Hybrid modeling and dynamic simulation of automated batch plants

A proposal is presented for the hybrid modeling and dynamic simulation of automated batch processing plants with dominant discrete-event behavior. The proposal encompasses current techniques for modeling continuous-time/discrete-event processes, synthesizing discrete-event controllers as well as the use of industrial standards for batch control. The result is a hierarchical-modular model of a plant in which process and control tasks are clearly differentiated. Implementation rules are established for a specific dynamic simulator capable of handling hybrid systems. The approach is demonstrated by building and verifying a complete model for an automated milk pasteurization plant. Results show that handling problems of realistic complexity is feasible using state-of-the-art technology.     

Ant colony optimization for job shop scheduling using multi-attribute dispatching rules

This paper proposes a heuristic method based on ant colony optimization to determine the suboptimal allocation of dynamic multi-attribute dispatching rules to maximize job shop system performance (four measures were analyzed: mean flow time, max flow time, mean tardiness, and max tardiness). In order to assure high adequacy of the job shop system representation, modeling is carried out using discrete-event simulation. The proposed methodology constitutes a framework of integration of simulation and heuristic optimization. Simulation is used for evaluation of the local fitness function for ants. A case study is used in this paper to illustrate how performance of a job shop production system could be affected by dynamic multi-attribute dispatching rule assignment.     

A discrete-event simulation approach with multiple-comparison procedure for stochastic resource-constrained project scheduling

Aiming to minimize the average project duration, a discrete-event simulation (DES) approach with multiple-comparison procedure is presented to solve the stochastic resource-constrained project scheduling problem (SRCPSP). The simulation model of SRCPSP is composed of a resource management model and a project process model, where the resource management model is used to administrate resources of the project, and the project process model based on an extended-directed-graph is proposed to describe the precedence constraints and resource constraints in SRCPSP. A simplified simulation strategy based on activity scanning method is used in the simulation model to generate feasible schedules of the problem. A multiple-comparison procedure based on the common random numbers is adopted to compare the multiple scheduling alternatives obtained from the stochastic simulation model and provide more information to select the optimal scheduling alternative. The cases are given to compare with other methods for the same SRCPSP from literature and show that the simulation tool by utilizing DES with a statistical method improves the efficiency of simulation in stochastic project planning.     

集成系统设计中的经营过程成本分析技术研究

在描述系统方案的过程模型基础上，通过生成二次模型建立层次性的成本动因，从直接发生的活动对成本进行归集，并依照活动的目标进行分配，然后应用离散事件仿真技术模拟资源约束下的成本发生、归集和分配情况，分析系统集成过程中发生的成本替代效应、转移效应、效率效应、质量效应和固化效应。系统地介绍了生成二次模型的原则，以及依据模型进行数据采集和分析的方法，最后，以一个案例介绍自主开发的GEM集成建模和仿真软件工具的应用情况。     

Simulation-based metamodels for the analysis of scheduling decisions in a flexible manufacturing system operating in a tool-sharing environment

This paper presents the salient aspects of developing simulation-based metamodels for scheduling a typical flexible manufacturing system (FMS) operating in a tool-sharing environment. A discrete-event simulation model of the FMS is developed for the purpose of experimentation. Seven scheduling rules from the literature are incorporated in the simulation model for part scheduling decision. The performance measures considered for analysis are mean flow time, mean tardiness, and percentage of tardy parts. Simulation experiments have been carried out for various scenarios arising out of the settings of the mean interarrival time of parts for processing in the system and due-date factor. The simulation results are used to develop regression-based metamodels. These metamodels have been subjected to systematic analysis. The metamodels are found to offer a good prediction of the performance of FMS within the domain of their definition.     

浅谈OpenGL在机器人三维仿真的应用

介绍对运动机器人进行三维实时科学可视化仿真的过程。采用目前流行的可视化仿真软件OpenGL．它具有优秀的场景和实时处理能力，同时为克服其不能绘制复杂三维模型的缺点，还引入三维建模软件3DSMAX，先用建模软件来建立机器人的逼真模型，再将模型数据读人到OpenGL中，同时结合可视化软件编程工具VC＋＋成功实现对运动机器人的实时三维可视化仿真。     

Group shop scheduling with uncertain data and a general cost objective

In this paper, a stochastic group shop scheduling problem with a due date-related objective is studied. The group shop scheduling problem provides a general formulation including two other shop scheduling problems, the job shop and the open shop. Both job release dates and processing times are assumed to be random variables with known distributions. Moreover, earliness and tardiness of jobs are penalized at different rates. The objective is to minimize the expected maximum completion cost among all jobs. A lower bound on the objective function is proposed, and then, a hybrid approach following a simulation optimization procedure is developed to deal with the problem. An ant colony optimization algorithm is employed to construct good feasible solutions, while a discrete-event simulation model is used to estimate the performance of each constructed solution that, taking into account its lower bound, may improve the best solution found so far. The proposed approach is then evaluated through computational experiments.     

