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\begin_layout Title
A New Open Source 3D-printable Mobile Robotic Platform for Education
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\begin_layout Author
J.
 Gonzalez-Gomez, A.
 Valero-Gomez, A.
 Prieto-Moreno, M.
 Abderrahim
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\begin_layout Institute
J.
 Gonzalez-Gomez, A.
 Valero-Gomez, M.
 Abderrahim 
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at
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 Robotics Lab, Carlos III University of Madrid, Spain,
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email{{jggomez,avgomez,mohamed}@ing.uc3m.es}
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and
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 A.
 Prieto-Moreno 
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at
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 Autonomous University of Madrid, Spain, 
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email{aprieto@uam.es}
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abstract{In this paper we present the Miniskybot, our new mobile robot aimed
 for educational purposes, and the underlying philosophy.
 It has three new important features: 3D-printable on low cost reprap-like
 machines, fully open source (including mechanics and electronics), and
 designed exclusively with open source tools.
 The presented robotic platform allows the students not only to learn robot
 programming, but also to modify easily the chassis and create new custom
 parts.
 Being open source the robot can be freely modified, copied, and shared
 across the Internet.
 In addition, it is extremely cheap, being the cost almost exclusively determine
d by the cost of the servos, electronics and sensors.}
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\begin_layout Section
Introduction
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Mobile robotics is increasingly entering the curricula of many technical
 studies.
 Robotics is gaining terrain in industry and consequently more firms are
 recruiting candidates with experience in robot programming.
 For this reason, many universities are teaching robotics in their master
 and degrees programmes
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key "Verner:1999, Rawat:2004"

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.
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A common approach when teaching robot programming is the use of simulations,
 in which the user can create different robot configurations with low effort.
 These ad-hoc robots can be also shared with other people, multiplying the
 number of 
\shape italic
out-of-shell
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 platforms 
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key "Carpin:Usarsim, Player:Stage"

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.
 Furthermore, the cost is zero, you may have as many robots as you want,
 and they will never break.
 But this solution has one drawback: simulated robots are not like real
 robots.
 Things working on simulation may not work the same on a real platform.
 In addition, students will not enjoy the same testing their ideas on a
 real robot than on a simulated one.
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	filename eps/Miniskybot-hand.eps
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Left: The new Miniskybot v1.0 robot.
 Right: The educational skybot robot
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name "fig:Miniskybot-skybot"

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Should it not be great that robots could be shared in the same way that
 code is shared (like in simulation)? If this could be possible researchers,
 professors and students could share their open source robots through the
 Internet, exchange ideas with other research groups, compare prototypes,
 test their algorithms on different configurations, evolve proposals from
 others..., such an idea is now possible and affordable thanks to the open
 source Reprap-like 3D printers
\begin_inset CommandInset citation
LatexCommand cite
key "erik:print3d"

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.
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\begin_layout Standard
This opens a new way of teaching robotics with the following advantages:
\end_layout

\begin_layout Itemize
Fast prototyping of robotic platforms.
 
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\begin_layout Itemize
Low cost printing of robot parts.
 
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\begin_layout Itemize
Easy reconfiguration and adaptation of the platform (evolution).
 
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\begin_layout Itemize
Easy sharing of robot models among people.
 
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\begin_layout Itemize
Motivation for students not only to implement algorithms on an existing
 platform but also to design and build new platforms.
 
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\begin_layout Standard
In this paper, our new 3D printable Miniskybot robot platform is presented
 (shown in figure 
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LatexCommand ref
reference "fig:Miniskybot-skybot"

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).
 It is fully open source (both the mechanical and electronics parts) and
 exclusively designed with open source tools (Openscad, Freecad and Kicad).
 The parts were furtherer printed in a Makerbot Cupcake 3D printer.
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\begin_layout Section
Motive and Problem Statement
\end_layout

