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Experiences on using Arduino for laboratory experiments of Experiences using for laboratory Experiences on on using Arduino Arduino forand laboratory experiments of of Automatic Control Roboticsexperiments Automatic Control and Robotics Automatic Control and Robotics

F. A. Candelas, G. J. García, S. Puente, J. Pomares, C.A. Jara, J. Pérez, D. Mira, F. Torres F. F. A. Candelas, G. J. García, S. Puente, J. Pomares, C.A. Jara, J. Pérez, D. Mira, F. Torres F. A. A. Candelas, Candelas, G. G. J. J. García, García, S. S. Puente, Puente, J. J. Pomares, Pomares, C.A. C.A. Jara, Jara, J. J. Pérez, Pérez, D. D. Mira, Mira, F. F. Torres Torres University of Alicante, Carretera de San Vicente del Raspeig, s/n, PO Box 03690, Alicante, Spain University Carretera Vicente Raspeig, s/n, 03690, Spain University of Alicante, Carretera de San Vicente del Raspeig, s/n, PO Box 03690, Alicante, Spain University of of Alicante, Alicante, Carretera de de San Sanjpomares, Vicente del del Raspeig, jpalepuz, s/n, PO PO Box Box 03690, Alicante, Alicante, Spain (e-mail: {francisco.candelas, gjgg, santiago.puente, carlos.jara, damian.mira, fernando.torres}@ua.es) (e-mail: {francisco.candelas, gjgg, santiago.puente, jpomares, carlos.jara, jpalepuz, damian.mira, fernando.torres}@ua.es) (e-mail: (e-mail: {francisco.candelas, {francisco.candelas, gjgg, gjgg, santiago.puente, santiago.puente, jpomares, jpomares, carlos.jara, carlos.jara, jpalepuz, jpalepuz, damian.mira, damian.mira, fernando.torres}@ua.es) fernando.torres}@ua.es) Abstract: The free hardware platforms have become very important in engineering education in recent Abstract: The free hardware become very important education in recent years. Among platforms,platforms Arduinohave highlights, by in its engineering versatility, popularity and low Abstract: The free platforms have become very in engineering education recent Abstract: The these free hardware hardware platforms have becomecharacterized very important important in engineering education in in recent years. Among these platforms, Arduino highlights, characterized by its versatility, popularity and low price. This paper describes the implementation of four laboratory experiments for Automatic Control and years. Among these platforms, Arduino highlights, characterized by its versatility, popularity and years. Among these platforms, Arduino highlights, characterized by its versatility, popularity and low low price. This paper describes the implementation of four laboratory experiments for Automatic Control and Robotics courses at the University of Alicante, which have been developed based on Arduino and other price. This paper describes the implementation of four laboratory experiments for Automatic Control price. This paper describes the implementation of four laboratory experiments for Automatic Control and and Robotics courses the of which been based Arduino other existing were evaluated taking into have account thedeveloped views of students, that the Robotics courses at the University of Alicante, which have been developed based on Arduino and other Roboticsequipment. courses at at Results the University University of Alicante, Alicante, which have been developed based on on concluding Arduino and and other existing Results into the views of the proposed experiments havewere beenevaluated attractivetaking to them, and they theconcluding knowledgethat about existing equipment. Results were evaluated taking into account the views of students, concluding that the existing equipment. equipment. Results were evaluated taking into account account the have viewsacquired of students, students, concluding that the proposed experiments have been and hardware that to wasthem, intended. proposed experiments have been attractive to them, and they have acquired the knowledge about proposed configuration experiments and haveprogramming been attractive attractive to them, and they they have have acquired acquired the the knowledge knowledge about about hardware configuration and programming that was intended. hardware configuration and programming that was hardware configuration and Federation programming thatExperiments, was intended. intended. © 2015, IFAC (International of Automatic Control)Laboratory, Hosting by Elsevier Ltd. All rights reserved. Keywords: Arduino, Automation, Education, Robotics. Keywords: Arduino, Automation, Education, Experiments, Laboratory, Robotics. Keywords: Arduino, Automation, Education, Experiments, Laboratory, Robotics. Keywords: Arduino, Automation, Education, Experiments, Laboratory, Robotics.   

