线激光扫略的白车身装配特征机器人在线检测技术研究

为实现白车身装配特征位置参数的在线检测,监控和保障白车身焊接尺寸质量,研制了一种基于线激光摆动扫略的白车身装配特征机器人在线检测系统.提出了摆动式线激光单目视觉传感器的测量系统方案和传感器参数标定方法及传感器摆动运动标定方法;分析了传感器摆动采集光刀图像的特点,进而提出了面向孔槽、柱状类装配特征的光刀点云提取算法及位置参数计算方法;进行了系统集成,开发了在线检测系统,并展开工程应用验证.验证结果表明:本技术实现了对白车身各类装配特征快速、精密、稳定的检测.     

基于XGBoost的车身尺寸装配质量智能预测模型

针对汽车多级制造系统中传统机器学习方法处理多元数据样本时间久、精度低等问题,提出一种基于XGboost的车身尺寸装配质量智能预测模型,解决多级制造系统的车身装配精准预测控制问题。首先,通过对车身多级装配过程的分析,对数据样本进行预处理,建立基于Spearman系数的不同特征要素的绝对相关性矩阵;其次,对生产流程的相关数据实时采集、清洗及挖掘分析,提出数据分析流程与数据处理框架,建立基于XGBoost的车身尺寸装配质量智能预测模型,并通过对模型性能的有效评估实现对车身尺寸装配的精准控制;最后,仿真实例对比分析表明,基于XGboost的质量智能预测模型能精准地解决多级制造系统中的车身装配质量控制问题。     

机械装配偏差源及其偏差传递机理研究

分析和研究机械装配偏差源和偏差传递机理用于机械装配精度的预测,机械装备的偏差源按照装尺寸、形位精度、定位精度等影响装配功能的因素可以大致分为三类,即装配位置偏差、几何位偏差和几何形状偏差,建立偏差源的统一表达形式,分析机械装配中零件之间和零件内部的偏差传递机理以及相互作用,明确机械装配中偏差传递的偏差流类型,偏差流可通过偏差向图来进行表达,通过建立机械装配偏差有向图来表达偏差传递和装配功能之间的关系。本文就机械装配精度预测进行简单的说明,着重介绍了机械装配偏差源及其类型,并对机械装配偏差源偏差的传递机理进行了研究。     

装配尺寸式的研究

 以装配体内零件要素特征和装配关系信息量最大为目标,对装配体内的各种要素用文字进行描述;提出目标尺寸和相关尺寸概念,以装配基准为线索探索目标尺寸形成的过程,从而建立目标尺寸与相关尺寸之间关系的文字表达式——装配尺寸式,为计算机自动建立装配尺寸关系提供一条新的途径.      

完善的计量管理体系为车身质量护航

<正>作为奇瑞汽车进入发展第二阶段的代表作品,ARRIZO 7是自主品牌中完整运用与国际汽车行业通行做法接轨的正向开发模式打造出的首款产品,它不仅是奇瑞研发体系能力整体提升的体现,也是中国汽车工业历经60年发展,自主品牌逐级走向成熟的印证,具有"里程碑"的意义。汽车车身装配的典型特征之一就是柔性薄板冲压件多工位焊接,冲压件偏差和焊装夹具偏差是影响车身尺寸质量最主要的因素。在焊接过程中,由于薄板件刚性差易变形,为了保证零部件之间正确的相     

三坐标自动测量——角点参考测量法

在白车身三坐标自动测量中,存在因车身尺寸的漂移导致角点测量发生采点错误,从而产生粗大误差的现象,该文探讨了如何通过参考测量产生的反馈,使测量程序自动纠正粗大误差的原理和验证经过。     

Bootstrap重采样Bayesian方法在白车身制造尺寸不合格率估计中的应用

白车身质量是汽车整车质量控制中的重要环节,针对白车身制造尺寸质量控制中检测数据属于小样本数据、数据处理分析不能采用一般大样本条件下统计分析方法的问题引入Bootstrap重采样Bayesian方法。通过对白车身尺寸质量的不合格率进行定义,分析简单计算、滑动计算、β分布Bayesian计算等3种估计不合格率的方法,引入Bootstrap重采样技术结合Bayesian方法进行不合格率的估计,并通过Matlab软件对4种算法进行仿真比较。仿真结果表明,Bootstrap重采样Bayesian方法的预测精度高于其余3种方法,适用于小样本情况下白车身制造尺寸不合格率的估计。最后通过一个实例演示了Bootstrap重采样Bayesian方法在白车身制造尺寸不合格率估计中的应用流程。     