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Among the commercial educational platforms we can find a great variety of
 opportunities, starting with the well known Lego Robot, and going through
 the Meccano Robot, the RoboRobot robotic kit
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http://roborobo.koreasme.com/educational-robot-kit.html
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, or the OWI Robot Arm Edge
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http://www.owiroboticarmedge.com/
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.
 These products are quite extended in the educational environment, they
 are affordable, and easy to use.
 They usually come with associated software, which allows users to interface
 with the robot, having access to sensors and actuators, program them, and
 so forth.
 These platforms have been present for some years now in the educational
 environment.
 In 
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key "lund:robocup98"

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 the authors demonstrated the idea of a children’s league for RoboCup, using
 robots constructed and programmed with the LEGO MindStorms kit to play
 soccer.
 Since then, RoboCupJunior has evolved into an international event where
 teams of young students build robots to compete in one of three challenges:
 soccer, rescue and dance 
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key "lund:robocup2000, Skar:robocup2002"

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.
 Goldmand et al.
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key "Goldman:2004"

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 presented an educational robotics curriculum to enhance teaching of standard
 physics and math topics to middle and early high school students.
 This project was also centered around the Lego MindStorm.
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The major disadvantage of these platforms is that they are close.
 The users can hardly adapt them to their necessities, and instead, they
 must adapt to them.
 The reconfiguration of the platform may be a great advantage in order to
 be able to deploy all the initiative of the researchers, professors or
 students.
 The Lego MindStorm inherits the "build-it-yourself" of the Lego traditional
 toys, but users are constrained to use the sensors provided by the manufacturer
, as well as the development software.
 An effort could be done to work around this limitation, but this goes beyond
 the original design of the platform.
 A work trying to meet the "open source" and the "non-free" directions is
 done by O'Hara et al
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key "O'Hara:2003"

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.
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Ad-hoc mini-robots have been built by research groups or university spin-offs
 mainly for educational purposes.
 These solutions overcome the limitations of the commercial robots, providing
 cheaper and more adapted solutions.
 Efforts have been done with the intention of developing effective and low-cost
 robots for education and home use, designed and built to fit the particular
 requirements of a teaching programme.
 Examples are those of IntelliBrain-Bot 
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http://www.ridgesoft.com/intellibrainbot/intellibrainbot.htm
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, Martin F.
 Schlogl's robots
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http://www.mfs-online.at/robotics.htm
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, the TankBot
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http://profmason.com/?p=320
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, the Trikebot 
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key "Hsiut:trikebot"

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 among many others.
 
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This had been also our way of teaching robotics during many years, with
 our Skybot
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http://goo.gl/MdRJs
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 platform (shown in figure 
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reference "fig:Miniskybot-skybot"

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).
 In our courses, the students build the Skybot from scratch and then program
 it.
 Sometimes they are so motivated that they propose wonderful modifications
 to the robot design.
 Even though some modifications are known beforehand that will not work
 well, we would like the student to discover it by himself.
 But in any case, it is not possible to implement these modifications during
 the course due to the time it takes to the manufacturer to build the parts.
 At the end we had to keep the platform, or in the best case, change it
 for the next course with new students.
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To summarize, the classical way of teaching robotics must focus, by necessity,
 on the programming of the robotic agent given a particular platform.
 Even if only this can be quite challenging and inspiring, with our current
 proposal of open source printable robots, the teaching programme must not
 be focused any more 
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only
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 on the robotic agent, but it may also include its mechanical design.
 Beginning with a basic platform, like the Miniskybot, students can be guided
 through the design and programming process.
 In this way, they may discover the tight relation between hardware and
 software, and how each of them can and must, adapt to the other requirements
 in order to achieve a precise task.
 They may learn that a particular mechanical design suits better a precise
 task, test different alternatives, and so forth.
 And something that is hardly considered in robotic programmes, students
 may learn that a change in the mechanical design could solve a problem
 better, faster, and more robustly than a software solution.
\end_layout

\begin_layout Section
On low-cost 3D Printers
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Bradshaw et.
 al 
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key "bradshaw:3d"

