978-1-4799-6002-6/14/$31.00 ©2014 IEEE

Discovering electronics to aerospace engineers

Rafael Masot Peris Electronic Engineering Department

School of Design Engineering Universidad Politécnica de Valencia

Valencia, Spain e-mail: ramape@eln.upv.es

Miguel Alcañiz Fillol Electronic Engineering Department

School of Design Engineering Universidad Politécnica de Valencia

Valencia, España e-mail: mialcan@upvnet.upv.es

Luís Gil Sánchez Electronic Engineering Department

School of Design Engineering Universidad Politécnica de Valencia

Valencia, España e-mail: lgil@eln.upv.es

Abstract— Two electronics subjects are taught in the Bachelor's Degree in Aerospace Engineering at the School of Design Engineering (ETSID) of the Polytechnic University of Valencia (UPV). “Electronics Engineering” in which the fundamental of electronics are studied and “Electronics Technology” in which students apply the knowledge acquired in the previous one. The teaching methodology employed in this subject is the project based learning by means of the design and implementation of electronic projects related with the aeronautical engineering.

Keywords — Project Based learning (PBL); electronic engineering; electronic technology, aerospace engineering

I. INTRODUCTION

Discovering electronics to aerospace engineers with only 10.5 ECTS credits is not an easy task. But with an appropriate, direct and effective contents structure it is possible to provide students with a good education in a subject that does not correspond exactly to the profile of an aerospace engineer. In this paper authors describe how they achieve this education by means of the Project Based Learning (PBL) [1], where the students working in groups have to face the challenge of developing a real electronic engineering project applied to the aerospace engineering.

Most of the proposed works have a multidisciplinary character as it happens in the real world where the combination of different disciplines (electronic engineering, control theory, mechanics, manufacturing engineering, etc…) is needed to implement a viable project. Therefore students have to face the challenge of establishing a work time planning, preparing a budget where the cost of the different parts of the project is considered, working in teams, taking decisions, coordinating with other subjects laboratories and solving the problems found during the project development. At the end of the semester the knowledge acquired by the students is evaluated according to:

The performance of the designed electronic system

The daily work in the laboratory

The level of involvement and commitment to the project

The presentation/exhibition of the project

The quality of the project report

The teachers’ tasks in this subject are on the one hand to guide students during the project development helping them to solve specific problems, and on the other hand to provide them with the resources needed to successfully achieve the proposed design. This requires an extra effort on the part of the teachers with regard to the availability and project supervision.

A. Project Based learning

The Project Based Learning methodology [2] is one of the most effective teaching methods. It enables the students not only to develop the scientific-technical capabilities inherent to the subject, but also to improve their knowledge at organizational and management level. Besides it promotes social skills as team work, leadership, communication, planning, etc.

This methodology [3][4] is widely used in different disciplines. For example, in the field of electronic engineering the work of J. Macías-Guarasa et al. [5] describes the curriculum design of the subjects corresponding to the Electronic Systems block at the School of Telecommunications Engineering of the Polytechnic University of Madrid founded on the project based learning. M. Arias et al. [6] analyze the results obtained when applying the project based learning methodology to the subject “Digital Electronic Systems” corresponding to the degree en Telecommunication Engineering at the University of Oviedo. Similarly the work of R. Hong Chu et al. [7] describes the use of this methodology in

the subject “Power Electronics” at of the School of Electrical and Information Engineering of the University of Sydney. In the field of the aerospace engineering T. Andernach and G. N. Saunders-Smits [8] explain the need of teaching assistants for the tutoring of the projects developed at the Faculty of Aerospace Engineering of Delft University of Technology in Holland. I. K. Dabipi et al. [9] describe the process of design and implementation of a stereoscopic aerial imaging platform carried out by students of Department of Engineering and Aviation Sciences of the University of Maryland Eastern Shore, USA. B. M. Gordon [10] publishes a report where the results and conclusions obtained when applying the PBL methodology to engineering education at UK universities are presented.

The important advantages of the project based learning with respect to traditional education led some teachers of the Electronic Engineering Department (DIE) to apply this method in the electronic subjects of the Bachelor's Degree in Aerospace Engineering at the School of Design Engineering (ETSID) of the Polytechnic University of Valencia (UPV).

