The following topics are not covered in this thesis, but it is believed that future investi-gations could be beneficial.
• In Chapter 5 an adaptive observer is designed for simultaneous estimation of the electrical states, the speed, and the inter-turn short circuit of the induction mo-tor. In the design proposed here, the parameters of the motor are assumed known.
However, an adaptive observer is used. Therefore it should be possible to find a transformation of the induction motor model, making it possible for the adap-tive observer to adapt to the motor parameters. If this is possible, the proposed algorithm becomes parameter independent.
• In Chapter 5 also a Linear Matrix Inequality (LMI) approach was used for both analysis and synthesis of the observer gain in the proposed adaptive observer. It could be interesting to include the concept of LMI regions in the proposed analysis and synthesis. Hereby, it would be possible to state demands on the damping ratio in the system, as well as the convergence rate.
• In Chapter 6 a new concept, for realization of subsystems identified using Struc-tural Analysis, was presented. This concept should be further investigated.
Es-pecially Assumption 6.2.3, stating the condition for the existence of a state space transformation, should be considered.
• In Chapter 7 a detection scheme, based on the steady state model of the pump, was proposed. Because of the steady state model, transient phases can force the residual to be different from zero, even in the no fault cases. Therefore, means for detecting these transient conditions, must be established before implementing the algorithm in real life applications.
• A set-valued approach was proposed for obtaining robustness in the residual gen-eration in Chapter 7. This approach utilizes interval models. Extending the set-valued approach, to include interval models of each fault case, it might be possible to state which fault has happened in a robust manner. Hereby robustness is intro-duced in the identification of incipient faults.
Tom M. Apostol. Mathematical Analysis, second edition. Addison-Wesley Publishing Company, Inc., 1974. ISBN 0-201-00288-4.
M. Arkan, D. K. Perovic, , and P. Unsworth. Online stator fault diagnosis in induction motors. IEE proceedings on electrical power applications, Vol. 148, No. 6, 2001.
Neil Arthur and Jim Penman. Induction machine condition monitoring with higher order spectra. IEEE Transaction on Industrial Electronics, Vol. 47, No. 5, 2000.
S. Backir, S. Tnani, T. Poinot, and J. C. Trigeassou. Stator fault diagnosis in induction machines by parameter estimation. IEEE, International Symposium on Diagnostics, Grado, Italy, 2001.
Antonio Baldassarre, Maurizio De Lucia, and Paolo Nesi. Real-time detection of cav-itation for hydraulic turbomachines. Real-Time Imaging 4, Page 403 - 416, 1998.
Michele Basseville and Igor V. Nikiforov. Detection of Abrupt Changes - Theory and Application. www.irisa.fr/sigma2/kniga/, 1998.
Alberto Bellini, Fiorenzo Filippetti, Giovanni Franceschini, Carla Tassoni, and Ger-ald B. Kliman. Quantitative evaluation of induction motor broken bars by means of electrical signature analysis. IEEE Transaction on Industry Applications, Vol. 37, No.
5, 2001.
Mohamed El Hachemi Benbouzid. A review of induction motors signature analysis as a midium for faults detection. IEEE Transactions on industrial electronics vol. 47 no.
5, 2000.
Gildas Besancon. Remarks on nonlinear adaptive observer design. ELSEVIER, System
& Control Letters, Vol. 41, No. 4, 2000.
Søren Abildsten Bøgh. Fault Tolerant Control Systems - a Development Method and Real-Life Case Study. PhD thesis, Aalborg University, Department of Control Engi-neering, 1997.
Péter Bóka and Gábor Halász. Dynamic behaviour of centrifugal pumps. Proceedings of the XXIst IAHR Symposium on Hydraulic Machinery and Systems, Lausanne, 2002.
Mogens Blanke. Consistent design of dependable control systems. Control Eng. Prac-tice, Vol. 4, No. 9, 1996.
Mogens Blanke, Michel Kinnaert, Jan Lunze, and Marcel Starowiecki. Diagnosis and Fault-Tolerant Control. Springer Verlag, 2003. ISBN 3-540-01056-4.
Julien Le Bleu Jr. and Ming Xu. Vibration monitoring of sealess pumps using spike energy. Sound and Vibration, Vol. 29, No. 12, 1995.
Austin H. Bonnett and George C. Soukup. Cause and analysis of stator and rotor failures in three-phase squirrel-cage induction motors. IEEE Transaction on Industry Applications, Vol. 28, No. 4, 1992.
A. Boukhris, D. Mandel, and J. Ragot. Data validation using interval algebra. UKACC International Conference on Control, CONTROL’98, 1998.
Fernando Briz, Michael W. Degner, Antonio Zamarron, and Juan M. Guerrero. Online stator winding fault diagnosis in inverter-fed ac machines using high-frequency signal injection. IEEE Transactions on Industry Applications, Vol. 39, No. 4., 2003.
Cash, M. A., Habetler, T. G., and Kliman, G. B. Insulation failure prediction in in-duction machines using line-neutral voltages. IEEE Industry Applications Conference, Thirty-Second IAS Annual Meeting, IAS ’97, 1997.
Jie Chen and R. J. Patton. Robust Model-Based Fault Diagnosis for Dynamic Systems.
Kluwer Academic Publishers, 1999. ISBN 0-7923-8411-3.
Young Man Cho and Rajesh Rajamani. A systematic approach to adaptive observer synthesis for nonlinear systems. IEEE Transactions on Automatic Control, Vol. 42, No.
4, 1997.
Tommy W. S. Chow and Hong-Zhou Tan. Hos-based nonparametric and parametric methodologies for machine fault detection. IEEE Transaction on Industrial Electron-ics, Vol. 47, No. 5, 2000.
David Cox, John Little, and Donal O’Shea. Ideals, Varieties, and Algorithms, An introduction to computational algebraic geometry and comutative algebra. Springer-Verlag Inc., 1997. ISBN 0-387-94680-2.
Sergio M. A. Cruz and A. J. Marques Cardoso. Stator winding fault diagnosis in three-phase synchronous and asynchronous motors, by the extended park’s vector approach.
IEEE Transaction on Industrial Applications, Vol. 37, No. 5, 2001.
M. Cudina. Detection of cavitation phenomenon in centrifugal pump using audible sound. Mechanical Systems and Signal Processing, Vol. 17, No. 6, 2003.