Regelungstheorie

The workshop “Regelungstheorie” (control theory) covered a broad variety of topics that were either concerned with fundamental mathematical aspects of control or with its strong impact in various fields of engineering

Model based fault detection for two-dimensional systems

Fault detection and isolation (FDI) are essential in ensuring safe and reliable operations in industrial systems. Extensive research has been carried out on FDI for one dimensional (1-D) systems, where variables vary only with time. The existing FDI strategies are mainly focussed on 1-D systems and can generally be classified as model based and process history data based methods. In many industrial systems, the state variables change with space and time (e.g., sheet forming, fixed bed reactors, and furnaces). These systems are termed as distributed parameter systems (DPS) or two dimensional (2-D) systems. 2-D systems have been commonly represented by the Roesser Model and the F-M model. Fault detection and isolation for 2-D systems represent a great challenge in both theoretical development and applications and only limited research results are available. In this thesis, model based fault detection strategies for 2-D systems have been investigated based on the F-M and the Roesser models. A dead-beat observer based fault detection has been available for the F-M model. In this work, an observer based fault detection strategy is investigated for systems modelled by the Roesser model. Using the 2-D polynomial matrix technique, a dead-beat observer is developed and the state estimate from the observer is then input to a residual generator to monitor occurrence of faults. An enhanced realization technique is combined to achieve efficient fault detection with reduced computations. Simulation results indicate that the proposed method is effective in detecting faults for systems without disturbances as well as those affected by unknown disturbances.The dead-beat observer based fault detection has been shown to be effective for 2-D systems but strict conditions are required in order for an observer and a residual generator to exist. These strict conditions may not be satisfied for some systems. The effect of process noises are also not considered in the observer based fault detection approaches for 2-D systems. To overcome the disadvantages, 2-D Kalman filter based fault detection algorithms are proposed in the thesis. A recursive 2-D Kalman filter is applied to obtain state estimate minimizing the estimation error variances. Based on the state estimate from the Kalman filter, a residual is generated reflecting fault information. A model is formulated for the relation of the residual with faults over a moving evaluation window. Simulations are performed on two F-M models and results indicate that faults can be detected effectively and efficiently using the Kalman filter based fault detection. In the observer based and Kalman filter based fault detection approaches, the residual signals are used to determine whether a fault occurs. For systems with complicated fault information and/or noises, it is necessary to evaluate the residual signals using statistical techniques. Fault detection of 2-D systems is proposed with the residuals evaluated using dynamic principal component analysis (DPCA). Based on historical data, the reference residuals are first generated using either the observer or the Kalman filter based approach. Based on the residual time-lagged data matrices for the reference data, the principal components are calculated and the threshold value obtained. In online applications, the T2 value of the residual signals are compared with the threshold value to determine fault occurrence. Simulation results show that applying DPCA to evaluation of 2-D residuals is effective.Doctoral These

Quantum Control in Open and Periodically Driven Systems

Quantum technology resorts to efficient utilization of quantum resources to realize technique innovation. The systems are controlled such that their states follow the desired manners to realize different quantum protocols. However, the decoherence caused by the system-environment interactions causes the states deviating from the desired manners. How to protect quantum resources under the coexistence of active control and passive decoherence is of significance. Recent studies have revealed that the decoherence is determined by the feature of the system-environment energy spectrum: Accompanying the formation of bound states in the energy spectrum, the decoherence can be suppressed. It supplies a guideline to control decoherence. Such idea can be generalized to systems under periodic driving. By virtue of manipulating Floquet bound states in the quasienergy spectrum, coherent control via periodic driving dubbed as Floquet engineering has become a versatile tool not only in controlling decoherence, but also in artificially synthesizing exotic topological phases. We will review the progress on quantum control in open and periodically driven systems. Special attention will be paid to the distinguished role played by the bound states and their controllability via periodic driving in suppressing decoherence and generating novel topological phases.Comment: A review articl

