共查询到20条相似文献,搜索用时 15 毫秒
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精确补偿磁测误差是确保地磁导航精度的一项关键技术。针对磁干扰补偿问题,提出了一种改进的基于模糊自适应卡尔曼滤波的矢量补偿方法。该方法对卡尔曼滤波中的观测矩阵进行修改,有效地解决了某些参数收敛过慢的问题;通过监视实时得到的量测新息的实际方差与理论方差的比值,应用模糊控制理论对卡尔曼滤波的量测噪声协方差进行递推修正,使其逐渐逼近真实噪声水平,进而得到最优估计参数。仿真结果表明,该方法对于时变的量测噪声具有较强的自适应性,总场补偿误差从175.8 nT降低到6.7nT,X、Y、Z方向的补偿误差分别由59.2、110.2、122.2 nT降低到6.0、1.7、1.5 nT,总量和分量补偿精度显著提高。最后通过构建矢量测量系统实验验证了改进方法具有较快的收敛速度且具有更高的补偿精度,为磁场测量误差矢量补偿提供了良好的借鉴。 相似文献
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Calculation of the unit normal vector using the cross-curve moving mask method for probe radius compensation of a freeform surface measurement 总被引:1,自引:0,他引:1
This paper proposes a cross-curve moving mask method to calculate the unit normal vector based on 5 or 9 data points of a freeform surface measurement for probe radius compensation. This is done in order to simplify the calculation and thus, produce a more efficient and time-saving process. Passing through the middle point and 4 or 8 neighboring points, two crossed curves – longitude and latitude can be constructed. The unit normal vector at the middle point can be determined by calculating the cross product of two tangent vectors along these two crossed curves. Different curve fitting methods for the curves passing through 5 or 9 data points, such as Bézier and B-spline methodologies, have been investigated. Three kinds of surfaces, namely, a spherical surface, a cosine-like surface and a shoe-shaped surface (hereby termed “shoe last”) are selected for evaluating the accuracy of the calculated unit normal vectors. 相似文献
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为了简化光纤磁场与温度传感器的结构并提高传感器灵敏度,设计并制作了马赫-曾德尔干涉集成化的全光纤磁场与温度传感器。将单根光纤的马赫-曾德尔模间干涉结构和双臂马赫-曾德尔干涉结构结合:将总长度为1.2m的单模光纤部分制备成长度为2.7cm、锥腰直径为30.1μm的锥形微纳光纤,并得到了拉锥时间与锥腰直径的关系。将锥形微纳光纤放置尼龙槽内并包覆磁凝胶构成传感头,实现模间干涉的马赫-曾德尔磁场传感器;将磁场传感器通过两耦合比为50%∶50%的耦合器并联带有可调谐光衰减器的单模光纤形成马赫-曾德尔干涉的温度传感器。从理论上分析了光谱漂移对磁场和温度传感的特性关系,实验测得室温下磁场强度在25~50mT时,磁场传感的灵敏度为0.301 14nm/mT;在磁场强度为0,温度由25℃升高到30℃时,温度传感的灵敏度为0.518 86nm/℃。该传感器可广泛应用于电力系统放电检测、材料加工、安全监控等领域。 相似文献
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《Measurement》2016
When measuring the tooth flank of hypoid gear, the measurement datum surface (the large end surface of the gear) does not always coincide with the design bases (the theoretical mounting distance), and this non-coincidence error would affect the tooth flank measurement results. Based on the measurement theory of the hypoid gear tooth flank, a precision matching method of the theoretical tooth surface and the measured tooth surface is designed, the objective function of the tooth flank matching method is established, and the search iterative method was used to calculate the compensation value of the measurement error of the tooth flank, when the two gear tooth surface is most accurately matched. As the mounting distance of the hypoid gear changes, two experiments are done to verify the proposed method. The experiment results show that, for different tooth flank of the measured gear, the measuring error of the tooth flank along Z-axis dropped significantly after compensated by this method, more than 80% of the error along Z-axis are compensated. It is obvious that this method could improve the measurement accuracy of the tooth flank form of hypoid gear. 相似文献
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基于椭圆约束的新型载体磁场标定及补偿技术 总被引:7,自引:1,他引:7
