Research on Integrated Process Planning System for Assembly

研究的目的是开发计算机辅助系统，使工艺设计者能够在装配工艺规划的不同阶段设计合适的装配单元和装配系统。研究成果如下：1.提出了装配工艺规划活动的统一数据表示模型。产品和装配机的结构、装配机的运动以及各运动之间的有序关系可以用EAR(实体属性关系)模型来表示，并用LISP框架结构来实现。开发了基于产品装配模型的装配序列规划系统。将装配模型表示为零件的实体模型集和匹配零件之间的约束条件。该系统不仅可以根据各零件的可行运动和由约束条件得到的优先关系自动生成可行拆卸序列，而且可以根据实体模型对零件之间的干涉检测来生成可行拆卸序列。开发了装配机设计系统。该系统使工艺设计者能够基于三维模型进行电机、气缸、轴承、齿轮等机械零件的装配，并基于顺序控制图和表情处理软件对机床的运动进行仿真。开发了自动生成装配机和单元控制程序的CASE工具。该工具用于由图像处理单元、测距仪、六轴机器人和PC机组成的柔性零件进给单元的程序开发。利用DFD对过程进行结构化分析，参照传感器和机器人的规格和配置，半自动生成程序的C语言源代码。

The purpose of the research is to develop the computer aided system which enables process planners to design suitable assembly cell and assembly system in different phases of process planning of the assembly. The results of the research are summarized as follows ;1. The uniform date model for representing activities concerning with process planning of the assembly, was proposed. The structure of the product and assembling machine, motion of the assembling machine, and ordered relation among various motions of the machines, can be represented by EAR (Entity Attribute Relationship) Model, and was implemented as LISP frame structure.2. The assembly sequence planning system based on the assembly model of the product was developed. The assembly model was represented as the set of solid models of parts and the constraint conditions between mating parts. The system can automatically generate the feasible de-assembling sequence based not only on feasible movement of each part and precedence relation derived from constraint conditions, but also on the interference detection between parts by solid models.3. The design system for the assembling machine was developed. They system enables the process planner to compose machine elements such as motor, air cylinder, bearing, gear etc. based on 3D model to make mechanism, and to simulate motions of the machine based on sequence control diagram and expression processing software.4. The CASE tool to automatically generate the control program for the assembling machine and cell is developed. The tool is applied to the program development for the flexible parts feeding cell which consists of image processing unit, range finder, 6-axis robot and personal computer. The structured analysis of the process was done by using DFD, and the C source code of the program can be semi-automatically generated by referring to the specification and configuration of the sensors and the robot.