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 have recently made a study on low-cost 3D printing.
 They briefly run through the history of 3D printing, beginning in the late
 1970s.
 These more than thirty years have driven to affordable 3D printers for
 individuals
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LatexCommand cite
key "Bowyer:3d"

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, and allow them to print complex engineering parts entirely automatically
 from design files that it is straightforward to share over the Internet.
 While open source software development has been studied extensively, relatively
 little is known about the viability of the same development model for a
 physical object design.
 3D printers are offering new possibilities of sharing physical objects.
 As they can be defined using code, researchers can share their own parts,
 evolve them and "build" them straight forward using 3D printers.
 This allows for a decentralized community to independently produce physical
 parts based on digital designs that are shared via the Internet.
 Apart from improving the device, dedicated infrastructures were developed
 by user innovators.
 As Bruijn shows in his master thesis 
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key "erik:print3d"

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, a considerable improvement of hardware are proposed by people sharing
 parts and having access to 3D printers.
 This hardware modifications are relatively easy for others to replicate.
 As it has been the case with software for many years, currently, there
 are also on-line repositories of parts, where people can download and upload
 their designs
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http://www.thingiverse.com
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.
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Pictures of some open source 3D printers.
 From left to the right: RepRap Darwin, the first generation (May, 2007);
 Reprap Mendel (Sep, 2009) the second generation; Makerbot Cupcake (April,
 2009), the first commercial open-source 3D printer; Makerbot Thing-o-Matic
 (Sep, 2010), second version
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In figure 
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 four of the most important open source 3D-printers are shown.
 The origin of these kind of printers was the reprap project
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http://reprap.org/wiki/Main_Page
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key "Jones2011"

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 started by Adrian Bowyer in 2004.
 The aim of this project was to develop an open-source self-replicating
 machine.
 In May 2007 the first prototype, called Darwin was finished and some days
 later, in May 29th the first replication was achieved.
 Since then, the reprap community (original reprap machines and derived
 designs) has been growing exponentially
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key "erik:print3d"

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.
 The current estimated population is around 4500 machines.
 The second reprap generation, called Mendel, was finished in September
 2009.
 Some of the main advantages of the Mendel printers over Darwin are bigger
 print area, better axis efficiency, simpler assembly, cheaper, lighter
 and more portable.
 
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Initially, both Darwin and Mendel were not designed for the general public
 but for people with some technical background.
 As the reprap project was open-source, small companies were created to
 start shelling these 3D printers, as well as derived designs.
 The first company was Makerbot Industries
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http://www.makerbot.com/
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, who shipped a first batch of their Cupcake CNC in April 2009.
 By the end of 2009 they had shipped nearly 500 complete kits.
 After operating for a year they had sold about 1000 kits in April 2010.
 Their latest design is the thing-o-matic printer, announced in September
 2010.
 It is really easy to build and use, and their cost is around 950€.
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Our open source 3D printers at Carlos III University of Madrid.
 On the left: the Makerbot Thing-o-matic, called MADRE.
 On the right: a Prusa Mendel prototype, being built by the students
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name "fig:Carlos-III-3D-printers"

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Currently, at the System Engineering and Automatic Department of Carlos
 III University of Madrid we have one thing-o-matic available for the students,
 shown in figure 
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reference "fig:Carlos-III-3D-printers"

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.
 It was fully assembled by the students.
 Anyone has free access to it so that they can print whatever designs they
 want.
 Our main goal is to stimulate their imagination and enhance their creativity.
 