B. Bachelor's Degree in Aerospace Engineering

The Bachelor's Degree in Aerospace Engineering was created in the 2010-2011 academic year at the ETSID of the UPV. It replaced the former Degree in Aeronautic Engineering that was created in the same School in the 1999-2000 academic year. The curriculum, like most of the other degrees, includes 240 ECTS credits organized in four academic years; 60 of these credits correspond to basic education, 88.5 to mandatory subjects, 79.5 to elective subjects and 12 to the Final Degree Project.

The group of mandatory subjects of the Degree in Aerospace Engineering includes a module of 18 credits called Electricity, Electronics and Control that comprises three subjects: Electrical Engineering (2nd academic year semester A), Electronic Engineering (2nd academic year semester B) and Automatic Control (3rd academic year semester A) with 6 credits each of them.

Besides the School offers an important number of elective subjects, including Electronic Technology with 4.5 which is taught in semester B of the 3rd academic year. For each elective subject the maximum number of students is limited to 25.

One of the characteristics of this degree is that students have to obtain a high mark in the University Access Exams to be admitted into the degree program. This guarantees that most of them have a strong academic background and a great motivation to receive a good education that will permit them to have a good professional development in a field as highly competitive and attractive as aerospace engineering.

II. ELECTRONIC SUBJETS OF THE BACHLEOR’S DEGREE IN

AEROSPACE ENGINEERING

Students of the Bachelor's Degree in Aerospace Engineering have their first contact with electronics in the second semester of the second academic year in the mandatory subject “Electronic Engineering” of 6 ECTS credits. Basics and fundamentals principles of analog and digital electronics

are established in this subject. The final objective of the subject is to teach the students to analyze and design electronic measurement systems including physical parameters sensing, analog signal conditioning, digital processing and data display and storage. The subject syllabus is divided in two blocks:

The first block includes the study of the fundamental analog electronic components (diode, transistor and operational amplifier) as well as an introduction to analog signal conditioning and measurement systems.

The second block includes the study of the main digital electronic components and circuits: combinational and sequential systems and memories. Also microprocessor/microcontroller systems are introduced in this block. In particular the basic architecture and some internal peripherals of the microcontroller PIC18F4520 from Microchip Technology Inc. are studied. Students learn to program the microcontroller using the C18 programming language, the MATLAB development environment and the electronic circuit simulation software PROTEUS release 7.10 from Labcenter Electronics.

The second electronic subject in the degree is “Electronic Technology” taught in the first semester of the third academic year. It is a 4.5 ECTS credits elective subject in which the knowledge acquired in the previous subject is applied. The teaching methodology implemented in this subject is the Project Based Learning. This methodology is explained in the section below.

III. METHODOLOGY

The main objective of the subject “Electronic Technology” is to provide students with the practical electronic knowledge needed for their professional development by means of the implementation of aerospace engineering related project. The 25 students enrolled in the subject are divided in groups of 2 or 3 people so that 9 or 10 groups are formed.

As it is a 4.5 ECTS credits subject, students have to attend one class of 3 hours every week. During these 3 hours students and teachers work together in order to solve problems which arise in the project development. Outside these hours students have access to the laboratory as long as it is not occupied.

Over the course of the semester each group will study, design and implement a project related with aerospace engineering. In order to achieve this goal the subject is divided in the following parts:

A. First part (4 weeks)

It includes four weeks during which students have to define the project they want to develop and at the same time they receive theoretical and practical lessons in order to complete their electronic education. The concepts and applications taught in these lessons are:

Data display on LCD

Programming and debugging with MPLAB

Serial communication buses (UART and I2C)

Wireless communication

Control of servomotors and PWM signal generation using the ECCP (Enhanced Capture/Compare/PWM) functional unit of the PIC microcontroller

PC applications programming using MATLAB

Component soldering on a prototype board

During these 4 weeks students select the project they are going to development. They can choose one of the projects offered by the teachers or they can propose their own project. At the end of the 4 weeks students have to prepare a “feasibility report” of the project including the following information:

