This thesis describes the implementation of Yao’s adaptive robust control to an aircraft control system. This control law is implemented as a means to maintain stability and tracking performance of the aircraft in the face of failures and changing aerodynamic response. The control methodology is implemented as an outer loop controller to an aircraft under nonlinear dynamic inversion control. The adaptive robust control methodology combines the robustness of sliding mode control to all types of uncertainty with the ability of adaptive control to remove steady state errors. A performance measure is developed in to reflect more subjective qualities a pilot would look for while flying an aircraft. Using this measure, comparisons of the adaptive robust control technique with the sliding mode and adaptive control methodologies are made for various failure conditions. Each control methodology is implemented on a full envelope, high fidelity simulation of the F-15 IFCS aircraft as well as on a lower fidelity full envelope F-5A simulation. Adaptive robust control is found to exhibit the best performance in terms of the introduced measure for several different failure types and amplitudes.

The main goal of this thesis is to study the saturation problem arisen from the integrator in a sigma- delta analog- to- digital modulator , especially when the order of the circuit is higher than two .Signal passes through each stage of integrators yield saturation problem. This situation will miss some part of messages .Unable to deliver datas accurately to next stage of the integrator , the output digital signals will be incorrect and can't be recovered to original analog signals . Hence, this thesis proposes an anti-wind-up method by taking sliding mode control theory to avoid integrator saturation. After that, we are going to design and implement two third order sigma-delta modulators based on this method. Simulation and experiment results show the validity of the method and the significant improvement of avoiding saturation problem, and guarantee the designed circuits can translate signals to terminal accurately .

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Η παρούσα διπλωματική εργασία πραγματεύεται τη μελέτη και κατασκευή ενός μετατροπέα συνεχούς τάσης σε εναλλασσόμενη (αντιστροφέας) που προορίζεται για τη σύνδεση ενός φωτοβολταϊκού πλαισίου στο δίκτυο χαμηλής τάσης. Η εργασία εκπονήθηκε στο Εργαστήριο Ηλεκτρομηχανικής Μετατροπής Ενέργειας του Τμήματος Ηλεκτρολόγων Μηχανικών και Τεχνολογίας Υπολογιστών του Πανεπιστημίου Πατρών. Αρχικά, παρουσιάζονται, συνοπτικά, πληροφορίες για τη φωτοβολταϊκή τεχνολογία και για τους τρόπους διασύνδεσής τους με την κατανάλωση ή το δίκτυο. Στη συνέχεια, γίνεται αναφορά στον αντιστροφέα της διπλωματικής εργασίας. Πιο συγκεκριμένα, μελετάται ένας διαφορικός αντιστροφέας τύπου boost, ένα χαρακτηρισμό που τον οφείλει στην δυνατότητα, να επιτευχθεί μέσω αυτού εναλλασσόμενη τάση εξόδου με ενεργό τιμή μεγαλύτερη της συνεχούς τάσης εισόδου. Ο μετατροπέας αυτός αποτελείται στην ουσία από δύο επιμέρους μετατροπείς dc-dc τύπου boost, με τη συνδυασμένη λειτουργία των οποίων επιτυγχάνεται η επιθυμητή μετατροπή. Η ονομαστική ισχύς για την οποία πραγματοποιείται ο σχεδιασμός του μετατροπέα είναι ίση με 250W. Με δεδομένα τα μεγέθη ρευμάτων και τάσεων, καθώς και των κυματώσεων στα ρεύματα των πηνίων και στις τάσεις των πυκνωτών, υπολογίστηκαν οι τιμές των στοιχείων, βάσει των οποίων έγιναν οι προσομοιώσεις. Κατόπιν, δοκιμάστηκαν σε προσομοίωση διάφορες μορφές ελέγχου του αντιστροφέα, με μόνη ικανοποιητική αυτή του έλεγχου με ολίσθηση στο πεδίο καταστάσεων. Αυτός ήταν και ο έλεγχος που τελικά επιλέχθηκε για τη διάταξη που μελετήθηκε, γι’ αυτό και γίνεται αναλυτική περιγραφή του ελέγχου αυτού. Λόγω των απαιτήσεών του αποφασίστηκε ο έλεγχος να υλοποιηθεί χωρίς χρήση μικροελεγκτή, αλλά με χρήση αποκλειστικά ολοκληρωμένων αναλογικών κυκλωμάτων. Ακολουθεί η περιγραφή της διαδικασίας σχεδίασης και κατασκευής του μετατροπέα που έγινε στο Εργαστήριο Ηλεκτρομηχανικής Μετατροπής Ενέργειας και παρουσιάζονται τα επιμέρους στοιχεία και οι συνδεσμολογίες που χρησιμοποιήθηκαν. Τέλος, περιγράφονται τα πειράματα που πραγματοποιήθηκαν και παρατίθενται τα αποτελέσματα που προέκυψαν, αποδεικνύοντας την ορθή λειτουργία της διάταξης. Επίσης, εξάγονται τα ανάλογα συμπεράσματα. / In this diploma thesis, a Power Inverter in order to connect an Alternating Current-Photovoltaic (AC-PV module) to the low voltage grid is analyzed, designed and manufactured. The work was carried out in the Laboratory of Electrical and Mechanical Energy Conversion at the Department of Electrical and Computer Engineering of the Polytechnic School, University of Patras, Greece. At first, some data and information concerning the photovoltaic technology are presented as well as the connection modes of a PV system or module. Secondly, the operation and structure of the inverter is described. Specifically, a differential output boost inverter is examined, the title of which is derived from its ability to produce an output voltage larger than the input voltage. In fact, this converter consists of two boost dc-dc converters, the combined operation of which achieves the desirable operation of the inverter. The nominal power of the inverter is chosen to be equal to 250W. Depending on the expected values of the currents and voltages, as well as on the ripple voltages of the capacitors and the ripple currents of the inductors, the component values were calculated. The following step was to simulate the operation of the converter under different control techniques. The only control method with satisfying results which was eventually applied to the inverter was the sliding mode control, so it is extensively described. Due to its requirements, this control technique was implemented without using a microcontroller, but only using analog integrated circuits. The design and implementation of the inverter is then described along with the selected components and some individual circuits. Finally, the results of the conducted experiments are presented, the good operation of the setup is confirmed and the related conclusions are derived.

