My name is Muhammad Abdullah, and I'm from the Hasso Plattner
Institute. This layout is produced by Roadkill, a software
tool that lays out laser-cut 3D models, so that matching parts
are adjacent. This allows Roadkill layouts to be assembled
2.4 times faster than traditional layouts.
If we build the chair model using the traditional laser
cutting workflow, it would take a long time to model the
individual plates, then cutting is really fast and then assembly
would take some time. But with software like flatfab and kyub
modeling for laser cutting has also gotten fast. And what we
see now is that the step of assembling which was previously
negligible becomes the bottleneck. To further speed up
the process, we need to increase the assembly speed. There are
two steps in the assembly process searching for the right
parts, and then joining them. Here's the typical method to
help users find the correct plates. Lookup numbers are
engraved on pairs of edges, and the user has to perform a
quadratic search to find the corresponding numbers. So what
we saw here is that plate search scales quadratically. As the
total number of plates increases, it will take
increasing amounts of time to find the right plate. But once
the user finds the right pair of plates joining them is a linear
process. So to really speed up assembly, our objective is to
minimize plate search. Roadkill achieves this by creating
layouts based on eight design elements. Roadkill creates a
preview thumbnail to indicate which part the user is
assembling, in this case, the bottom of the chair. Roadkill
indicates starting plates with exposed finger joints. Plates
can be inserted from above into cavity shaped jigs. The user
continues by inserting into the immediately adjacent plate
and then follows the arrow. Now we see that the next plate has
no further neighbors.
So the user continues with another plate that has exposed
finger joints. This sub-assembly is now complete. And the user
inserts it into position indicated by the matching label.
And now the user follows the assembly order and continues
with sub-assembly two.
In our users study, participants assembled this model in around
10 minutes, and were on average 2.4 times faster than assembling
a traditional layout with engraved numbers. Roadkill
achieves this by maximizing adjacency while minimizing
numbers. While Roadkill eliminates the need to search
for individual plates, it introduces the need to search
for sub-assemblies. The reason Roadkill works is because it
replaces the search for many parts with the search for very
few sub-assemblies. The Roadkill algorithm thinks of assembly as
the reverse of disassembly. Roadkill starts by disassembling
the plate that has the highest number of connections in the
model. Roadkill then removes the plates that were connected to
the previous plate while making sure that all of them can be
removed independently of each other. Roadkill repeats this
step till all plates are part of the disassembly tree. Next
Roadkill makes sure that all branches of the tree can be
assembled independently. In this case, the brown plate is
blocking the two branches Roadkill resolves this by making
the branches sub-assemblies of the blocking plate. This makes
sure that that the user will assemble them and connect them
to the blocking plate before the next step. Next, Roadkill
creates the 2D layout by placing connecting plates adjacent to
each other. Roadkill then resolves overlaps by either
linking through arrows or creating further sub-assemblies.
For more details, please look at our paper. Finally, we
integrated Roadkill into the export pipeline of kyub, a 3D
modeling software for laser cutting.
To validate our design, we conducted a user study. We
recruited 12 participants, each participant assembled both the
Roadkill and the traditional layouts.
We found that on average users assembled Roadkill layouts 2.4
times faster than traditional layouts. To understand how this
performance benefit came about, we downloaded the top 60 models
from the kyub repository and ran the Roadkill algorithm. The test
models were made from one to 100 plates, which roadkill organized
into one to 25 sub-assemblies. We found that the number of
sub-assemblies roughly scaled linearly with the number of
plates and on average roadkill grouped five plates into one
sub-assembly. Roadkill replaces the time required to search for
plates with visual search for sub-assemblies. Given that plate
search has quadratic complexity, this reduces the user effort by
a factor of five squared or 25 times. So in conclusion,
Roadkill minimises plate search, speeding up the assembly process
and in turn speeding up the entire laser cutting workflow.
Zooming out, the objective of Roadkill is to accelerate rapid
prototyping by another step. Before the introduction of
fabrication technology, one might have outsourced the
creation of a chair model like this one to a craftsman. The
introduction of 3D printing and laser cutting allow doing this
in-house. My objective is to speed-up prototyping to the
point where it can be performed within the timeframe of a
meeting. I would like to thank my collaborators for the time
and effort they spent on this project. And I look forward to
discussing this work in the Q&A and at the demonstration.