condition monitoring of variable speed machinery
TRANSCRIPT
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Advancing the Online Monitoring of Variable Speed Machinery
Jordan McBain, [email protected]
Sudbury, Ontario
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Introduction
• Monitoring of machinery largely limited to constant conditions
• Changes in speed and load termed ‘nuisance parameters’
• Variable speed/load machinery ubiquitous
• Resonances/vibration power
Ref: Stack
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Novelty Detection
• Limited data characterizing normal state– Little or no data for
abnormal states• Compute feature vectors
of vibration (e.g. AR model)
• Methods– SVDD and Statistical
Boundaries
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Statistical Parameterization
• Vibration strongly tied to temp (speed)• Advanced by Keith Worden (Structural health monitoring)
– Segment feature vectors into small groups of modal value – Compute statistics for each group (bin)– Trend with regression or interpolation
• Suffers from– Double curse of dimensionality
• Describe healthy state for all segments of modal parameter
– Gaussian distribution• Good heuristic
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Multi-Modal Novelty Detection
• Employ intuition from Statistical Parameterization– Don’t flatten data into bins– Add modal parameter (speed) to feature vector– Use any novelty detection technique– One parameter only
• Gaussian Distribution – eliminated
• Curse of dimensionality– Dependent on underlying
novelty detection technique
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Experimental Methodology
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Experimental Methodology• Sensors
– 2500 ppr Tach– 4 accel (10 kHz)– AE– Hall effect sensors– Inline torque meter
• Variable Speed/Fixed Load (10 Nm)• DAQ and Control
– NI FPGA and Accel Card
• Vibration data– Segmentation: 30 shaft rotations, 70% overlap, Gaussian window – Feature vectors: Auto-Regressive (AR) Models and Statistics– Training: 20% of data for training, 80% for validation
• Faults– Gears (96:32 and 80:48): missing tooth, root crack, chipped pinion– Bearings: rough ball, outer race, inner race, chopped ball
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Classification Results
• No speed adaptation (SVDD)
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Classification Results
• Statistical Parameterization
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Classification Results
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Conclusions
• No speed adaptation = poor results• Statistical Parameterization– Good results– Double Curse of Dimensionality– Gaussian Distribution
• Multi-Modal Novelty Detection– Comparable Results– More to come
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Future Work
• Novelty Detection Augmented for Fault Detection with Variable Speed Machinery (MSSP)
• Multi-Modal Novelty Detection for Variable Load and Speed Machinery
• Other multi-modal novelty detection techniques– No modal sensors
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References
• [1] J McBain, M Timusk. Fault detection in variable speed machinery: Statistical parameterization, Journal of Sound and Vibration 327 (2009) 623-646.
• [2] K Worden, H Sohn, CR Farrar. Novelty detection in a changing environment: Regression and interpolation approaches, J.Sound Vibrat. 258 (2002) 741-761.
• [3] JR Stack, TG Habetler, RG Harley. Effects of machine speed on the development and detection of rolling element bearing faults, IEEE Power Electronics Letters. 1 (2003) 19-21.