The aim of this thesis is to investigate the development and control of electro-pneumatic actuators in a haptic teleoperation system. For controlling the mass flow rate of such actuators, two types of valve technology are sudied, i.e. solenoid (on/off) valve and proportional servovalve. The servovalves have found widespread applications in which high accuracy of force/position control are needed. They are however typically expensive due to the requirements of high-precision manufacturing. Therefore, the low-cost solenoid valves can be an alternative to the servovalves for achieving acceptable-performance pneumatic control. Generally, the highly nonlinear of the pneumatic actuator is heightened when it uses on/off solenoid valves instead of servovalves. In this case, precise control is challenging due to the discrete-input nature of the system. Our first objective is to demonstrate that it is possible to design an acceptable performance teleoperation system using master-slave robots that have pneumatic actuators equipped with only inexpensive on/off solenoid valves. To control efficiently the switching valves, several control approaches have been proposed, namely pulse width modulation (PWM), hybrid algorithm, and sliding mode control. A hybrid control theory, which includes more switching control modes, than PWM, allows to reduce the chattering problem and improve the energy consumption of the valves. Another strategy (i.e. a sliding mode control), which does not depend on the pneumatic model, is proposed. This control stratgy allows to perform not only the transparent analysis but also the stability analysis. In order to improve the dynamic performance and reduce the chattering problem in solenoid valve actuated pneumatic teleoperation systems, a five-mode sliding control scheme has been used, which can be considered as an extension of the three-mode sliding controller. Our study demonstrates that by increasing the number of possible control actions for the valves, we can reduce the valves' switching activities, hence improving the valve's life times at no cost to teleoperation transparency. The second objective of the thesis involves in implementing the proportional servovalves on the pneumatic teleoperation system. A comparison related to the teleoperation performance between an on/off valve and a servovalve is carried out. In experiments, it is observed that with the bilateral teleoperation architecture employing solenoid valves or servovalves, satisfactory force and position tracking between the master and the slave is obtained. In bilateral teleoperation control, force sensors are often omitted to save cost and to lessen weight and volume. Therefore, another aspect of our work consists in using observers for an estimation of operator and environment forces. Experimental results show that acceptable teleoperation transparency based on a simple Nicosia observer and a tangent linear control approach can be achieved.

One of the most common goals in manufacturing is to improve the quality and accuracy of the parts being fabricated without reducing productivity. Aiming at this goal, many different manufacturing processes have been developed. Among them, machining plays a major role in increasing product accuracy. As an important machining process, grinding is a vital step that can produce both fine finish and dimensional accuracy for applications in which the workpiece material is either hard or brittle. Currently, the ball screw is the most frequently used setup for grinding machine tool feed drive. However, the existence of transmission components induces wear, high friction, backlash, and also lower system stiffness; therefore, applications of conventional feed drives for high speed and high accuracy machining are very limited. As a promising technology, a linear motor feed drive discards the transmission system; therefore, it eliminates transmission induced error, such as backlash and pitch error, and avoids stiffness reduction as well. As a result, a linear motor drive can achieve both high speed and high accuracy performance. A linear motor feed drive will be subject to external disturbances such as friction, force ripple and machining force. Due to the lack of a transmission unit, the tracking behavior of a linear motor feed drive is prone to be affected by external disturbances and model parameter variations. Thus, in order to deliver high performance, a controller should be capable of achieving high accuracy in the presence of external disturbance and parameter uncertainty. This dissertation proposes a general robust motion control framework for the CNC design of a linear motor feed drive to achieve high speed/high precision as well as low speed/high precision. An application to the linear motor feed drives in grinding machines was carried out. One of the developed algorithms is the HSMC, which combines the merits of a reaching law based sliding mode control and a modified disturbance observer for precision tracking to address the practical issues of friction, force ripple, and grinding force disturbances. Another algorithm presented is ASMC, which combines the reaching law based sliding mode control with adaptive disturbance estimation to achieve an adaptive robust motion control.