1. INTRODUCTION 1. INTRODUCTION 1. 1. INTRODUCTION INTRODUCTION Before the rise of open hardware platforms such as Arduino, Before the and rise of open hardware platforms as Arduino, hardware prototyping wassuch complex and Before open platforms such as Before the the rise rise of ofsoftware open hardware hardware platforms such as Arduino, Arduino, hardware and software prototyping was complex expensive. Therefore, many universities and research centres hardware and software prototyping was complex and hardware and software prototyping was complex and and expensive. Therefore, many universities and research centres began to develop cheaper and easier alternatives in the late expensive. Therefore, many universities and research centres expensive. Therefore, many universities and research centres began and easier in twentieth century. cheaper But these were not general and began to develop cheaper and easier alternatives in the late began to to develop develop cheaper andsolutions easier alternatives alternatives in the the late late twentieth century. But these solutions were not general and they were not popular outside the institution where they twentieth and twentieth century. century. But But these these solutions solutions were were not not general general was and they were not popular outside the institution where they was used. This was true until Arduino was born in 2005 in the they they were were not not popular popular outside outside the the institution institution where where they they was was used. This was true until Arduino was born in 2005 in the IVREA institute (Italy) as a student project run by Massimo used. used. This This was was true true until until Arduino Arduino was was born born in in 2005 2005 in in the the IVREA institute (Italy) as a student project run by Massimo Banzi, applied of freerun and IVREA institute (Italy) as student by IVREA who institute (Italy)the as aaconcepts student project project runhardware by Massimo Massimo Banzi, who applied concepts of free hardware and software, which meantthe a major change D., 2011). Banzi, applied the concepts of free and Banzi, who who applied the concepts of (Kushner, free hardware hardware and software, which meant a major change (Kushner, D., 2011). The concept of free hardware relates to a design of software, which meant a major change (Kushner, D., 2011). software, which meant a major change (Kushner, D., 2011).a The hardware relates to of microprocessor-based is available The concept of free hardware relates to design of The concept concept of of free free electronic hardware system relates which to aaa design design of aaa microprocessor-based electronic system which is available for free use. microprocessor-based electronic microprocessor-based electronic system system which which is is available available for for free use. for free free use. use. Nowadays, there are available a great variety of Arduino Nowadays, are aaa great of boards withthere different processors, sizesvariety and connectivity Nowadays, there are available great variety of Arduino Nowadays, there are available available great variety of Arduino Arduino boards with different processors, sizes and connectivity features. The Arduino hardware has become cheap and easy boards boards with with different different processors, processors, sizes sizes and and connectivity connectivity features. The Arduino become easy to acquire, priceshardware ranging has from about cheap 20 € and to 52 € features. The Arduino hardware has become cheap and easy features. Thewith Arduino hardware has become cheap and easy to acquire, with prices ranging from about 20 € to 52 € (+VAT) depending on models. Regarding the software to to acquire, with prices ranging from about 20 € to 52 to acquire, with prices ranging from about 20 € to 52 €€ (+VAT) depending on models. Regarding the software to program Arduino, the IDERegarding (Integrated (+VAT) on models. the software (+VAT) depending depending on same models. Regarding theDevelopment software to to program Arduino, the same IDE (Integrated Development Environment) is used for all boards, and it is available for program Arduino, the same IDE (Integrated Development program Arduino, the same IDE (Integrated Development Environment) is all and is different OS (Arduino, 2015). This IDE and free,for as Environment) is used for all boards, and it is available for Environment) is used used for for all boards, boards, andis it itopen is available available for different OS (Arduino, 2015). This IDE is open free, well as easy to get, start and use. C/C ++ is used different and free, as different OS OS (Arduino, (Arduino, 2015). 2015). This This IDE IDE is is open open and and free, as as well to use. C/C is programming whichand enables fromas well as easy to get, start and use. C/C ++ is used as well as as easy easy language, to get, get, start start and use. user C/C to++ ++create is used used asa programming language, which enables user to create from a simple program based on procedures in an single file, to programming programming language, language, which which enables enables user user to to create create from from aa simple program based on procedures in an single file, to a complex object-oriented in in multiple files. simple based procedures an file, to simple program program based on on program procedures in an single single file,Other to aa complex object-oriented program in multiple files. Other relevant aspect of the Arduino platform is the big amount of complex object-oriented program in multiple files. Other complex object-oriented program in multiple files. Other relevant aspect of the Arduino platform is the big amount information available about it, ranging from the basic relevant aspect of the Arduino platform is the big amount of relevant aspect of the Arduino platform is the big amount of of information available about it, ranging from the basic documentation in the official web site, to full books for information available about it, ranging from the basic information available about it, ranging from the basic documentation in official web site, to for different application fields (Banzi, 2011; al. 2011). documentation in the official web site, to full books for documentation in the the official web site,Warren to full fullet books books for different application fields (Banzi, 2011; Warren et al. 2011). different different application application fields fields (Banzi, (Banzi, 2011; 2011; Warren Warren et et al. al. 2011). 2011). Another fact that shows the success of the Arduino platform Another fact the success of is the amount of shows specific that areplatform offered Another fact that shows the success of the Arduino platform Another fact that that shows thecourses successabout of the theitArduino Arduino platform is the amount of specific courses about it that are offered today, some of them supported by outstanding institutions, is is the the amount amount of of specific specific courses courses about about it it that that are are offered offered today, some of them supported by outstanding institutions, today, today, some some of of them them supported supported by by outstanding outstanding institutions, institutions,

