IEEE Robotics & Automation Magazine - September 2023 - 140

ORH through the stages of design, documentation, and dissemination,
which will help an ORH project become widely
adopted by many users for a long period of time. We also discuss
how developers can determine fabrication methods most
suitable for their ORH. And along the way, we refer to some
useful strategies from ORH projects previously surveyed that
new developers can implement themselves.
DESIGN AND FABRICATION
DESIGN AND PART FILES
An ORH project vitally shares the design files for the hardware
so that users can manufacture components as well as
modify and share their adaptations. To this end, the developer
should publish all part documents, including 3D CAD files
(for any machined, 3D-printed, or molded parts), 2D fabrication
files (for laser cutting, waterjet cutting, or similar process),
and any auxiliary files required for fabricating
components (for example, machine drawings or circuit board
layouts). If any of the part files have special software requirements,
the developer should highlight those in the shared
documentation. As such, open source projects should rely on
freely available software so that the cost of meeting the software
requirements do not prohibit users from accessing the
released design and part files. That said, the majority of ORH
are developed in proprietary CAD systems like SolidWorks
or Autodesk Fusion, usually due to the lack of free, advanced
3D modeling software, which are suitable for the design complexity
of some mechanical components. Nonetheless, projects
like Metabot [80], MuSHR [98], Veter [92], and
Miniskybot [90] use free and open source 3D modeling tools
like OpenSCAD, FreeCAD, or Blender, and others like
FarmBot [120] use free versions of design platforms like
Onshape. Even if editable design files are made with these
freely available modeling tools, they might still remain out of
reach of many users who do not have access to expensive
computers capable of opening and modifying large projects
with lots of components and subassemblies. In contrast, programs
like Onshape and Autodesk Fusion have the benefit of
being cloud based, which eliminates the requirement of having
sufficient local computing power to run CAD software,
and allows users to flexibly work on design files from any
computer with a good Internet connection.
It is worth noting that a simple replication of an ORH
may not require editable CAD files. For instance, if a robot
requires only 3D-printed components, STL files may be sufficient.
However, editable 3D CAD models of the components
allow users to adapt designs and make changes as necessary,
which can then be shared with the rest of the user community
or even released as another ORH. Editable CAD files could
be in formats directly saved by programs (like .sldprt from
SolidWorks). But most of the major CAD programs are not
able to easily import file formats native to other programs. So,
designs can be made even more accessible by exporting files
to neutral-interchange formats like .step or .iges because
of their cross-platform compatibility. The .step format is regularly
updated to include more solid model data (such as geometry,
configurations, colors, layers, geometric dimensioning
and tolerancing, and more) and is thus preferred over the older
.iges format, which retains surface-model data only. The EasyHand
[28] project is an example of ORH redistribution after
modification of the Yale OpenHand project [23] because the
3D models were made available for OpenHand. The sharing of
files in modifiable formats also applies to 2D part files, such
as laser or vinyl cutting files as well as electronics components
of the hardware, such as schematics for circuit board layouts.
To encourage adaptations of the design and contributions
from users, the features in part files should be added such that
they clearly convey purpose and function of the design choices.
Breaking the top-level intricate assembly down into simple,
understandable subassemblies can further help improve the
ease of parsing through the files. Both the ESA's ExoMy [94]
and NASA's JPL Open Source Rover [95] have an involved,
top-level assembly with several off-the-shelf components and
3D-printed parts. The ExoMy project details a part-naming
convention for its mechanical design files, along with a folder
structure guide to navigate the assemblies and 3D-printed
parts. The Open Source Rover provides a similar folder structure
guide but also outlines a subsystem road map to provide
users with a high-level view of the subassemblies, and at which
point along the fabrication and assembly process the user is at
any time [95].
(a)
(b)
(c)
(d)
FIGURE 7. Miscellaneous ORH projects. (a) The Piccolo CNC bot [119], (b) FarmBot CNC robot [120], (c) HapKit haptics platform [121],
and (c) robotic gondola for a lighter-than-air (LTA) airship [129].
14 IEEE ROBOTICS & AUTOMATION MAGAZINE SEPTEMBER 2023

IEEE Robotics & Automation Magazine - September 2023

Table of Contents for the Digital Edition of IEEE Robotics & Automation Magazine - September 2023