白车身顶盖激光钎焊焊缝装配尺寸控制方法研究

目的研究白车身顶盖与侧围激光钎焊装配尺寸控制方法,提高顶盖侧围激光钎焊焊缝装配精度,降低激光焊缺陷率。方法顶盖与侧围焊接配合形面由传统的面贴合设计更改为线贴合,降低对车身焊接合拼精度的要求;顶盖与侧围模具结构上采用整体整形及压料镶块提升零件的尺寸精度,避免因镶块交接造成的翻边面缺陷而影响激光钎焊质量;顶盖与侧围的成形焊夹具设计成y向浮动以及在激光焊夹具上设计z向夹紧功能,来实现侧围与顶盖装配间隙的调整。结果实际应用表明,侧围与顶盖激光钎焊装配尺寸得到了有效控制,满足激光钎焊的要求。结论顶盖与侧围产品的设计优化、冲压模具工艺和结构的创新和优化以及焊装焊接夹具的柔性化适配功能,可以有效保证白车身顶盖钎焊搭接部位尺寸精度。     

浅析门式起重机变型设计

在基因重组的基础上,提出建立装配变形设计的思想。对所装配产品的变型设计原理和变型设计方法进行分析和研究,通过定义装配产品中零件对象的信息模型,建立零件之间的尺寸约束关系模型。以装配门式起重机的部件刚性支腿为研究对象,构建出模型并验证变型过程。     

轿车车身测试技术

一、前言在轿车的制造过程中，车身设计、制造是最关键和复杂的环节之一。新车型的设计，往往要先做个泥车型，然后测试其形状和尺寸：根据测试数据，设计制造冲压模具；由模具冲压车身零部件，再组装成白车身。其中泥车模型、模具、白车身等均需测试。在生产过程中，白车身需要经常检测，冲压模具也要定期检测，以保证冲压件的尺寸和形状正确。二、冲压模具的测试轿车的车型属空间自由曲面，其中模具的测试即是对空间自由曲面的测试。一辆轿车的冲压模具数量很多，需要进行快速检测才能满足生产的要求。为此需研究在三坐标测量机上，采用非…     

Identification of the deviation from the mean and multimodal distribution in the automotive assembly process: Correspondence analysis approach

The dimensional integrity of an automobile is one of the key quality characteristics, since poor fit can impact not only the downstream production processes, but also the customer's perception of quality. Principal component analysis (PCA) has been widely used to identify patterns of dimensional variation in the automotive body assembly process. It enables engineers to find measurement points that have large variances but fails to identify the measurement points that have large deviation from the mean with small variances. Correspondence analysis (CA) was applied to identify the deviation from the mean and bimodal distribution of measurement points in the automotive body assembly process. Two case studies are presented. By applying both CA and PCA, we have a better understanding for the deformation patterns in automotive body assembly process.     

A Bayesian network approach for fixture fault diagnosis in launch of the assembly process

Verification and correction of faults related to tooling design and tooling installation are important in the auto body assembly process launch. This paper introduces a Bayesian network (BN) approach for quick detection and localisation of assembly fixture faults based on the complete measurement data set. Optimal sensor placement for effective diagnosis of multiple faults, structure learning of the Bayesian network and the diagnostic procedure are incorporated in the proposed approach. The effective independence sensor placement method is used to reach the desired number of optimal sensor locations, which provide the concise and effective sensor nodes to build the diagnostic Bayesian network. A new algorithm based on conditional mutual information tests is put forward to learn the Bayesian network structure. The body side assembly case was used to illustrate the suggested method and the simulation analysis was performed to evaluate the effectiveness of the diagnostic network. The work demonstrated that the proposed methodology composes a feasible and powerful tool for fixture fault diagnosis in launch of the assembly process.     

基于扭杆摆的汽车动力总成惯量参数测量实现

针对传统测量汽车动力总成惯量参数的繁琐操作,依据扭摆测惯量原理,设计了一个由称重传感器支撑的可升降的扭杆摆平台,利用三坐标仪建立动力总成坐标系,根据平台与总成上一些特征点的空间位置关系,求得任意姿态下动力总成坐标系各坐标轴与平台转轴的空间夹角,进而求得过动力总成质心惯量参数。标准块测试数据结果表明,利用该测量方法能够测得动力总成的惯性参数,且具有较高精度。     

