Multi-system and multi-fault evaluation towards generalisable fault monitoring for efficient pneumatic systems : a measurement-based approach

Abstract

Pneumatic fault monitoring is crucial for improving the sustainable performance of compressed air systems. Research has focused on developing Fault Detection and Diagnosis (FDD) systems, leveraging measurements for fault monitoring. Pressure and cycle time are commonly logged in industrial setups and studies have investigated their potential for this application. However, research is often case-specific, limiting broader applicability. This study uses a measurement-based approach for development of generalisable pneumatic FDD systems, evaluating measurement aspects across three System Complexity Levels (SCLs) and seven Fault Profile Levels (FPLs). Findings highlight the robustness of delta pressure (ΔP1) measurements, especially under unregulated pressure, detecting and characterising continuous faults such as leaks or pressure drops. Statistical ranking using the Kruskal-Wallis method, resulted that the RMS, Mean, and Shape Factor indicators based on ΔP1, are reliable for fault monitoring across all SCLs. For instance, when monitoring a ∅ 0.5 mm leak, the RMS increased by 17.0 % and 19.4 % across two different setups, irrespective of a ≈sixfold difference in baseline flow rate. Cycle time measurements proved capable in detecting actuator faults and isolating them throughout all SCLs. Study findings also proved that this measurement could monitor continuous faults. A ∅ 1.0 mm pipe leak and 0.3 bar pressure drop were also identified through a 3.9 % and 4.6 % increase in actuator retraction time, respectively. Ultimately, this study found indicators: ΔP1 RMS, ΔP1 Mean, ΔP1 Shape Factor, and Mean Cycle Time, reliable in identifying and diagnosing faults across all SCLs and FPLs, having high potential for generalisable pneumatic FDD systems.