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In addition we have started a project, called 
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Clone wars
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http://asrob.uc3m.es/index.php/Proyecto:_Clone_wars
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, in which a group of students are building their own reprap printers from
 the scratch.
 All the parts are being printed in our thing-o-matic, which has been named
 MADRE (that means mother in spanish).
 We have chosen the Prusa Mendel model as the design to build, because it
 is very well documented and it is rather easy to assemble.
 In figure 
\begin_inset CommandInset ref
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reference "fig:Carlos-III-3D-printers"

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(on the right) the first prototype is shown.
 In total the students are building 20 of them.
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\begin_layout Section
The Miniskybot mobile robot platform
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\begin_layout Subsection
Introduction
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The new Miniskybot robotic platform
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http://www.thingiverse.com/thing:7989
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 is open source: all the mechanical and electronic design has been released
 with a copy-left license.
 Furthermore, only open source software tools have been employed.
 This is important because in doing so it is guaranteed that anyone will
 be able to read, understand and modify the design files without license
 issues and using their preferred computer platform (Linux, Mac, BSD, Windows...).
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talk about the open-source-hardware squared!!!
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\begin_layout Standard
The Miniskybot is a differential drive robot composed of printable parts
 and two modified (hacked) hobby servos.
 It has been designed so that it can be printed on open source reprap-like
 3D-printer.
 Two mechanical designs have been developed: the minimal version and the
 1.0.
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\begin_layout Subsection
Minimal version
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Miniskybot.
 Minimal version
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name "fig:Miniskybot-Minimal-version"

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The first prototype developed was a minimal robot chassis.
 The idea was to design a printable robot with the minimal parts, a kind
 of 
\begin_inset Quotes eld
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hello world
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 robot.
 It is shown in figure 
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reference "fig:Miniskybot-Minimal-version"

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.
 It consist of only four printable parts: the front, the rear and two wheels.
 They are all attached to the servos by means of M3 bolts and nuts.
 Standard O-rings are used as wheel tires.
 For making the robot stable, the rear part has two support legs that slide
 across the floor.
 Therefore this prototype is only valid for moving on smooth flat surfaces.
 The goal of this first design was to show the students a minimal fully
 working mobile robot for stimulating their minds.
 They were encouraged to improve this initial design.
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\begin_layout Subsection
Miniskybot 1.0
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\begin_inset Caption

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Miniskybot Robot.
 Version 1.0
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name "fig:Miniskybot-Robot-v1.0"

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The version 1.0 chassis is an evolution of the previous design (figure 
\begin_inset CommandInset ref
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reference "fig:Miniskybot-Robot-v1.0"

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).
 It consist of nine printable parts: the front, the rear, two wheels, the
 battery compartment, the battery holder and the castor wheel.
 An important feature is that the parts have been parameterized, just changing
 some parameters new parts are obtained.
 For example the battery compartment is automatically changed if the parameter
 battery type is set from AAA to AA.
 In this case a new compartment capable of holding AA batteries (instead
 AAA) is generated.
 
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The parametric feature is possible thanks to the open source Openscad
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http://openscad.org
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 software used for designing the pieces.
 The parts themselves are not graphical meshes but scripts that determine
 how they are built by primitive geometric forms.
 When these scripts are 
\begin_inset Quotes eld
\end_inset

compiled
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 the graphical part is generated and rendered on the screen, and later exported
 as an STL file for 3D printing.
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\begin_layout Standard
This approach is very flexible because the parts are ASCII scripts that
 can be easily shared through Internet, stored in repositories and so forth.
 Therefore the mechanical designs can be modified, used, and printed easily
 by different people around the world.
\end_layout

\begin_layout Subsection
Electronics and sensors
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Electronics.
 Skycube board
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name "fig:Electronics-Skycube-board"

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\end_layout

\end_inset


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Electronic diagram
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The Miniskybot's electronics is the Skycube board
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http://www.iearobotics.com/wiki/index.php?title=Skycube
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.
 It was previously designed for fitting into the Y1 modules for controlling
 the modular robots used for research purposes
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LatexCommand cite
key "Gonzalez-Gomez2008"

\end_inset

.
 It is a minimal design with only the necessary components for controlling
 the robot.
 It includes an 8-bit pic16f876a micro-controller, headers for connecting
 the servos, an I2C bus for the sensors, serial connection to the PC, a
 test led and a switch for powering the circuit (figure 
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reference "fig:Electronics-Skycube-board"

