Process Modeling And Planning Of Top-down Collaborative Assembly Design

With the increasing complexity of the modern product, the development cycle of the product should be shorten, the cost of the product should be reduced and the development efficiency and the economic benefit should be increased for the enterprises to improve the competitive capacity and come to the top at the intensive market competitive environment. The top-down collaborative assembly design is a new design mode, which brings many challenges for effective management and planning of the design process. This dissertation focuses on the modeling and planning technology of the process of top-down collaborative assembly design. And the main contributions are described as follows:1. Based on the characteristics of top-down collaborative assembly design, the process model for top-down collaborative assembly design is constructed using the hierarchical colored Petri-net (HCPN) which adopts the design activities as the modeling objects. The process model is effective for depicting the complex behaviors and dig out the connotations of the design process.2. Based on the high concurrency and tightly coupling relationships of top-down collaborative assembly design process planning, the design structure matrix (DSM) is adopted to describe the relationships among tasks. An improved genetic algorithm (GA) based on multi-objective for the task grouping is developed according to two principles: one is that the workload should be equilibrium among the design teams; the other is that the tasks with high coupling relationships should be grouped into the same task group. The rational task grouping is implemented. The development cycle and the interaction among design teams are reduced significantly.3. According to the comprehensive capability of the design team, the uncertain and multi-attribute decision method is used to choose the design teams. Task group assignment principle is proposed based on the key degree of the task and the comprehensive capability of the design team, and a task group assignment algorithm called the searching procedure tree is developed, which guarantees the rational task assignment and the optimal scheduling of the organizing resources.4. According to the high parallel and the dependent relationships among the tasks of the top-down collaborative assembly design process, a task time window algorithm is put forward. Based on the outside and inside dependent relationships of the tasks, two methods are adopted to determine the task time window constraints. During calculating the task time window, the methods of resolving conflicts and decreasing the design process waiting time are put forward after analyzing the reasons for conflicts. Finally, a stochastic planning algorithm is put forward to implement the design process planning based on design structure matrix, which can determine the task time window and get the optimal design process scheme.5. According to the static planning model and the characteristics of top-down collaborative assembly design, a dynamic model of process planning based on hierarchical object-oriented Petri-net (HOOPN) is constructed. Based on the dynamic model, the dynamic supervising and scheduling of the design process are implemented. The fuzzy overall evaluation model (FOEM) is utilized for risk evaluation of the design process, which determines the local and global risk level of the design process. The risk decision-making mechanism is presented based on the risk level, which is utilized to dynamically adjust and control the whole process planning.