Sebastián Dormido

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.

Development of a Web-Based Control Laboratory for Automation Technicians: The Three-Tank System

This paper introduces a Web-based control laboratory for experimentation on a nonlinear multiple-input-multiple-output (MIMO) system: the three-tank plant. Using this application, automation technician students can learn in a practical way many fundamental aspects of control processes. The client-side of the virtual laboratory has been developed using the programming support provided by Easy Java Simulations (EJS), an open-source tool for teachers with limited programming skills who want to create Java applications and applets. The lab has been integrated in the collaborative Web-based experimentation environment eMersion which provides more flexibility for the students performing the laboratory experiments.

Simulation of Greenhouse Climate Monitoring and Control with Wireless Sensor Network and Event-Based Control

Monitoring and control of the greenhouse environment play a decisive role in greenhouse production processes. Assurance of optimal climate conditions has a direct influence on crop growth performance, but it usually increases the required equipment cost. Traditionally, greenhouse installations have required a great effort to connect and distribute all the sensors and data acquisition systems. These installations need many data and power wires to be distributed along the greenhouses, making the system complex and expensive. For this reason, and others such as unavailability of distributed actuators, only individual sensors are usually located in a fixed point that is selected as representative of the overall greenhouse dynamics. On the other hand, the actuation system in greenhouses is usually composed by mechanical devices controlled by relays, being desirable to reduce the number of commutations of the control signals from security and economical point of views. Therefore, and in order to face these drawbacks, this paper describes how the greenhouse climate control can be represented as an event-based system in combination with wireless sensor networks, where low-frequency dynamics variables have to be controlled and control actions are mainly calculated against events produced by external disturbances. The proposed control system allows saving costs related with wear minimization and prolonging the actuator life, but keeping promising performance results. Analysis and conclusions are given by means of simulation results.

Real-time collaboration of virtual laboratories through the Internet

Web-based learning environments are becoming increasingly popular in higher education. One of the most important web-learning resources is the virtual laboratory (VL), which gives students an easy way for training and learning through the Internet. Moreover, on-line collaborative communication represents a practical method to transmit the knowledge and experience from the teacher to students overcoming physical distance and isolation. Considering these facts, the authors of this document have developed a new dynamic collaborative e-learning system which combines the main advantages of virtual laboratories and collaborative learning practices. In this system, the virtual laboratories are based on Java applets which have embedded simulations developed in Easy Java Simulations (EJS), an open-source tool for teachers who do not need complex programming skills. The collaborative e-learning is based on a real-time synchronized communication among these Java applets. Therefore, this original approach provides a new tool which integrates virtual laboratories inside a synchronous collaborative e-learning framework. This paper describes the main features of this system and its successful application in a distance education environment among different universities from Spain.

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.

The learning of control concepts using interactive tools

This paper discusses the creation of interactive computer simulations that implement virtual laboratories in the field of Control Engineering education. Easy Java Simulations (Ejs, http://fem.um.es/Ejs/), a Java‐based tool that helps create interactive dynamic simulations, is introduced. This tool can be used on its own, generating stand‐alone Java applications or applets, or in conjunction with Matlab/Simulink, using them as the internal engine that describes and solves the model. We describe in this paper this particular feature in detail, and provide some examples that show the advantages that this tool offers to the world‐wide engineering education community. Ejs is a freeware, open source, tool aimed for educators with low profile in programming but deep knowledge on certain technical and scientific fields. The tool allows to develop complete, interactive simulations in three steps: describing the mathematical model (optionally using Matlab/Simulink), building the user interface using off‐the‐shelf graphical elements, and connecting certain properties of these elements to the variables of the model. This last step is the key point to transform a classical simulation into a full interactive application.

Interactive teaching of constrained generalized predictive control

In this paper, an interactive educational tool for teaching the basic concepts of constrained generalized predictive control is described. Students gain insight into the selection of design parameters and discover how controlled system performance and closed-loop stability are influenced by this selection through a user-friendly presentation of constrained and unconstrained cases.

On the Application of Different Event-Based Sampling Strategies to the Control of a Simple Industrial Process

This paper is an experimental study of the utilization of different event-based strategies for the automatic control of a simple but very representative industrial process: the level control of a tank. In an event-based control approach it is the triggering of a specific event, and not the time, that instructs the sensor to send the current state of the process to the controller, and the controller to compute a new control action and send it to the actuator. In the document, five control strategies based on different event-based sampling techniques are described, compared, and contrasted with a classical time-based control approach and a hybrid one. The common denominator in the time, the hybrid, and the event-based control approaches is the controller: a proportional-integral algorithm with adaptations depending on the selected control approach. To compare and contrast each one of the hybrid and the pure event-based control algorithms with the time-based counterpart, the two tasks that a control strategy must achieve (set-point following and disturbance rejection) are independently analyzed. The experimental study provides new proof concerning the ability of event-based control strategies to minimize the data exchange among the control agents (sensors, controllers, actuators) when an error-free control of the process is not a hard requirement.

Developing Networked Control Labs: A Matlab and Easy Java Simulations Approach

The new information technologies provide great opportunities in control education. One of them is the use of remote control labs to teach the behavior of control systems through a network. In this paper, a new approach to create interactive networked control labs is described. Two main software tools are used: Matlab and Easy Java Simulations. The first one is a widely used tool in the control community, whereas the second one is an authoring tool, designed to build interactive applications in Java without special programming skills. The remote labs created by this approach give to students the opportunity to face the effects of network delays on the controlled system and also to specify on the fly their own control algorithm.

Virtual and remote robotic laboratory using EJS, MATLAB and LabVIEW.

This paper describes the design and implementation of a virtual and remote laboratory based on Easy Java Simulations (EJS) and LabVIEW. The main application of this laboratory is to improve the study of sensors in Mobile Robotics, dealing with the problems that arise on the real world experiments. This laboratory allows the user to work from their homes, tele-operating a real robot that takes measurements from its sensors in order to obtain a map of its environment. In addition, the application allows interacting with a robot simulation (virtual laboratory) or with a real robot (remote laboratory), with the same simple and intuitive graphical user interface in EJS. Thus, students can develop signal processing and control algorithms for the robot in simulation and then deploy them on the real robot for testing purposes. Practical examples of application of the laboratory on the inter-University Master of Systems Engineering and Automatic Control are presented.