Temperature Estimation of Asynchronous Machines Using Kal- man Filters ..... For this purpose an Android application for Smart-Phones .... experimental cost is.
Technische Universität Berlin
Annual Report 2016
Electronic Measurement and Diagnostic Technology Technische Universität Berlin Prof. Dr.-Ing. Clemens Gühmann Electrical Engineering and Computer Science Chair of Electronic Measurement and Diagnostic Technology Sekr. EN 13, Einsteinufer 17 10587 Berlin, Germany Phone: +49 30 314-22280 http://www.mdt.tu-berlin.de
Dear ladies and gentlemen, dear colleagues and friends, By tradition we would like to give you a review of the last year’s events. In this annual report you will find more details on our projects: • Condition Monitoring and Remaining Useful Lifetime Prediction of Hydrodynamic Journal Bearings integrated in Future Planetary Gearboxes of Geared Turbofans • Condition Monitoring and Fault Diagnosis of Future Planetary Gearboxes in Aero Engines • Hybrid Bearing Monitoring • Use of Compressed Sensing in Sensor Networks • StreetProbe - Cooperative Cloud-Based Road Condition Monitoring • Photogrammetric Pavement Distress Detection and Classification • Temperature Estimation of Asynchronous Machines Using Kalman Filters • Coordinated Control Strategy for State Transition in ECVT • Dry Clutch Control Based on Lifetime Prediction • Design of Experiments for Calibrating ECU Software Functions • Optimization of Iterative Online Methods for the Determination of Steady-state Data Driven Models in Terms of Combustion Engine Calibration and a summary of our teaching activities and the news from our workshops. A special highlight in 2016 was once again the conference "Simulation and Testing for Vehicle Technology". The conference picked up current trends in modeling, simulation, control unit testing in connection with developing automotive electronics. Currently we are organizing the international conference „International Calibration Conference - Automotive Data Analytics, Methods, DoE“. In June scientists and developers from all over the world will 1
discuss about modern engine and powertrain calibration methods here in Berlin. The conference will expand on the topics discussed at the IAV conference entitled „DoE in Powertrain Development“ with the related areas of „machine learning“ and „big data“. Now its ninth outing, the conference will in be a forum on which to critically engage with the future challenges of the digital revolution. Both conferences are executed in cooperation with our industrial partner IAV GmbH. This year a further step toward the improvement of teachers’ education at TU Berlin could be done. The School of Education TU Berlin (SETUB) was founded and the elected Institute Council began to work. The SETUB serves as a central point of contact and coordinates the teachers’ education at TU Berlin. The ceremonial opening of SETUB will be on 25 January 2017 in the Lichthof to which all those interested are welcome. Finally, I would like to thank all partners and the whole MDTTeam. I hope you will enjoy our annual report. Please contact us if you have any questions or comments. I wish you and your families a blessed Christmas and a Happy New Year, Clemens Gühmann
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Condition Monitoring and Remaining Useful Lifetime Prediction of Hydrodynamic Journal Bearings Integrated in Future Planetary Gearboxes of Geared Turbofans Noushin Mokhtari
To provide thrust turbofans use both air passing through the turbine as well as air bypassing the turbine. High bypass ratios (ratio of the air mass-flows) increase the efficiency of turbofans in terms of fuel reduction and noise emission. To reach high bypass ratios the fans radius has to be increased. In conventional turbofans the fan, the low pressure compressor (LPC) and the low pressure turbine (LPT) run at the same speed. The increase in radius is therefore limited due to maximum tip speeds. Geared turbofans use a planetary gearbox between fan and LPC to decouple the rotational speeds. The fans lower speed enables an increased bypass ratio without sonic speed at the fans blade tips. The following research project is conducted on behalf of Rolls-Royce Deutschland Ltd & Co KG and funded by the Federal Ministry of Economic Affairs and Energy. A planetary gearbox consists of many parts such as gear wheels, shafts and bearings. The failure of one of these components could lead to the breakdown of the whole turbofan. Therefore, the project LAROS deals with the condition monitoring and remaining useful lifetime prediction of hydrodynamic journal bearings (HJB) in planetary gearboxes of geared turbofans. The most essential damaging mechanism for HJB is wear as a re-
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sult of mixed or boundry friction. These friction states are caused by conditions like start/stop cycles, insufficient oil supply, overload or oil contamination. To examine these conditions a journal bearing test rig was built at TU Berlin. Acoustic emission technology (AE) is a promising method to detect friction in HJB. Compared to vibration sensors AE sensors can detect failures much earlier. Therefore, the identification of AE signals of the mentioned conditions is required. A challenge to the use of AE sensors are the relativly high frequency ranges (30kHz-2Mhz) in which acoustic emissions occur. To record such high frequencies a measurement card with the ability to sample at high ranges was bought. First results show many similarities to the Stribeck curve, which indicates the relationship between speed, load and viscosity and the coefficient of friction. The next step is to run more experiments to better understand the
friction behaviour of HJB and to extract the best features for the condition monitoring purpose. For the prediction purpose the relationship between friction intensity and duration is needed. In 2017 it is planned to run tests at a greater journal bearing test rig, which belongs to the TU Clausthal. At this test rig the developed algorithms can be validated and improved.
