Analysis of Effective Working Hours of Automatic Assembly Equipment for Aircraft Assembly Stations

To improve the accuracy of capacity analysis and prediction for the aircraft assembly stations,an approach for calculating the effective working hour(EWH)of automatic assembly equipment is introduced by using the dynamic mixed Weibull distribution(DMWD)model.Firstly,according to the features of aircraft assembling,a DMWD model considering the dynamic reliability of multiple subsystems and their synthetic effects on the whole equipment is established.A typical automatic drilling&riveting machine is selected as the research object,and the dynamic weights of reliability of three subsystems are modeled and solved.Subsequently the unknown parameters of the DMWD model are estimated based on maximum likelihood estimation(MLE)and Newton-Raphson method.Finally,the EWH of an automatic station is defined and modeled by using the solved dynamic reliability function.Based on the experimental study on a real automatic drilling&riveting machine from a wing panel assembly station,it is shown that the proposed DMWD and EWH models could effectively calculate the equipment reliability with full consideration of its multiple subsystems.The DMWD model is more suitable for improving the solution precision of EWH than the traditional three-parameter Weibull distribution.

A Laser Line Scanner Based Hole Position Correction Mechanism for Automatic Drilling and Riveting in Aircraft Assembly

The low-stiffness of aircraft skins may results in the differences between aircraft actual parts and their theoretical models,which will consequently affect the accuracy of automatic drilling and riveting in aircraft assembly.In this paper,a novel approach of hole position correction using laser line scanner(LLS)is proposed to assign a single row of holes on the parts’surfaces.First,we adopt a space circle fitting method and the random sample consensus(RANSAC)to obtain the precise coordinates of center of the datum holes’coordinates.Second,LLS is calibrated by the laser tracker,and the relations between the LLS coordinate system and the tool coordinate system(TCS)can be calculated.Third,the kinematics model of the automatic riveting machine is established based on a two-point referencing strategy proposed in this paper.Thus,the positions of the holes to be drilled can be adjusted.Finally,the experimental results show that in TCS the measurement error of LLS is less than 0.1 mm,and the correction error of the hole position is less than 0.5 mm,which demonstrates the reliability of our method.

Automatic Modification of Local Drilling Holes via Double Pre-Assembly Holes

Manufacturing accuracy, especially position accuracy of fastener holes, directly affects service life and security of aircraft. The traditional modification has poor robustness, while the modification based on laser tracker costs too much. To improve the relative position accuracy of aircraft assembly drilling, and ensure the hole-edge distance requirement, a method was presented to modify the coordinates of drilling holes. Based on online inspecting two positions of pre-assembly holes and their theoretical coordinates, the spatial coordinate transformation matrix of modification could be calculated. Thus the straight drilling holes could be modified. The method improves relative position accuracy of drilling on simple structure effectively. And it reduces the requirement of absolute position accuracy and the cost of position modification. And the process technician also can use this method to decide the position accuracy of different pre-assembly holes based on the accuracy requirement of assembly holes.

Integrated Virtual Assembly Process Planning System

Assembly process planning（APP） for complicated products is a time-consuming and difficult work with conventional method. Virtual assembly process planning（VAPP） provides engineers a new and efficiency way. Previous studies in VAPP are almost isolated and dispersive, and have not established a whole understanding and discussed key realization techniques of VAPP from a systemic and integrated view. The integrated virtual assembly process planning（IVAPP） system is a new virtual reality based engineering application, which offers engineers an efficient, intuitive, immersive and integrated method for assembly process planning in a virtual environment. Based on analysis the information integration requirement of VAPP, the architecture of IVAPP is proposed. Through the integrated structure, IVAPP system can realize information integration and workflow controlling. In order to mode/the assembly process in IVAPP, a hierarchical assembly task list（HATL） is presented, in which different assembly tasks for assembling different components are organized into a hierarchical list. A process-oriented automatic geometrical constraint recognition algorithm（AGCR） is proposed, so that geometrical constraints between components can be automatically recognized during the process of interactive assembling. At the same time, a progressive hierarchical reasoning（PHR） model is discussed. AGCR and PHR will greatly reduce the interactive workload. A discrete control node model（DCNM） for cable harness assembly planning in IVAPP is detailed. DCNM converts a cable harness into continuous flexed line segments connected by a series of section center points, and designs can realize cable harness planning through controlling those control nodes. Mechanical assemblies （such as transmission case and engine of automobile） are used to illustrate the feasibility of the proposed method and algorithms. The application of IVAPP system reveals advantages over the traditional assembly process planning method in shortening the time-consumed in assembly planning and in minimizing the handling difficulty, excessive reorientation and dissimilarity of assembly operations.

