【作者】 胡广华；

【导师】 陈幼平； 周祖德；

【作者基本信息】 华中科技大学 ， 机械电子工程， 2007， 博士

【摘要】 车间布局设计是制造系统规划中的重要一环,其结果对生产系统运行过程中的物料搬运费用、搬运效率,乃至系统的实际产能、生产效率等均有重大影响。尽管车间布局设计研究一直方兴未艾,但由于问题的NP-难属性及实际布局问题的多样性,这些研究还远不能说充分、彻底;而随着制造理念和制造模式的发展变化,现有的大量设计模型及求解算法也已经越来越难以适应现代制造车间布局设计的需要。本文针对现代制造车间的特点,全面考察了车间布局从总体规划到详细设计各个阶段所面临的关键设计问题及要素,并就其优化建模、模型求解算法,以及可视化辅助设计等方面分别进行了研究。首先,针对传统布局设计采用分步、孤立的设计模式易导致系统最终设计结果偏离全局最优解的缺点,基于并行设计思想提出了一种可操作的、集成化的车间布局设计框架。按照这一框架,设计过程中相互影响较大、耦合关系较紧密的环节被作为一个整体加以考虑,避免问题解空间因为解耦而遭受损失,从方法上保证了优化设计的整体质量,为后续研究打下了基础。其次,从物流成本的角度研究了产品设计/工艺规划、制造单元分组,以及单元布局设计三者之间的内在联系,提出了考虑产品多工艺路线的单元构建与设备布局的集成设计方法和设计模型,克服了分步优化方法易陷入局部最优解的缺点。模型将单元构建个数作为决策结果自然输出,避免了在设计前预先分配的困难。利用遗传算法(GA)的快速搜索特性,研究设计了模型的求解算法。与同类算法相比,本文所提出的算法基于一维编码结构,降低了遗传操作设计的复杂度;进化过程中不产生非法个体,免去了修正算子的设计步骤。利用文献中的典型算例进行测试和对比,结果表明本文所提出的方法能更加有效地降低全局物流成本,充分说明了该方法的有效性与实用性。对于单元系统布局问题,本文提出了基于割树结构的单元系统布局模型,克服了传统方块布局模型难以满足单元形状约束和物料装卸点位置等约束的缺点。针对以往研究中普遍存在的损害解空间、需要修复操作以保证解的合法性等局限,基于二叉树顺序等价字符串的表达形式提出了一种新的统一字符集编码/解码方法,解决了割树与编码的相互映射问题。运用该编码技术,设计开发了一个基于遗传算法和模拟退火算法(SA)的混合智能优化算法,并以相关实验验证了该算法的有效性,取得了满意的效果。由于目前大量设施布局方法均基于各类平面分割法,但此类方法无法生成非切割形式的拓扑结构,故易造成潜在更优解的丧失。另一方面,在以往的研究中,单元系统布局与物流网络的设计一般分开、独立地进行,无法保证设计结果的整体最优性。为此,本文以最小化物流成本为目标,提出了二者的集成设计方法,并建立了相应的数学模型。该模型考虑了车间、单元边界对物流路径的约束,较好地解决了连续平面环境下非自由型物流网络建模困难的问题。将次序对技术引入到模型的求解中,提出了一种允许单元布置在连续平面任意位置的单元系统布局生成算法。实验证明,经过简单扩充,该算法对车间中存在禁止布局区域的情形也具有相当的适应能力。最后运用模型的分解技术,提出了层次化的总体优化求解算法,并通过实例说明了算法的有效性。在布局的详细设计阶段,由于设计任务的繁杂性,难以借助精确的数学模型进行求解。为此,研究了增强现实(AR)技术用于可视化布局设计的巨大优势及其可行性,提出了一种易于实现和扩展的基于AR的可视化布局设计框架,并就其中两大关键模块的设计进行了详细论述。以ARToolKit、OpenGL,以及MFC为基本开发工具,实现了一个桌面式可视化布局设计原型系统,并结合相关实例介绍了该系统的使用特点。最后,运用VC++为平台,开发了车间集成布局设计原型系统,并给出了相关运行实例。更多还原

