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The primary objective of this thesis is to leverage on the framework of H∞ loop-shaping control to formulate efficient and powerful optimization algorithms in LMI framework for the synthesis of performance loop-shaping weights. The H∞ loop-shaping design procedure is an efficient controller synthesis technique that combines classical loop-shaping concepts with H∞ synthesis. This procedure establishes a good tradeoff between robust stability and robust performance of a closed-loop system in a systematic manner. However, the selection of pre- and/or post-compensators, a crucial step in the design procedure, is nontrivial as factors such as the right half plane poles/zeros of the nominal plant, roll-off rate around the crossover frequency, strength of cross-coupling in multi-input multi-output systems, expected bandwidth, etc. must be adequately considered.Firstly, a frequency-dependent weight optimization framework is formulated in state-space form in order to remove the dependency on frequency while retaining the objective of maximizing the robust stability margin of a closed-loop system. This formulation facilitates the synthesis of low-order controllers, which is desirable from an implementation perspective.A weight optimization framework that incorporates smoothness constraints in order to prevent the cancellation of important modes of the system, for example, lightly damped poles/zeros of flexible structures, is subsequently formulated. The proposed formulation is intuitive from a design perspective as the smoothness constraints are expressed as gradient constraints on a log-log scale in dB/decade, consistent with the notation used in Bode plot for single-input single-output systems and singular value plots for multi-input multi-output systems.Thereafter, an optimization framework that maximizes the robust performance of a closed-loop system is presented. The philosophy in this framework is in line with practical design objectives that give the best achievable robust performance on a particular problem once a level of robust stability margin is demanded.Lastly, a novel unmanned vehicle is proposed. The vehicle uses a full six-degree-of-freedom tri-rotor actuation, capable of fully decoupled thrust and torque vectoring in all the 3D space. This vehicle can act as an unmanned ground vehicle or unmanned aerial vehicle, but the objective herein is restricted to the upright stability of the vehicle while operating on the ground as this is a precursor to rolling motion. The full nonlinear model of the vehicle is derived and linearized for subsequent controller synthesis, and this is thereafter validated by means of numerical simulations.

Ce travail étudie les stratégies de contrôle des limites pour l'analyse de stabilité et la stabilisation d'un système hyperbolique de premier ordre couplé à des conditions limites dynamiques non linéaires. La modélisation d'un écoulement à l'intérieur d'un tube (phénomène de transport de fluide) avec une stratégie de contrôle des limites appliquée dans une installation expérimentale physique est considérée comme une étude de cas pour évaluer les stratégies proposées. Dans le contexte des systèmes de dimension finie, des outils de contrôle classiques sont appliqués pour traiter des systèmes hyperboliques de premier ordre ayant des conditions limites données par le couplage d'un modèle dynamique de colonne de chauffage et d'un modèle statique de ventilateur. Le problème de suivi de cette dynamique complexe est abordé de manière simple en considérant des approximations linéaires, des schémas de différences finies et une action intégrale conduisant à un système linéaire à temps discret augmenté avec une dimension dépendant de la taille d'échelon de la discrétisation dans l'espace. Par conséquent, pour la contrepartie dimensionnelle infinie, deux stratégies sont proposées pour résoudre le problème de contrôle de frontière des systèmes hyperboliques de premier ordre couplé à des conditions de frontière dynamique non linéaires. Le premier se rapproche de la dynamique du système hyperbolique de premier ordre par un retard pur. La stabilité convexe et les conditions de stabilisation des systèmes quadratiques non linéaires retardés d'entrée incertaine sont proposées sur la base de la théorie de la stabilité de Lyapunov-Krasovskii (LK) qui sont formulées en termes de contraintes de l'inégalité matricielle linéaire (LMI) avec des variables supplémentaires lâches (introduites par le lemme de Finsler ). Ainsi, des fonctions strictement de Lyapunov sont utilisées pour dériver une approche basée sur LMI pour la stabilité de la frontière régionale robuste et la stabilisation des systèmes hyperboliques de premier ordre avec une condition de frontière définie au moyen d'un système dynamique non linéaire quadratique. Les conditions de stabilité et de stabilisation proposées pour LMI sont évaluées en tenant compte de plusieurs exemples universitaires et de l'écoulement à l'intérieur d'une étude de cas. / This work studies boundary control strategies for stability analysis and stabilization of first-order hyperbolic system coupled with nonlinear dynamic boundary conditions. The modeling of a flow inside a pipe (fluid transport phenomenon) with boundary control strategy applied in a physical experimental setup is considered as a case study to evaluate the proposed strategies. Firstly, in the context of finite dimension systems, classical control tools are applied to deal with first-order hyperbolic systems having boundary conditions given by the coupling of a heating column dynamical model and a ventilator static model. The tracking problem of this complex dynamics is addressed in a simple manner considering linear approximations, finite difference schemes and an integral action leading to an augmented discrete-time linear system with dimension depending on the step size of discretization in space. Hence, for the infinite dimensional counterpart, two strategies are proposed to address the boundary control problem of first-order hyperbolic systems coupled with nonlinear dynamic boundary conditions. The first one approximates the first-order hyperbolic system dynamics by a pure delay. Then, convex stability and stabilization conditions of uncertain input delayed nonlinear quadratic systems are proposed based on the Lyapunov-Krasovskii (L-K) stability theory which are formulated in terms of Linear Matrix Inequality (LMI) constraints with additional slack variables (introduced by the Finsler's lemma). Thus, strictly Lyapunov functions are used to derive an LMI based approach for the robust regional boundary stability and stabilization of first-order hyperbolic systems with a boundary condition defined by means of a nonlinear quadratic dynamic system. The proposed stability and stabilization LMI conditions are evaluated considering several academic examples and also the flow inside a pipe as case study.