Design of Drilling and Riveting Multi-functional End Effector for CFRP and Aluminum Components in Robotic Aircraft Assembly

To fulfill the demands for higher quality,efficiency and flexibility in aviation industry,a multi-functional end effector is designed to automate the drilling and riveting processes in assembling carbon fiber reinforced polymer(CFRP)and aluminum components for a robotic aircraft assembly system.To meet the specific functional requirements for blind rivet installation on CFRP and aluminum materials,additional modules are incorporated on the end effector aside of the basic processing modules for drilling.And all of these processing modules allow for a onestep-drilling-countersinking process,hole inspection,automatic rivet feed,rivet geometry check,sealant application,rivet insertion and installation.Besides,to guarantee the better quality of the hole drilled and joints riveted,several online detection and adjustment measures are applied to this end effector,including the reference detection and perpendicular calibration,which could effectively ensure the positioning precision and perpendicular accuracy as demanded.Finally,the test result shows that this end effector is capable of producing each hole to a positioning precision within ±0.5 mm,aperpendicular accuracy within 0.3°,a diameter tolerance of H8,and a countersink depth tolerance of±0.01 mm.Moreover,it could drill and rivet up to three joints per minute,with acceptable shearing and tensile strength.

Realization Techniques of Virtual Assembly Process Planning System

The key realization techniques of virtual assembly process planning （VAPP） system are analyzed, including virtual assembly model, real-time collision detection, automatic constraint recognition algorithm, cable harness assembly process planning and visual assembly process plan at the workshop. A virtual assembly model based on hierarchical assembly task list （HATL） is put forward, in which assembly tasks are defined to express component assembling operations and are sequentially and hierarchically organized according to different subassemblies, which can perfectly model the construction process of product, And a multi-layer automatic geometry constraint recognition algorithm of how to identify assmbly constraint relations in the virtual environment is proposed, then a four-layer collision detection algorithm is discussed. A VAPP system is built and some simple mechanical assemblies are used to illustrate the feasibility of the proposed method and algorithms.

Approach to Interference Riveting Process Control of Aircraft Automatic Drilling and Riveting

Interference fit riveting is an effective way to improve the fatigue life of aircraft.The accurate control of riveting interference of aircraft automatic drilling and riveting equipment is achieved by process parameters including upsetting force and upset head height.It is valuable for aircraft manufacturing engineering.An approach to interference riveting process control based on the analysis of interference riveting stress field is proposed.According to assembly structure,the upsetting force is calculated by the material property and interference fit level,and the upset head height is deduced by the upsetting force.The experimental result shows that the interference fit level can be controlled accurately by the upsetting force and upset head height,and then,the quality of aircraft automatic riveting can be improved.The proposed approach is verified by the good match between the predicted result and the experimental result.

Immune and Genetic Algorithm Based Assembly Sequence Planning

In this paper an assembly sequence planning model inspired by natural immune and genetic algorithm (ASPIG) based on the part degrees of freedom matrix (PDFM) is proposed, and a proto system — DSFAS based on the ASPIG is introduced to solve assembly sequence problem. The concept and generation of PDFM and DSFAS are also discussed. DSFAS can prevent premature convergence, and promote population diversity, and can accelerate the learning and convergence speed in behavior evolution problem.

机器人人工拣选环境下混流装配线齐套物料配送优化

为了提高汽车制造企业配送的智能化水平、解决混流装配线齐套物料人工拣选效率低、成本高的问题,引入基于齐套物料配送策略的机器人人工拣选模式,通过优化自动拣选机器人、工人的配置数量及配送周期,使包含机器人使用成本、劳动力成本和在制品库存成本在内的总成本最小。为求解该配送优化问题,提出了改进量子蚁群算法,利用量子比特的叠加性增加种群多样性,避免算法陷入局部最优,同时设计了改进量子旋转门更新机制和基于差分进化操作的非最优个体优化策略,提高了算法收敛速度和寻优质量。最后,通过算例分析验证了模型的正确性与算法的有效性,并分析了拣选批量对总成本的影响。

面向RISC-V的基础数学库实现

RISC-V指令集架构(Instruction Set Architecture,ISA)作为一种新兴的精简ISA,因免费、开源、自由等特点而得到快速发展.由于国内外对RISC-V的研究主要集中在硬件开发,软件生态相较于成熟ISA还很薄弱,实现一套RISC-V指令集高性能基础数学库可以进一步丰富RISC-V软件生态.本文基于自动化移植技术实现申威数学库到RISC-V的移植,为RISC-V指令架构提供首个使用向量指令优化的基础数学库系统.本文提出向量寄存器自动分支查表法与路径标记插入法,重点解决不同架构间寄存器映射过程中的寄存器复用问题,实现寄存器正确高效映射,并依据不同指令等价转换策略自动化移植数学函数69个.测试结果表明,RISC-V基础数学库函数可实现正确计算,最大误差为1.90ULP,函数性能平均为157.03节拍.