Title and authors

Project description

Block diagram

Budget

References

B. Second part (12 weeks)

Once the report is reviewed and approved by the teachers, students start the project development. During the next weeks, and always under the supervision of the teacher, students design and implement the different parts of the project:

Simulation. The designed circuit is simulated using the electronic circuit simulation software Proteus. All the design includes a µC PIC18F4520 which is programmed in C language by means of the MPLAB development environment and the C18 compiler. Depending on the characteristics of the project, the uC program can include one of the following parts: analog sensors reading using the A/D converter, digital sensors communication with external devices through an I2C interface, signal processing and filtering, data display in an LCD, actuators control signal generation or wireless communication using a UART interface. Some projects also include the programming of a PC application in MATLAB.

Hardware. Once the system has been simulated students have to build a prototype. They have to assemble all the parts included in the project. Normally all the projects include a µC PIC18F4520 and a sensor block which depends on the type of project (Inertial Measurement Unit IMU with an accelerometer and a gyroscope, pressure sensor, optical sensor, GPS, temperature sensor, etc.). Projects can also contain an LCD display, a wireless communication module, servomotors, brushless motors or an autonomous power system including a battery and some filtering and regulation components.

Mechanics/Manufacturing. Students design and build the physical structure of their project in the subject “Aerospace Manufacturing” that is taught in the same semester as “Electronic Technology”.

C. Exposición pública y memoria

At the end of the semester students carry out a public exhibition of their projects (Fig. 1) at the Hall of the ETSID and they deliver a report of the developed work. In this presentation students present their work to the university community (teachers, students, technicians, etc.) and explain the details of their projects solving any doubt that may arise.

Fig. 1. Public exhibition of the projects

D. Evaluation

The evaluation of the subject is based on the monitoring of the evolution of the project, the student implication in the project and the quality of the project report.

IV. PROJECTS

Among all the developed projects the following are highlighted because of their special relevance and complexity:

A. Quadcopter

The electronics and the control algorithm to stabilize a quadcopter have been designed in this project (Fig. 2).

Fig. 2. Design of a quadcopter

The attitude information (pitch and roll) are read by the PIC18F4520 from an inertial measurement unit (IMU). The control algorithm calculates the duty of the PWM signals

needed for each one of the four motors in order to compensate the imbalance and stabilize the system. The movements of the quadcopter are controlled from a PC by means of a MATLAB application communicated with the quadcopter through a wireless communication module. It has been one of the most difficult projects due to the complexity of the implementation of the stabilization algorithm.

B. Flying wing

The electronics to control the control surfaces and the propulsion system of a flying wing has been designed in this project (Fig. 3). The position of the ailerons is modified by means of servomotors.

Fig. 3. Design of a flying wing

C. Explorer vehicle

An explorer vehicle remotely controlled from a MATLAB application has been designed in this project. The system can display on the PC screen real time video captured by the camera of a smartphone placed on the vehicle and connected to the PC through the WiFi network of the ETSID (Fig. 4).

Fig. 4. Design of an explorer vehicle

D. Recovery system for a model rocket

The design of the electronics and parachute opening system for a model rocket has been carried out in this project (Fig. 5). The system monitors the rocket altitude every 20 ms by means of a barometric pressure sensor and activates the parachute opening system when an altitude loss is detected.

Fig. 5. Design of a recovery system for a model rocket

E. Positionning system based on GPS

The design of a positioning system has been implemented in this project. The system reads the longitude and latitude coordinates form a GPS module and sends the information to a PC through a wireless communication module to a PC where the position of the system is display on Google Earth (Fig. 6).

Fig. 6. Design of a positioning system based on GPS

F. Hovercraft

This project includes the design of the lift, propulsion and steering systems of an air-cushion vehicle. Lift and propulsion are achieved by means of brushless motors while steering is done using servomotors (Fig. 7).

Vehicle movements are controlled from a gamepad connected to the USB port of a PC. A MATLAB application processes the commands coming from the gamepad and transmits them to the hovercraft through a wireless communication module.

Fig. 7. Design of a hovercraft

G. G-force monitoring

A g-force monitoring system based on an accelerometer has been designed in this project (Fig. 8). This project will be used in the design of a race car that is being developed by UPV students within the “Formula Student” project.