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Condition Monitoring and Fault Diagnosis of Future Planetary Gearboxes in Aero Engines Mateusz Grzeszkowski
Future bypass engines in civil aviation will provide a planetary gearbox in the drivetrain to uncouple the fan from the low pressure turbine shaft. Using this configuration a higher bypass ratio can be achieved through a larger fan diameter. But the application of a gearbox increases the risk of gearbox failures through wear and gear defects. Therefore a model-based condition monitoring system is built to identify deviations from the nominal vibration behaviour, which are caused by gear failures at an early stage. However, to gain robust monitoring features the failure mechanisms have to be investigated on one hand and on the other hand the impact of certain gear manufacturing deviations on the feature extraction methods have to be characterized. Therefore within the scope of the project DeFiHog gear geometry variations were investigated to evaluate the sensitivity of condition features. The goal is to distinguish between manufacturing variations and failure modes. The co-operation partner within this project is Rolls-Royce Deutschland Ltd & Co KG and the project is funded by the Federal Ministry of Economic Affairs and Energy. This year a spur gear test bench of the MDT chair was extended to a planetary gear test bench. Using preliminary considerations from the foregoing project Kerntriebwerk NT suitable sensors like structureborne sound sensors were applied on the ring gear to investigate defined gear failures. First results showed that a window-based evaluation of the structure-borne signals is the most promising approach for the diagnosis of locally distributed gear failures. Therefore high attention is paid to the analysis of rotation angle-windowed signals of meshing gears. Correlating features can then be extracted from the Wigner-Ville distribution and the order spectra of the residual and the differential signals. Furthermore, a multi-body system model has been developed to simulate the nominal vibration behaviour of the planetary gearbox. In future steps the model parameters have to be estimated through measurements at the test bench, to allow a discrimination between manufacturing variations and gear failures. In 2017 measurements on a Back-to-Back test rig at the RWTH Aachen will start, to evaluate the developed condition monitoring features against gears with manufacturing variations. 5
Hybrid Bearing Monitoring Marc Seimert (Publication 2016: [7])
The aim of the project HyZyRo is to research new bearing technologies. It focuses on the use of hybrid roller bearings (ceramic rolling elements between steel races) in aircraft engines. The following companies and research institutes are involved: RollsRoyce Deutschland Ltd & Co KG (RRD), Dahlewitz; FAG Aerospace GmbH & Co. KG, Schweinfurt and our chair (MDT). The project HyZyRo is a sub-project of the ongoing national aeronautics research program, funded by the Federal Ministry of Economic Affairs and Energy. The aim to reduce carbon dioxide emissions and aircraft noise makes it necessary to design ecologically friendly engines. One part of this is a new kind of bearing. Hybrid bearings have important advantages over conventional steel bearings, including higher stiffness to achieve higher engine speeds and lower friction to reduce losses. The objective of the project is to develop a monitoring system that detects damages and the failure progress in hybrid roller bearings. Failure detection, classification and prediction should be designed in a way so they can be integrated into an aircraft engine monitoring system. The challenge is to diagnose the bearing health in this highly disturbed environment of an aircraft engine. This year first tests were done with a full-scale hybrid roller bearing. A focus here was to get an understanding of roller slippage. The problem with slippage is that a steady change can cause a faster degradation of the bearing. Tests with sub-scale bearings were also done this year. A new sensor material with higher temperature resistance was tested. A small damage at the roller was detected and some investigation to roller slippage was done. In the next and the last year of the project the test will continue and the focus is on the analysis of the measurement data and our aim is to detect roller damage with the temperature resistant sensor at the full-scale bearing.
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Use of Compressed Sensing in Sensor Networks José-Luis Bote-Garcia
Compressed Sensing (CS) is a new technique that allows to surpass the traditional limits of the sampling theory by measuring signals with far less measurements then the Nyquiste Theorem states. It takes advantage of the fact that there are orthogonal bases Φ that represent signals s using only a few nonzero coefficients. Such a sparse representation of a signal is for example the Fourier Transformed where just k coefficients are significant, when s is composed of sinusoids. If so, it can be shown that we can represent a signal s of length n by so called measurements b of length m with k < m
