Pilar Merchán

Bio: Pilar Merchán is an academic researcher from University of Extremadura. The author has contributed to research in topics: Silhouette & Cultural heritage. The author has an hindex of 10, co-authored 45 publications receiving 309 citations.

Two digital realizations of fractional controllers: Application to temperature control of a solid

Abstract: The purpose of this paper is to make a contribution for solving one of the major drawbacks for using fractional controllers: the controller implementation. This is done, in digital form, by applying a two step method: the use of trapezoidal rule for discretizing the fractional order integro-differential operators, and the use of the continued fraction expansion technique for approximating the discretized fractional operators. Simulation results are presented by the application of a PD fractional controller to temperature control of a solid.

A comparison of hole-filling methods in 3D

Abstract: This paper presents a review of the most relevant current techniques that deal with hole-filling in 3D models. Contrary to earlier reports, which approach mesh repairing in a sparse and global manner, the objective of this review is twofold. First, a specific and comprehensive review of hole-filling techniques as a relevant part in the field of mesh repairing is carried out. We present a brief summary of each technique with attention paid to its algorithmic essence, main contributions and limitations. Second, a solid comparison between 34 methods is established. To do this, we define 19 possible meaningful features and properties that can be found in a generic hole-filling process. Then, we use these features to assess the virtues and deficiencies of the method and to build comparative tables. The purpose of this review is to make a comparative hole-filling state-of-the-art available to researchers, showing pros and cons in a common framework.

Filling Holes in 3D Meshes using Image Restoration Algorithms

Abstract: This work describes a method for filling holes in a 3D mesh based on 2D image restoration algorithms. Since these algorithms need an image as input, the first stage of the method concerns a 3D to 2D transformation. By projecting the 3D surface onto a squared plane, a 2D image is generated in such a way that the depth information is stored in each grid. The image restoration algorithms are applied to it. Once the image has been repaired, the inverse transformation 2D to 3D is performed and the repaired 3D surface recovered. To test the method, artificial holes have been generated on a set of 3D surfaces. The goodnessof the results has been measured from the comparison between the 3D original surfaces and the 3D repaired ones. An evaluation with commercial software has been carried out to show thevalidityof themethod. Theimage restorationalgorithms have been applied to 3D cultural heritage modeling with good results. Specifically, sculptures of the collection from the National Museum of Roman Art in Spain have been reconstructed.

Feedback vs. feedforward common-mode control: a comparative study

Abstract: A comparison among feedforward (CMFF) and the traditional common-mode feedback (CMFB) loops, based on the most frequently used common-mode (CM) signal detectors for CM control in fully-differential (FD) circuits, is carried out. Simulated results confirm that CMFF shows a better performance in terms of induced nonlinear signal distortion, speed, and amplifier output signal swing. It is demonstrated that feedforward approach results very attractive for low-voltage applications.

Fractional order control - A tutorial

Abstract: Many real dynamic systems are better characterized using a non-integer order dynamic model based on fractional calculus or, differentiation or integration of non-integer order. Traditional calculus is based on integer order differentiation and integration. The concept of fractional calculus has tremendous potential to change the way we see, model, and control the nature around us. Denying fractional derivatives is like saying that zero, fractional, or irrational numbers do not exist. In this paper, we offer a tutorial on fractional calculus in controls. Basic definitions of fractional calculus, fractional order dynamic systems and controls are presented first. Then, fractional order PID controllers are introduced which may make fractional order controllers ubiquitous in industry. Additionally, several typical known fractional order controllers are introduced and commented. Numerical methods for simulating fractional order systems are given in detail so that a beginner can get started quickly. Discretization techniques for fractional order operators are introduced in some details too. Both digital and analog realization methods of fractional order operators are introduced. Finally, remarks on future research efforts in fractional order control are given.

Fractional Order Systems: Modeling and Control Applications

Abstract: Fractional Order Systems Fractional Order PID Controller Chaotic Fractional Order Systems Field Programmable Gate Array, Microcontroller and Field Programmable Analog Array Implementation Switched Capacitor and Integrated Circuit Design Modeling of Ionic Polymeric Metal Composite

Discretization schemes for fractional-order differentiators and integrators

Abstract: For fractional-order differentiator s/sup r/ where r is a real number, its discretization is a key step in digital implementation. Two discretization methods are presented. The first scheme is a direct recursive discretization of the Tustin operator. The second one is a direct discretization method using the Al-Alaoui operator via continued fraction expansion (CFE). The approximate discretization is minimum phase and stable. Detailed discretization procedures and short MATLAB scripts are given. Examples are included for illustration.