三层虚拟工作流模型的非线性制造工艺多目标优化算法研究EI北大核心CSCD

时间、生产质量和成本是加工制造中相互制约的重要参数,平衡此参数使制造工艺最优是一个NP(Non-deterministic polynomial)难题,对此出现了许多优秀的调度方法.然而这些方法的优化对象均为线性工艺,对于普遍存在的非线性工艺却无法调度优化.针对此不足,本文以非线性工艺为优化对象提出了三层虚拟工作流模型Three-VMG(Three-virtual model graph)及其优化算法Three-OVMG(Three-optimal virtual model graph).该模型和算法首先建立非线性工作流,采用虚拟技术寻找虚拟结点进行重构,将其改造为虚拟线性工作流;其次结合工艺特点对模型进行分段,采用逆向分层串归约来实现段内最优解,采用累积最优解来衔接各段间的值;最后根据优化结果自顶向下完成各层资源的优化调度.实验表明,该过程较传统时间最小化优化调度算法具有显著的优化效果,其性能及可操作性也能满足工程要求.

Multi-objective Optimization Algorithm for Non-linear Manufacturing Process Based on Three-tier Virtual Workflow Model

Time, production quality and cost are important parameters of mutual constraints in manufacturing. Balancing these parameters to make the manufacturing process more reasonable is an NP (non-deterministic polynomial) problem, and there are many excellent scheduling methods to solve this problem. However, the optimization objects of these methods are linear processes, so they can not be scheduled and optimized for the prevalent non-linear processes. To overcome the deficiency, a three-tier virtual workflow model, Three-VMG (three-virtual model graph), and its optimization algorithm, Three-OVMG (three-optimal virtual model graph), are proposed to optimize the non-linear processes in this paper. The model and algorithm first establish a non-linear workflow, using virtual technology to find virtual nodes for reconstruction, thus transforming it into virtual linear workflow. Secondly, according to the process characteristics, the model is segmented. Uses serial reduction strategy to calculate reverse hierarchical solution in each segment, and then cumulative values of solutions between segments. Finally, according to the optimization results, the optimal scheduling of resources at each level is top-down accomplished. Experiments show that the process has a significant optimization effect compared with the traditional time minimization optimal scheduling algorithms. In addition, the performance and operability of the algorithm can meet the engineering requirements.