Novel Robust Control Using a Fractional Adaptive PID Regulator for an unstable system

Recent advances in fractional order calculus led to the improvement of control theory and resulted in potential use of fractional adaptive PID controller in advanced academic and industrial applications as compared to the conventional adaptive PID controller. Basically, a fractional order  adaptive PID  controller  is  an  improved version of classical  integer  order  adaptive PID  controller that outperformed  its classical  counterpart. In case of a closed loop system, a minute change would result in instability of the overall system. An efficient PID controller can be used to control the response of such system.  Among various parameters of an instable system, speed of the system is an important parameter to be controlled efficiently. The current research work presents the speed controlling mechanism for an uncertain instable system by using fractional order adaptive PID controller.To validate the arguments, effectiveness and robustness of the proposed fractional order adaptive PID controller have been studied in comparison to the classical adaptive PID controller using The Criterion of quadratic error. Simulation findings and comparisons demonstrated that the proposed controller has superior control performance and outstanding robustness in terms of percentage overshoot, settling time, rising time, and disturbance rejection

Zaman gecikmesi içeren üçüncü derece sistemler için kesir dereceli PD denetleyici tasarımı

Due to the lack of integral operator, proportional derivative controllers have difficulties in providing stability and robustness. This difficulty is especially felt in higher order systems. In this publication, analytical design method of fractional proportional derivative controllers is presented to ensure the stability of third order systems with time delay. In this method, it is aimed to achieve the frequency characteristics of a standard control system to ensure stability. It is aimed to provide the desired gain crossover frequency, phase crossover frequency and phase margin properties of the system. In this way, the stability and robustness of the system can be obtained by choosing the appropriate values. The reason for choosing a fractional order controller is that the controller parameters to provide these features can be tuned more accurately. In order for the obtained stability to be robust to unexpected external effects, it is aimed to flatten the system phase. In the literature, phase flattening is performed by setting the phase derivative to zero at a specified frequency value. This can lead to mathematical complexity. In this publication, the phase flattening process is provided graphically by correctly selecting the frequency characteristics given above. Thus, an accurate and reliable controller design method is presented, avoiding mathematical complexity. The effectiveness of the proposed method has been demonstrated on three different models selected from the literature. The positive contribution of the method to the system robustness has been proven by changing the system gain at certain rates.İntegral operatörünün eksikliğinden dolayı, oransal türev denetleyiciler kararlılık ve dayanıklılığı sağlama konularında zorlanabilmektedir. Bu zorluk, özellikle yüksek dereceli sistemlerde kendini daha çok hissettirmektedir. Bu yayında, zaman gecikmesi içeren üçüncü derece sistemlerin kararlılığının sağlanması için kesir dereceli oransal türev denetleyicilerin analitik tasarım yöntemi sunulmuştur. Bu yöntemde kararlılığın sağlanması için standart bir kontrol sisteminin sahip olduğu frekans özelliklerine ulaşılması hedeflenmiştir. Sistemin istenen kazanç kesim frekansı, faz kesim frekansı ve faz payı özelliklerini sağlaması hedeflenmiştir. Bu şekilde uygun değerler seçilerek sistemin kararlılığı ve dayanıklılığı elde edilebilecektir. Kesir dereceli bir denetleyicinin seçilme sebebi de bu özelikleri sağlayacak denetleyici parametrelerinin daha doğru şekilde ayarlanabilmesidir. Elde edilen kararlılığın beklenmeyen dış etkilere karşı dayanıklı olması için de sistem fazının düzleştirilmesi hedeflenmiştir. Literatürde faz düzleştirme işlemi, faz türevinin belirlenen bir frekans değerinde sıfırlanması ile gerçekleştirilmektedir. Bu da matematiksel karmaşıklığa yol açabilmektedir. Bu yayında ise faz düzleştirme işlemi yukarıda verilen frekans özelliklerinin doğru şekilde seçilmesi ile grafiksel olarak sağlanmaktadır. Böylece matematiksel karmaşıklıktan kaçınılarak, doğru ve güvenilir bir denetleyici tasarım yöntemi sunulmuştur. Önerilen yöntemin etkinliği literatürden seçilmiş üç farklı model üzerinde gösterilmiştir. Yöntemin sistem dayanıklılığına pozitif katkısı ise sisteme kazancının belli oranlarda değiştirilmesi ile ispatlanmıştır