Fig. 8. G-force monitoring

V. MATERIALS AND DEVELOPMENT TOOLS

A fully equipped electronic laboratory is available for the students. Each bench can be occupied by a maximum of three students and includes a Promax power supply (FAC-363B), a Tektronix oscilloscope (TDS 210), a Promax signal generator (GF-232), a Lendhermack handheld multimeter (IMY-64) and a Personal computer that incorporates the PROTEUS electronic circuit simulation software, Microchip MPLAB development tool and the MATLAB software.

Students have also the possibility to build their prototypes in the workshop annex to the electronic laboratory where they can find several soldering stations, printed circuit boards etching materials, drilling machines, cutting tools, etc..

One of the main objectives of the subject is to strength the students’ capacity to solve problems that arise during the development of an engineering project. Taking into account this objective the tools made available to the students should fulfill two requirements. They should allow the development of the proposed projects, but they should have some limitations in order to enforce their creative capabilities and to force them to face the difficulties raised during the development of real systems. That is why tools like Arduino based platforms, where the design process is reduced to assemble prebuild hardware modules and to program the system using libraries without a real understanding from the part of student of what the software is doing, were discarded.

The microcontroller used in the projects is the Microchip PIC18F4520. It is an 8-bit microcontroller that allows the development of medium-level applications but that has some limitations mainly with mathematical operations. It is the microcontroller that students learn in the previous academic year subject “Electronic Engineering”. So they are already familiar with it. As mentioned in section III, during the first classes teachers do a review of the microcontroller basics and introduce new features that will be needed for the development of the projects. The programming language used to write the microcontroller programs is C and the development tool used to edit and compile the code is the Microchip MPLAB software. The code programming and debugging tasks are done using the PICKit 3 programmer/debugger.

In an initial stage, until the project is fully defined and components for the project are selected and purchased, students can use the Proteus simulation software in order to test their design (generally only a part of the design can be simulated).

Once the project materials and components are available, students have to do the hardware assembly. In order to facilitate the assembly stage a board including the µC PIC18F4520 with all the reset, clock and programming/debugging circuits is provided to the students. This board incorporates also some connectors so that the µC can be connected to the rest of the peripherals of the system. Besides students can use different hardware modules including:

Wireless communication modules (working at 868 MHz) to communicate the µC with PC or laptop.

Bluetooth modules to communicate the µC with a Smartphone.

Inertial Measurement Units (IMU) to measure the acceleration and the attitude of vehicles or mobile systems.

Temperature, pressure and humidity sensors.

GPS modules.

Servomotors to establish the position of control surfaces, to activate opening mechanisms or to set the angle of a rotating structure.

DC motors and brushless DC motors.

Electronic Speed Controllers (ESC) to control the speed of brushless DC motors

Most of the projects require a communication with a PC. In some cases it is a wired communication and in others cases (quadcopter, explorer vehicle, hovercraft, etc.) the communication is established by means of an 868 MHz wireless communication module. The RF modulation/demodulation is done by the module, but the students should design and implement the communication protocol according to the requirements of each project. The tool used to develop the PC application is MATLAB as it is the tool that students use in other subjects of the degree.

Another problem students have to deal with is the voltage supply of the system. As in some systems modules with different supply voltage are combined, students have to introduce the circuits (voltage regulator) needed to generate the proper supply voltage for each module.

If the system implementation requires soldering components students can used prototype pre-drilled boards where they can place and solder the components.

VI. CONCLUSIONS

Two electronic subjects are taught in the Bachelor's Degree in Aerospace Engineering at the School of Design Engineering of the Polytechnic University of Valencia: “Electronic Engineering” a mandatory subject taught in the 2nd academic year and “Electronic Technology” an elective subject taught in the 3rd academic year. The teachers of the Electronic Engineering Department have made a great effort to develop a syllabus and a teaching methodology which aims to provide to students the knowledge, the capabilities and the abilities in the field of electronics needed to face the challenges of the world of work. The teaching methodology selected for the second subject is the Project Based Learning.

