Automatic assembly path planning for wiring harness installations

The automotive industry of today is becoming more focused on electrified and hybrid solutions, where both conventional combustion engines and battery supplied electrical engines need to fit in an already densely packed vehicle. Many quality problems are related do flexible parts. In particular, the assembly of electric cables and wiring harnesses is difficult due to its concealed routing, multiple branching points, weights and the flexibility in the material. To avoid late detection of assembly problems, the assembly aspect must be considered early during conceptual design and production preparation with respect to both feasibility and ergonomics. Development of automatic path planning methods in virtual manufacturing tools supporting deformable parts is therefore highly motivated.     

System design and user evaluation of Co-Star: An immersive stereoscopic system for cable harness design

The system design and results of a user evaluation of Co-Star an immersive design system for cable harness design is described. The system used a stereoscopic head mounted graphical display, user motion tracking and hand-gesture controlled interface to enable cable harnesses to be designed using direct 3D user interaction with a product model. In order to determine how such a system interface would be used by a designer and to obtain user feedback on its main features a practical user evaluation was undertaken involving ten participants each completing three cable harness design tasks with the system. All user interactions with the system were recorded in a time stamped log file during each of the tasks, which were also followed by questionnaire (5 point scale) and interview sessions with each participant. The recorded interaction data for the third task was analysed using functional decomposition techniques and used to construct a single activity profile for the task based on the mean results obtained from the participant group. The goal was to identify in general terms the relative distribution of user activity between specific purposes during practical system operation, and it was found that in this task Navigation accounted for 41%, Design 27%, System Operation 23% and looking at Task Instructions 9% of all user activity. The scored questionnaire data collected immediately after the completion of each task was used to rank the major features of the system according to user opinion. This was further enhanced by also collecting real interview comments from the user group about these same features. The combination of both quantitative performance analysis and subjective user opinion data obtained during a practical design exercise has enabled an in depth evaluation of the system, leading to a much greater understanding of many of the key user and interface requirements that should be considered during the development of immersive interfaces and systems for practical engineering applications.     

A real-time network simulation infrastructure based on OpenVPN

We present an open and flexible software infrastructure that embeds physical hosts in a simulated network. In real-time network simulation, where real-world implementations of distributed applications and network services can run together with the network simulator that operates in real-time, real network packets are injected into the simulation system and subject to the simulated network conditions computed as a result of both real and virtual traffic traversing the network and competing for network resources. Our real-time simulation infrastructure has been implemented based on Open Virtual Private Network (OpenVPN), modified and customized to bridges traffic between the physical hosts and the simulated network. We identify the performance advantages and limitations of our approach via a set of experiments. We also present two interesting application scenarios to show the capabilities of the real-time simulation infrastructure.     

基于改进蚁群算法的线缆路径规划技术研究

线缆布线是复杂机电产品设计中的普遍性难题。针对线缆布局设计中存在的效率低、可靠性差等问题,提出了一种基于改进蚁群算法的线缆路径规划方法。采用分段式空间划分方法对待布线空间进行环境建模,同时对布线空间进行栅格化处理,以获取三维布线路径的规划空间。为解决基本蚁群算法在进行路径搜索时路径点容易发散的问题,引入了基于重力规则的蚁群算法路径搜索策略,提高了路径规划的真实度。在仿真实验中,将所提出的方法与基本蚁群算法进行了对比分析,验证了该算法的可行性和有效性。     

基于距离场和扫掠剪除算法的线缆碰撞检测技术

针对线缆具有柔性可变形特性而引起线缆碰撞检测难的问题,提出了基于距离场和扫掠剪除算法的线缆碰撞检测方法。基于距离场的碰撞检测方法主要用于检测线缆与线缆、线缆与结构件之间的碰撞：首先通过建立线缆体廓包围球,完成线缆多细节层次球面调和的表达;然后生成三维距离场映射,获取线缆或结构件表面法向量和穿刺深度等碰撞反馈信息。基于扫掠剪除算法的碰撞检测方法主要用于检测线缆的自碰撞：先构建线缆分段数学模型,然后通过线缆离散点扫掠剪除完成线缆自碰撞检测。最后对算法进行了验证,算法具有较好的准确性和快速性,可以满足工程实际的要求。     

基于人工神经网络的线缆敷设质量综合评判

针对复杂机电产品线缆敷设过程复杂、难以规范和统一而导致的线缆敷设质量难以控制与评判的问题,提出了一种基于人工神经网络的复杂机电产品线缆敷设质量综合评判方法。在对线缆敷设过程中的影响因素分析后建立了线缆敷设质量等级指标体系;在该指标体系的基础上,运用层次分析法（Analytic Hierarchy Process,AHP）对各因素进行定性定量分析,结合专家打分法获得量化的决策结果;采用人工神经网络与AHP法混合的多指标综合评判方法模拟专家对线缆敷设质量进行评价,并将敷设质量的模型评估结果与专家的评估结果进行比较,分析人工神经网络的学习能力。利用某飞机中的线缆敷设数据进行实例分析,验证了方法的有效性和可行性,展现了人工神经网络在综合评价方面的优越性。     