基于Pro/E的翻车机的三维动画仿真

利用Pro／E软件建立了翻车机的装配体及其零件的三维实体模型，然后转成STL文件导入3ds max软件，对翻车机的工作流程进行三维动态处理，实现了一种新型三车翻车机的动画仿真。     

Computer simulation machining a 3D free surface by using a 3-RPRU parallel machine tool

A novel computer aided geometric approach is proposed to machine a 3D free surface by adopting a 3-RPRU parallel machine tool. Based on the geometry constraint and dimension-driving technique, a 3-RPRU parallel simulation mechanism is first created. Next, a 3D free surface and a guiding plane of tool path are constituted. Finally, the 3-RPRU parallel simulation mechanism, the 3D free surface, and the guiding plane of the tool path are combined together, and a novel 3-RPRU simulation parallel machine tool is created for machining a 3D free surface. In the light of two specified tool paths, the extension of the three driving rods and the position of the moving platform are solved and visualized dynamically. Based on the computer simulation results, some analytic formulas are derived to solve the extension of driving rods of the 3-RPRU parallel machine tool in a reverse solving process. From the simulation and analytic results, it is proven that the computer simulation machine tool approach is equivalent to the analytic approach to machine 3D free surfaces. The computer simulation machine tool approach is straightforward without compiling computer programs, and is also advantageous from the viewpoint of accuracy and repeatability. This project is supported by NSFC 50575198.     

基于拟蒙特卡罗方法的三维公差综合仿真

针对计算机辅助三维公差综合中蒙特卡罗仿真计算收敛速度慢以及结果不稳定的不足,提出了基于拟蒙特卡罗的三维公差综合仿真方法。在基于旋量参数和旋量矩阵的三维公差表示方法的基础上,利用机器人学中刚体坐标变换及广义逆矩阵的相关知识建立了三维公差综合仿真等式。给出了拟蒙特卡罗方法中采用Halton序列产生正态分布随机数的方法以及基于拟蒙特卡罗的三维公差综合仿真流程。最后,将所提方法应用于齿轮泵装配实例,结果表明,拟蒙特卡罗方法收敛速度快,获得的结果稳定、可靠,可以简单高效地应用于计算机辅助三维公差综合的模拟仿真。     

塑料注射成形过程仿真软件的开发和应用

智能型3维注射成形过程仿真系统HSCAE　3D解决了用3维实体／表面模型取代中性层模型的关键性技术难题，通过数值计算与人工智能技术的结合，使仿真软件由传统的被动式计算工具提升为主动式优化系统。实验和实践证明，HSCAE　3D为注塑制品与模具的虚拟制造奠定了坚实的理论和技术基础，构成了注塑制品成形质量全面控制的核心技术，已在模具行业中得到了很好的应用。     

Improving the development of event-driven control systems in the batch processing industry. A case study

This paper presents the results of an academia-industry collaborative project whose main objective was to test novel techniques for the development of event-driven control systems in the batch processing (e.g., pharmaceutical, fine chemicals, food) industries. Proposed techniques build upon industrial standards and focus on (i) formal synthesis of phase control logic and its automatic translation into procedural code, and (ii) verification of the complete discrete-event control system via dynamic simulation. In order to test the techniques in an engineering environment, a complete discrete-event control system was produced for a benchmark batch process plant based on a standard development method employed by one of the industrial partners. The control system includes functional process specification, control architecture, distributed control system (DCS) proprietary programming code for procedural control at equipment, unit, and process cell levels, and human-machine interfaces: A technical assessment of the development method and the obtained control system was then carried out. Improvements were suggested using the proposed techniques in the specification, code generation and, verification steps. The project assessed the impact of these techniques from both an engineering and economic point of view. Results suggest that the introduction of computer aided engineering (CAE) practices based on the benchmarked techniques and a structured approach could effect a 75% reduction of errors produced in the development process. This translates into estimated overall savings of 7% for green-field projects. Figures were compared with other partners' experience. It is expected that the work load on a given project will shift, increasing the load on process engineers during the specification stage and decreasing the load on the software engineers during the code writing.     

小型双足机器人拟人步态建模与行走仿真研究

步态仿真是双足机器人设计技术的重要环节之一.针对现有步态仿真存在二维仿真不够直观、三维联合仿真会带来链接失败和数据转换丢失等问题,从简化仿真流程和增强仿真视觉效果出发,提出了仅运用三维软件UGNX完成一种小型双足机器人步态的三维仿真.参照该物理样机构型,首先建立了双足行走机构的运动学模型.通过对拟人步态的合理规划,将直行动作分解为10个子动作,以实现序列动作的连续仿真.由于机器人行走时无固定支撑点,通过对脚底板与虚拟环境间添加接触约束和摩擦力,建立了UGNX环境下虚拟样机,最终完成拟人步态的运动学仿真.仿真结果与现场实验对比表明,采用三维软件UGNX进行双足机器人步态建模与行走仿真研究具有较强的可行性.     