such as the course organized by the Spanish Committee in such course organized by the in Automatic 2015). like Committee this, not only such as the course organized by the Spanish Committee in such as as the theControl course (CEA, organized by Courses the Spanish Spanish Committee in Automatic Control (CEA, 2015). Courses like this, not only are addressed to people with particular interest in Electronics Automatic Automatic Control Control (CEA, (CEA, 2015). 2015). Courses Courses like like this, this, not not only only are people particular interest in and Robotics,to alsowith to teachers want to use the are addressed to people with particular interest in Electronics are addressed addressed tobut people with particularwho interest in Electronics Electronics and Robotics, but also to teachers who want to use the platform in education. and and Robotics, Robotics, but but also also to to teachers teachers who who want want to to use use the the platform in education. platform platform in in education. education. All previously mentioned features have made Arduino All previously mentioned features have made Arduino become a very popular platform and widely in the All mentioned features have made All previously previously mentioned features have extended made Arduino Arduino become a very popular platform and widely extended context of education, both in bachelor and higher degrees. become a very popular platform and widely extended in the become a very popular platform and widely extended in in the the context of education, both in bachelor and higher degrees. Arduino is especially popular in education on Electronics, context of education, both in bachelor and higher degrees. context of education, both in bachelor and higher degrees. Arduino in Automatic Control orpopular Robotics (Barber on et Electronics, al. 2013; Arduino is especially popular in education on Electronics, Arduino is is especially especially popular in education education on Electronics, Automatic Control or Robotics (Barber al. Granvillano C. 2014; Ishikawa et al., 2009; et al. Automatic et al. 2013; Automatic Control Control or or Robotics Robotics (Barber (Barber et etSobota al. 2013; 2013; Granvillano C. 2014; Ishikawa et al., 2009; Sobota 2013; Úbeda et al., 2009; Valera et al., 2014). Granvillano et al. Granvillano C. C. 2014; 2014; Ishikawa Ishikawa et et al., al., 2009; 2009; Sobota Sobota et et al. al. 2013; Úbeda et al., 2009; Valera et al., 2014). 2013; 2013; Úbeda Úbeda et et al., al., 2009; 2009; Valera Valera et et al., al., 2014). 2014). Considering all the features of the Arduino platform, as well Considering features of theresearchers, Arduino platform, as well as the works all andthe results of other authors thought Considering all the features of as Considering all the features of the the Arduino Arduino platform, platform, as well well as the works and results of other researchers, authors thought this platform was results a goodof which to build laboratory as works other researchers, authors thought as the the works and and results ofchoice other on researchers, authors thought this was aaa good choice which build laboratory experiments subjects theyon way, certain this platform was good choice on which to build laboratory this platform platform for wasthe good choice onteach. whichInto tothis build laboratory experiments for the subjects they teach. In this way, existing deficiencies related to the subjects were resolved, as experiments for the subjects they teach. In this way, certain experiments for the subjects they teach. In this way, certain certain existing deficiencies related the next section explains. existing deficiencies related to the subjects were resolved, as existing deficiencies related to to the the subjects subjects were were resolved, resolved, as as the the next section explains. the next next section section explains. explains. The remaining content of this paper is organized as follows. The content this is as Section 2 explains the of reasons that led to use Arduino, the The remaining content of this paper is organized as follows. The remaining remaining content of this paper paper is organized organized as follows. follows. Section 2 explains the reasons that led to use Arduino, the subjects where it has been applied, and the academic context. Section Section 22 explains explains the the reasons reasons that that led led to to use use Arduino, Arduino, the the subjects where it has been applied, and the academic context. The mainwhere aspects of the developed are described subjects it been applied, and context. subjects where it has has been applied, experiments and the the academic academic context. The main aspects of the developed described in 3. Section 4 presents theexperiments results of a are survey to the The main of developed experiments are described TheSection main aspects aspects of the the developed experiments are described in Section 3. Section 4 presents the results of a survey students about their view on the use of Arduino. Finally, in Section 3. Section 4 presents the results of a survey to the in Section 3. Section 4 presents the results of a survey to to the the students about their view on the use of Arduino. Finally, main conclusions of the work are discussed in Section 5. students about their view on the use of Arduino. Finally, the students about their view on the use of Arduino. Finally, the the main main conclusions of the work are discussed in Section 5. main conclusions conclusions of of the the work work are are discussed discussed in in Section Section 5. 5. 2. CONTEXT AND MOTIVATION 2. 2. CONTEXT AND MOTIVATION 2. CONTEXT CONTEXT AND AND MOTIVATION MOTIVATION The work developed includes the design and implementation The work developed includes design implementation of someand subjects The work developed includes the design and implementation Thefour worklaboratory developedexperiments includes the thefor design andoptional implementation of four laboratory experiments for some optional subjects taught in official engineering studies of the University of of of four four laboratory laboratory experiments experiments for for some some optional optional subjects subjects taught in official engineering studies of the University of Alicante (Spain), and especially, in the Master’s Degree in taught in official engineering studies of the University taught in official engineering studies of the University of of Alicante (Spain), and especially, in the Master’s Degree in Automatics and Robotics (MAR). The experiments, which Alicante (Spain), and especially, in the Master’s Degree Alicante (Spain), and especially, in the Master’s Degree in in Automatics and Robotics (MAR). The experiments, which Automatics Automatics and and Robotics Robotics (MAR). (MAR). The The experiments, experiments, which which

