IEEE Robotics & Automation Magazine - September 2023 - 142

services (like Protolabs, Shapeways, Fictiv, Xometry, and many
more) to recommend to users as an alternative to fabricating
parts on their own.
DOCUMENTATION AND INSTRUCTION
The design and part files on their own do not suffice for easy
reproduction of the ORH. Thorough documentation, along
with visual guides for fabrication and assembly, are essential
to ensure accessibility for users, with a range of expertise in
the processes required to build and operate the robot hardware.
The ORH projects that have been widely adopted have
clear and detailed instruction sets that indicate each step of
the manufacturing and assembly process. The documentation
package of the OpenHand project illustrates some of
these good documenting techniques. A list of all the fabricated
and purchased components in the form of a BOM is
listed at the top of each section of the assembly guides, as
shown in Figure 8 [27]. The instructions for building OpenBionics
hands [34] is also exemplary of some best practices
[136]. For instance, each section has an accompanying list of
materials and annotated images of the parts for users to
quickly reference assembly steps and the requisite components
at hand. The BOM for the Piccolo bot [119] and Punyo
gripper [113] help link where each component can be
sourced, or alternately, specify the fabrication process if it is
a custom component [137], [138]. However, a user might
have acquired all the requisite components and realize midway
through the build process that he or she does not have a
particular tool. Projects like Poppy [54], WoodenHaptics
[122], and ExoMy [94] avoid such a situation by listing and
visually showing all the tools and equipment required to
carry out the assembly [139], [140].
Once all the components and tools are obtained by the user,
the documentation should then direct he or she through each
step of the assembly process. Visual guides are very effective
in conveying the process, in addition to textual instructions.
The InMoov project uses images of the partially assembled
components after each step for users to compare their output
with that in the guide [62]. A number of other projects, including
the Yale OpenHand [23], Punyo gripper [113], OSL [72],
Poppy [54], and more, have videos of an individual assembling
the components so that users can conveniently follow along,
e.g., [141] shows videos for fabricating an actuator body in
the Soft Robotics Toolkit [102]. Such assembly videos, even
more so than still photos, can unambiguously communicate
the minute details of the process, compared to just reading the
text; for instance, the user may pick up on how much clamping
force to apply through the individual's actions in a video. The
HOPPY project [71] and CASTOR robots build instructions
[58] instead of using video animations of the various CAD
model's exploded views, which also effectively articulate how
parts connect with one another.
Inconsistencies at the user's end depending on the type of
fabrication equipment, tools used for assembly, or alternative
off-the-shelf components sourced are likely to occur and need
to be addressed when the developer prepares the documentation
packet for the ORH. The previous section detailed how
the design of the hardware can account for such variations.
The documentation and instruction guides can also aid the
user's ability to identify discrepancies by highlighting which
design features the user should check before proceeding with
the assembly, and then to compare with the developer's setup
for differences (for example, make of the 3D printer or model
number of the actuator). The Yale OpenHand instruction documents
have annotated images and schematics to call the user's
attention to evaluate specific features on his or her molded and
3D-printed parts [27]. This helps debug any issues in fabrication
early on in the assembly so that users can reproduce wellfunctioning
robot hands.
Developers are also strongly encouraged to provide as
FIGURE 8. The BOM visually shown and annotated images of the
exploded assembly view in the documentation of Yale OpenHand's
Stewart hand [27].
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much information to users as possible about the appropriateness
of various fabrication technologies, including specific
machine models used for the project's components. For
example, the ExoMy rover project lists all the 3D printers that
its rover has been successfully manufactured with [142], and
users are encouraged to notify the developers if they printed
the rover with a different 3D printer so that the developers
can update this list. For more multistep fabrication processes,
such as those for the Punyo gripper [113], the documentation
thoroughly guides the user through the process steps and,
most importantly, includes safety precautions and fabrication
errors to look out for along the way [143]. The projects that
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