IEEE Robotics & Automation Magazine - March 2017 - 80

and actuators, with the exception of the internal lithiumpolymer battery recharging logic, which uses a specific chip
for safety reasons.
For our specific design, we needed custom-made mechanical parts. To reduce the price, all mechanical parts are injected plastic, for a total production cost of fewer than US$4.
Our choice of electronic components implies different
degrees of automatization in the production. Full assembly is
required for the robots to be certified for use by children. As
full automatization requires investments that are beyond the
possibilities of this project, the current production combines
automatization for most components of the printed circuit
board (PCB) and manual operations for the final assembly
and is performed in China due to the low cost of manual
work. We have thus far produced more than 16,000 robots in
batches of 2,000 units, with a cost per robot of US$39. The
strict quality control, the management of the production, the
after-sales support, part of the development costs of the software, and the margins for distributors result in a final selling
price of US$130.
Multiage and Gender-Neutral Feature Set
Several design choices, such as the variety of sensors, the multiple ways of interacting with the robot, the neutral hull
design, the various programming environments, and the possible customization with accessories, contribute to make Thymio accessible to girls and boys of different age groups from
kindergarten to university [17]. These design choices were
made and implemented thanks to an important contribution
by industrial designers of the University of Art and Design of
Lausanne (http://www.ecal.ch). The white neutral hull is a key
element in this set of choices, and it is the opposite of the
technical look chosen for the LEGO robots. The look of Edison, designed after Thymio, is also technical due to its transparent cover. These latter two robots implicitly target a group
of people interested in technical systems, mostly males, while
Thymio is open to both genders and a larger target audience.
Promoting Creativity
The white neutral hull is also meant to represent a blank
page that can be decorated and drawn upon, and the hull's
shape allows easy integration into a larger structure. The
square format of the hull facilitates the use of the robot as a
base for the user's own constructions. To that end, Thymio
is compatible with LEGO bricks, both on the body and on
the wheels. This last connection can be used to actuate elements elsewhere in the added structure [Figure 2(e)] or to
lift the robot's own weight (Figure 2(f)]. Therefore, we chose
more powerful motors than strictly necessary to move the
robot around. Paper can also be used to change the body
shape or add body movements, as illustrated in Figure 2(a)
by the orca opening and closing its mouth while moving
forward or by the bat [Figure 2(b)] moving its wings. But
paper and cardboard can also radically change the locomotion principle, as illustrated in the Figure 2(c) by the zombie, where the wheels of the robot activate the legs. The
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IEEE ROBOTICS & AUTOMATION MAGAZINE

March 2017

paper structure can also be used to interact with the sensors,
as illustrated in Figure 2(d) by the bear, which extends its
paw in front of the sensors to drive its iceberg (the robot).
The same fixation points can be used to attach three-dimensional (3-D) printed customized parts, as illustrated by the
winder shown in the Figure 2(g) and (h). Moreover, one
can use paper to create environments, either flat with
patterns that can be used in association with the ground
sensors [Figure 2(i)] or 3-D objects, such as the trees beside
the zombie in Figure 2(c). Finally, it is also possible to link
several Thymio by software, allowing the coordination of
complex multi-Thymio robotic structures.
Facilitating Learning
When designing Thymio, we took care to provide many
incentives for the users to learn new things throughout their
direct interaction with the robot. This translates into specific
hardware and software choices.
At the hardware level, we render visible the activity of
the various robot components by adding an LED next to
each of them, for a total of 39 LEDs. These LEDs locally
color the hull and allow the user to see immediately where
and when the robot perceives a change in its environment:
proximity of objects, changes in the ground color, temperature, sound, or accelerations. Some LEDs display data
exchanges from the infrared remote control receiver or
with the micro-secure digital card. The capacitive buttons
give both visual and acoustic feedback. The link between a
sensor and its feedback can be turned off when programming the robot so that the LEDs and loudspeaker can be
used for other purposes.
At the software level, we provide a set of programming
environments (see the "Programming Environment" section)
that enable beginners to discover programming progressively.
First, we teach them the basic rules of programming using a
purely visual interface, then they discover the construction of
syntax trees by assembling graphical blocks, and finally, we
provide a full text-based coding environment with advanced
debugging tools, such as real-time inspection of the variables
of the robot and plotting features, providing a visual way to
understand time-related concepts.
Fast Access to Robotics Behaviors
Many existing robots need to be built or configured before
showing any operational behavior. For instance, the Edison
robot needs to read a bar code, and the mBot needs to be
assembled. This can be a barrier for school activities, one we
wanted to avoid; rather, we wanted a robot able to show interesting behaviors right out of the box. Therefore, Thymio has
six different basic behaviors, stored in flash permanently,
accessible as soon as the robot is started. These basic behaviors allow people starting Thymio to immediately interact
with it, while illustrating the many possibilities of the robot.
The user can begin creating constructions on top of these
basic behaviors without the need for programming, such as in
the paper creations shown in Figure 2(a)-(d).

http://www.ecal.ch

Table of Contents for the Digital Edition of IEEE Robotics & Automation Magazine - March 2017