Developing a remote laboratory for engineering education

Abstract

New information technologies provide great opportunities for education. One such opportunity is the use of remote control laboratories for teaching students about control systems. This paper describes the creation of interactive remote laboratories (RLs). Two main software tools are used: Simulink and Easy Java Simulations (EJS). The first is a widely used tool in the control community, whereas the second is an authoring tool designed to build interactive applications in Java without special programming skills. The RLs created by this approach give students the opportunity to perform experiments with real equipment from any location, at any time, and at their own pace. The paper ends with an evaluation of this approach according to students’ criteria and academic results.

Introduction

Control engineering education must adapt to the opportunities that information and communication technologies provide (Dormido, 2004, Heck, 1999). In this context, traditional laboratories can benefit from the Internet, which can be used by students for remote access to laboratory equipments (or plants). Remote operation of real plants is commonly known as remote laboratories (RLs) and can be incorporated into control engineering courses in order to avoid typical constraints of traditional laboratories, such as scheduling, cost of equipment and location. Although, simulations or virtual laboratories can be also used to overcome the disadvantages of traditional laboratories, any simulation is simply a model of a physical process, which is just an approximation that can not reproduce every aspect of the real phenomenon. So, the use of remote laboratories can be considered as an intermediate activity between simulations and traditional laboratories.

Recently, the control community has made many advances in implementing remote laboratories (Dormido et al., 2008, Gomes and Bogosyan, 2008, Gomes et al., 2007, Jara et al., 2009, Lazar and Carari, 2008). However, much work remains to improve these learning resources from a pedagogical point of view. Among others, visualisation and interactivity are two interesting features that can be considered as criteria for remote laboratories used for pedagogical purposes (Dormido, 2004, Sánchez et al., 2005).

In control engineering, typical analysis of system response is performed on various characteristics of output signals (such as waveform, periodicity, etc.). Because output signals are not actually read by humans, response analysis of a system is neither direct nor intuitive. Without suitable visualisation, remote laboratories can be hard to understand for many students. Moreover, interactive RLs should allow the student to simultaneously visualise the response of the real plant to any change introduced by the student. Immediate observation of a change in system response in reaction to user interaction is what really helps the student to develop useful practical insight into control systems theory (Sánchez et al., 2005). Without interactivity, the passivity of students slows down their learning process considerably.

Although the importance of interaction and visualisation is accepted by the engineering education community, their use is not the norm (Phillips, & Rodden, 2001; Uran & Jezernik, 2008). The main reason for this may be that adding interactivity and visualisation to computer applications requires advanced programming skills. Instructors, who are not often programming experts, can run into trouble when trying to add user interaction or advanced visualisation to applications. The variety of different computer languages, programming techniques, network protocols, and so on, makes this task even more complicated.

This paper focuses on providing an approach to teachers for facilitating the creation of remote laboratories for pedagogical purposes. Many advances in the creation of RLs have been done by the control community.

Lazar and Carari (2008) presented an approach to creating networked control systems using the LOOKOUT SCADA software of National Instruments. This laboratory allows the students to develop network-based control systems with server–client applications operating on real pilot plants via the Internet. In this kind of system, the controller and the plant are physically located in different places and are directly linked by a data network for remote closed-loop control. The quality of this control depends greatly on network traffic, which causes delays. However this is a good tool for education in control engineering.

In Dormido et al. (2008), a web-based virtual control laboratory for experimentation with a nonlinear system was presented. Server–client architecture was implemented using Easy Java Simulations (EJS) on the client side and LabVIEW on the server side. The main purpose of this application was for students to learn many fundamental aspects of process control in a practical way. Using this application, students can immediately observe the resulting dynamics and thus become aware of several physical phenomena that are difficult to explain from a purely theoretical point of view. The main difference between this application and our work is that we use MATLAB on the server side.

Gomes and Bogosyan (2009) presented a deep analysis of the current trends in the use of remote laboratories in engineering education and research. The authors described the components, benefits, usage, evolution topologies, platforms, integration with LMS (Learning Management Systems) and similar experiences of remote laboratories. Several of the approaches presented are focused only on remote labs for the simulation of electronic circuits, sequential logic networks, finite-state machine designs, microcomputer interfacing and assembly programming, whereas many applications related to education in automatic control are described only briefly.

The works of Calvo, Zulueta, Oterino, and Lopez-Guede (2009) and Leva and Donida (2008) presented web-based remote laboratories for basic courses in control engineering in which several experiments may be performed using the Ball & Hoop system. Client–server architecture is used here. LabVIEW is used on the server side to acquire and handle process data, whereas OPC technology is used to connect the remote server with the client side. The client side is the remote HMI (human–machine interaction) that students’ computers execute within a web browser. These remote applications were programmed with Visual Basic as ActiveX controls that were integrated with Internet Explorer. The Active X controls established a connection to the OPC server available at the server side that provided the process variables of interest to remote users. In parallel with the remote applications, a dedicated video camera was used to provide remote visual feedback to the students. The main limitation of this remote laboratory is that it is not possible to interact with the plant in real time.

Our approach is different to the mentioned alternatives because instructors can use the de facto standard software Simulink (The MathWorks Inc., 2009a) as the main tool on the sever side to control the real plant. Simulink is a modelling tool based on MATLAB (The MathWorks Inc., 2009b), which provides a graphical user interface for building models in the form of block diagrams using click-and-drag mouse operations. With this interface, instructors can draw models just as they would with pencil and paper (or as most textbooks depict them). However Simulink diagrams lack of interactivity in the sense that we just described. Instructors also face serious difficulties trying to add interactivity and visualisation to Simulink models. Easy Java Simulations (EJS) is a supplement for this purpose that we use in our approach. EJS is an authoring tool designed to create interactive applications in Java without special programming skills (Esquembre, 2004, Esquembre, 2010).

Using these tools, teachers can build a Simulink diagram to control a real plant and then move to EJS to create graphical user interface with high degree of interactivity and visualisation. A special built-in link of EJS can be used to manipulate the Simulink model (and therefore the real plant) from the interactive user interface. For safety reasons, the real plant is controlled only by one user interface, thus the approach does not allow the manipulation of the remote laboratory by multiple users simultaneously. Although a multi-user scheme similar to the described in (Jara et al., 2009), where one user manipulates the real plant and the rest of users only observe, could be implementing in the future.

This paper is organized as follows. In Section 2, the connection between EJS and Simulink is introduced. Section 3 describes the creation of the remote laboratory using a ball and hoop system. Several experiments with the remote laboratory are shown in Section 4. An education evaluation of the implemented system is discussed in Section 5. Finally, Section 6 presents the main conclusion of the work.