Robust control stability using the error loop

The paper briefly formulates the error loop as a tool for designing robust stability control systems in front of structured and unstructured uncertainties. The error loop indicates that a tool for accommodating such uncertainties is the noise estimator, which is the unique feedback channel from plant to control. It is shown that the causality constraint preventing perfect cancellation of causal uncertainties (unknown disturbance), makes also control law to play a role, offering a further degree of freedom. Employing asymptotic expansions of the closed-loop transfer functions, simple, explicit design formulae derive from stability inequalities: they relate closed-loop eigenvalues to model parameter and requirements. A simple example is provided from a ball and beam plan

Control de velocidad de un motor de reluctancia variable de 4 fases y 6 polos, utilizando técnicas de control clásico

155 páginas. Maestría en Ciencias en Ingeniería Electromagnética.En este trabajo se presenta el análisis y diseño de un sistema de control de velocidad de un motor de reluctancia variable de seis polos y cuatro fases. El modelo no lineal de motor incluye la no linealidad de la fricción de Coulomb más la fricción viscosa. Se lleva a cabo el análisis estructural del modelo no lineal el cual es linealizado en el punto de operación establecido a las 2000rpm. Tanto el modelo no lineal como el lineal son comparados tanto en su estructura como en sus respuestas mediante simulaciones digitales encontrándose que bajo ciertas condiciones ambos tienen comportamientos similares. Posteriormente, con base en el modelo lineal se diseña un controlador clásico PI y se somete a pruebas de regulación, seguimiento y variaciones del torque de carga. El diseño del controlador se realiza mediante la técnica de Bode shaping garantizando márgenes de ganancia y fase adecuados con un ancho de banda mayor al modo del subsistema mecánico. La robustez es verificada mediante la simulación digital del sistema de control utilizando el modelo no lineal, el cual es, además, sometido a variaciones de carga encontrándose que el controlador PI tiene excelente desempeño tanto en regulación como en seguimiento. Por último, se proponen dos controladores adicionales: el primero se trata de un controlador PII, cuyo objetivo es reducir el efecto de la no linealidad llamada zona muerta presente en el motor en el arranque o a bajas velocidades. El segundo es un controlador PI que agrega una nueva técnica para la reducción del rizo presente en las respuestas de velocidad y torque, características de este tipo motor.In this work, the analysis and design of a speed control system of a variable reluctance motor with six poles and four phases is presented. The nonlinear motor model includes the nonlinearity of the Coulomb friction plus the viscous friction. The structural analysis of the non-linear model is carried out, which is linearized at the operating point established at 2000rpm. Both the non-linear and linear models are compared both in their structure and in their responses through digital simulations, finding that under certain conditions both have similar behaviors. Subsequently, based on the linear model, a classic PI controller is designed and subjected to regulation, tracking and load torque variation tests. The controller design is carried out using the Bode shaping technique, guaranteeing adequate gain and phase margins with a higher bandwidth than the mechanical subsystem mode. The robustness is verified by means of the digital simulation of the control system using the non-linear model, which is also subjected to load variations, finding that the PI controller has excellent performance in both regulation and tracking. Finally, two additional controllers are proposed: the first is a PII controller, the objective of which is to reduce the effect of the non-linearity called dead zone present in the motor at start-up or at low speeds. The second is a PI controller that adds a new technique for reducing the ripple present in the speed and torque responses, characteristics of this type of motor.Investigación realizada con el apoyo del Programa Nacional de Posgrados de Calidad del Consejo Nacional de Ciencia y Tecnología (CONACYT)