触发开关自动化装配与调测系统设计

在触发开关生产过程中,实现自动化和智能化是提升产能保证装调质量的先决条件。针对触发开关自动装调和检测的问题,设计一套触发开关自动化装调系统,提出一种动作过载调测自主学习算法,实现触发开关螺钉拧紧距离的自动调测。利用机器视觉方法对装配过程中的关键部件进行缺陷检测,以快速完成装配质量检测。该系统可实现触发开关的自动装配、铆接、检测、调测、灌封和固化等功能。

双目结构光视觉引导的螺栓自动装配系统设计

为解决螺栓自动化装配过程中存在的零件位姿快速获取和在弱纹理、反光等复杂场景中实现精确定位等难题,基于双目结构光视觉原理,研制了一套螺栓自动装配系统。首先,通过双目结构光视觉系统获取工件场景的三维信息,涉及光栅条纹图案的获取、双目标定、多频外差法求解绝对相位、相位校正、极线校正、立体匹配,接着采用欧式聚类对重建的点云数据进行分割,获取单个螺栓的三维点云聚类,然后利用迭代最近点(ICP)算法估计模板点云到目标点云的位姿变换矩阵,识别连接螺栓在空间中的位姿,最后结合机械臂末端进行自动装配拧紧。实验结果表明,整个装配过程可自动完成,单个螺栓拧紧装配时间约为10 s,系统测试平均轴孔对中误差不超过1.20 mm,误差标准差不超过0.11 mm。

基于虚拟现实技术的杯盖装配智能生产线设计

为解决传统机械自动化设计周期长、效率低、成本高等困境,将虚拟现实技术与传统设计相结合,提高传统设计的效率和数字化。以某企业的保温杯的杯盖装配自动化生产线设计为案例,分析虚拟现实技术与机械自动化设计的融合方法和路径。首先将虚拟现实技术应用到机械设计的模型构建上,并对机械零件装配的仿真模拟,模拟其在虚拟环境中的运动,明确机械零件的运动轨迹,记录机械零件运动时的坐标,保障虚拟装配的准确性;其次利用虚拟现实技术实现虚拟装配,实现机械零件在虚拟环境中的拆装展示,支持设计人员与虚拟环境的交互。利用虚拟现实技术,实现了对杯盖装配自动生产线的设计,使设计真能够更清楚地了解到产品设计的效果,不仅降低了开发生产线所需的成本,而且减少了复杂的生产线物理模型,测试生产线所需的场地维护费用也随之降低。同时大幅缩短了生产线设计时间,使产品快速、高效地投向市场。

涡旋盘非标自动化装配设备研发

空调压缩机中的涡旋盘正背面需要装配销钉和阀片。目前该道工序主要是由人工完成,劳动强度大,效率低,次品率高。针对这种现状,根据涡旋盘装配的特点,设计了一套涡旋盘自动装配装置,详细介绍了总体设计方案、结构布局、机械结构、电气结构和控制系统。设备主要分为涡旋盘上料工站、定位销自动压装工站和阀板自动安装与气密性检测工站,电气控制部分采用三菱IQ-F系列80点的PLC,外加128点的扩展IO以及4路模拟量输入,方便以后PLC并入MES系统,并且该系列具有较好的FB功能,可以将一些通用的控制方式写入FB,方便今后类似的设备直接调用调试好的程序,避免重写带来的不必要麻烦,考虑到有3个伺服电机,方便伺服与PLC通讯,减少焊线带来的不必要的问题,采用三菱JET系列的伺服,与PLC进行CC-LINK IE TSN组态,使用绝对值系统,即使断电后,伺服放大器依旧能识别电机的位置。经实践该套装置大大提高了生产效率、提高了产品质量、降低了人工成本。

