Hierarchical fault diagnosis and recovery in discrete-event systems

故障检测和恢复系统在保护生命财产和提高工业系统的自主性和可靠性方面发挥着至关重要的作用，因此在过程、电力和航空航天等各个行业中都具有重要意义。故障诊断系统和恢复程序的设计是一个复杂的问题，需要系统和形式化的方法。最近，申请人和他的学生开发了一个基于“离散事件”模型的框架来解决这些问题。在诊断中使用离散事件模型的挑战之一是设计过程的计算复杂性。降低复杂性的一种方法是利用许多复杂系统中存在的层次结构。我们设计了一种分层离散事件系统诊断系统的设计方法。此外，我们开发了一种诊断技术，其中用于诊断的模型的复杂性根据所需的诊断分辨率进行调整。在提出的研究计划中，我们计划合并上述分层和多分辨率框架，从而得出一种充分利用系统架构来控制计算复杂性的方法。在本研究中，我们还研究了回收程序的合成。我们希望为故障恢复问题开发一种分层解决方案，其中高级主管（控制器）发出高级命令，这些命令由低级控制器转换和实现。高级控制器是基于简化的对象的高级模型设计的，因此，与基于对象的低级详细模型设计的控制器相比，应该具有更简单的结构。上述回收程序是“离线”设计的（在系统开始运行之前）。在许多情况下，由于大量的故障场景，将所有恢复过程存储在计算机内存中可能是不可行的。我们打算开发的另一种方法是“在线”生成恢复程序，一旦诊断出故障，就“在线”计算合适的恢复顺序。

Fault detection and recovery systems play a crucial role in protecting life and property and in increasing the autonomy and reliability of industrial systems, and thus, are of great importance in various industries such as process, power and aerospace. The design of fault diagnosis systems and recovery procedures is a complex problem requiring a systematic and formal approach. Recently, a framework for solving these problems based on "discrete-event" models has been developed by the applicant and his students. One of the challenges associated with the use of discrete-event models in diagnosis is the computational complexity of the design procedure. One way of reducing complexity is to take advantage of the hierarchical structure present in many complex systems. We have devised a methodolgy for designing diagnosis systems for hierarchical discrete-event systems. Furthermore, we have developed a technique for diagnosis in which the complexity of the model used for diagnosis is adjusted according to the required diagnosis resolution. In the proposed research program, we plan to merge the above hierarchical and multi-resolution frameworks, and thus arrive at a methodlogy that takes full advantage of system architecture to control computational complexity. In the proposed research, we also study the synthesis of recovery procedures. We would like to develop a hierarchical solution for the fault recovery problem in which a high-level supervisor (controller) issues high-level commands that are translated and implemented by a low-level controller. The high-level controller is designed based on a simplified high-level model of the plant and hence, should have a simpler structure compared to a controller designed based on the low-level, detailed model of the plant. The above-mentioned recovery procedures are designed "off-line" (before the system becomes operational). In many cases, storing all recovery procdures in computer memory may not be feasible due to the large number of failure scenarios. An alternative approach that we intend to develop is the "on-line" generation of recovery procedures in which a suitable recovery sequence is computed "on-line" once a failure is diagnosed.