Quasi Ellipsoid Gear Surface Reconstruction Based on Meshless Local Petrov-Galerkin Method and Transmission Characteristic

Special transmission 3D model simulation must be based on surface discretization and reconstruction,but special transmission usually has complicated tooth shape and movement,so present software can't provide technical support for special transmission 3D model simulation.Currently,theoretical calculation and experimental method are difficult to exactly solve special transmission contact analysis problem.How to reduce calculation and computer memories consume and meet calculation precision is key to resolve special transmission contact analysis problem.According to 3D model simulation and surface reconstruction of quasi ellipsoid gear is difficulty,this paper employes meshless local Petrov-Galerkin(MLPG) method.In order to reduce calculation and computer memories consume,we disperse tooth mesh into finite points-sparseness points cloud or grid mesh,and then we do interpolation reconstruction in some necessary place of the 3D surface model during analysis.Moving least square method(MLSM) is employed for tooth mesh interpolation reconstruction,there are some advantages to do interpolation by means of MLSM,such as high precision,good flexibility and no require of tooth mesh discretization into units.We input the quasi ellipsoid gear reconstruction model into simulation software,we complete tooth meshing simulation.Simulation transmission ratio during meshing period was obtained,compared with theoretical transmission ratio,the result inosculate preferably.The method using curve reconstruction realizes surface reconstruction,reduce simulation calculation enormously,so special gears simulation can be realized by minitype computer.The method provides a novel solution for special transmission 3D model simulation analysis and contact analysis.     

An integrated methodology for operations analysis of computer integrated manufacturing systems: Application to an FMS for manufacture of medical instruments

This paper contributes a novel methodology for operations analysis of computer integrated manufacturing systems. The methodology employs an integrated set of personal computer-based manufacturing systems modelling software, and is conducted in three stages. The methodology is illustrated in detail for analysis of materials flow and staffing for a flexible manufacturing system (FMS) installed at a medical instruments manufacturing plant. First, a rough-cut capacity and materials flow analysis was performed using a queueing model. Second, a detailed analysis of FMS system characteristics was conducted by creating and analysing a discrete-event simulation model. Finally, a graphical animation package was used to verify previous results and provide visual feedback on FMS system performance. Analysis results were obtained rapidly and conveniently, and were used to advise manufacturing managers regarding FMS operating policy. This analysis methodology can be applied to a wide range of computer integrated manufacturing systems and manufacturing cells.     

基于UG的专用数控铣床铣头结构设计与运动仿真

以数控螺杆铣床铣头为研究对象,利用三维仿真软件UG建立模型并对其进行动态仿真,实现了铣头结构的虚拟设计、虚拟装配及三维动态仿真,验证了铣头结构设计的合理性。     

集成于CAD系统的体积成形三维有限元仿真系统

对体积成形三维有限元仿真的难点：多工位体积成形中的信息传递、三维六面体网格再划分技术、三维模具几何信息的精确描述、动态边界处理等进行了总结,并实现了相应的解决技术。利用这些技术,自行开发了集成于ＣＡＤ系统的体积成形三维有限元仿真系统Ｆｏｒｍ ｉｎｇ３,介绍了Ｆｏｒｍ ｉｎｇ３ 的主要特征     

3-Dimensional profile distortion measured by stylus type surface profilometer

In this paper, the distortion effect in measured profiles caused by stylus tip radius size of stylus-typed surface profilometer was analyzed in terms of 2D and 3D. On the basis of our analysis results, we propose selection criteria for the stylus tip radius to improve the reliability of measurement results. For this purpose, a simulation algorithm has been devised and implemented for 2D and 3D measurement simulations, and the 3-dimensional surface texture used in simulation was obtained using an Atomic Force Microscope (AFM) on an actual machined surface to improve the reliability of simulation results. The simulation results are compared with the measured results from the same specimen using a roughness tester, and the validity of analysis via the simulation proposed in this study is confirmed. Cumulative power spectral analysis was performed for the 2D and 3D simulated profiles obtained from simulation. On the basis of the analysis results, an effective frequency components field using a stylus type profilometer is clarified, and the selection criteria of the stylus tip radius for measurement is proposed considering the surface texture characteristics of the specimen. The purpose of this paper is to provide a basis of a simple and effective method which could be an alternative of some engineering standard that specifies selection of stylus tip radius for the measurement using only nominal Rq for machined surface.     

基于OpenGL的摆动滚子从动件盘形凸轮机构三维运动交互仿真

通过OpenGL 3D编程接口技术,分析了盘形凸轮机构的三维人机交互仿真问题,给出了凸轮机构实现人机交互仿真的设计方法,并实现了凸轮机构的参数化设计和仿真验证.     

三维场景图形建模和场景对象管理方法

图形建模是三维场景仿真中的重要环节，结合在列车虚拟运行场景仿真中的具体运用，详细阐述了图形建模的多种方法和原理，并给出了场景对象管理的有效方法。