IEEE Robotics & Automation Magazine - September 2023 - 138

of use and adaptability to different applications also make them
suitable for educational settings in addition to robotics research.
COMPONENT MODULES AND TOOLKITS
In some of the newest domains of robotics, building one's
own hardware might be the only option available to a
researcher because no similar off-the-shelf products are commercially
available for purchase. For such domains, ORH can
provide valuable tools for users to iterate and test new robot
structures instead of developing hardware from scratch.
Soft robotics is one of these fields in robotics that has grown
rapidly over the last few years, and researchers have been open
sourcing their hardware to allow other researchers to create
their own soft robotic devices. One such core component in
a soft robotic mechanism is the actuator, and PneuFlex [99]
was one of the earliest soft actuators that developers released
publicly, along with CAD models, 3D printing files, and a
detailed fabrication guide [100]. The actuator was later used
in the compliant Robotics and Biology Lab hands [101]. A lot
of soft robot component technologies have also been compiled
on open platforms that host tools and guides to test new soft
mechanisms quickly, further accelerating the development
of novel applications for soft robots. The Soft Robotics Toolkit
[102] offers instructions and guides on several common
components of soft robots to enable speedier development of
soft devices, as shown in Figure 6(a). The toolkit was developed
with contributions from a number of research groups and
has even been used to support educators in hands-on robotics
courses. Another such platform supporting the fast development
of articulated soft robots is the Natural Machine Motion
Initiative (NMMI) [103]. The NMMI is composed of hardware
modules that users can put together to create complex
and novel robotic structures. Both of these platforms are continually
updated with the latest developments in soft robotics
and grow with more contributions from developers and other
research groups.
The practice of open sourcing the tools and components
required to build a robot hardware has gained traction not only
in soft robotics but has also seen prevalence in other evolving
domains of robotics, such as modular and swarm robotics. The
Molecubes [104] platform was openly distributed to promote
new developments in reconfigurable and modular robotics. The
project underwent multiple iterations and invited modifications
and enhancements from the user community [105]. Swarm
robot hardware has similarly been made publicly available in
projects like the centimeter- or millimeter-sized Jasmine [106]
and Kilobot [107] robots. The Swarm Robotics Construction
System (SRoCS) [108] is another open source swarm robot
platform that was released for studying multirobot coordination,
specifically in construction tasks [see Figure 6(c)].
Finally, hardware that spans multiple areas in robotics can
also significantly benefit from open source technologies. Electronics
platforms like Arduino [109] and Raspberry Pi [110],
common components such as tactile-sensing arrays like TakkTile
[111] and Digit [112], and soft tactile grippers in Punyo
[113] are constituent in robot hardware for many different
areas [see Figure 6(d)]. Electronics hardware, in particular,
has a long, sustained history of open source communities and
repositories like Open Electronics [114], Kitspace [115], Hackaday
[116] and many more and have been surveyed in fieldspecific
academic reviews [117] and special issues of journals
[118]. Although the wide breadth of open source electronic
platforms and components is beyond the scope of this review,
their widespread adoption and thriving community can inspire
best practices and methods in disseminating ORH projects.
Moreover, the success of these repositories also confirms that
ORH projects that release component modules and technologies
can notably expedite prototyping and testing of new robot
structures, which can be especially vital for identifying novel
applications in fast-moving domains of robotics.
MISCELLANEOUS
CNC ROBOTS
Open source hardware has been pervasive in many other
robotics domains in addition to the ones outlined previously.
CNC robots are so called for their similarity to CNC machines.
These simple three-axis robots with orthogonal actuation DoF
are potent tools for automating a variety of 2D tasks. They can
be equipped with any suitable end effector for the task. For
instance, the tiny Piccolo CNC bot [119] applies this architecture
as a drawing robot with a distal pen attachment [see
Figure 7(a)]. Piccolo is often used in educational workshops to
give users hands-on experience in building and programming
(a)
(b)
(c)
(d)
FIGURE 5. Mobile robot ORH projects. (a) The e-puck two-wheeled robot [88]. (b) NASA's JPL Open Source Rover [95].
(c) The TurtleBot3 Waffle platform [96]. (d) The MuSHR miniracecar [98].
13 IEEE ROBOTICS & AUTOMATION MAGAZINE SEPTEMBER 2023
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IEEE Robotics & Automation Magazine - September 2023

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