Improved Fault Diagnosis Method for PLC-Based Manufacturing Processes with Validation through a Cyber-Physical System

Most manufacturing systems in the industry nowadays are controlled by Programmable Logic Controllers (PLCs), which are characterized by their high robustness and low cost. The systems controlled by PLCs are typically described as Discrete Event Systems (DESs), and it is often difficult to detect faults and behavioral abnormalities related to the PLC process. Researchers proposed an automated tool called fault and behavior monitoring tool for PLC (FBMTP) whose main advantage is its ability to effectively handle inaccuracies with large-scale PLC-controlled manufacturing systems. Although FBMTP effectively addresses the issues in PLC-controlled systems, only the Boolean I/O signals (1/0) intercepted from the memory area of the PLC are examined. However, PLC I/O often involves analog signals, which are real values. Therefore, we introduced a new parameter to increase the diversity of this mechanism, an improved fault and behavior monitoring tool for PLC (IFBMTP). Cyber-Physical System (CPS) technology is applied across various fields. In the manufacturing sector, it is used for real-time monitoring, production control, and information sharing, enhancing the flexibility of manufacturing systems. Moreover, CPS is practical for simulating and testing different fault detection models, such as IFBMTP, given the limited availability of large-scale equipment for testing in industries. Presently, many software platforms focus primarily on animation or integer computations but cannot accurately reflect physical analog data, making integration among multiple technologies challenging. Automation Studio, developed by Famic Technologies Inc., stands out for its rapid modeling, multi-technology integration, and application in virtual commissioning. We leveraged Automation Studio as the development platform to create an integrated CPS and validated the robustness of IFBMTP under various scenarios for debugging and testing. Such integration of multiple technological virtual systems is essential for industrial applications and validations.