We present STRAIDE: A research platform for shape-changing spatial displays based on actuated
strings.
My name is Severin Engert and this is joint work together with Konstantin Klamka, Andreas
Peetz, and Raimund Dachselt.
We are all from the Interactive Media Lab Dresden.
A lot of HCI research is looking for novel approaches that go beyond graphical user interfaces
with a focus on other qualities like appearance, calmness, or tangibility.
For our work, tangible and shape-changing interfaces are particularly promising as they
give physical access to digital data through direct manipulation.
However, these systems are often complex and monolithic.
Therefore, we see great potential in modular approaches and toolkits, which simplify prototyping
and exploration.
On the other hand, we are inspired by the flexibility and appearance of string-based
installations.
But we would like to bring them from stages and other large-scale applications to everyday
spaces.
This would render situated visualizations with direct interaction possible.
With these inspirations in mind, we developed STRAIDE, a string-actuated Interactive Display
Environment.
STRAIDE allows to prototype and evaluate spatial displays with string-actuation.
We developed modular hardware made from readily available components and added functional
elements to create interactive physical user interfaces.
To further ease the application development, we additionally provide a set of easy-to-use
software tools.
In detail, our main contributions are: A design rationale for string-actuated spatial
displays in everyday spaces A comprehensive research platform with modular
hardware and tailored firm- and software We demonstrate the usefulness of the toolkit
in different real-world use-cases And in the paper, we also evaluate insights
from our iterative development and discuss feedback from application developers
As highlighted in the beginning, our work relates to research fields like data physicalizations
and physical user interfaces.
First of all, we looked at shape-changing interfaces and 2.5D pin arrays.
These are often complex prototypes with hundreds of physical bars as for instance in the EMERGE
system.
For us particularly interesting were also modular approaches like shapecanvas with shapeclips.
As our intended visualizations are quite similar, we further studied mid-air interfaces with
for instance magnetic levitation as showcased by ZeroN.
However, we wanted to rather employ a much simpler string-based actuation as demonstrated
by artistic installations for stages or showrooms, here for instance Breaking Wave or Kinetic
Lights.
For STRAIDE, we aimed to combine the advantages of these approaches: we wanted to create a
real user interface with direct interaction but we would also like to achieve the magical
appearance of mid-air visualizations while making use of large strokes with fine granularity
To achieve this, we investigated the design parameters of such a string-based system which
affect its configuration, appearance, or functionality.
To create mid-air visualizations, we first thought about different elements.
These range from passive shapes of different materials to elements with embedded electronics
or complex internal structures.
Next, we wanted to have modular actuators that can be arranged in different layouts
or wherever they are needed for situated use cases.
These two combined could enable physical visualizations.
We focused on casual visualizations with only a few elements, and ways to combine individual
elements into symbols and other expressive visualizations.
To create an interactive user interface, we wanted to add interaction to our system.
Here, our main focus is on direct interaction with touch or drag but we also considered
combinations with smart devices.
Based on these design considerations, we iteratively designed the physical components of our toolkit.
We aimed for a modular structure to facilitate the exploration of situated use cases with
different physical setups.
Additionally, we kept fabrication as simple as possible so that researchers can easily
rebuild our toolkit.
We began testing different actuators and went with stepper motors due to their fine-granular
actuation.
During initial tests, we studied their properties to infer precise actuation control for our
tailored firmware later on.
After committing to NEMA14 steppers, we iteratively developed space-efficient mounts.
They are made from laser-cut acrylic, containing the motors, a limit switch, and a roller mechanism
which uses a braided string to lift the attached element.
As we wanted to achieve dense arrangements, we stacked 4 actuators in a motor tower to
create these self-contained units.
You only have to add power and Ethernet and then you can actuate 4 elements individually.
To prove their versatility in different scenarios, we applied these actuation units to 3 different
physical setups.
We have tested: 1 tower in a home environment, then 4 towers on top of a whiteboard and 16
towers in a dense matrix arrangement with overall 64 actuated elements.
To support diverse visualizations, we fabricated and tested a variety of elements.
These range from passive geometries to shape-changing, illuminated, or even interactive objects.
Now, we can combine actuators and elements into a specific spatial display.
However, creating meaningful visualizations in custom applications remains challenging.
To simplify control over many connected actuation units, we added a central NodeJS server which
handles the hardware control.
In combination with our STRAIDE libraries, custom applications can easily operate the
physical interface using WebSocket communication.
For remote development in desktop environments, we developed a platform emulator.
It replicates the hardware and its interface and can be used for application development
on regular screens or even stereoscopic displays.
Additionally, we contribute augmented reality previews.User can use AR glasses to view an
envisioned device or application in its intended environment which helps to judge appearance
and ambiance.
Finally, we thought about how to simplify the ideation process and how to involve users
without programming expertise.
Therefore, we developed our visual designer.
It is a web-based tool for sketching ideas on two canvases with a live preview directly
on the device.
All these software components can be interchanged due to the versatility of the WebSocket communication.
Overall, this simplifies the challenging ideation, design, and development of novel applications
for such a 2.5D shape-changing interface.
To show the feasibility of our hardware and software toolkit, we developed several real-world
applications using the previously presented instances.
In our single setup: an individual element is used to show ambient information.
Here, the blue drop conveys the water level of this plant.
Here is another example using our linear setup: the physical line augments the hand-drawn
sketches on a white-board and with direct interaction, the user can adjust the dynamic
graph.
This weather application shows different conditions like sunny or rainy weather but as ambient
visualizations.
These matrix applications were implemented by a team of students.
After a one-semester-long practical course, they evaluated our software tools and details
on their feedback can be found in our paper.
To conclude: Our STRAIDE research platform enables rapid prototyping of shape-changing
spatial displays.
Therefore, we provide modular hardware and versatile software tools which we evaluated
in several real-world scenarios.
With this, we hope to simplify the exploration of situated physical visualizations in the
future.
Want to further work on and extend this toolkit and would love to test it with practitioners.
Therefore, we published all development resources on our project page.
Further details can also be found in our full paper.
Thank you for your attention.