Broadband Impedance Matching of Antenna Radiators

In the design of any antenna radiator, single or multi-element, a significant amount of time and resources is spent on impedance matching. There are broadly two approaches to impedance matching; the first is the distributed impedance matching approach which leads to modifying the antenna geometry itself by identifying appropriate degrees of freedom within the structure. The second option is the lumped element approach to impedance matching. In this approach instead of modifying the antenna geometry a passive network attempts to equalize the impedance mismatch between the source and the antenna load. This thesis introduces a new technique of impedance matching using lumped circuits (passive, lossless) for electrically small (short) non-resonant dipole/monopole antennas. A closed form upper-bound on the achievable transducer gain (and therefore the reflection coefficient) is derived starting with the Bode-Fano criterion. A 5 element equalizer is proposed which can equalize all dipole/monopole like antennas. Simulation and experimental results confirm our hypothesis. The second contribution of this thesis is in the design of broadband, small size, modular arrays (2, 4, 8 or 16 elements) using the distributed approach to impedance matching. The design of arrays comprising a small number of elements cannot follow the infinite array design paradigm. Instead, the central idea is to find a single optimized radiator (unit cell) which if used to build the 2x1, 4x1, 2x2 arrays, etc. (up to a 4x4 array) will provide at least the 2:1 bandwidth with a VSWR of 2:1 and stable directive gain (not greater than 3 dB variation) in each configuration. Simulation and experimental results for a solution to the 2x1, 4x1 and 2x2 array configurations is presented

Interfaz gráfica para sintonía de controladores fraccionarios mediante algoritmo de evolución diferencial

Este proyecto final de carrera se centra en el desarrollo de una interfaz gráfica en MATLAB a través de su herramienta GUIDE, sobre la que se debe integrar el algoritmo de Evolución Diferencial para sintonizar controladores PIλDμ fraccionarios. De entre los distintos métodos de sintonía disponibles para el diseño de un controlador, se ha optado por elegir este algoritmo evolutivo porque permitirá crear una interfaz más versátil. Esto se debe a que dichos algoritmos realizan un ajuste basado en la optimización de una función objetivo, la cual mide el grado en que se cumplen varias especificaciones de diseño. Esta nueva herramienta de simulación le ofrece al usuario las funcionalidades necesarias para llevar a cabo la sintonía de controladores fraccionarios tanto en el dominio del tiempo como de la frecuencia, así como la configuración de los diversos parámetros del filtro de optimización. Finalmente, se incluirá un manual de ayuda para que el usuario pueda consultar todo lo referente a esta interfaz de sintonización fraccionaria. Tanto la interfaz como su manual de ayuda se elaborarán en inglés con vistas a que esta herramienta software pueda tener una difusión de ámbito internacional.This work focuses on the development of a graphical user interface in MATLAB through its GUIDE toolbox, on which the Differential Evolution algorithm should be integrated to tune fractional PIλDμ controllers. Among the different tuning methods available for the design of a controller, the evolutionary algorithm has been chosen because it will allow to create a more versatile method. This type of algorithm performs an adjustment based on the optimization of a target function. The flexibility of this fitness function makes it possible to meet multiple design specifications. This new simulation tool provides the user with all the functionalities to carry out the time and frequency domain tuning of fractional controllers and to configure the different parameters of the optimization filter. Finally, a help guide will be included so that the user could check the method performance regarding this fractional tuning interface. Both the interface and the help guide will be developed in English with the aim of making this software tool internationally spread and well known.Ingeniería Industria

Performance limits and robustness issues in the control of flexible link manipulators

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1992.Includes bibliographical references (leaves 179-186).by Carlos Eduardo Padilla Santos.Ph.D

The Fifth NASA/DOD Controls-Structures Interaction Technology Conference, part 1

This publication is a compilation of the papers presented at the Fifth NASA/DoD Controls-Structures Interaction (CSI) Technology Conference held in Lake Tahoe, Nevada, March 3-5, 1992. The conference, which was jointly sponsored by the NASA Office of Aeronautics and Space Technology and the Department of Defense, was organized by the NASA Langley Research Center. The purpose of this conference was to report to industry, academia, and government agencies on the current status of controls-structures interaction technology. The agenda covered ground testing, integrated design, analysis, flight experiments and concepts