483 research outputs found
Stability of switched linear differential systems
We study the stability of switched systems where the dynamic modes are
described by systems of higher-order linear differential equations not
necessarily sharing the same state space. Concatenability of trajectories at
the switching instants is specified by gluing conditions, i.e. algebraic
conditions on the trajectories and their derivatives at the switching instant.
We provide sufficient conditions for stability based on LMIs for systems with
general gluing conditions. We also analyse the role of positive-realness in
providing sufficient polynomial-algebraic conditions for stability of two-modes
switched systems with special gluing conditions
Observer based active fault tolerant control of descriptor systems
The active fault tolerant control (AFTC) uses the information provided by fault detection and fault diagnosis (FDD) or fault estimation (FE) systems offering an opportunity to improve the safety, reliability and survivability for complex modern systems. However, in the majority of the literature the roles of FDD/FE and reconfigurable control are described as separate design issues often using a standard state space (i.e. non-descriptor) system model approach. These separate FDD/FE and reconfigurable control designs may not achieve desired stability and robustness performance when combined within a closed-loop system.This work describes a new approach to the integration of FE and fault compensation as a form of AFTC within the context of a descriptor system rather than standard state space system. The proposed descriptor system approach has an integrated controller and observer design strategy offering better design flexibility compared with the equivalent approach using a standard state space system. An extended state observer (ESO) is developed to achieve state and fault estimation based on a joint linear matrix inequality (LMI) approach to pole-placement and H∞ optimization to minimize the effects of bounded exogenous disturbance and modelling uncertainty. A novel proportional derivative (PD)-ESO is introduced to achieve enhanced estimation performance, making use of the additional derivative gain. The proposed approaches are evaluated using a common numerical example adapted from the recent literature and the simulation results demonstrate clearly the feasibility and power of the integrated estimation and control AFTC strategy. The proposed AFTC design strategy is extended to an LPV descriptor system framework as a way of dealing with the robustness and stability of the system with bounded parameter variations arising from the non-linear system, where a numerical example demonstrates the feasibility of the use of the PD-ESO for FE and compensation integrated within the AFTC system.A non-linear offshore wind turbine benchmark system is studied as an application of the proposed design strategy. The proposed AFTC scheme uses the existing industry standard wind turbine generator angular speed reference control system as a “baseline” control within the AFTC scheme. The simulation results demonstrate the added value of the new AFTC system in terms of good fault tolerance properties, compared with the existing baseline system
Finite-Time Stability and Stabilization of Itô-Type Stochastic Singular Systems
This paper is concerned with the finite-time stability and stabilization problems for linear Itô stochastic singular systems. The condition of existence and uniqueness of solution to such class of systems are first given. Then the concept of finite-time stochastic stability is introduced, and a sufficient condition under which an Itô stochastic singular system is finite-time stochastic stable is derived. Moreover, the finite-time stabilization is investigated, and a sufficient condition for the existence of state feedback controller is presented in terms of matrix inequalities. In the sequel, an algorithm is given for solving the matrix inequalities arising from finite-time stochastic stability (stabilization). Finally, two examples are employed to illustrate our results
Stability results for constrained dynamical systems
Differential-Algebraic Equations (DAE) provide an appropriate framework to model and
analyse dynamic systems with constraints. This framework facilitates modelling of the
system behaviour through natural physical variables of the system, while preserving the
topological constraints of the system. The main purpose of this dissertation is to investigate
stability properties of two important classes of DAEs. We consider some special cases of
Linear Time Invariant (LTI) DAEs with control inputs and outputs, and also a special class of
Linear switched DAEs. In the first part of the thesis, we consider LTI systems, where we focus
on two properties: passivity and a generalization of passivity and small gain theorems called
mixed property. These properties play an important role in the control design of large-scale
interconnected systems. An important bottleneck for a design based on the aforementioned
properties is their verification. Hence we intend to develop easily verifiable conditions to
check passivity and mixedness of Single Input Single Output (SISO) and Multiple Input
Multiple Output (MIMO) DAEs. For linear switched DAEs, we focus on the Lyapunov stability
and this problem forms the basis for the second part of the thesis. In this part, we try
to find conditions under which there exists a common Lyapunov function for all modes
of the switched system, thus guaranteeing exponential stability of the switched system.
