基于平行Petri网的制造系统调度与控制一体化方法

为了消除制造系统调度层与控制层之间的隔阂,实现对生产事件快速灵活响应,本文提出了一种调度与控制一体化的方法.首先,定义了一种新型Petri网模型,即平行Petri网,从而集成地描述了传感器、执行器、任务和资源信息,构建制造系统的信息物理系统模型;其次,提出了一种从平行Petri网到赋时Petri网的抽象简化方法,大规模压缩优化调度所需搜索的状态空间;再次,定义了策略Petri网以描述最优调度策略.最后,给出了平行Petri网与策略Petri网同步执行算法,使得平行Petri网与物理系统同步执行.

The Integrated Method of Scheduling and Control for Manufacturing Systems Based on Parallel Petri Nets

In order to eliminate the gap between the scheduling layer and the control layer and achieve fast and flexible response to production events of manufacturing systems, an integrated method of scheduling and control is proposed in this paper. First, a novel Petri-net model that is called a parallel Petri net is defined, which integrates sensors, actuators, tasks and resources to establish the cyber-physical system model of a manufacturing system. Secondly, a method of transforming parallel Petri nets to timed Petri nets is proposed to much compress the state space required to be searched for optimal scheduling. Thirdly, a strategy Petri net is defined to describe an optimal scheduling strategy. Finally, the algorithm for synchronizing executions of a parallel Petri net and a strategy Petri net is given, which realizes the synchronous execution of parallel Petri nets and physical systems.