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7th IFAC International Symposium on Fault Detection, Supervision and Safety of Technical systems, SAFEprocess'09

作者： Muenchhof, Marco Beck, Mark Isermann, Rolf Technische Universität Darmstadt Institute of Automatic Control Laboratory for Control Systems and Process Automation Darmstadt Germany

ISBN: (纸本)9783902661463

As fault detection and fault diagnosis are more and more finding their way into modern industrial mechatronic products, it is now time to take the next step. Based on the research efforts for fault detection and diagnosis, a platform has been prepared for research on fault management, i.e. automatic reactions of the system to continue operation after the detection of faults. These reactions may employ hardware redundancy (i.e. switching from a faulty actuator to another, intact one) or analytical redundancy (i.e. switching from a faulty sensor to a "model sensor" or "soft sensor"). A total fault tolerance concept must encompass all components of a system, i.e. the actuators and drives, the sensors as well as the controller and communication. In many cases, a degradation of functions has to be accepted after a fault has appeared. This contribution will center on actuators and drives showing real-world examples of prototypical realizations and examples from industrial products. Concentrating on the most widespread actuation principles, the paper will focus on electric drives and hydraulic actuators. First, a review is given on fault tolerance principles and general structural considerations e.g. hot-standby and cold-standby, focusing on the scheme of an overall fault-tolerant control system. Then, fault statistics for real actuators and drives will be presented. These fault statistics give hints on the parts of the actuators that are most susceptible to faults. Different designs of fault tolerant actuators and drives, which have been realized, shall be presented and evaluated with respect to their capabilities of sustaining faults. Finally, an outlook for fault-tolerant mechatronic systems will be given. © 2009 IFAC.

关键词： Aerospace applications

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Neural-net model based fault diagnosis for hydraulic servo axes

Neural-net model based fault diagnosis for hydraulic servo a...

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作者： Muenchhof, Marco Clever, Sebastian Technische Universität Darmstadt Institute of Automatic Control Laboratory for Control Systems and Process Automation 64283 Darmstadt Germany

ISBN: (纸本)9783902661463

In this paper, fault detection methods for hydraulic systems based on a parity equation approach with neural net models are presented. Hydraulic systems are used in manifold applications in industry. They are however not yet the subject of intense research in the area of fault detection and diagnosis, which can be mainly attributed to their strong nonlinear behavior, which exacerbates the physical modeling extensively. To avoid the difficulties associated with the physical modeling, a data-driven modeling approach based on the LOLIMOT neural network will be presented in this paper. Different subsystems of the hydraulic servo axis will be modeled using different sensor configurations. Experimental data from a real testbed allow to compare the model fidelity of the different resulting neural nets and can also be used to illustrate the capabilities of the parity-equation based fault detection approach, which in general allows the detection of tiny faults, such as sensor offset faults in the area of a few percent of the maximum sensor readout. © 2009 IFAC.

关键词： Fault detection

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Identification of nonlinear static processes with local polynomial regression and subset selection

Identification of nonlinear static processes with local poly...

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15th IFAC Symposium on System Identification, SYSID 2009

作者： Sequenz, Heiko Schreiber, Alexander Isermann, Rolf Institute of Automatic Control Laboratory of Control Engineering and Process Automation Technical University Darmstadt Germany

ISBN: (纸本)9783902661470

The presented method for nonlinear system identification is based on the LOLIMOT algorithm introduced by Nelles and Isermann [1996]. The LOLIMOT algorithm divides the input space by a tree-construction algorithm and interpolates the local linear models by local membership functions. Instead of assuming local linear models, the presented algorithm utilizes general local nonlinear functions, which make the algorithm more flexible. These are approximated by a multidimensional Taylor series. Since the amount of regressors grows fast with the number of inputs and the expansion order, a subset selection procedure is introduced. It reveals significant regressors and gives information about the local functional behavior. The local subset selection is implemented as a stepwise regression with replacement of regressors. Mallows' Cp-statistic is used for the subset selection algorithm and is also implemented for final model selection. The benefit of the extended algorithm lies in the higher flexibility in the local models, which results in less partitions of the input space by a similar approximation quality. © 2009 IFAC.

