Е-Публикации
Технически университет - София

Abstract: Highlights: What are the main findings? The proposed cyber-physical digital twin with QFT and NIS2 security (CPDTQN) achieves high-precision joint and Tool Center Point (TCP) tracking under parametric uncertainty, worst-case dynamics, and external disturbances. Secure PLC-MATLAB-ROBOGUIDE integration demonstrates real-time consistency between simulation and twin execution, with negligible latency introduced by NIS2-aligned security mechanisms. What are the implications of the main findings? The CPDTQN architecture enables reliable deployment of robust controllers in industrial Operational Technology (OT) environments, maintaining stability even under communication delays, jitter, and cyber-resilience enforcement layers. Digital twin-based validation provides a safe, repeatable, and traceable framework for verifying control robustness, cyber-resilience, and regulatory (NIS2) compliance prior to physical deployment. This article presents an integrated framework for robust control and cybersecurity of an industrial robot, combining Quantitative Feedback Theory (QFT), digital twin (DT) technology, and a programmable logic controller–based architecture aligned with the requirements of the NIS2 Directive. The study considers a five-axis industrial manipulator modeled as a set of decoupled linear single-input single-output systems subject to parametric uncertainty and external disturbances. For position control of each axis, closed-loop robust systems with QFT-based controllers and prefilters are designed, and the dynamic behavior of the system is evaluated using predefined key performance indicators (KPIs), including tracking errors in joint space and tool space, maximum error, root-mean-square error, and three-dimensional positional deviation. The proposed architecture executes robust control algorithms in the MATLAB/Simulink environment, while a programmable logic controller provides deterministic communication, time synchronization, and secure data exchange. The synchronized digital twin, implemented in the FANUC ROBOGUIDE environment, reproduces the robot’s kinematics and dynamics in real time, enabling realistic hardware-in-the-loop validation with a real programmable logic controller. This work represents one of the first architectures that simultaneously integrates robust control, real programmable logic controller-based execution, a synchronized digital twin, and NIS2-oriented mechanisms for observability and traceability. The conducted simulation and digital twin-based experimental studies under nominal and worst-case dynamic models, as well as scenarios with externally applied single-axis disturbances, demonstrate that the system maintains robustness and tracking accuracy within the prescribed performance criteria. In addition, the study analyzes how the proposed architecture supports the implementation of key NIS2 principles, including command traceability, disturbance resilience, access control, and capabilities for incident analysis and event traceability in robotic manufacturing systems.

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