The analysis of feature-based measurement error in coordinate metrology

Coordinate measurement systems (CMSs) dominate the dimensional control and diagnostics of various manufacturing processes. However, CMSs have inherent errors caused by the lack of a tracing ability for some of the measured part features. This is important for product inspection and process variation reduction in a number of automated manufacturing systems, such as for example the automotive body assembly process. The lack of a feature tracing ability means that instead of measuring a given feature, the CMS may actually measure the area around the selected feature. In this paper, a principle for the part feature tracing ability and the resultant feature-based measurement error analysis are developed to estimate the aforementioned deficiencies in the CMSs. The impact of feature type and part(s) positional variation on the feature-based measurement error is explored. The proposed approach is applicable to both contact and non-contact CMSs including both mechanical and optical coordinate measuring machines An analysis of the error for different measurement algorithms is presented. We show that the developed feature-based measurement error can have a significant impact on the measurement accuracy and hence on process control and the diagnostic algorithms currently used in manufacturing. A feature-based error map and error compensation approach are also developed and presented. Simulations, experimental results and two industrial case studies illustrate the proposed method.     

集合体──制图教材改革的重大突破

直接运用点集的理论定义各种几何元素,提出采用不同的集合操作方法,改变点的集合状态,得到不同形状的集合体的新概念。通过分析贴合面边界的有效性,研究形体表面某些特殊线段的处理,阐迷了集合体的构形过程及画图的原则。     

Understanding multivariate components – sheet metal assembly relationships using dimensional slow build studies

This paper presents a methodology to analyse and determine the effects of dimensional changes for multidimensional components through their assembly process. The methodology entails performing a series of measurement studies at different interim stages of a manufacturing process, i.e. a dimensional slow build study, and then analysing the part measurement data using a multivariate technique based on partial least squares regression (PLSR). Because of the high degree of collinearity among dimensional measurement points, PLSR is used to decompose assembly variance and is shown to be effective for analysing multidimensional sheet metal stamped components and their subsequent assemblies. The methodology presented in this paper is validated using a manufacturing case study of an automotive door assembly process studied during the launch of a new vehicle. The results of the case study show the importance of interim process measurements for diagnosing variation problems of assemblies with relatively high within-product correlation (measurements on the same part) and relatively low between-operation correlation (measurements from one operation to the next).     

飞机大部件位姿调整的关键测量特征点误差控制权值计算方法

为了实现飞机大部件的最佳位姿调整,基于层次分析-误差评定组合方法,研究了一种应用于综合评估数字化装配中关键测量特征点的误差控制权值的计算方法。采用引入权值的最小二乘法求解大部件位姿调整量,提高装配精度。通过层次分析(AHP)方法确定关键测量特征点主观权值,误差评定法确定关键测量特征点客观权值,两者结合综合评定关键测量特征点权值。以最小装配误差为优化目标,利用权值实现多个关键测量特征点的误差分配优化。实例分析中,将超差的对接交点误差由1.23 mm降低到了0.72 mm,满足各个测量点的容差要求。以奇异值分解算法求解目标优化初值,采用牛顿法迭代求解,得到部件的最优位姿,并以中后机身对接为对象分析验证权值分配的合理性。     

基于点云三维重构的配合面装配间隙分析方法研究

在大型航空复合材料零部件装配过程中难免出现装配对接间隙,由于间隙较小,当构件固定之后内部间隙不可达,难以测量。因此,为了克服这一难题,完成装配体小间隙的测量,本文提出了利用逆向重建和虚拟装配的方式进行装配间隙测量的方案。本文基于大型航空复合材料零部件测量的背景,结合双目视觉测量原理,采用视觉与激光相结合的测量方式,研究从点云获取至装配仿真模型的逆向重建技术,在CATIA的虚拟环境下完成装配间隙的测量。     

A new method for measurement of three dimensional residual stresses in a multi-pass butt welded joint

In this paper, a new method for the measurement of three dimensional residual stresses in a multi-pass butt welded joint is presented. The method involves the measurement of strain changes at a through hole surface as a coupon of material with the hole is separated from the body of interest and split. The finite element calculations are used to relate the strain changes at the measurenent points to the initial residual stresses at the hole location. The accuracy of the method is demonstrated by using it to measure a known stress field in a bent beam. The method has been used to measure the through thickness distribution of three dimensional residual stresses in a multi-pass butt welded joint. It could also be applied to the measurement of residual stresses in other welded joints.     

三维坐标转换精度及其影响因素的研究

为了对大空间组合测量中的三维坐标转换精度进行分析,指导现场测量公共点的布置方案,通过对坐标转换参数的最小二乘不等精度估计,建立了坐标转换精度在空间中分布的数学模型.通过模型可以得到空间中任意被测点的转换精度,并且转换精度受到公共点的测量点位误差及其几何分布的影响.最后结合多个公共点三维坐标数据分析了转换精度影响因素.实验表明,通过改进公共点坐标测量精度及几何分布能够有效地提高三维坐标转换精度.