EDX and XRD.  相似文献   

20.
Cubic boron nitride(c-BN) film was deposited on a Si (100) substrate by the RF-magnetron sputtering.The mainly problems for fabrication of c-BN films are the low purity and high intrinsic compressive stress. In order to solve the two problems, the c-BN film with the buffer interlayer was deposited on the substrate which had been implanted with nitrogen and/or boron ions. The results show: the implantation of nitrogen ions can obviously increase c-BN content and reduce the internal stress slightly; while the implantation of boron shows no obvious improvement to the content of c-BN, which can reduce the internal stress in the film obviously. In addition, it is suggested that the implantation of nitrogen and boron shows the best result, which not only can increase the content of c-BN, but also reduce the internal stress in the c-BN film obviously.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司    京ICP备09084417号-23

京公网安备 11010802026262号