在地磁导航中进行地磁测量时会受到载体磁场的影响,因此必须对测量数据中的载体磁场进行精确补偿,以提高磁场测量精度.本文根据硬磁材料磁场和软磁材料磁场的数学模型,提出了一种基于椭圆约束的载体磁场标定及补偿方法.该方法首先采用带椭圆约束的最小二乘拟合方法对捷联式磁传感器测量数据进行椭圆拟合,保证了拟合曲线必为椭圆,从而实现载体磁场的准确标定,然后利用标定参数实现对载体磁场的精确补偿.最后进行了一系列的仿真试验.试验结果表明了该方法具有简单快速,易于实现的特点,可以达到与磁传感器等精度的补偿效果,且在低信噪比情况下具有较强的鲁棒性 相似文献
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针对三轴磁力仪在磁场测量过程中的磁干扰问题,提出了基于阻尼粒子群优化算法的磁测误差补偿方法。建立了磁力仪误差和载体磁干扰的一体化误差补偿模型,分别采用阻尼粒子群算法和Two-step方法对非线性观测模型进行参数估计。以质子磁力仪数据作为真值,借助无磁转台充分连续采样,实验结果显示,阻尼粒子群算法对于磁场测量误差具有良好的抑制作用。补偿后,由阻尼粒子群算法和Two-step方法得到的均方根误差分别由1 025.7降至60.304 4、581 n T。结果表明,阻尼粒子群算法取得了更好的补偿效果,补偿精度提高了至少一个数量级,为磁场测量误差提供了一种非常有效的补偿方法。 相似文献
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An integrated error compensation method based on on-machine measurement for thin web parts machining
Thin webs are widely used in the aerospace industry for the advantages of compact structure, light weight and high strength-to-weight ratio. Due to its low rigidity, serious machining error may occur, therefore, Finite Element method and mechanism analysis are usually utilized to modeling its deformation. However, they are very time-consuming and only suitable for elastic deformation error. In this study, an integrated error compensation method is proposed based on on-machine measurement (OMM) inspection and error compensation. The OMM inspection is firstly applied to measure the comprehensive machining errors. The Hampel filtering is then used to eliminate outliers, followed by the triangulation-based cubic interpolation as well as a machine learning algorithm which are used to establish the compensation model. At last, the real time compensation of high-density cutting points is realized by developing the compensation system based on External Machine Zero Point Shift (EMZPS) function of machine tool. Three sets of machining experiment of a typical thin web part are conducted to validate the feasibility and efficiency of the proposed method. Experiment results revealed that after compensation, the comprehensive machining errors were controlled under different machining conditions and 58.1%, 68.4% and 62.6% of the machining error ranges were decreased, respectively. This method demonstrates immense potential for further applications in efficiency and accuracy improvement of thin-walled surface parts. 相似文献
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介绍二维加工条件下刀具半径补偿原理及算法,提出一种基于方向余弦的转接矢量算法,给出在不同转接条件下基于方向余弦的转接点坐标值的计算方法,其算法简单、方程为显式,适于控制系统的控制速度要求。 相似文献
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针对目前动态测量误差序列预测方法的局限性,提出了动态测量误差序列的支持向量机非线性组合预测方法,以进行误差修正,提高动态测量精度.该方法首先利用支持向量机和小波神经网络对动态测量误差序列分别进行预测,然后再运用支持向量机对单项预测结果进行非线性组合.理论分析和预测实例表明:该方法的预测精度明显高于传统的单一预测方法,具有很强的学习与泛化能力,在处理动态测量误差序列的预报问题和提高动态测量精度方面具有很好的应用价值. 相似文献
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针对单光束SERF原子磁强计磁补偿过程中的三轴磁场耦合问题,提出了一种对磁强计三轴顺序补偿值进行反向校准的方法,用于减小三轴补偿过程中产生的耦合磁场。首先,构建了三轴磁场耦合数学模型,即一个3×3的耦合系数矩阵,来描述三轴之间的磁场耦合关系,并对实验室磁强计样机进行了三轴耦合系数测试。然后,提出了一种应用三轴耦合系数对三轴顺序补偿值进行反向校准的方法;最后,对比了校准前后的磁补偿效果。实验表明,经三轴顺序补偿反向校准后,磁强计的响应线宽平均变窄2~10 Hz,灵敏度提高3~5 fTHz1/2,验证了该方法的有效性,为进一步优化磁补偿技术奠定了基础。 相似文献
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基于 3D 打印技术制备曲面共形电路具有广阔的应用前景,然而,由于曲面基材加工误差和导电线路定位误差的影响,
导致曲面电路 3D 打印头高度难以精确控制,进而影响打印精度。 为此,本文以气动式直写打印为研究对象,提出了一种“在机
测量+线路模型重构”的打印头高度误差补偿方法。 设计了一种曲率自适应测量点选取方法,利用 NURBS 曲线反算法对测量
数据进行重构,还原真实线路模型。 通过生成真实线路的打印轨迹,替换原始理论打印轨迹,补偿了打印头高度误差。 自主搭
建了一套集成了在机测量系统的曲面共形电路 3D 打印平台,设计了直线、圆弧与 NURBS 自由曲线 3 种形状的线路,进行补偿
前后电路打印的对比实验。 结果表明,未进行补偿前,在线路曲率较大的地方,线路在基板上的波峰处会产生拉丝现象,波谷处
会产生堆叠现象,而补偿后的导线线宽比较均匀;进一步对每条导线的电阻进行测量,发现各条线路补偿前的电阻值波动较大,
补偿后的电路的电阻值均匀,且相较补偿前平均降低 65. 99% ,最大电阻降幅达 85. 75% 。 相似文献