These results are primarily developed for continuous-time systems. However, simulation and
control design of a dynamic system requires a discrete-time representation of the system
that we are interested in. Thus, it is critical to establish whether discrete-time systems,
inherit fundamental properties of the continuous-time systems from which they are derived.
Hence, the third part of our thesis is dedicated to the problems of preserving passivity,
mixedness and Lyapunov stability under discretization. In this part, we examine several
existing discretization methods and find conditions under which they preserve the stability
properties discussed in the thesis
Stability results for constrained dynamical systems
Differential-Algebraic Equations (DAE) provide an appropriate framework to model and
analyse dynamic systems with constraints. This framework facilitates modelling of the
system behaviour through natural physical variables of the system, while preserving the
topological constraints of the system. The main purpose of this dissertation is to investigate
stability properties of two important classes of DAEs. We consider some special cases of
Linear Time Invariant (LTI) DAEs with control inputs and outputs, and also a special class of
Linear switched DAEs. In the first part of the thesis, we consider LTI systems, where we focus
on two properties: passivity and a generalization of passivity and small gain theorems called
mixed property. These properties play an important role in the control design of large-scale
interconnected systems. An important bottleneck for a design based on the aforementioned
properties is their verification. Hence we intend to develop easily verifiable conditions to
check passivity and mixedness of Single Input Single Output (SISO) and Multiple Input
Multiple Output (MIMO) DAEs. For linear switched DAEs, we focus on the Lyapunov stability
and this problem forms the basis for the second part of the thesis. In this part, we try
to find conditions under which there exists a common Lyapunov function for all modes
of the switched system, thus guaranteeing exponential stability of the switched system.
These results are primarily developed for continuous-time systems. However, simulation and
control design of a dynamic system requires a discrete-time representation of the system
that we are interested in. Thus, it is critical to establish whether discrete-time systems,
inherit fundamental properties of the continuous-time systems from which they are derived.
Hence, the third part of our thesis is dedicated to the problems of preserving passivity,
mixedness and Lyapunov stability under discretization. In this part, we examine several
existing discretization methods and find conditions under which they preserve the stability
properties discussed in the thesis
THE DEVELOPMENT OF A TRANSACTIONAL ANALYSIS PSYCHOMETRIC TOOL FOR ENHANCING FUNCTIONAL FLUENCY
Functional Fluency denotes efficacy of interpersonal functioning in terms of flexibility and
balance of the behavioural modes a person uses. The aim of this project is to design and create a
psychometric tool for mapping the patterns of such functioning. The intention is that feedback on
the test results will stimulate the insights and understanding to support and encourage positive
behavioural change. This process, involving the development of self-awareness, which is a key
aspect of emotional intelligence, will thus promote emotional literacy.
Transactional Analysis (TA) ego state theory provides the basis for the rational-theoretical
strategy of instrument construction, which uses the author's expanded TA model of ego state
function, the Functional Fluency model. The resulting self-report questionnaire, the Transactional
Behaviour Profile, comprises a nine-scale index of Functional Fluency, the FFI.
Methodological process includes construct conceptualisation, generation of behavioural
indicators and transformation of these into test items. Validation of test items leads into instrument
construction followed by a Pilot Study with over 300 respondents from a broad span of human
service provision. Quantitative and qualitative data analyses provide evidence of both theoretical
coherence and validity of the model as well as practical efficacy of the instrument in terms of the
project aims. Indications for further refinement and correlation studies are examined, and plans
proposed.
The theory of Transactional Analysis addresses both the interpersonal and the intrapsychic.
The FFI is designed to do likewise. Thus, although the FFI model is essentially one of
interpersonal functioning, appropriate in a tool for training and personal development, it could
potentially contribute an objective form of behavioural diagnosis in psychotherapeutic contexts,
because of its coherent theoretical links with TA structural ego state models.
The thesis constitutes the research basis for what will be ongoing development of the
Transactional Behaviour Profile for indexing Functional Fluency in a variety of contexts
Visual Servoing
The goal of this book is to introduce the visional application by excellent researchers in the world currently and offer the knowledge that can also be applied to another field widely. This book collects the main studies about machine vision currently in the world, and has a powerful persuasion in the applications employed in the machine vision. The contents, which demonstrate that the machine vision theory, are realized in different field. For the beginner, it is easy to understand the development in the vision servoing. For engineer, professor and researcher, they can study and learn the chapters, and then employ another application method
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