关键词： Membership functions

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Absolute stability of Lur'e singularly perturbed systems with multiple nonlinearities

Absolute stability of Lur'e singularly perturbed systems wit...

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American control Conference

作者： Chunyu Yang Qingling Zhang Jyh-Horng Chou Yingwei Zhang Key Laboratory of Integrated Automation of Process Industry Ministry of Education Northeastern University Shenyang 110004 P.R. China Institute of Systems Science Northeastern University Shenyang 110004 P.R. China Institute of System Information and Control Engineering National Kaohsiung First University of Science and Technology I University Road Yuanchau Kaohsiung 824 Taiwan

ISBN: (纸本)9781424474264

This paper investigates the absolute stability problem for Lur'e singularly perturbed systems with multiple nonlinearities. The objective is to determine if the system is absolutely stable for any epsilon E (0, (epsilon)_(0)], where epsilon denotes the perturbation parameter and (epsilon)_(0) is a pre-defined positive scalar. Firstly, an epsilon-dependent Lyapunov function of Lur'e-postnikov form is constructed. Then, a stability criterion expressed in terms of epsilon-independent linear matrix inequalities (LMIs) is derived. Finally, an example is given to show the feasibility and effectiveness of the obtained method.

关键词： Robust stability Stability criteria control systems Lyapunov method Power system stability Power system modeling Educational institutions Nonlinear control systems control nonlinearities USA Councils

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Identifiability study of a pressurizer in a pressurized water nuclear power plant 10

Identifiability study of a pressurizer in a pressurized wate...

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2009 10th European control Conference, ECC 2009

作者： Szederkenyi, Gabor Process Control Research Group Systems and Control Laboratory Computer and Automation Research Institute Budapest Hungary

ISBN: (纸本)9783952417393

In this paper, the identifiability of a pressurizer model is investigated. The modeled physical system is located in the primary circuit of a pressurized water nuclear power plant. A simple first principle model for the pressurizer is used for the calculations and it is shown that both the appropriately transformed and the original physical model parameters are structurally identifiable. © 2009 EUCA.

关键词： Nuclear power plants

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Fault management for a Three Mass Torsion Oscillator 10

Fault management for a Three Mass Torsion Oscillator

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2009 10th European control Conference, ECC 2009

作者： Bahr, Joachim Munchhof, Marco Isermann, Rolf Institute of Automatic Control Laboratory for Control Systems and Process Automation Technische Universität Darmstadt Landgraf-Georg-Str. 4 Darmstadt64283 Germany

ISBN: (纸本)9783952417393

A model-based fault management system for a Three Mass Torsion Oscillator is described. Fault management includes fault detection, fault diagnosis and fault compensation. A process model of system dynamics is derived. Friction effects are modelled by a neuro-fuzzy Local Linear Model Tree (LOLIMOT) approach. Parameter estimation is obtained with two simple experiments. A friction estimation stage is used to support fault diagnosis and potential control applications. Parity equations are used to detect and diagnose speed sensor failures. In case of sensor failures, the fault management system initiates reconfiguration operations. The failure of one sensor is compensated by substituting the sensor signal with the output of a process model fed by other, intact sensors. The methods presented are evaluated using experimental measurements of a test rig. © 2009 EUCA.

关键词： Failure analysis

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Force-induced bone growth and adaptation: A system theoretical approach to understanding bone mechanotransduction

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IOP Conference Series: Materials Science and Engineering 2010年第1期10卷

作者： Solvey Maldonado Rolf Findeisen Laboratory for Systems Theory and Automatic Control Institute for Automation Engineering (IFAT) Otto-von-Guericke-Universität Magdeburg 39106 Magdeburg Germany

The modeling, analysis, and design of treatment therapies for bone disorders based on the paradigm of force-induced bone growth and adaptation is a challenging task. Mathematical models provide, in comparison to clinical, medical and biological approaches an structured alternative framework to understand the concurrent effects of the multiple factors involved in bone remodeling. By now, there are few mathematical models describing the appearing complex interactions. However, the resulting models are complex and difficult to analyze, due to the strong nonlinearities appearing in the equations, the wide range of variability of the states, and the uncertainties in parameters. In this work, we focus on analyzing the effects of changes in model structure and parameters/inputs variations on the overall steady state behavior using systems theoretical methods. Based on an briefly reviewed existing model that describes force-induced bone adaptation, the main objective of this work is to analyze the stationary behavior and to identify plausible treatment targets for remodeling related bone disorders. Identifying plausible targets can help in the development of optimal treatments combining both physical activity and drug-medication. Such treatments help to improve/maintain/restore bone strength, which deteriorates under bone disorder conditions, such as estrogen deficiency.

