Fernando Morilla

A Java/Matlab-based environment for remote control system laboratories: illustrated with an inverted pendulum

In this paper, a novel environment is described that provides 24-h-a-day access to a Web-based lab for the remote control of different didactic setups. The control of an inverted pendulum is used to demonstrate the use of such an environment. The main attributes of this Web-based lab are: 1) the on-line interactivity with the didactic setup, 2) the possibility of defining different experiments by using parameter files, and 3) the open architecture of the environment which allows easy development of new experiments with other didactic setups. The structure of this Web-based lab not only provides students with quantitative information feedback but also allows visual supervision. Now, a remote-controlled camera plays an important role within a remote experimentation environment with mobile parts. Students can handle the camera on-line, just as they can control the didactic setup over the Internet.

Virtual and remote control labs using Java: a qualitative approach

This article describes a new way of teaching adopted at the Universidad Nacional de Educacion a Distancia (UNED) that uses dynamic and interactive simulations in a stand-alone or Web-based environment to permit control engineering students to do practical work at a distance. The article focuses on how this new stand-alone experimentation environment maintains a clear separation between the graphical experimentation interface, developed in Java, and the math and simulation engine. By constructing the environment in this fashion, the math engine can be replaced with a different one or with a real plant, or can even be ported to a remote server. A Web-based, multiuser virtual lab is also possible without the necessity of reprogramming the experimentation interface code. Other differences with respect to tools are the dynamic simulations, the user interactivity, the generation of new experiments as goals change, and the opportunity to practice with classical or advanced control strategies in different plants: a heat exchanger, a tank, a distillation column, or an inverted pendulum.

An iterative method for tuning decentralized PID controllers

ABSTRACT In this paper a method of timing decentralized PID controllers for multivariable systems is presented. It is based on an iterative numeric algorithm, and it uses information coming from the frequency response of the full matrix of the system transfer functions. Then, the effects of the interaction are included in the design because the off-diagonal elements in this matrix are taken into account. The aim is to meet the design specifications that were gain margins, phase margins or a combination of both in the different experiments earned out. Three examples are shown: two obtained from the literature and one from a real plant. The results are compared with another type of MIMO tuning.

Centralized PID control by decoupling for TITO processes

This paper presents a new methodology to design multivariable PID controllers for two-input and two-output systems. The proposed control strategy, which is centralized, combines four PID controllers plus two possible delays and two P controllers. The proportional gains in the P controllers act as tuning parameters in order to modify the behavior of the loops almost independently. The design procedure consists of three steps: first, an ideal decoupler including integral action is determined. Second, the decoupler is approximated with four PID controllers plus two possible delays. Third, the proportional gains are tuned to achieve the specified performance. The proposed method is applied to three representative processes.

Tuning decentralized PID controllers for MIMO systems with decouplers

In this paper, a method for controlling multivariable processes is presented. The controller design is divided into two parts: firstly, a decoupling matrix is designed in order to minimize the interaction effects. Then, the controller design is obtained for the process + decoupler block. For this purpose, an iterative numeric algorithm, proposed by same authors, is used. The aim is to meet the design specifications for each loop independently. This sequential design method for multivariable decoupling and multiloop PID controller is applied to several examples from literature. Decentralized PID controller design, specifications analysis and time response simulations has been made using the TITO tool, a set of m functions written in Matlab. It can be obtained in web page http://www.uco.es/~in2vasef. Copyrigth  2002 IFAC.

Reduction of the dimensionality of dynamic programming: a case study

This paper deals with the reduction of the computational complexity of dynamic programming, the well known curse of dimensionality. We show how it can be overcome by using different reduction techniques. Three of the most significant ones are introduced and compared with an example. The main conclusion is that the computational load can be reduced several orders of magnitude in an easy and intuitive way.

Methodologies for the Tuning of PID Controllers in the Frequency Domain

Abstract This paper collects the authors experience about the tuning of PID controllers in the frequency domain and suggests solutions to several of the outlined problems. The paper presents: (1) a tuning methodology of non-interactive PID controllers by phase or gain margin, whose advantages becomes evident when a process model is available, and (2) a formulation of the combined tuning by phase and gain margin, in which priority is given to the phase margin. The graphic interpretation of the combined tuning shows great difficulties for the numeric methods and it can be used to establish a strategy on how to relax gain margin with the purpose of finding a solution.

Conceptual Learning of Control by Java-Based Simulations

Abstract The combination of Java applications as graphical user interfaces and the Matlab-Simulink environment as the simulation engine seems to be a good solution for taking a particular control lab to distant students. In this paper, it is presented a new kind of simulation environment for qualitative teaching on concepts of Control Engineering by means of a suitable configuration of experiments by the tutor or teacher.

Educational Tool for Optimal Controller Tuning Using Evolutionary Strategies

In this paper, an optimal tuning tool is presented for control structures based on multivariable proportional-integral-derivative (PID) control, using genetic algorithms as an alternative to traditional optimization algorithms. From an educational point of view, this tool provides students with the necessary means to consolidate their knowledge on these control structures, which are of particular relevance in control engineering. The graphical user interface designed for the tool allows for the following: the selection of the control structure, the desired decoupling, the type of PID, the analysis of the interaction effects through relative gain array (RGA), the planning of several optimal tuning processes, the comparison of different designs (through graphics or the numeric results obtained), and the management of data files saved during the planned optimal tunings process. The developed tool was made available to students for them to solve a practical problem and, subsequently, the impact of its use was evaluated.

Practical advantages of inverted decoupling

This paper presents a study of the main advantages of inverted decoupling in 2×2 processes. Two simulation examples and an experimental process are used to show these advantages in comparison with simplified decoupling. The study focuses on the following practical advantages: the apparent process is the same as that obtained if one loop changes to manual; bumpless transfer and anti-windup are achieved easily using a feed-forward input in the controllers; and abnormalities of secondary loops do not affect the opposite loop. Because of this, inverted decoupling may be a good and easy way to improve the performance of industrial TITO (two inputs and two outputs) processes with interaction problems (when it can be applied).