Observer theory

AbstractThe paper is devoted to a comprehensive exposition of the theory of partial state observers in the state space context and the elucidation of the connection between this theory and the theory of observers in the behavioral context, as developed in Valcher and Willems [1999]. For this we use several techniques, including geometric control theory, polynomial and rational models, shift realizations, coprime factorizations, partial realizations and the basic results on behaviors and behavior homomorphisms. A connection between observers and the construction of state maps is made

Control Engineering

Control means a speci?c action to reach the desired behavior of a system. In the control of industrial processes generally technological processes, are considered, but control is highly required to keep any physical, chemical, biological, communication, economic, or social process functioning in a desired manner

Behavioral periodic systems

Doutoramento em MatemáticaEsta tese dedica-se ao estudo de sistemas periódicos comportamentais, tendo como base, por um lado, a abordagem clássica aos sistemas periódicos de espaço de estados e, por outro, a abordagem comportamental aos sistemas dinâmicos. Usando uma formulação invariante no tempo anteriormente proposta na literatura, estabelecem-se vários resultados sobre as propriedades de várias descrições matemáticas (representações) dos comportamentos periódicos. Estudam-se também algumas importantes propriedades destes comportamentos, como a controlabilidade e a observabilidade.This thesis is devoted to the study of behavioral periodic systems, based on the classical approach to periodic state space systems on the one hand, and on the behavioral approach to dynamical systems on the other hand. Using a time-invariant formulation, which has already been proposed in the literature, some results are obtained as regards to several mathematical descriptions (or representations) of periodic behaviors. Some important properties are also studied such as controllability and observability

A Study of dynamic force measurement based on the levitation mass method

In this thesis, methods based on the levitation mass method (LMM) for evaluating the frictional characteristics of a linear ball bearing, the electro-mechanical characteristics of a voice coil and a piezo-electric actuator and for removing the velocity limitation of laser Doppler interferometer (LDI) are proposed. In the LMM, the inertial force of a levitated mass used as the reference force for measuring dynamic force is measured as the product of the mass and acceleration. For evaluating the dynamical friction of linear ball bearing, two corner-cube prisms (CC) are attached to a moving part which is connected to the ball bearing. The acceleration of the gravity center of the moving part is estimated from the accelerations of the two CCs which are measured using a dual axis LDI. The frictional force is measured as the product of the mass of the moving part and the acceleration of the gravity center. For evaluating the voice coil actuator, a moving part levitated using an aerostatic linear bearing is connected to the coil. The dynamic force generated by the coil is measured as the inertial force of the moving part. The velocity of the moving part is measured using a LDI. Other mechanical characteristics such as position, acceleration and force are calculated from the measured velocity. With the electrical characteristics mea-sured using a digital voltmeter, the relationships between electrical and mechanical characteristics are evaluated. For measuring the electro-mechanical characteristics of piezo-electric actuator, a CC considered as an inertial mass is attached to the top of the actuator instead of the moving part. The dynamic force generated by the actuator is measured as the inertial force of CC. Based on this method, the force-displacement behavior of the actuator under dynamic condition is evaluated. The relationship of energy conversion between electrical and mechanical domains is also evaluated based on the observed results. In the LMM, the velocity of moving part is measured using a LDI whose laser source is a Zeeman-type two-frequency laser. However, the measurable velocity of LDI is limited by the frequency di.erence of laser in back and forth motion. In order to get high measurable velocity in back and forth motion, a dual beat-frequencies laser Doppler interferometer (DB-LDI) is developed and applied. In DB-LDI, two laser beams with di.erence frequency (f1,f2) are divided into reference beams and signal beams by a non-polarized beams splitter. They are used to produce two beat signals. When the object moving, the beat frequencies of beat signals are detected as |f ′ . f2| and |f ′ . f1|, respectively. For back and forth motion, although the 12 velocity of the object calculated from one beat frequency reaches critical velocity, the velocity calculated from the other one is far from critical velocity. The DB-LDI has been applied to realize a high-speed impact testing. During the collision, the velocity of the mass, even higher than the critical velocity, is accurately measured using the DB-LDI.学位記番号：工博甲47