基于物理模型的火苗动画

本文提出了一种基于物理模型的火苗数值模拟方法。真实感和实时性是计算机图形学追求的两个目标。传统的动画技术生成的物体运动是虚拟的,并不能完全反映物体的真实运动。与传统的动画技术相比,基于物理的动画更能表现运动的真实性。本文在用非粘性不可压欧拉方程表示火苗物理模型的基础上,利用破开算予法将其分解成外力项、对流项和投影项分别进行求解,每一步都稳定,因而整个求解也就稳定。求解过程的稳定性保证了模拟可以用大时间步长,也就保证了模拟的实时性。与传统的方法相比,能同时满足计算机图形学的真实感和实时性要求。     

A data-driven generic simulation model for logistics-embedded assembly manufacturing lines

Simulation has been used to evaluate various aspects of manufacturing systems. However, building a simulation model of a manufacturing system is time-consuming and error-prone because of the complexity of the systems. This paper introduces a generic simulation modeling framework to reduce the simulation model build time. The framework consists of layout modeling software and a data-driven generic simulation model. The generic simulation model was developed considering the processing as well as the logistics aspects of assembly manufacturing systems. The framework can be used to quickly develop an integrated simulation model of the production schedule, operation processes and logistics of a system. The framework was validated by developing simulation models of cellular and conveyor manufacturing systems.     

Mesh cutting during real-time physical simulation

The ability to cut through meshes in real-time is an essential ingredient in a number of practical interactive simulations. Surgical simulation, cloth design, clay sculpting and many other related VR applications require the ability to introduce arbitrary discontinuities through models to separate, reposition, and reshape various pieces of the model as needed for the target application. In addition, in order to provide the necessary realism for these applications, model deformations must be computed from an underlying physically-based model—most commonly a continuum-based finite element model.In this work, we present a method for representing and computing, at interactive rates, the deformations of a mesh whose topology is being dynamically modified with multiple virtual tools. The method relies on introducing controlled discontinuities in the basis functions used to represent the geometry of deformation, and on fast incremental methods for updating global model deformations. The method can also generate the forces needed for force rendering in a haptic environment. The method is shown to scale well with problem size (linearly in the number of nonzeros of the Cholesky factor) allowing realistic interaction with fairly large models.     

Efficient cable arrangement in cable stayed bridges based on sensitivity analysis of aeroelastic behaviour

Construction of cable supported bridges has experienced a great impulse in the past decade. Bridges having more than 800 m of span length were built in France and Japan and some bridges with span length of more than 1 km are going to be built, such as the Stonecuters bridge in Hong-Kong, and the Chongming in China (Fig. 1). Because of the increasing length of this class of bridges, they are becoming prone to phenomena like flutter in a similar way than long span suspension bridges.

Cable stayed bridges may present a few different alternatives for the cable system. At least harp, fan or modified fan arrangements can be discussed at the beginning of the design. Also variations in the number of cable planes can be studied.

Usually, during the design process changes are made by carrying out a number of analyses and using trial and error techniques relying in heuristic rules that are based upon the particular skills of the engineer. This approach can be inefficient in new problems and commonly it needs to be supported with results coming from experimental testing which makes more expensive the whole design process. Instead of that, an approach based in sensitivity analysis can be very helpful for the designer.     

分布式实时仿真系统高精度时间同步技术研究

在采用PC机和Windows操作系统的局域网上用软硬件相结合的方式实现高精度、高效率的时间同步是提高分布式实时仿真系统置信度、降低系统硬件成本的关键。给出了一种局域网时间对齐（LTS）算法和一种基于PC机自身资源的时钟构造方法。LTS算法在局域网环境下比目前广泛使用的NTP(网络时间协议)算法有更好的时间对齐效果，新时钟在性能上远远优于Windows系统时钟。最后设计了一个完整的时间同步方案，该方案达到了高精度、高效率时间同步和降低硬件成本的目的。     

A novel vision-based method for 3D profile extraction of wire harness in robotized assembly process

Automating stages for deformable objects in the production line, in which assembling a wire harness into a predefined position is a complex task owing to the specialized characteristics of the objects. Besides a few automatized systems proposed in the other studies to implement this task under simplified setup conditions, a significant portion of this process remains to be completed manually in industrial environments. To construct an automatic wire harness assembly system, the development of a method that can automatically detect the wire harness profile in a 3D environment and, consequently, guide robot arms to implement assembly tasks is indispensable. Therefore, this study presents an approach that satisfies this requirement, which not only proposes a deep learning-based system to detect the wire profile, but also improves the accuracy of the detected results through a correction method according to the depth values of contiguous areas. The verification of the approach in a robot system that highlights its usefulness and practicality demonstrates the potential of the proposed method to replace people and consequently, reduce labour costs in factory environments.     