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).
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\begin_layout Standard
An electric connection diagram is shown in figure 
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reference "fig:Electronic-diagram"

\end_inset

, where the servos are connected directly to the board.
 The speed is set by means of two PWM signals.
 The two ultrasound sensors in the robot's front are connected thought the
 I2C bus.
 Robot version 1.0 have two ultrasound sensors, but as they are connected
 to the I2C bus, more sensors can be easily added.
 For the power supply four AAA type standard batteries are used.
 The board can be connected to the PC by a serial RS232 connection for downloadi
ng the firmware.
 The PCB has been designed with the open source Kicad tool
\end_layout

\begin_layout Standard
The robot is programed in C language using the open source SDCC cross compiler
 and the binary files are downloaded into the board by means of a serial
 cable.
 Previously a bootloader firmware needs to be burned in the flash memory
 by means of the ICSP connector.
 Loading the firmware this way the students do not need to use any programming
 hardware but just a simple cable.
 Also, the download is done very fast, where it takes only a few seconds
 to complete the whole process.
 
\end_layout

\begin_layout Section
Derived designs from Miniskybot
\end_layout

\begin_layout Standard
In contrast to our previous Skybot robot which remained unmodified for many
 years, the MiniSkybot has inspired the imagination of the students which
 have developed new designs in record time.
 There were two main reason for this motivation, according to the students:
 1) Full access to the Miniskybot 
\begin_inset Quotes eld
\end_inset

source code
\begin_inset Quotes erd
\end_inset

, 2) Being able to turn their thoughts on real physical objects very fast,
 thanks to the 3D printer.
 The former let the students to fully understand a real robot and realize
 that it is not so difficult to design the mechanical parts.
 Instead of starting from the scratch, they just simply start modifying
 the Miniskybot parts.
 The latter is related to the strong feeling of happiness and power that
 the students have when they see their designs become a reality.
 
\end_layout

\begin_layout Standard
In the following sections two new derived design are presented, fully created
 by second year undergraduate engineering students with no special knowledge
 on mechanics.
\end_layout

\begin_layout Subsection
Caterpillator
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wide false
sideways false
status open

\begin_layout Plain Layout
\align center
\begin_inset Graphics
	filename eps/orugator.eps
	scale 70

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
The caterpillator robot
\begin_inset CommandInset label
LatexCommand label
name "fig:The-caterpillar-robot"

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Plain Layout

\end_layout

\end_inset


\end_layout

\begin_layout Standard
The Miniskybot robot uses two drive wheels for moving.
 Two students wonder if it was possible to design a robot with tracks instead
 of wheels.
 Inspired by this chain an pinions design in thingiverse
\begin_inset Foot
status collapsed

\begin_layout Plain Layout
http://www.thingiverse.com/thing:5656
\end_layout

\end_inset

, Olalla Bravo and Daniel Gomez decided to create the first printable track
 for mobile robots.
 After some initial failed tries, they succeed in building a parametric
 track
\begin_inset Foot
status collapsed

\begin_layout Plain Layout
http://www.thingiverse.com/thing:7209
\end_layout

\end_inset

.
 The beauty of this design was not only its functionality but its property
 of being parametric.
 Just changing some parameters, different tracks can be obtained, as well
 as the necessary pinions.
 In addition, 3mm plastic spool was used as pins for the links.
 Therefore no special screws and nuts were necessary.
\end_layout

\begin_layout Standard
The latest version is shown in figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:The-caterpillar-robot"

\end_inset

.
 It is also available in thingiverse
\begin_inset Foot
status collapsed

\begin_layout Plain Layout
http://www.thingiverse.com/thing:8559
\end_layout

\end_inset

, along with some videos showing how it moves.
\end_layout

\begin_layout Subsection
UniTrack and F-Track
\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status open

\begin_layout Plain Layout
\align center
\begin_inset Graphics
	filename eps/unitrack.eps
	scale 64

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
Unitrack (left) and F-track (right) robots
\begin_inset CommandInset label
LatexCommand label
name "fig:Unitrack"

