资源配置混杂Petri网的混杂系统生产过程动态调度

为了增强混杂生产过程应对突发事件的能力,以一种新的混杂Petri网(资源配置混杂Petri网)为研究模型,给出了相应的使能和激发规则.并在资源配置混杂Petri网建立的仿真模型的基础上,融入事件逻辑网和逻辑规划,提出一种适用于混杂系统动态生产调度建模和优化的方法.以典型的混杂生产过程为例,研究混杂系统生产过程建模及优化.研究结果表明,资源配置混杂Petri网模型描述能力强,能够有效描述混杂系统生产过程,所提出的动态调度方案切实有效.     

一类混合生产过程的混杂Petri 网建模与调度

针对混合整数线性规划方法在解决混合生产过程调度中存在的问题,提出一种混合间歇/连续生产过程的时间约束混杂Petri网模型,该模型能够对间歇操作时间可变和连续速率可变的混合生产过程进行有效描述.结合模型行为演变和遗传算法提出一种新的混合生产过程调度方法.实验结果表明了所提出方法的有效性.     

Modeling, analysis, synthesis, and performance evaluation of multioperational production systems with hybrid timed Petri nets

Hybrid timed Petri nets (HTPNs) are derived to study random topology and complexity multioperational production systems where parts of one type follow the same route to produce a final product. Each production system is first decomposed into a fundamental multiproductive machine, multiassembly and multidisassembly modules, followed by derivation of their corresponding HTPN models. The overall system HTPN model is obtained via individual module synthesis, satisfying system constraints. Individual module and overall HTPN models nodes (places and transitions) are calculated. Individual module and overall system model invariants are derived mathematically. Performance and possible tradeoffs due to varying operational constraints (buffer capacity, work in process, machine utilization, backlog, etc.) are investigated through extensive simulations. Results show the applicability of the proposed methodology and justify its modeling power and generality.     

Petri net based decision system modeling in real-time scheduling and control of flexible automotive manufacturing systems

This paper presents the design and the implementation of a Petri net (PN) model for the control of a flexible manufacturing system (FMS). A flexible automotive manufacturing system used in this environment enables quick cell configuration, and the efficient operation of cells. In this paper, we attempt to propose a flexible automotive manufacturing approach for modeling and analysis of shop floor scheduling problem of FMSs using high-level PNs. Since PNs have emerged as the principal performance modeling tools for FMS, this paper provides an object-oriented Petri nets (OOPNs) approach to performance modeling and to implement efficient production control. In this study, we modeled the system as a timed marked graph (TMG), a well-known subclass of PNs, and we showed that the problem of performance evaluation can be reduced to a simple linear programming (LP) problem with m − n + 1 variables and n constraints, where m and n represent the number of places and transitions in the marked graph, respectively. The presented PN based method is illustrated by modeling a real-time scheduling and control for flexible automotive manufacturing system (FAMS) in Valeo Turkey.     

Re-thinking diagnosis for future automation systems: An analysis of current diagnostic practices and their applicability in emerging IT based production paradigms

With the advent of the Internet and the progressive development and consolidation of a wide range of web standards and technologies as well as the advances in distributed artificial intelligence (DAI), namely the multi agent system concept, new opportunities have emerged for conceiving, modelling and enhancing shop floor's performance and response.Modern IT-supported production paradigms denote a common concept where the shop floor is a lively entity composed by interacting intelligent modules whose individual and collective function adapts and evolves ensuring the fitness and adequacy of the organization, owning the system, in tackling profitable but volatile business opportunities.The self-organizing and peer to peer nature of these systems renders a collective behaviour and dynamics that are fundamentally new. Conventional diagnostic methods and tools have not been designed targeting the envisioned systems therefore lack the required support. In this paper the emerging IT-based production paradigms are surveyed as well as the existing diagnostic methods whose adequacy is analysed. The resulting requirements and characteristics are exposed to stress the need for rethinking current diagnostic practices in future automation systems.     

Control of technological and production processes as distributed parameter systems based on advanced numerical modeling

The paper describes some practical control problems of technological and production processes as nonlinear distributed parameter systems. These are solved based on advanced numerical modeling in virtual software environments offered for the numerical dynamic analysis of technological and production processes with co-simulations. The controlled systems are interpreted as nonlinear lumped input and distributed parameter output systems. Synthesis of control in space relation is solved by approximation methods in temporal relation by methods of control of lumped parameter systems. Some results are demonstrated by the control of the secondary cooling in the continuous casting of steel, based on a software sensor. Furthermore, the control of a casting die preheating process is introduced in this framework using a programmable logic controller (PLC).