2405-8963 © IFAC (International Federation of Automatic Control) Copyright © 2015, 2015 IFAC 105 Hosting by Elsevier Ltd. All rights reserved. Peer review©under responsibility of International Federation of Automatic Control. Copyright 2015 IFAC 105 Copyright © 105 Copyright © 2015 2015 IFAC IFAC 105 10.1016/j.ifacol.2015.11.221

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were implemented during the last two academic years (20132015), are the following:

the other hand, students who are experts in Computer Science and programming but have a limited knowledge of Automatic Control.

- Simple temperature control for a 3D printer hot-end by using a PID. This experiment is developed in two subjects which introduce students to the Automatic Control: Automation and Robotics (6 ECTS) of the Degree in Computer Engineering, and Industrial Automation (6 ECTS) of the Degree in Chemical Engineering.

Bearing in mind the characteristics of Arduino, authors thought that this could be a good platform to develop laboratory experiments which are attractive for the two kinds of students. On the one hand, students with a more industrial or electronics profile could learn object-oriented programming with C++, benefiting from their knowledge on hardware. On the other hand, students from Computer Engineering could learn to connect devices such as sensors and actuators, while taking advantage of his training in programming. This was other important reason to do the work described here.

- Automation of a Cartesian robot. The main objective of this experiment is to teach students how to use and program a microcontroller as a controller for an industrial machine in the subject Industrial Computing (3 ECTS) of the MAR. - Humanoid robot programming. This experiment is taught in the subject New Trends in Robotics (3 ECTS) of the MAR, and its main aim is to show students the working and control of a type of robot very different from other ones seen in other subjects of the master.

3. DEVELOPED EXPERIMENTS 3.1 Temperature control for 3D printer hot-end

- Follower robot programming. Different activities are developed with a follower robot in order to introduce Robotics, not only in subjects of engineering degrees as the previously mentioned Automation and Robotics, but also in activities for free-elective credits.

The objectives of this laboratory experiment are to introduce the Arduino environment to students, teach students how to develop a simple circuit for temperature control, and program and adjust a digital PID controller.