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A current measurement method through magnetic field detection by magnetic force microscopy was proposed and demonstrated. We observed the magnetic field induced by an AC below 2.2 μA around a GaAs/AlGaAs mesa stripe. To achieve high sensitivity in magnetic field detection, we tuned the AC bias frequency to the torsional resonant frequency of the cantilever. As a result, the sensitivity of the magnetic field detection was much improved and specific features of the magnetic field around the mesa stripe were clearly observed at a current in sub-μA range. 相似文献
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Light field imaging technology can obtain three-dimensional (3D) information of a test surface in a single exposure. Traditional light field reconstruction algorithms not only take a long time to trace back to the original image, but also require the exact parameters of the light field system, such as the position and posture of a microlens array (MLA), which will cause errors in the reconstructed image if these parameters cannot be precisely obtained. This paper proposes a reconstruction algorithm for light field imaging based on the point spread function (PSF), which does not require prior knowledge of the system. The accurate PSF derivation process of a light field system is presented, and modeling and simulation were conducted to obtain the relationship between the spatial distribution characteristics and the PSF of the light field system. A morphology-based method is proposed to analyze the overlapping area of the subimages of light field images to identify the accurate spatial location of the MLA used in the system, which is thereafter used to accurately refocus light field imaging. A light field system is built to verify the algorithm's effectiveness. Experimental results show that the measurement accuracy is increased over 41.0%compared with the traditional method by measuring a step standard. The accuracy of parameters is also improved through a microstructure measurement with a peak-to-valley value of 25.4%and root mean square value of 23.5%improvement. This further validates that the algorithm can effectively improve the refocusing efficiency and the accuracy of the light field imaging results with the superiority of refocusing light field imaging without prior knowledge of the system. The proposed method provides a new solution for fast and accurate 3D measurement based on a light field. 相似文献
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为使测量机完成空间旋转曲面及3D轮廓面的测量,提出等分度测量法及等距测量法。关闭测针半径补偿按技术要求测量空间曲面上4个测量点,利用其中3个测量点在空间曲面上建立投影面为"正三角形"的"微型三角形",另一个测量点的投影在该正三角形中为重心点,以该测针中心坐标为其测量目标点,即方法1;也可以计算出该"微型三角形"的重心坐标为测量目标点,即方法2。应用向量计算该"微型三角形"法矢量,启动测针半径补偿做该空间轮廓的精密测量;用标准球作3D实验探讨"正三角形高"的取值;应用DEAPPL语言设计程序,一次性快速完成空间曲面上4条曲线的测量及其8个数据文件的生成,该文件组可应用于逆向工程、计量检定及曲面的分析研究和改进。按上述方法设计的程序经标准球实验,测量精度可达平均偏差0.001 mm以内,对应标准偏差在0.002 mm以内,能广泛用于高速烟机设计中对空间旋转曲面或3D轮廓面的测量及制造;在我国制造行业,能完成对叶片、叶轮的测试和反求,并为三维空间曲线面的测量提出一种新方法。 相似文献
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介绍了一种基于声学法的工业锅炉温度场的重组测量方法。以最小二乘法为基础.阐述了二维温场重建的基本原理、步骤。针对燃烧时出现单峰对称温场,双峰温场等不同情况.对工业锅炉二维温场重建进行了仿真,通过各项误差指标.证明了仿真结果的正确性。 相似文献
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钢绞线是大跨度桥梁必不可少且最重要的受力构件之一,但受必需的防腐蚀措施影响,目前仍缺乏有效的在役桥梁钢绞线应力检测监测方法。超声导波在钢绞线中传播带有明显的应力特征,通过在时 频域内进行导波信号的小波包分解提取不同应力状态下小波包分解系数矩阵,并以系数矩阵的奇异值向量为特征参量,建立具有学习能力的支持向量回归模型检测钢绞线应力值。结果表明,导波的奇异值向量是有效的应力特征参量,逐级加载过程中奇异值向量距与钢绞线应力值呈单调线性变化关系;以奇异值向量构建的支持向量回归模型预测钢绞线应力,其结果确定系数达到0973 9,对比神经网络方法,支持向量回归模型应力预测结果更为稳定。 相似文献