Compositional Methods for the Control of Concurrent Timed Discrete-Event Systems

随着越来越多的自主操作模式和多个通信组件的技术系统的出现，有必要对其建模和控制采取新的方法，以保证其正确的行为。离散事件系统是由事件异步发生所控制的动态系统。这样的系统通常在技术人造系统中遇到，例如自动化运输系统、自动化制造和一般物流。这些应用领域促进了DES监控技术的发展。术语“监督控制”指的是这样一种控制范例，其中要合成的控制器将禁用可能最终导致不可接受的闭环行为的某些事件，但将允许所有其他事件。参考典型目标应用的多组件结构，在supervisorycontroller的合成中的主要挑战是整体状态集在组件数量方面的指数增长。这是解决的组合方法，避免了明确的整体模型的建设。在其基本形式中，DES对事件的顺序进行建模，这足以合成保证系统安全运行的监督程序;例如，对于自动化运输，一段轨道一次只能由一列火车使用才是安全的。然而，对于许多应用，性能明确地与物理时间相关;例如，对于自动化运输，我们关注的是所有可用列车和轨道实现的总吞吐量。在这里，文献提供了多种建模框架，不同的表现力。在范围的一端，有Brandin-Wonham框架，它使用全局tick事件来表示时间的流逝，还有定时事件图（TEG），这是一种特定类型的Petri网，可以转换为线性（max，+）方程。对于这两个框架，控制器合成是很好理解的。然而，在低端的表现力，这两个框架都有严重的局限性。与Brandin-Wonham，一个不能建模并发系统与多个实时时钟，和TEG不能解决逻辑决策。在这个研究项目中，我们将建立有效的方法来控制定时DES，比Brandin-Wonham框架和TEG更有表现力。从技术上讲，我们将考虑所谓的（最大，+）-自动机和特定类的时间Petri网作为基础模型，以开发模块化和层次化的方法来监督控制，包括相应的合成算法。我们的研究结果将大大扩大基于模型的DES控制器综合的范围。

The emergence of technological systems with more and more autonomous modes of operation and several communicating components brought the necessity of new approaches to their modeling and control in order to guarantee their correct behavior. Discrete-Event Systems are dynamical systems governed by asynchronous occurrences of events. Such systems are typically encountered in technological man made systems, such as automated transport systems, automated manufacturing, and logistics in general. These application areas have stimulated the development of supervisory control of DES. The term "supervisory Control" points to a control paradigm where the controller to be synthesized will disable certain events that may eventually lead to an unacceptable closed loop behavior, but will allow all other events. Referring to the multi-component structure of the typical target application, the main challenge in the synthesis of a supervisorycontroller is the exponential growth of the overall state set in terms of the number of components. This is addressed by compositional methods which avoid the explicit construction of an overall model. In their basic form, DES model the order of events and this is adequate to synthesise supervisor that guarantees safe operation of the system; e.g. for automated transport, a segment of a track shall only be used by one train at a time to be safe. However, for many applications performance explicitly relates to physical time; e.g. for automated transport, we are concerned about the overall throughput realised with all available trains and tracks. Here, the literature provides multiple modelling frameworks which differ in expressiveness. On the one end of the range, there are the Brandin-Wonham framework, which uses a global tick-event to represent the elapse of time, and there are timed events graphs (TEG), which are a specific type of Petri nets that translate to linear (max, +)-equations. For both frameworks, controller synthesis is well understood. However, being on the low end regarding expressiveness, both frameworks have severe limitations.With Brandin-Wonham, one cannot model concurrent system with multiple real-time clocks, and TEG cannot address logical decision making. In this research project, we will establish efficient methods for the control of timed DES that are more expressive than the Brandin-Wonham framework and TEG. Technically, we will consider so called (max, +)-automata and specific classes of timed Petri nets as base models, in order to develop modular and hierarchical approaches to supervisory control, including the respective synthesis algorithms. Our results will considerably enlarge the scope for model based controller synthesis of DES.