IEEE Robotics & Automation Magazine - September 2023 - 143

parts, should be aware of the level of complexity and cost that
would discourage potential users. The OSL project [72] has
several machined parts due to functional requirements of the
hardware, but the developers provide all the necessary files to
outsource the machining fabrication, such as drawings, part
quotes, and even sample e-mails to send to manufacturers.
Thoughtfully created documentation packages are thus
critical to accompany the chosen fabrication technologies.
The practices typified in the aforementioned
ORH projects significantly lower
the barrier of entry for novice users, and
they should be referenced by prospective
developers intending to create ORH documentation
that improves the reproducibility
of their hardware.
When releasing an open source project, developers need
to decide which type of license should be applied to their
original design files as well as the accompanying software
and documentation. Different parts of the project can have
distinct
licenses applied to them; for example, the BOM
"
DISSEMINATION
The key characteristic of an ORH project
is that the prepared design files and documentation
packet are disseminated in an
open manner for potential users to find
and access them. For this purpose, many
ORH projects host project repositories on
platforms like GitHub or the Open Science
Framework, which allows public dissemination
of the project, along with an
ability to version-control files for any necessary
updates. More hardware-focused
platforms like Thingiverse and Hackaday
are popular with maker communities but
have also been used for distributing new research hardware
[29]. Wherever the developer decides to host the project files,
they should track revisions and updates to convey changes in
the latest version to users. In fact, the developer should try to
ensure proper maintenance of the ORH project over its active
duration of time by releasing patches and fixing persistent
issues that users may be encountering. To publicize an ORH,
developers can utilize academic journals on open source
hardware such as HardwareX [18], The Journal of Open Engineering
[19], and The Journal of Open Hardware [20], which
can serve as valuable tools for broadcasting one's work within
the research community. ORH projects such as the Eva
humanoid face [67], HRI hand [32], and SRoCS [108] were all
published through these open hardware journals. Other dissemination
strategies for advertising ORH specifically to reach
academic and research communities can also be used, such as
sending e-mails to popular robotics mailing lists, publishing
papers in field-specific journals, and participating in conferences,
workshops, and tutorials. Developers should also contact
directories like the ORH initiative [16], which compile
ORH projects. OSHWA [17] maintains a similar directory of
open source hardware projects but requires developers to
undergo a certification process beforehand. Certifying the
project with OSHWA ensures that it complies with the requirements
set for their open source hardware standard, further adding
credibility to an ORH with the OSHWA certification logo.
EXPLICIT MENTION OF
THE LICENSE ON THE
PROJECT'S REPOSITORY
for HRI hand [32] and SRoCS [108] note the open source
license next to each part in the table. The applied license
stipulates whether users need to attribute the original work
(attribution), whether they can modify or
adapt the work (derivative), whether they
can distribute the adapted work under a
different license (permissive, as opposed
to copyleft or viral), and whether
they
AND DOCUMENTATION
CONVEYS TO PROSPECTIVE
USERS HOW THEY
CAN IMPLEMENT AND
USE THE WORK AND
SHOULD THUS BE CAREFULLY
CONSIDERED
BY THE DEVELOPER.
„
can use the original open source work
for a monetary advantage (commercialization).
There are several open source
licenses with different characteristics that
developers can choose from to apply to
their designs [144]. Some of the most commonly
applied licenses are from Creative
Commons [145], which has several licenses
with different provisions on attribution, use
of derivatives, copyleft, and commercial
use. A comprehensive comparison of the
Creative Commons licenses can be found
in [145] and [146]. Popular open source
software licenses like GNU General Public
License (GPL) [148], MIT license [149],
and BSD license [150] are often applied to
open source hardware, primarily as a way
to waive liability and warranty. They differ from each other
in one major way: the GPL is copyleft and requires any future
modifications to be released under the same license, whereas
the MIT and BSD licenses are far more permissive and do not
have many licensee requirements. The Apache license [151] is
similar to the MIT one but has explicit provisions for patents
on derived projects. Although all of these licenses are written
with software projects in mind, some licenses have also been
written to specifically protect hardware. Both Tucson Amateur
Packet Radio [152] and Centre Européen de Recherches
Nucléaires (CERN) [153] have copyleft licenses for hardware
similar to the GPL (CERN even has different variants), and
the Solderpad license [154] is a permissive hardware license
derived from Apache.
Clear and explicit mention of the license on the project's
repository and documentation conveys to prospective users
how they can implement and use the work and should thus be
carefully considered by the developer. Some repositories like
GitHub even provide the option to select a license when creating
a new project. In general, developers should include the license
information in every file or at least in the README [17]. Similar
licensing principles also apply to nonhardware files of the
project, such as any accompanying code and even supporting
documentation packages, and developers can choose to apply
different licenses to each of these elements. Overall, it is strongly
encouraged that developers pick an open source license with
SEPTEMBER 2023 IEEE ROBOTICS & AUTOMATION MAGAZINE
143
IEEE Robotics & Automation Magazine - September 2023

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