With the developed experiments, authors have tried to achieve three basic objectives, as follows:

On the one hand, students have to implement and verify the necessary circuitry for controlling the temperature in the extrusion head, commonly called hot-end, of a standard 3D printer. As Figure 1 shows, the hot-end has a resistor for heating the filament flowing through it, and a thermistor to measure the temperature. Thus, two basic circuits are necessary to connect the hot-end to the Arduino ONE used as controller (see Figure 2). The first circuit for the temperature reading through an analog input, and the second one for actuating the resistor via a digital output.

- Experiments should be attractive to students, and easy to start with them, so that students focus on the important issues, and they do not lose much time learning how a specific device is configured. The Arduino platform meets this purpose. Besides, the knowledge learned about Arduino in one subject is useful to other later subjects. - Some existing equipment with little or no previous use, but which could be interesting for teaching the subjects, should be reused, replacing the original controller with an Arduino. - It was no possible to acquire more than one unit of the equipment for some experiments, mainly due to the costs of some of the robots. However, each student could have an additional Arduino board on which to carry out the development and a basic testing. This enables students to develop a first program that can be executed in the final equipment, and makes easier to share that equipment.

Fig. 1. 3D printer hot-end mounted on a holder.

In addition to the previously mentioned objectives, there is another important aspect that has been taken into account to choose the Arduino platform. The entering students to the MAR come from different degrees in engineering (Computer Science, Electronics, Industrial Engineering, Production Design, Telecommunications, etc.), and, while all them have a good basis in engineering, it has been found that the levels of knowledge about programming and hardware aspects depend heavily on the source degree. This fact also depends on the double orientation of the MAR, professional and research. There are students who are professionals enrolled mainly to catch up in hardware or programming technologies. In this way, it can be considered two kinds of students in general. On the one hand, students with good background in hardware or Automatic Control, but not in programming. On

Fig. 2. Circuits connecting Arduino with the hot-end. 106

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On the other hand, the student has to develop a program for Arduino, which reads and scales the sensor temperature, compares it with the reference, applies a PID control algorithm, and activates the heater resistor by using a hysteresis loop. Student has to tune the PID to meet an overshoot and a settling time, as well as adjust the parameters of the hysteresis.

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between the 24V I/O signals and the 5V logic of Arduino, the authors have developed the adaptation circuits, which also include electrical insulation to avoid surge problems in the Arduino and the PC. The circuit for the input signals is also responsible for directing the signals from the encoders and other relevant sensors, such as the limit switches and the emergency button, to the interrupt inputs of Arduino, being necessary to share interruptions for some sensors.

Students had 6 hours to carry out individually the different phases of the experiment. An Arduino and a set of the necessary components to assembly the circuits, including the hot-end, were provided to each student. For the assessment, each student has to deliver a report summarizing his results. 3.2 Automation of a Cartesian robot This experiment is based on a Cartesian robot which moves a carriage along the axes horizontal and vertical, covering a planar working area close to 4m2, as Figure 3 shows. The main goals of this experiment are to show students the basic elements of an industrial automation system, and teach them to develop a control program that interacts with the sensors and the actuators to move the carriage to the desired target positions accurately. Students also have to bear into mind the alarm conditions such as the emergency button or the alarm signals from the motor drivers.

Fig. 4. Cartesian robot and its main components. To ensure that all students know the robot operation and they are able to make a basic control program, without preventing the most outstanding students to consider more advanced features, two blocks of tasks are proposed. The first block includes these mandatory tasks: calibrate the axles, control the vertical axis brake, detect the limit switches, move the carriage in both axes with the joystick, manage the emergency button, and detect possible alarms from inverters. As optional work, the following task are proposed: use of speed ramps for movements, develop a graphical interface for a PC and communicate this with the Arduino, as well as move the carriage to a target position, either according to a number of encoder steps, or according to a distance in meters. For the assessment, students had to show the teacher how the tasks proposed were carried out by real robot using their program, while they explained how the program solved the tasks. The experiment was developed by pairs of students, not only because the number of students (12) or the fact that only there was one robot, but also because this experiment was considered to be a bit complex. Students had 12 hours of laboratory for this experiment.

Fig. 3. Scheme of the Cartesian robot. The robot includes basic elements used in many industrial automation equipment, as Figure 4 shows. As actuators, the robot has two triphasic power motors, managed by two inverters, and a pneumatic brake on the vertical axis. Each inverter has several input logic signals to control the direction and the speed, as well as output signals indicating the state of the motor (running, overcurrent alarm). The sensors are four limit switches and two incremental encoders. In addition, the robot has a control panel with a joystick for manual movements, an emergency button, and several lights.