一种特高压交直流电网数模混合实时仿真系统

本文设计了一种特高压交直流电网数模混合实时仿真系统,其操作系统采用Linux,仿真软件采用Hypersim,借助信号接口以及功率接口完成了仿真程序和物理装置之间的有效互联,同时借助SGI超级计算机,最终出色完成了实时仿真试验工作。该仿真系统已经服务于若干个实际工程。实践及本试验表明,对特高压交直流大电网的运行进行研究时,数模混合实时仿真系统能够以其强大且全面的功能为其提供良好的技术支持。     

Physically based modeling and simulation with dynamic spherical volumetric simplex splines

In this paper, we present a novel computational modeling and simulation framework based on dynamic spherical volumetric simplex splines. The framework can handle the modeling and simulation of genus-zero objects with real physical properties. In this framework, we first develop an accurate and efficient algorithm to reconstruct the high-fidelity digital model of a real-world object with spherical volumetric simplex splines which can represent with accuracy geometric, material, and other properties of the object simultaneously. With the tight coupling of Lagrangian mechanics, the dynamic volumetric simplex splines representing the object can accurately simulate its physical behavior because it can unify the geometric and material properties in the simulation. The visualization can be directly computed from the object’s geometric or physical representation based on the dynamic spherical volumetric simplex splines during simulation without interpolation or resampling. We have applied the framework for biomechanic simulation of brain deformations, such as the brain shifting during surgery and brain injury under blunt impact. We have compared our simulation results with the ground truth obtained through intra-operative magnetic resonance imaging and real biomechanic experiments. The evaluations demonstrate the excellent performance of our new technique.     

神经网络在船舶轮机训练器实时仿真建模中的应用研究

文运用反向传播 (BP)神经网络理论 ,设计了一个仿真 10 5单缸柴油机示功图的BP网络模型 ,并对之进行了讨论和研究 ,说明该神经网络模型不但可以满足船舶轮机仿真训练器的精度要求 ,并且还可以保证轮机仿真过程的实时性 ,从而提出了船舶轮机训练器实时仿真建模的又一种有效的方法     

典型化工过程软硬件一体仿真系统实现

为了研究、设计和拓展过程监控系统研究的试验平台,开发了基于TE过程(Tennessee Eastman process)的软硬件一体实时仿真系统。本文对这套仿真系统的硬件构造及功能,TE过程的实时仿真数据采集、数据处理、数据图形及表格显示等功能的实现予以详细地阐述。实验表明该系统功能完善,达到了预期的教学及科研目的。     

AR-based deep learning for real-time inspection of cable brackets in aircraft

In the process of aircraft assembly, there exist numerous and ubiquitous cable brackets that shall be installed on frames and subsequently need to be manually verified with CAD models. Such a task is usually performed by special operators, hence is time-consuming, labor-intensive, and error-prone. In order to save the inspection time and increase the reliability of results, many researchers attempt to develop intelligent inspection systems using robotic, AR, or AI technologies. However, there is no comprehensive method to achieve enough portability, intelligence, efficiency, and accuracy while providing intuitive task assistance for inspectors in real time. In this paper, a combined AR+AI system is introduced to assist brackets inspection in a more intelligent yet efficient manner. Especially, AR-based Mask R-CNN is proposed by skillfully integrating markerless AR into deep learning-based instance segmentation to generate more accurate and fewer region proposals, and thus alleviates the computation load of the deep learning program. Based on this, brackets segmentation can be performed robustly and efficiently on mobile devices such as smartphones or tablets. By using the proposed system, CAD model checking can be automatically performed between the segmented physical brackets and the corresponding virtual brackets rendered by AR in real time. Furthermore, the inspection results can be directly projected on the corresponding physical brackets for the convenience of maintenance. To verify the feasibility of the proposed method, experiments are carried out on a full-scale mock-up of C919 aircraft main landing gear cabin. The experimental results indicate that the inspection accuracy is up to 97.1%. Finally, the system has been deployed in the real C919 aircraft final-assembly workshop. The preliminary evaluation reveals that the proposed real-time AR-assisted intelligent inspection approach is effective and promising for large-scale industrial applications.     

基于粒子系统的流体交互应用*

为模拟水流的真实交互行为,采用基于光滑粒子流体动力学方法的粒子系统进行水流的物理仿真。给出利用八叉树建立有序树并进行最近相邻粒子搜索的方法,采用两种虚粒子结合的方法处理边界条件。在三维虚拟场景中模拟了水流与障碍物交互的过程,证明了该方法的实时性和可行性。