Abstract
Complex systems are composed of numerous interconnected subsystems, each designed to perform specific functions. The different subsystems use many technological items that work together, as for the case of cyber-physical systems. Typically, a cyber-physical system is composed of different mechanical actuators driven by electrical power devices and monitored by sensors. Several approaches are available for designing and validating complex systems, and among them, behavioral-level modeling is becoming one of the most popular. When such cyber-physical systems are employed in mission- or safety-critical applications, it is mandatory to understand the impacts of faults on them and how failures in subsystems can propagate through the overall system. In this paper, we propose a methodology for supporting the failure mode, effects, and criticality analysis (FMECA) aimed at identifying the critical faults and assessing their effects on the overall system. The end goal is to analyze how a fault affecting a single subsystem possibly propagates through the whole cyber-physical system, considering also the embedded software and the mechanical elements. In particular, our approach allows the analysis of the propagation through the whole system (working at high level) of a fault injected at low level. This paper provides a solution to automate the FMECA process (until now mainly performed manually) for complex cyber-physical systems. It improves the failure classification effectiveness: considering our test case, it reduced the number of critical faults from 10 to 6. The remaining four faults are mitigated by the cyber-physical system architecture. The proposed approach has been tested on a real cyber-physical system in charge of driving a three-phase motor for industrial compressors, showing its feasibility and effectiveness.
Highlights
Complex systems are composed of devices belonging to different technological areas
We propose a method to perform FMECA, based on commercial electronic design automation (EDA) tools originally introduced for design, allowing the analysis of a complex cyber-physical system composed of analog, power, digital, and mechanical subsystems
The behavioral model of each subsystem present in the whole complex system is prepared. It can be obtained from the design phase of the complex system, or by identifying the transfer function between the as discussed in Section 2.3 and in [38,39], in this paper, we consider only the catastrophic faults model applied at the subsystem under test (SSUT) circuit diagram level or inside a power device
Summary
Complex systems are composed of devices belonging to different technological areas. For example, cyber-physical systems often include power subsystems implemented by combining power devices, analog low-voltage circuits, and digital devices. FMECA is performed after the design to whole system; in the event of a failure of a subsystem, it is necessary to understand the effects determine if some of the faults that can affect the components prevent the system from satisfying the that a failed subsystem has on other subsystems In this way, the possible propagation of the fault safety level associated with its functions. In [6,7,10,11], in this paper mainly lies in the simulation approach proposed, which allows for considering lowthe FMECA methodology is proposed for the systems dedicated to the generation of electricity, such as level faults in each subsystem and to analyze their impact on the whole cyber-physical system, solar photovoltaic and wind power.
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