Although only one robot was available, the teacher supplied each group of students with an Arduino Mega, a prototyping board, and a set of components such as LEDs, push-buttons and encoders. These elements enabled students to simulate many of the features of the robot while they were developing the program.

The Cartesian robot is usually controlled by a PLC S220 from Siemens, which uses 24V logic. But in this experiment, the PLC is replaced with an Arduino Mega 2560. This Arduino is characterized by having many I/O lines, which is essential to interact with all the elements of the robot. In order to have the option of switching between the original PLC and the Arduino, and to convert the voltage levels

3.3 Humanoid robot programming The Robonova is a humanoid robot (biped and with two arms) of about 31cm high, developed by HiTec. Although this robot is no longer sold, today there are many similar 107



alternatives. Thanks to its 16 degrees of freedom, this robot can perform many movements including walking, bending or lifting, up or down stairs, etc. The robot was supplied with the controller MR-C3024 which was quite limited in choices of programming and connection of sensors. Therefore, owners used to change the controller (Perea et al. 2010).

task of walking is not as easy as it may seem because the student not only has to define the movements, but also guarantee that the robot has a stable balance. Before facing up the robot programming with the Arduino IDE and C++, the student has to estimate the values of the key positions for the servos, and the time intervals that are required to run the basic trajectories that are necessary for the desired tasks, like take a step, lift the robot, etc. This can be done with some software application that simulates the Robonova, as for example the free program "RZ1 Action" (Micono Utilities, 2008). After estimating the positions and times, the student can begin the program design. The program must sent the positions previously stored in memory to the servos, in the right time, and repeat a sequence to get the robot walks step by step. The use of an interpolation algorithm is recommendable to smooth the movement. Finally, when the program is running, the student have to readjust the movements to get the robot walks properly.

In this experiment, students have to become familiar with the working of the humanoid robot, and program it to walk. For the experiment, the Robonova has been modified to use an Arduino DUE as a controller, as Figure 5 shows.

As optional part of the experiment, the student can consider that there may be big obstacles in the middle of the path by which the robot moves. Thus, he has to modify the program so that the robot can detect obstacles with its sensors, and avoid the objects in its path. Since the subject in which the experiment was developed had only 5 enrolled students, students were enabled to carry out the experiment individually. Although there was one Robonova only, each student had available an Arduino DUE, a prototyping board, and a set of components such as LEDs, push-buttons, IR sensors, and servomotors. This enabled students to test some functions of the program without the Robonova, and made easier to share the robot.

Fig. 5. Robonova modified with Arduino Due. The Arduino DUE is characterized by using a 32-bit ARM processor, which is far more powerful than those of traditional Arduinos, besides having more memory for program and data. This way, the Arduino DUE is able to execute complex programs while accurately generates the PWM control signals for the 16 digital RC servos of the robot, which are directly connected to it. The Arduino also receives the signals from four bumpers located at the feet of the robot, and three IR distance sensors placed on the shoulders. In addition, three LEDs that can be controlled from the Arduino have been included in the head of the robot.

For the assessment, the teacher asked each student to show the robot running and to explain his program. The quality of movement of the robot when walking, the program structure, and the degree of development of the optional part, were considered for the qualification. Student had about 15 hours to carry out the experiment.

In the program, all servos are managed as a vector of 16 objects created from the standard Arduino library "Servo". These objects are initialized for the range [600μs, 2.400μs] allowed by the Robonova servos, which matches to an angle of 0 to 180 degrees, and differs from the standard range [544μs, 2.400μs]. The library generates the PWM signals to the servos by software, with aid of the Arduino timers. In order to generate the 16 PWM signals with greater precision and stability, it is possible take advantage of the fact that the Arduino DUE has more timers than other versions, by setting the parameter SERVOS_PER_TIMER in the source file "servo.h" to 4.

3.4 Follower robot programming This experiment is based on the GoShield-GR robot (see Figure 6), designed jointly by the online shop GoShield and some of the authors of this work. The GoShield-GR is a line tracker robot specially designed for tracking competitions, a task for which the robot has twenty photo-reflective sensors on its bottom side. The robot's brain is an Arduino DUE. Taking advantage of the number of devices included in the GoShield-GR robot, different activities are proposed to the student, so that he learns the operation of the robot step by step. This way, he will be able to program increasingly sophisticated functions within the time schedule of the course. The number of activities presented to the students depends on the course in which the robot is used.