精密加速度计组件自动装配及焊接系统

悬丝摆式加速度计广泛应用于航空、航天、惯性导航等领域,其装配质量对加速度测量精度有很大的影响,其关键组件的装配涉及位置和姿态的调整,同时悬丝在装配中需要控制张紧力并完成焊接。针对悬丝摆式加速度计组件的精密装配,研发了集成力、温度传感器和机器视觉的精密装配及焊接系统。采用相机配合转台实现待装配零件视觉测量,完成零件特征点的识别定位;利用精密滑台和转台调整待装配零件位姿;直线电机运动结合力反馈实现装配过程中零件间隙调整以及张紧力控制;开发专用焊接单元,实现在紧凑空间内对微小器件的自动温控焊接。试验结果表明,该系统能够完成加速度计组件自动装配及焊接,装配结果满足技术指标要求,焊点无虚焊,摆组件内边缘相对于磁钢边缘间隙偏差小于10μm,悬丝中心相对于加速度计底座地面位置精度优于20μm,悬丝张紧力偏差控制在±5 mN之内,能够达到产品装配质量要求。

长短焦双目三维成像算法研究与精度分析

针对复杂三维装配过程中提高三维位置精度会导致视野变窄造成三维装配定位失败的问题,提出一种基于自适应缩放因子估计的长短焦距双目三维成像算法。该算法先根据长短焦相机获取2幅图像的特征匹配结果估计特征尺度缩放因子并且实现特征尺度的归一化,再通过半全局立体匹配算法得到双目视差,最后计算出目标的三维点云。长短焦距成像和同焦距成像精度与视野大小的对比实验结果表明,该算法在感兴趣区域内与同焦距双目系统计算视差的最小错误估计比例小于2.6%,系统观测视野扩大32%。

锂电池电芯电极自动装配系统的设计与实现

针对块状锂电池电芯电极装配时,电芯电极装配定位不准确、效率低、安全性不高等问题,研究锂电池电芯电极的装配要点和生产特征,设计一种电芯电极装配工艺流程和与之相匹配的执行机械结构,并结合现场总线网络通信技术,设计出电芯电极装配控制系统。从机械结构方面入手着重探讨电芯电极装配的电芯翻面供给结构、方位矫正与传输机构、多工位移送结构、电芯电极装配结构、绝缘纸粘贴结构和下料结构的六级联动装置,再基于西门子PLC搭建通信网络拓扑结构,设计出控制程序算法步骤实现零件自动上料、电芯电极的自动装配及自动移送和下料过程,并建立电芯电极装配全过程、可视化的在线管理系统。该电芯电极自动装配控制系统已经在锂电池生产企业中得到应用,经济效益明显。

一种变速箱离合器自动安装机构的设计

离合器是变速箱的重要核心组件,也生产装配工艺中重要的环节。本文介绍了离合器在变速箱装配生产线上实现自动装配的方法和自动装配机构的设计,该自动装配机构和工业机器人组合应用,利用PLC作为电气控制核心,采集外部信号,通过Profinet总线网络与机器人交互信息,实现对离合器的自动化装配。这个机构设备可以很好的解决离合器在安装时容易磕碰到输入轴齿和油泵斜齿轮的问题。对工厂来说,解决了人工装配中的难点痛点,也节省了成本,提升变速箱的装配质量和效率。从自动装配行业来说,未来发展趋势是向着无人的方向发展,为以后提高变速箱装配线的自动化水平提供参考。

自动拧紧设备在汽车装配中的应用研究

随着近年来汽车行业的崛起,汽车工业已成为中国支柱型产业。随着工艺技术的不断优化,汽车装配过程中的各种拧紧设备也在不断发展变化。本文以半轴自动拧紧设备、变速箱悬置自动拧紧设备和多规格螺母自动拧紧机为例,介绍了自动拧紧设备在汽车装配中的应用,自动拧紧设备的应用,为汽车装配效果和效率的优化提供强大支撑,随着科学技术不断发展,必将涌现出越来越多新技术、新方法,针对拧紧技术的研究也将不断深入,开发出更加智能化、自动化的高精度自动拧紧设备,助力中国汽车行业的持续发展。

基于工艺设计的无线远传水表自动化装配设备研制

传统水表制造由人工装配完成,存在生产周期长、生产效率低、生产费用高等问题。分析了水表的结构组成和各零件之间的相互配合,以国内主流的无线远传水表为例,设计了一款由6个设备组成的自动化装配生产线。完成了生产线的整体布局和物料在各个设备之间的流转,经过现场安装和运行调试,实现了自动化生产装配线的可靠稳定运行。有效提高了生产效率和装配精度,适应企业产业升级的需求,为自动化生产装配线提供了设计新思路,具有实际借鉴意义。