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Raul Rivas-Perez

Bio: Raul Rivas-Perez is an academic researcher from Polytechnic José Antonio Echeverría. The author has contributed to research in topics: PID controller & Control theory. The author has an hindex of 11, co-authored 34 publications receiving 399 citations. Previous affiliations of Raul Rivas-Perez include Instituto Politécnico Nacional & Pontifical Catholic University of Peru.

Papers
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Journal ArticleDOI
TL;DR: In this article, the authors proposed a new strategy for the control of water distribution in an irrigation main canal pool characterized by large time-varying time delays using fractional order PI controllers combined with Smith predictors that yield control systems which are robust to changes in the process time delay.

65 citations

Journal ArticleDOI
TL;DR: In this article, a simple fractional order controller combined with a Smith predictor scheme was proposed for controlling the temperature of a steel slab reheating furnace, where the preheating zone of this process was obtained from an identification procedure applied in an industrial furnace.
Abstract: This paper proposes a simple fractional order controller combined with a Smith predictor scheme for controlling the temperature of a steel slab reheating furnace. The dynamic model of the preheating zone of this process is obtained from an identification procedure applied in an industrial furnace. This identification procedure yields a second order plus time delay transfer function which undergoes large time delay changes. A fractional order integral controller combined with a Smith predictor is therefore designed. Simulated results compare the performances of the proposed fractional order controller with a standard PI controller, also combined with a Smith predictor, an LQR controller, and an H ∞ robust controller, in the case of the nominal process, and when the time delay varies. Four performance indexes have been used in this comparison: three related to the output performance (settling time, overshooting, and integral absolute error (IAE)), and a fourth one related to the control effort (TV). The analysis of these indexes shows that the simple fractional order controller provides lower values of the compared indexes when time delay becomes much higher than the nominal value.

45 citations

Journal ArticleDOI
TL;DR: In this article, a robustness analysis of fractional-order PI controllers is presented by assuming a frequency domain tuning of the regulators to control a first order plus time delay plant.

26 citations

Journal ArticleDOI
TL;DR: In this paper, a new technique for designing fractional order controllers applied to the automation of main canal pools of a water irrigation system has been proposed and compared with the standard combination of a Smith Predictor with a proportional-integral (PI) controller.
Abstract: This paper proposes a new technique for designing fractional order controllers applied to the automation of main canal pools of a water irrigation system. As large variation of all the plant parameters is present in such systems, a fractional order family of controllers combined with a Smith Predictor is designed using time domain specifications.The designed controllers are compared with the standard combination of a Smith Predictor with a proportional-integral (PI) controller. All these controllers are tuned to fulfil the same time specifications in the case of canal nominal dynamics. In some canals the plant parameters may experience large changes that deteriorate the time response, and can even unstabilize the closed-loop system. The fractional controllers are therefore designed to minimize the loss of performance of the system to variations in these parameters. Simulated results show the performance improvements achieved with these controllers compared with a conventional PI controller.

26 citations

Journal ArticleDOI
TL;DR: In this paper, a new robust fractional-order PI controller for hydraulic canals whose parameters can vary in a wide range is proposed, whose robustness to gain changes has particularly been increased.
Abstract: This paper deals with the development of a new robust fractional-order PI controller for hydraulic canals whose parameters can vary in a wide range. Robustness to gain changes has particularly been increased. A method to design these controllers through the use of frequency specifications is proposed. Analysis of the frequency response of the closed-loop canal shows that the general robustness was also enhanced. Two of these fractional controllers have been experimentally implemented in a laboratory hydraulic canal characterized by time-varying dynamical parameters. A comparison between the real-time responses of the fractional-order control system and those of the standard PI demonstrates the effectiveness of the proposed fractional-order control strategy in terms of performance and robustness.

22 citations


Cited by
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Book ChapterDOI
01 Jan 2015

3,828 citations

01 Nov 1981
TL;DR: In this paper, the authors studied the effect of local derivatives on the detection of intensity edges in images, where the local difference of intensities is computed for each pixel in the image.
Abstract: Most of the signal processing that we will study in this course involves local operations on a signal, namely transforming the signal by applying linear combinations of values in the neighborhood of each sample point. You are familiar with such operations from Calculus, namely, taking derivatives and you are also familiar with this from optics namely blurring a signal. We will be looking at sampled signals only. Let's start with a few basic examples. Local difference Suppose we have a 1D image and we take the local difference of intensities, DI(x) = 1 2 (I(x + 1) − I(x − 1)) which give a discrete approximation to a partial derivative. (We compute this for each x in the image.) What is the effect of such a transformation? One key idea is that such a derivative would be useful for marking positions where the intensity changes. Such a change is called an edge. It is important to detect edges in images because they often mark locations at which object properties change. These can include changes in illumination along a surface due to a shadow boundary, or a material (pigment) change, or a change in depth as when one object ends and another begins. The computational problem of finding intensity edges in images is called edge detection. We could look for positions at which DI(x) has a large negative or positive value. Large positive values indicate an edge that goes from low to high intensity, and large negative values indicate an edge that goes from high to low intensity. Example Suppose the image consists of a single (slightly sloped) edge:

1,829 citations

Journal ArticleDOI
TL;DR: This review investigates its progress since the first reported use of control systems, covering the fractional PID proposed by Podlubny in 1994, and is presenting a state-of-the-art fractionalpid controller, incorporating the latest contributions in this field.

447 citations

Journal ArticleDOI
TL;DR: This paper proposes a simple approach for designing a fractional order PI controller for controlling the speed of a DC motor, implemented on an FPGA target and its performance is compared to other possible benchmarks.

98 citations

Journal ArticleDOI
TL;DR: The purpose of this paper is to provide a state of the art that can be easily used as a basis to familiarize oneself with fractional order tuning strategies targeted for time delayed processes.
Abstract: Several papers reviewing fractional order calculus in control applications have been published recently. These papers focus on general tuning procedures, especially for the fractional order proportional integral derivative controller. However, not all these tuning procedures are applicable to all kinds of processes, such as the delicate time delay systems. This motivates the need for synthesizing fractional order control applications, problems, and advances completely dedicated to time delay processes. The purpose of this paper is to provide a state of the art that can be easily used as a basis to familiarize oneself with fractional order tuning strategies targeted for time delayed processes. Solely, the most recent advances, dating from the last decade, are included in this review.

89 citations