Research On Non-Invasive Real-Time Diagnosis Method For PLC Control System Of Minning Hoist

According to the actual demand of mine hoist's monitoring and fault diagnosis, this paper presents a new method of non-intrusive monitoring used in mine hoist's monitoring and fault diagnosis. The core of this detection method is using machine vision to capture the status image of PLC indicator. It is using non-invasive way to obtain the state information of control system rather than directly using parallel connection circuit. Monitoring system does not invade the internal control system. it means there is no electrical contact between the original control system and the monitoring-diagnosis system. In this way, electrical interference in the original control system can be avoided, so it can guarantee that electronic control system is more secure to run.Because the LED indicator of PLC directly reflect the state of control system's input or output, such as switches, relays, contactors, it can use the Machine Vision to obtain the state information indirectly. This is the basic principles of "non-invasive" surveillance.The key of this technology is indicating location of LED array automatically and state-recognition. The realization and related technologies of non-invasive detection system are introduced in the Chapter 2 and Chapter 3.In order to achieve monitoring and fault diagnosis, besides obtaining PLC module's information, it needs the information of hoist-drum's rotation-speed, angle, steering (corresponding to the container's speed, depth and direction) and the host-command-handle's state. This article also discusses the methods used to obtain the information with additional encoder.After the problem that information access is resolved, the critical step for fault diagnosis is how to deal with this information. Taking the example of TKM electronic control system, the fault symptoms and fault sources are classified according to the corresponding relation in the Chapter 4. The failure trees of main circuit, safety circuit, speed circuit, dynamic braking circuit and auxiliary circuit are constructed. This model uses the theory of downward method to obtain the minimum cut sets and determine the fault position. Quantitative analysis of the failure tree is introduced, so it provides theoretical basis for further establishment of FTA.On the basis of the above study, the software construction is analyzed in Chapter 5. It also provides the design description including communication module, real-time-monitoring module, fault diagnosis module and display module. The corresponding software of host computer is developed by Visual Basic to simulate the process-monitoring and failure analysis of TKM control system.