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Neural-Net Model Based Fault Diagnosis for Hydraulic Servo Axes

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IFAC Proceedings Volumes 2009年第8期42卷 1097-1102页

作者： Marco Muenchhof Sebastian Clever Technische Universität Darmstadt Institute of Automatic Control Laboratory for Control Systems and Process Automation 64283 Darmstadt Germany

关键词： Fault detection fault diagnosis hydraulic servo systems modeling neural nets

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Fault Tolerant Actuators and Drives – Structures, Fault Detection Principles and Applications

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IFAC Proceedings Volumes 2009年第8期42卷 1294-1305页

作者： Marco Muenchhof Mark Beck Rolf Isermann Technische Universität Darmstadt Institute of Automatic Control Laboratory for Control Systems and Process Automation Darmstadt Germany (Tel: +49-6151-16-3114) Technische Universität Darmstadt Institute of Automatic Control Laboratory for Control Systems and Process Automation Darmstadt Germany (Tel: +49-6151-16-2314) Technische Universität Darmstadt Institute of Automatic Control Laboratory for Control Systems and Process Automation Darmstadt Germany (Tel: +49-6151-16-2114)

As fault detection and fault diagnosis are more and more finding their way into modern industrial mechatronic products, it is now time to take the next step. Based on the research efforts for fault detection and diagnosis, a platform has been prepared for research on fault management, i.e. automatic reactions of the system to continue operation after the detection of faults. These reactions may employ hardware redundancy (i.e. switching from a faulty actuator to another, intact one) or analytical redundancy (i.e. switching from a faulty sensor to a “model sensor” or “soft sensor”). A total fault tolerance concept must encompass all components of a system, i.e. the actuators and drives, the sensors as well as the controller and communication. In many cases, a degradation of functions has to be accepted after a fault has appeared. This contribution will center on actuators and drives showing real-world examples of prototypical realizations and examples from industrial products. Concentrating on the most widespread actuation principles, the paper will focus on electric drives and hydraulic actuators. First, a review is given on fault tolerance principles and general structural considerations e.g. hot-standby and cold-standby, focusing on the scheme of an overall fault-tolerant control system. Then, fault statistics for real actuators and drives will be presented. These fault statistics give hints on the parts of the actuators that are most susceptible to faults. Different designs of fault tolerant actuators and drives, which have been realized, shall be presented and evaluated with respect to their capabilities of sustaining faults. Finally, an outlook for fault-tolerant mechatronic systems will be given.

关键词： Sensor and actuator faults structural analysis aerospace applications automotive applications electro-mechanical applications other applications

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Dynamical modeling and identification of a GnRH neuron

Dynamical modeling and identification of a GnRH neuron

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作者： Csercsik, Dávid Szederkényi, Gábor Hangos, Katalin M. Farkas, Imre Process Control Research Group Systems and Control Laboratory Computer and Automation Research Institute Budapest Hungary Department of Endocrine Neurobiology Institute of Experimental Medicine HAS Budapest Hungary

ISBN: (纸本)9783902661494

GnRH neurons, as key elements of the reproductive neuroendocrine system, have important central regulating role in the dynamics of the hormonal cycle. A Hodgkin-Huxley type neural model is proposed in this paper, that takes into account up-to-date biological literature data related to ion channels. The proposed neuron model is highly nonlinear in parameters and the evaluation of the objective function is computationally flexpensive, therefore the asynchronous parallel pattern search (APPS) procedure has been used for identification. The model with high number of estimated parameters provides a qualitatively good fit of both voltage clamp and current clamp traces. © 2009 IFAC.

关键词： Neurons

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