【Abstract】 Developing a plant layout is an important step when designing manufacturing facilities due to the impact of the layout on material handling cost and time, on throughput, and on productivity of the facility. Plant layout problems are now faced by industry more frequently due to a change from mass production towards more flexible batch production. And as a result, one has to face a lot of new issues which are significantly different from the traditional layout problems in the design of a plant layout. In this dissertation, several key issues involved in the design of the widely utilized cellular layout (GT layout) are studied, including the modeling, algorithms and visual layout design technologies.In general, the full layout design requires four major steps: (1) Cell formation, i.e., to group parts into part families and machines to machine cells; (2) Cell layout (intra-cell layout), i.e., to assign machines or work stations within each cell; (3) Cell system layout (inter-cell layout), i.e., to arrange cells within floor; (4) material handling (MH) system, i.e., to design material flow paths between the pickup/delivery (P/D) stations. The primary objectives in the formation and layout of manufacturing cell are concerned with minimizing the number and cost of inter-cellular moves and maximizing the utilization of machines.Traditionally, the optimization processes for the plant layout have been carried out sequentially and separately. Solutions obtained by this means can be far from the total optimum. To avoid the drawbacks of traditional layout methods, based on the principles of concurrent engineering, an integrated approach to the problem is proposed, which attempts to design the plant layout concurrently.A way to reduce the material handling cost without compromising the component functionality is to choose satisfactory design options. Also, the alternative processing route is one of the important design factors for the cell formation problem. Based on a full exploring of the close relationships among component design/process planning, cell formation and layout design, an integrated method for the formation of parts and machine families is then developed, together with the corresponding GA-based algorithm for solving it. Compared with those existing approaches, the proposed procedure attempts to solve cell formation, process planning and intra-cell layout in a single step, which improves the design quality and makes the problem’s solving simpler.Although the inter-cell layout problem is similar to a block layout problem in terms of concepts, models, and solution procedures, some definite differences between them make the inter-cell problem more complicated and thus, special issues need to be considered in the layout design. In this dissertation, an approach for solving the inter-cell layout problem is presented. The layout problem is modeled based on a slicing tree structure, considering the I/O station sides for each cell. This proposed approach incorporates the GA and SA with a new coding scheme which ensures that the search can cover the full solution space. The computational results show that the proposed approach is capable of obtaining optimal solutions for the test problems even with a higher reduction of the objective function value as compared with other methods. Moreover, it is also observed that the parameter set chosen for the hybrid algorithm is more relaxed than that of GA or SA alone.It has been known that both the cell system layout (CSL) problem and material handling system design problem are of NP-hard combinational problems. In this paper, an integrated approach to the problem is proposed, which attempts to design CSL and flow path structure simultaneously. The cells in question are assumed to be shape fixed and have pre-determined pickup/delivery (P/D) stations. A sequence-pair based CSL-generating algorithm allows cells to be placed at any possible positions on a continuous floorplan and leads to a corresponding feasible CSL. A grid graph for the CSL is accordingly constructed to provide possible flow paths for the layout. Then, the sum of the traveling distances, determined by the shortest path algorithm, is used to evaluate the CSL. These steps are embedded into a GA that searches the solution space to obtain optimal layouts based on the contour distances between the P/D stations. A comparison of the computational results with the existing methods indicates that the proposed approach is a viable alternative for effectively generating layout designs for CMS.Since it is very difficult to model all kinds of factors involved in a detailed layout design problem mathematically, an AR-based visual layout design system is developed. The prototype system shows that, when solving detailed layout problem, AR gives more promise than other possible techniques, say, VR.Finally, based on the aforementioned techniques, a prototypic software system is developed, which can be used to make the layout designer’s work easier. Besides, the running cases of the system are also given.更多还原