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Plain Layout

\end_layout

\end_inset


\end_layout

\begin_layout Standard
A different approach was taken by Jon Goitia.
 He focused on designing robots with articulated tracks.
 The first design was Unitrack
\begin_inset Foot
status collapsed

\begin_layout Plain Layout
http://www.thingiverse.com/thing:7640
\end_layout

\end_inset

, shown in figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:Unitrack"

\end_inset

 (on the left and in the middle).
 It is an autonomous track driven by a hacked Futaba 3003 servo (the same
 servo used for the Miniskybot).
 It consist of two wheels attached to the servo and five standard o-rings
 used as tracks.
 Another o-ring is used as the transmission system between the servo and
 one wheel.
 Unitrack is also parametric, therefore the wheel's diameter and number
 of o-rings can be easily changed.
 This innovative design was for one month the first most popular thing on
 thingiverse, which is not easy to achieve (currently there are more than
 ten thousand things!).
 
\end_layout

\begin_layout Standard
Once Unitrack was fully functional, the F-track robot was created, shown
 in figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:Unitrack"

\end_inset

 (on the right).
 It consist of four articulated independent Unitracks joined to a body.
 This design is an example on how the creativity emerges from some students
 when they are stimulated.
\end_layout

\begin_layout Section
A new design paradigm: evolutionary robots
\end_layout

\begin_layout Standard
Our new robotic platform combines two important features.
 On one hand it is open hardware, so that anyone can study, modify and distribut
e the robot.
 On the other hand the robot is printable making it very easy for the people
 to materialize it.
 The result is that anyone in the wold with access to Internet and to an
 open-source 3D printer can copy the robot, improve it or create derived
 design.
\end_layout

\begin_layout Standard
These features allow the emergence of a new design paradigm in robotics:
 Evolutionary robots.
 The robots can now be evolved by the community in the same way the open
 source movement creates and maintain in a distributed way new software
 applications, such as the Linux kernel, gnu tools, wikipedia, firefox and
 so forth.
 Now it is possible to bring these ideas into the robotics world.
\end_layout

\begin_layout Standard
In the previous section we have shown the derived robots created by a group
 of local students from the Miniskybot robot.
 It is difficult to imagine and foreseeing the wonderful robots that can
 be developed by thousand of people around the world collaborating together.
 
\end_layout

\begin_layout Standard
With the Miniskybot robot we have planted the seed.
 We have already gotten some indications of the potential of this idea:
 some weeks after the Miniskybot were published on thingiverse, at least
 three derived design were built.
 The first was printed by people from Makerbot at the RoboFest 2011 in Baltimore
, the second at the FUBAR hacklab space in New Jersey.
 They are using Roboduino as electronics.
 The third one was built by CW kreimer
\begin_inset Foot
status collapsed

\begin_layout Plain Layout
http://www.youtube.com/watch?v=2EqvuPXYKf0
\end_layout

\end_inset

 for teaching robotics at the Pittsburgh boy scout high tech camp.
\end_layout

\begin_layout Section
Results
\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status collapsed

\begin_layout Plain Layout
\align center
\begin_inset Graphics
	filename eps/Miniskybot-physical-parts.eps
	scale 59

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
The MiniSkybot robot printed in red ABS
\begin_inset CommandInset label
LatexCommand label
name "fig:The-MiniSkybot-robot"

\end_inset


\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Standard
The Miniskybot robot has been successfully printed on a Makerbot Cupcake
 3D printer in ABS plastic (Acrylonitrile Butadiene Styrene).
 The machine is equipped with the MK5 extruder and a heated build platform.
 It is very affordable with a total cost of 680€.
\end_layout

\begin_layout Standard
All the parts have been printed without raft.
 The software used was Replicator-G 0023 with Skeinforge 35.
 In figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:The-MiniSkybot-robot"

\end_inset

 a red prototype is shown, along with all the parts needed for assembling
 the robot.
 