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 152-158).

Thesis (Ph. D.)--Ohio State University, 2005. / Title from first page of PDF file. Includes bibliographical references (p. 120-126).

Thesis (MScEng)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: As control problems become more and more complex, techniques are required that surpass the capabilities of simple controllers that are linearized about certain parametric set points. Controllers that can operate over a large range of model parameter variations and even controllers that are largely model-independent are becoming more valuable and necessary. In this control application, voltage regulation is done on a direct AC-AC medium voltage regulator, making use of a type of regulated autotransformer configuration. The fifth order system is shown to be prone to oscillations on the input bus. This, together with the control requirement of robustness to load variations, provides a challenging control problem that is rarely addressed in literature. This thesis solves the control problem by means of applying sliding mode control on voltage regulator module level, and supervisory control on system level. / AFRIKAANSE OPSOMMING: Soos die soeke na oplossings vir hedendaagse beheer probleme al hoe meer uitdagend raak, word die behoefte vir model onafhanklike en robuuste beheerders dienooreenkomstig groter. Eenvoudige beheerders wat gelineariseer is om ’n parametriese werkpunt raak ondoeltreffend vir vandag se vereistes vir doeltreffende beheer ongeag van parametriese veranderinge. In hierdie tesis word spanning regulasie toegepas deur ’n direkte WS-na-WS medium spanning reguleerder in te span. Hierdie toestel maak gebruik van ’n tipe van outotransformator opstelling waar die sekondêre wikkelings gereguleer word deur die skakelaksie van die drywingselektroniese regulasie modules. Die vyfde-orde stelsel se intree bus is geneigd om onstabiel te raak, en moet dus aktief gedemp word terwyl die uitreespanning reguleer word. Die vereiste dat die beheer boonop robuus ten opsigte van las veranderings moet wees maak hierdie probleem ’n monster van ’n uitdaging wat skaars in die literatuur aangeraak is. Hierdie tesis los die probleem van robuuste beheer op deur glymodus beheer toe te pas op reguleerder module vlak, en ook deur toesighoudende beheer op stelsel vlak toe te pas.

A grande maioria dos robôs industriais disponíveis no mercado é de alto desempenho, principalmente com relação à precisão de posicionamento. Este aspecto é um dos fatores que mais influencia no seu preço final, levando em consideração toda a complexa cadeia de elementos que fazem com que o robô opere corretamente, desde os motores e componentes mecânicos, passando pela arquitetura e sistemas de controle até o sistema de programação. Tendo isto em vista, este trabalho visa projetar um robô industrial com preço mais acessível, adequado para o uso em processos industriais que não necessitem altos níveis de precisão. Para a redução de custos de fabricação e de componentes do robô, este trabalho viabiliza o uso de atuadores pneumáticos lineares como fonte motriz, pois os mesmos são relativamente baratos, leves, não poluentes, de fácil montagem e operação, além de apresentarem uma boa relação peso/potência. Para tanto, foi implementado uma estratégia de controle por modos deslizantes com objetivo de superar as dificuldades impostas pelo comportamento não-linear dos componentes pneumáticos. Com relação à redução de custos de programação e operação do robô, desenvolveu-se um ambiente de programação off-line, através de softwares de auxilio à manufatura e de engenharia usualmente encontrados em ambientes industriais. A estratégia fundamental neste trabalho, foi o desenvolvimento de uma metodologia de projeto própria, concebida especificamente para a aplicação em projetos de robôs industriais, com os atributos de facilidade de execução e modularidade das fases envolvidas. A qual, no presente trabalho, apresenta o desenvolvimento de um robô cartesiano com três graus de liberdade acionado por atuadores pneumáticos lineares. / The great majority of industrial robots available in the market have high performance, especially relative to position accuracy. This aspect is one of the factors that most influence its final price, taking into account all complicated web elements that makes the robot operates in the correct form, since the actuators and the constructive part, passing by the architecture and control systems until the system of programming. According to these, the present work aims to project an industrial robot with more accessible costs, adequate to use in industrial process that not require high level of accuracy. For the reduction of manufacture and components costs of the robot, this work make viable to use of pneumatic actuators like a motive source, because are relatively cheap, light, not pollutants, easy assembly and operation, besides presenting a good relation weight/power. For such purpose, the strategy of control was implemented by sliding mode control for the objective to surpass the difficulties imposed by the non-linear behavior of the pneumatic components. About the reduction of programming and operation costs of the robot, an off-line programming environment was developed through manufacturing aided software and a software of engineering both usually found in industrial environments. The basic strategy in this work, was the development of an own methodology of project, conceived specifically for the application in projects of industrial robots, with the attributes of easiness of execution and modularization of the wrapped phases. That methodology, in the present work, presents the development of a Cartesian robot with three degrees of freedom actuated by pneumatic servo drive.