As a mandatory part of the experiment, the student has to program the Arduino DUE of the Robonova in order to walk a distance, standing as straight as possible. For the assessment of the student, a smooth and natural movement, like that of a person, is valued. To program this robot, the student must keep in mind especially the servos of both legs, but moving the arms can also help to keep the balance. The 108

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4. STUDENT OPINION At the end of the courses, students were invited to make a voluntary survey in order to know their opinion on using Arduino in laboratory experiments, and also to know their level of initial and final knowledge about programming and hardware. Table 1 summarizes the survey questions. Table 1. Survey questions Fig. 6. Follower robot GoShield-GR.

N. Question Q1 Before starting the course, I had good programming skills. Q2 Before starting the course, I had knowledge of electricity and electronics. Q3 I found easy and quick to get started with the software and hardware Arduino. Q4 The available time to develop the experiments was enough. Q5 The material available to develop the experiments was adequate. Q6 Doing the experiments to control real equipment encourages the development of practical contents. Q7 Using Arduino for experiments, against other control equipment with closed hardware, is a wise move. Q8 I found it easy to create programs for Arduino with C ++. Q9 Using Arduino, I have learned or improved my knowledge of how to connect input and output devices. Q10 The knowledge gained about Arduino will enable me to use this platform to solve other control applications, automation and robotics on my own. Q11 I bought, or I'm going to buy an Arduino board to solve the experiments of the course or other applications. Q12 Probably I will use Arduino to solve applications in the future. Q13 I think Arduino is applicable also in the professional field, in addition to education. Q14 I missed working with a controller with more industrial characteristics.

The catalogue of activities developed with this robot, ordered from the simplest to the most complex, is summarized below: - Hello world, and semaphores. These beginner exercises are intended to program the LEDs so they flash with a certain cadence, or emulate traffic lights with the right timing. - Morse code. The student has to use the buzzer to generate beeps representing the word "SOS" in Morse code. - Roulette game. Using the LEDs, the buzzer and the pushbutton, the student has to design a roulette game where the LEDs turn on sequentially, and the player must try to press just when a particular LED is on. - Basic line tracker. The robot must follow a line with the minimum oscillation of its direction regarding to the line, at a constant speed. Figure 7 shows a picture of a test of this exercise. - Speed control. The robot must match the speed of its motors depending on the part of the racetrack in where it is, that is, depending on the straights and curves. - PID control for the direction. When the robot runs at high speed, it is necessary to apply a PID control to the direction in order to the robot does not leave the circuit.

The questions Q1 and Q2 refer to the previous knowledge of students about programming and hardware before the course. Q3 to Q5 address the availability of time and resources, as well as the difficulty to get started with the software and hardware of Arduino. The degree to which Arduino motivates conducting the experiments is addressed in Q6 and Q7. Student’s opinion about their results are captured in the Q8 to 10. Finally, Q11 to Q14 addressed other aspects.

- Identification of intersections. The student have to add to the program the logic that enables the robot to identify intersections and decide where to go, on a circuit with multiple ways. The intersections are identified by special marks on the track.

For each question, students had to answer an integer number between 1 and 5 indicating their level of agreement with the question, where 1 means "I disagree" and 5 means "I totally agree". Figure 8 summarizes the results of the survey.

Fig. 7. Follower robot during a test for a basic track. The robot gives many options and enables students to work with different aspects about programming simple mobile robots. Student have to carry out the activities individually or in pairs depending on the course. In any case, until now, the assessment of the student has been done by testing the working of the student's program on the robot, and the explanation that the student gives about his program.

Fig. 8. Results of the survey: degree of agreement of the student (1-5) for each question (Q1-Q14). 109



When the results are analysed, firstly it can be seen as the minimum and maximum values for Q1 and Q2 confirm the disparity in prior knowledge levels that students had for both programming and hardware. The result for Q3 shows that, in general, students thought their beginning with the Arduino platform was easy. Regarding the availability of time captured by Q4, the student opinion was varied, but not very bad. Students were strongly agree with the fact of using Arduino in laboratory, as reflected in the results of Q6 and Q7. The answers to questions Q8 to Q10 reflect students mainly believed they acquired or improved their knowledge. Also, responses to Q11 and Q12 reflect how students were quite willing to buy an Arduino board on their own. Regarding the use of Arduino on a more professional level, in contrast to the educational, the opinion was diverse, although positive in general, as indicated by the Q13. Finally, the responses to Q14 show that there was some disparity of opinion relating to whether it would have been more interesting to use a controller with industrial features.