This study evaluates a method for determining the quality of synthetic speech systems. The method involves the use of an auditory lexical decision task to assess the quality of synthetic speech generators relative to each other and to natural speech by using reaction time differences and error rates. Seven voices were evaluated; four synthesizers provided six voices (DECtalk 1.8 Perfect Paul, DECtaik 1.8 Beautiful Betty, DECtaik 2.0 Perfect Paul, DEC talk 2.0 Beautiful Betty, Votrax Personal Speech, Votrax Type'n'Talk) and natural speech provided the seventh voice. Both reaction times and error rates were higher for the low quality synthetic speech systems. The results document that the DECtalk can currently be considered a high quality synthesizer and that the Personal Speech and the Type'n'Talk can be considered low quality synthesizers. The results obtained by using this method can be explained by use of the Activation-Verification model (Paap, McDonald, Schvaneveldt, and Noel, 1986). Within the framework of this model, the results of this study suggest that the verification phase is the bottle-neck in processing words produced by synthetic speech generators. This interpretation suggests that by emphasizing the differences between different phonemes, to make them more uniquely identifiable, rather than concentrating on making them more "natural" might lead to improved results with synthesized speech. / Master of Science

The present research sought to investigate the correspondence between auditory and visual feature dimensions and to utilise this knowledge in order to inform the design of audio-visual mappings for visual control of sound synthesis. The first stage of the research involved the design and implementation of Morpheme, a novel interface for interaction with corpus-based concatenative synthesis. Morpheme uses sketching as a model for interaction between the user and the computer. The purpose of the system is to facilitate the expression of sound design ideas by describing the qualities of the sound to be synthesised in visual terms, using a set of perceptually meaningful audio-visual feature associations. The second stage of the research involved the preparation of two multidimensional mappings for the association between auditory and visual dimensions. The third stage of this research involved the evaluation of the Audio-Visual (A/V) mappings and of Morpheme's user interface. The evaluation comprised two controlled experiments, an online study and a user study. Our findings suggest that the strength of the perceived correspondence between the A/V associations prevails over the timbre characteristics of the sounds used to render the complementary polar features. Hence, the empirical evidence gathered by previous research is generalizable/ applicable to different contexts and the overall dimensionality of the sound used to render should not have a very significant effect on the comprehensibility and usability of an A/V mapping. However, the findings of the present research also show that there is a non-linear interaction between the harmonicity of the corpus and the perceived correspondence of the audio-visual associations. For example, strongly correlated cross-modal cues such as size-loudness or vertical position-pitch are affected less by the harmonicity of the audio corpus in comparison to weaker correlated dimensions (e.g. texture granularity-sound dissonance). No significant differences were revealed as a result of musical/audio training. The third study consisted of an evaluation of Morpheme's user interface were participants were asked to use the system to design a sound for a given video footage. The usability of the system was found to be satisfactory. An interface for drawing visual queries was developed for high level control of the retrieval and signal processing algorithms of concatenative sound synthesis. This thesis elaborates on previous research findings and proposes two methods for empirically driven validation of audio-visual mappings for sound synthesis. These methods could be applied to a wide range of contexts in order to inform the design of cognitively useful multi-modal interfaces and representation and rendering of multimodal data. Moreover this research contributes to the broader understanding of multimodal perception by gathering empirical evidence about the correspondence between auditory and visual feature dimensions and by investigating which factors affect the perceived congruency between aural and visual structures.

The aim of this work is to design a filter of the type low–pass of order 5th with Butterworth’s approximation in the range of over-tuning 10 – 100 kHz and if it will be possible so! achieve even higher marginal frequencies. To compare two typical representatives of the frequency filters cascading and non-cascading synthesis from the viewpoint the accuracy of an! approximation function, sensitivity to the tolerance values of components, number of the components (mainly OZ) and viability, especially the possibility of electronic over-tuning in selected frequency range. On the basis of these conditions will be chosen one design, which will be realized later. Further it will be necessary to consider the possibilities of electronic over-tuning and to choose for this over-tuning suitable component, to design user management changes of marginal frequency fm by the help of keyboard + LCD and control application on the PC. For this hardware will be programmed appropriate control software. At the end of this work will be constructed appropriate device, which fullfils requirements written above and will be subjected to the laboratory measurements that verify function of this device. The constructional details of the filter are presented in the enclosure at the end of this work. At the CD are available all materials, which were created during the master’s thesis or which are necessarily concerned.