The academic results obtained by the students enrolled in the “Electronic Technology” during the academic years 2012-2013 and 2013-2014 are an evidence of the success of the applied methodology. Students satisfaction is reflected in the students opinion polls (the obtained mark by the subject in the section corresponding to teaching methodology is two points higher than the average mark for the department as shown in Fig. 9) and in the commitment and enthusiasm that students show during the project development and the day of the exhibition. Many students have spent more hours working in the project than the corresponding to the ECTS credits of the subject, developing complex and sophisticate projects showing a great creativity, motivation and working capacity. A video showing the projects development and the final exhibition corresponding to the academic year 2012-2014 can be found in reference [11].

At the end of the course, students have to fill out a teacher’s evaluation survey. In the section that evaluate if the teaching methodology and developed activities have helped the student to learn, the obtained mark was 8.91 over 10.

Fig. 9. Survey result for the teaching methodology corresponding to the subject ”Electronic Technology”

At the end of the subject students have developed not only skills inherent to the subject but also many other social abilities as cooperation, coordination and multidisciplinary organization. This complements their university education and prepares them for the world of work. This methodology also stimulates and increments the competitiveness among the different groups and their commitment level.

Almost every student agrees in the evaluation of the subject. “The effort needed for this subject is worth it considering the great amount of knowledge and competencies acquired during the semester” is one of their comments. This methodology increases students’ self-esteem and confidence so that they fill ready and capable to face new and greatest challenges.

ACKNOWLEDGEMENTS

Teachers responsible for the electronic subjects in the Bachelor's Degree in Aerospace Engineering would like to thank the staff of the School of Design Engineering (ETSID) for setting up the hall of the School for the final exhibition providing tables, panels and electric supply power.

Finally we would like to thank students for their enthusiasm and implication during the projects development as well as for the high degree of commitment, responsibility and maturity they have shown.

REFERENCES [1] G. Solomon, “Project-Based learning: A Primer,” Technology and

Learning., vol. 23, no. 6, pp. 20–30, Jan. 2003.

[2] Jingxuan Wu ; Lei Fan, “Student experience in using Project-based Learning (PBL) in higher education ”, 6th International Conference on Digital Content, Multimedia Technology and its Applications (IDC), 2010 pp: 273 - 277.

[3] Markkanen, H., Donzellini, G. and Ponta, D., "NetPro: methodologies and tools for Project Based Learning in Internet," World Conference on Educational Multimedia, Hypermedia & Telecommunications (ED-MEDIA 2001), Chesapeake, VA, pp. 1230-1235. 2001.

[4] Ponta, D., Donzellini, G. and Markkanen, H, "NetPro: Network Based Project Learning in Internet," European Symposium on Intelligent Technologies, Hybrid Systems and their implementation on Smart Adaptive Systems 2002, Albufeira, Portugal, pp.703-708. 2002.

[5] J. Macías-Guarasa, J. M. Montero, R. San-Segundo, Á. Araujo, and O. Nieto-Taladriz, “A project-based learning approach to design electronic systems curricula,” IEEE Trans. Educ., vol. 49, no. 3, pp. 389–397, Aug. 2006.

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[7] R. Hong Chu, D. D. C. Lu, and S. Sathiakumar, "Project-Based Lab Teaching for Power Electronics and Drives," Education, IEEE Transactions on, vol. 51, pp. 108-113, 2008.

[8] Andernach, T., Saunders-Smits, G.N., “The Use of Teaching Assistants in Project Based Learning at Aerospace Engineering,” Proceedings of the 36th ASEE/IEEE Frontiers in Education Conference, San Diego, 2006.

[9] Dabipi, I.K., Hartman, C.E., Burrows-McElwain, J.B., Mohseni, S., "Design and Construction of A Stereoscopic Aerial Imaging Platform: A

Project-Based Platform for Teaching Freshman Engineering Students", 38th ASEE/IEEE Frontiers in Education Conference, Session F4C, 2008.

[10] R. Graham, “UK Approaches to Engineering Project-Based Learning” Bernard M. Gordon MIT Engineering Leadership Program. 2010.

[11] http://politube.upv.es/play.php?vid=57840