equipment. It is therefore advisable to maintain laboratory experiments using industrial and commercial equipment as far as possible, since those are the devices that students will find in the professional field. The students themselves say so. The compromise solution is to combine Arduino platform with real robots or machines, as it has been done in one of the experiments described in this paper. REFERENCES Arduino (2015). Arduino web page. Online (July 2015): http://www.arduino.cc. Banzi, M. (2011). Getting Started with Arduino. 2nd Edition. O’Reilly, USA. Barber, R., De La Horra, M., Crespo, J. (2013). Control Practices Using Simulink with Arduino as Low Cost Hardware. Proc. of the 10th IFAC Symposium on Advances in Control Education (ACE2013). Sheffield, UK. August 2013. CEA, Spanish Committee of Automation. 2015. Curso práctico on-line de Arduino Avanzado. Online (May 2015): http://www.ceautomatica.es/curso-online-de-ceacurso-practico-line-de-arduino-avanzado Granvillano C. (2014). Arduino as a programmable logic controller (PLC). Open Electronics. Online (June 2015): http://www.open-electronics.org/arduino-as-aprogrammable-logic-controller-plc/ Ishikawa, M., Maruta, I. (2009). Rapid prototyping for control education using Arduino and open-source technologies. Proceedings of 8th IFAC Symposium on Advances in Control Education. Kumamoto, Japan, October 2009. Kushner, D. (2011). The Making of Arduino. IEEE Spectrum. On-line: (May 2015): http://spectrum.ieee.org/ geek-life/hands-on/the-making-of-arduino Micono Utilities. (2008). RZ1Action: Action making software for Robonova. Online (May 2015): http://micutil.com/ RZE/ROBOMIC.html Perea, I., Puente, S., Candelas, F.A. & Torres, F. (2010). Nueva tarjeta de sensorización y control para robot humanoide. Proceedings of XXXI Jornadas de Automática. Jaén, Spain. September 2010. Sobota, J., Pišl, R., Balda, P., Schlegel, M. (2013). Raspberry Pi and Arduino Boards in Control Education (I). Proc. of the 10th IFAC Symposium on Advances in Control Education (ACE2013). Sheffield, UK. August 2013. Úbeda, D., Gil, A., Lucas, J.A., Jiménez, L.M., Reinoso, Ó. (2009). Ardilla: plataforma de prácticas docentes on-line mediante Arduino. Proc. of XXX Jornadas de Automática. Valladolid, Spain. September 2009. Valera, A., Soriano, A., Vallés, M. (2014). Low-Cost Platforms for Realization of Mechatronics and Robotics Practical Works. Revista Iberoamericana de Automática e Informática Industrial RIAI, Vol. 11 (4), 363-376. Elsevier. Warren, J.D., Adams, J. & Molle, H. (2011). Arduino Robotics (Technology in Action). Apress, USA.

5. CONCLUSIONS This paper describes how authors have managed to bring the Arduino platform to different laboratory experiments of engineering courses at the University of Alicante, which address different aspects of Automatic Control and Robotics. To put in practice Arduino in the labs has been relatively easy, thanks to previous experience of the researchers, as well as, the easiness of starting and using of Arduino platform. Furthermore, good results have been achieved on the interest shown by students and his learning, which has been verified through the academic results and a survey to students. The Arduino platform can be started and learned quickly. Thus students are focused on the problems of the experiments, such as the development and programming of control algorithms that make the robot or the machine works with the given specifications. One problem that arises in the teaching of subjects in the Master in Automation and Robotics is that students come from different engineering degrees and they have quite different knowledge levels on hardware and programming. With Arduino-based practices, it has found that students can learn best the skills they lack. Thus, students who knew best aspects of hardware, learn object-oriented programming, while students who have a better basis on computers enhance their knowledge about hardware. It has also been achieved to take advantage of several laboratory equipment that was available but it did not have a good use, after replacing the control electronics by a suitable Arduino controller. In addition, the low cost of Arduino hardware and its free software encourages students to buy their own devices in order to practice outside the laboratory classroom, and even develop their own projects. Although Arduino proves to be an excellent educational tool, and may also be useful for many real applications, it is undesirable to leave aside completely the professional 110