Research

About Machine Condition Monitoring

Unexpected system or component failures are detrimental to any business, and may mean interruption in the whole line of work, causing financial losses many times the component's worth. Therefore, predicting the failures and preventing them and/or taking precautions even before they took place is the sensible strategy . Preventive diagnosis is a method in which some characteristic parameters of an operating system are monitored and analyzed on-line and possible failures can be perceived before they occur, hopefully, revealing adequate tell-tale signs for an early warning. To this end, the characteristic parameters and their limiting values (thresholds) between which the system can run smoothly with reduced possibility of failure are determined and a database is formed. A general diagnostics is to be proposed based on experiencial and theoretic knowledge.

Sample Abstracts

ON THE PREDICTABILITY OF TIME SERIES BY METRIC ENTROPY,  by Hakkı E Sevil.

The computation of the metric entropy, a measure of the loss of information along the attractor, from experimental time series is the main objective of this study. In this study, replacing the current warning systems (simple threshold based, on/off circuits), a new and promising prognosis system is tried to be achieved by the metric entropy, i.e. Kolmogorov – Sinai entropy, from  chaotic time series. Additional to metric entropy, correlation dimension and time series statistical invariants were investigated. Condition monitoring of ball bearings and drill bits was achieved in the light of practical considerations of time series applications. Two different accelerated bearing run-to-failure test rigs were constructed and the prediction tests were performed. However, as a reason of shaft failure in both structures during the experiments, none of them is completed. Finally, drill bit breakage experiments were carried out. In the experiments, 10 small drill bits (1 mm diameter) were tested until they broke down, while vibration data were consecutively taken in equal time intervals. After the analysis, a consistent decrement in variation of metric entropy just before the breakage was observed. As a result of the experimental results, metric entropy variation could be proposed as an early warning system.

-Fractal Geometry Analysis of Time Series for Fault Identification,  by Aysun Kaya.

In the past two decades, fractal geometry has developed into a new and powerful  mathematical technique, capable of modeling a wide class of complex natural systems. Until recently, it has remained a novelty in explaining strange phenomena in nature. Today it is realized that the capability of fractals are beyond the basic self-similar illustration of snow flakes.  The use of fractals range from interpolation, estimation, modeling even as far away as to data compression. Detection of faults in mechanical systems has come under spotlight increasingly ever so with the advent of intelligent modeling tools in this field. By fractals, the analysis of time series could point at inherent flaws, cracks and impurities in the material. With the inception of an entity known as fractal dimension, mechanical surfaces may also be characterized. A comprehensive literature search has been conducted, and progress is made towards the fusion of the two important topics mentioned above. This research aims at providing a basis for setting up a model of such a fusion, and hopefully a new theoretical insight on the fractal geometry in fault diagnosis.

Funded Research

A 6 DOF Parallel Manipulator Simulation&Control, co-worker, $ 10,000 university grant, IYTE-10, 2002.

Probabilistic Localization & Path Planning in Dynamic Environments, $ 2000, university grant, IYTE-26, 2003.

A Study of Autonomous Navigation by Virtue of a Coupled GPS-INS System, Supported by a $ 21,890 DPT research grant , 2004.

Passive Process Monitioring by AE, 2005-IYTE-44, $3,000 university grant, 2005.

Condition Monitoring of a Gear Set by Accelerometers, 2005-IYTE-47,  co-worker, $4000, 2005.

Process Monitoring over the Ethernet/Internet,  2006-IYTE-43,  $3,000, university grant, 2006.

A Real Time Process Monitoring on a Gear Mechanism through an Accelerometer, co-worker , $3,000, 2006-IYTE-44, 2006.

Qualitative Machine Health Assessment by Running Quality Index, IYTE-08, $2000, 2007.