\end_layout

\begin_layout Standard
The total printing time is 2 hours and 50 minutes and the total robot cost
 is around 57€, as shown in table 
\begin_inset CommandInset ref
LatexCommand ref
reference "tab:Printing-time-cost"

\end_inset

.
 It can be seen that the cost of the chassis (the printable parts) is marginal:
 less than 1€.
 Therefore, the robot cost is only determined by the cost of the electronics,
 motors and sensors.
\end_layout

\begin_layout Standard
\begin_inset Float table
wide false
sideways false
status open

\begin_layout Plain Layout
\align center
\begin_inset Tabular
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Parts
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\end_inset
</cell>
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\begin_inset Text

\begin_layout Plain Layout

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Printable
\end_layout

\end_inset
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\begin_inset Text

\begin_layout Plain Layout

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\end_layout

\end_inset
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\begin_inset Text

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\end_layout

\end_inset
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\begin_inset Text

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\end_layout

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----
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\series bold
Total:
\end_layout

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\series bold
170 min (2h, 50min)
\end_layout

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\series bold
56.6€
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\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
Printing time and cost of the MiniSkybot v1.0 robot
\begin_inset CommandInset label
LatexCommand label
name "tab:Printing-time-cost"

\end_inset


\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Standard
Although this kind of 3D printers are not meant for production but for prototypi
ng, they can be used for building small series of robots for giving courses
 on robotics to small groups.
 Given that every 3h the parts for a new robot are built and if the machine
 is working without interruption, 8 robot chassis per day can be printed.
 In figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:Miniskybot-group"

\end_inset

 a group of six Miniskybots is shown, printed in different colors.
\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status collapsed

\begin_layout Plain Layout
\align center
\begin_inset Graphics
	filename eps/Miniskybot-group.eps
	scale 60

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
A group of six MiniSkybot robots (v1.0) in different colors
\begin_inset CommandInset label
LatexCommand label
name "fig:Miniskybot-group"

\end_inset


\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Section
Conclusion and future work
\end_layout

\begin_layout Standard
Using the latest open source 3D-printers a new printable robotic platform
 has been designed, built and tested.
 Our results confirm the viability of these new printable robots.
 They offer new important features for educational purposes.
 First, they are very flexible where the students can design new custom
 pieces easily which are printed and tested very fast.
 Therefore the robot can be mechanically evolved during the courses.
 Second, the robot can be thoroughly studied, modified, copied and distributed
 by anyone.
 This way the robot can evolute not only in our university but also around
 the world.
 This feature is enhanced by the fact that the mechanical parts are Openscad
 ASCII scripts, like any other software.
 Consequently, they behave like open source software and can be distributed
 and shared in a similar way.
 Finally, the total cost is very low, depending almost exclusively on the
 servos, electronics and sensors.
 The Miniskybot v1.0 costs 57€ and the printing time is around 3h, which
 means that eight robot chassis can be printed per day.
\end_layout

\begin_layout Standard
As a future work we are planning to continue evolving the robot in collaboration
 with our students, designing new parts for adding more sensors as well
 as creating new derived robots.
 Currently we are working on a new electronic board, with the same size
 than the Skycube but compatible with the Arduino software that is becoming
 more and more popular.
 In addition, we are developing a new idea on how to design mechanical parts
 using object oriented programing.
 We have called it as 
\emph on
object oriented mechanics language
\emph default
 (OOML).
 
\end_layout

\begin_layout Section*
Acknowledgements
\end_layout

\begin_layout Standard
We would like to thank Prof.
 Luis Moreno, head of the department, for supporting this educational initiative.
 Also we would like to thank all the students who have been involved in
 building our 3D printer MADRE.
 Special thanks to: Olalla Bravo, Jon Goitia and Daniel Gomez for their
 great contributions to the Miniskybot Robot.
\end_layout

\begin_layout Standard
\begin_inset CommandInset bibtex
LatexCommand bibtex
bibfiles "bibtex"
options "plain"

\end_inset


\end_layout

\end_body
\end_document
