Keywords

1 Introduction

In the era where cutting-edge technologies and hyper-connectivity is our everyday life, Virtual Reality (VR) and Augmented Reality (AR) have become a popular technology and will increase in importance over the next 10 years (Ezawa 2016).

Virtual and Augmented Reality are becoming an important tool in several fields (Craig 2013) and their application to an educational context will allow to the “Classroom of the Future” (Cooperstock 2001). We can already find some examples of its application in very different educational contexts (Kaufmann and Meyer 2008; Cheng and Wang 2008; Jarmon et al. 2009; McKerlich et al. 2011; Parton and Hancock 2012; Connolly and Hoskins 2014; Ibañez et al. 2014; Fonseca et al. 2014; Gutiérrez et al. 2015; Billinghurst and Kato 2002).

Software applications for mobile devices with AR help to learn difficult subjects and abstract concepts (Kotranza et al. 2009; Martín-Gutiérrez et al. 2010; Bujak et al. 2013), more than outdated methodology does. They can also give students a better motivation (Sotiriou and Bogner 2008; Di Serio et al. 2013; Martín-Gutiérrez and Meneses Fernández 2014) and improve their procrastination (Fabiani Bendicho et al. 2017).

Our work is focused to promote new educational experiences in engineering higher education (Martín-Gutiérrez et al. 2012, 2015) but we are just starting to generate didactic material for permanent use. In this context we present a new AR app to be used in a technological educational context to understand complex concepts and to encourage students to an autonomous exploration and learning.

2 Technical Description

The name of the developed app is ElectAR and its main objective is to serve as a learning tool in electricity practices at laboratory, helping students in the following fields:

  • Better understanding of specific hardwired logic diagrams, with the help of graphic information such as images, texts, videos and interactive 3D elements.

  • Being capable of accomplish practices’ goals, such as wiring, commissioning and testing of hardwired logic circuits, only with the information obtained through the app.

  • Provide students with a self-learning tool.

Software development has been characterized by the following key points (Behr et al. 2011):

  • An application focused to work on mobile devices.

  • Real-time processing capacity.

  • Virtual elements superimposed over real elements.

  • Targeting user-friendliness, achieved through graphic elements that ensure information can be understood easily.

  • High interaction with user.

To achieve these goals, app development has been done using Android Studio Integrated Development Environment (IDE), specifically for Android applications. The Software Development Kit (SDK) used for the Augmented Reality Engine is Metaio SDK. To improve the recognition of very simple marks (standardized electrical symbols are usually difficult to detect) we have included more complex intermediate symbols to define the environment.

Graphic design of the application has been done in a way that permits an attractive layout at the same time that uses a relatively low amount of resources. This allows the system to be used in a wide range of devices. The type of graphic elements used in real-time by the app can be divided into two categories:

  • Reference images, that need to be rich in details such as color contrast and non-symmetrical, to permit the software to be able to detect them in a robust way. The position of the information about electrical elements of the circuit are calculated relative to the position of reference images.

  • Images, 3D models and videos with optimum quality to be run in real time by the application and present augmented information about the circuit to the student.

On the main screen of the application, the user can choose from a list of available electrical practices, which one of them he/she wants to perform. After loading, the app will identify, through the camera device, the position of different symbols shown in the diagram and will help the student to understand how the specific circuit works, with the aid of 2D and 3D images, theoretical contents and videos (Fig. 1).

Fig. 1.
figure 1

Basic diagram with AR information: left 3D models and right theoretical contents.

Full size image

Once the practice is selected, the development of a specific practice to be added to the application can be divided into four parts:

  • Direct access button added to the main screen of ElectAR, with a unique name.

  • A loading screen, where the user can see which circuit is needed and also can read information about the practice before it starts.

  • A resource extraction activity, invisible to the user.

  • Main augmented reality activity, where the camera is activated and can detect reference images in the specific electricity circuit related, showing augmented information to the user.

Different functionalities have been added to the app, to allow a higher level of interaction with users. A list of them includes but are not limited to:

  • The screen captured frame can be stopped through a freeze button, allowing users to interact with AR elements in a more comfortable way.

  • Different actions can be performed on interactive elements like: dragging, changing size, changing orientation, and clicking on them to swap between graphic information and theoretical one.

3 App Validation

Test validation was done with upper grade educational cycle students. The test location was Upper Grade Educational Institute “Marítimo Pesquero”, in Santa Cruz de Tenerife, Spain. Test characteristics were the following:

  • It was a mandatory test.

  • The number of participants were 26.

  • 26 students were from two different courses of the institute, one with previous knowledge and the others without any prior knowledge about electricity and hardwired logic diagrams.

App tested had three different hardwired logic diagrams on it:

  • Motor commissioning with stop button.

  • Motor commissioning with stop button and also stopping through a metal proximity sensor.

  • Motor commissioning with star-delta configuration starting.

After the students were gathered, an explanation of the test was done, with the following description:

  • Students had a defined time to do the test.

  • No explanation was given about the practices included in the app. Diagrams themselves were given in paper format.

  • After a defined time, usability and satisfaction tests were given to them, in order to take the students’ first impressions.

To evaluate the product we have used a SUS usability and satisfaction questionnaire with a scale ranging from completely disagree (1) to totally agree (5). The questions and results are gathered in Table 1. We don’t see any significant difference between the two groups of students (with different previous knowledge level), so we present all students results together.

Table 1. Validation Test
Full size table

Results obtained showed that ElectAR app had a very high acceptance. From testers feedbacks we have select the followings as the most relevants:

  • Software extension with more tools and more circuits.

  • To expand the app to other topics.

  • To enable real-time simulation of current and circuit logic (e.g. switches).

  • Generic recognition (e.g. normalized symbol recognition).

4 Conclusions

We present ElectAR, a new AR app to interpret complex electrical diagrams. This app initially has an educational objective, but may also have practical applications in the field of engineering.

As observed with usability and satisfaction tests results ElectAR obtained mostly high results. A generalized opinion stated that the app is easy to use and may help in teaching of theoretical contents and abstracts subjects. Regarding self-teaching, screen pop-ups, when app opens for the first time, can help students to be completely autonomous.

One of the critical points is stability of contents in real time detection of very simple marks. This topic is much related to the recognition methods that Metaio SDK includes and needs to be improved. The complexity of the system can be reduced if software could detect circuit diagram symbols directly and not via intermediate more complex symbols.