Emmanuel Courtoux, Caroline Appert & Olivier Chapuis
Université Paris-Saclay, CNRS, Inria, LISN, Orsay, France
email: first.last@lisn.upsaclay.fr

Tangibles can enrich interaction with digital surfaces. Among others, they support eyes-free control or enhance awareness of others' actions. Tangibles have been studied in combination with horizontal surfaces such as tabletops, but not with vertical surfaces such as wall displays. The obvious obstacle is gravity as tangibles cannot be laid on the surface without falling. We present WallTokens, which are easy-to-fabricate tangibles to interact with a vertical surface. A WallToken is a plastic token whose footprint is recognized on a tactile surface. It is equipped with a push-handle that controls a suction cup. This makes it easy for users to switch between sliding or attaching it to the wall. This project is a step towards enabling tangible interaction in a wall display context.

Supplemental Material for:

Emmanuel Courtoux, Caroline Appert, and Olivier Chapuis. 2021. WallTokens: Surface Tangibles for Vertical Displays. In CHI Conference on Human Factors in Computing Systems (CHI ’21), May 8–13, 2021, Yokohama, Japan. ACM, 13 pages. https://doi.org/10.1145/3411764.3445404


A WallToken is made of separate parts that are then assembled together. The main structure consists of four 3D printed parts (push handle, central rod, grip, and base). The central rod is then augmented with a spring and a suction cup at assembly time.

STL files for fabricating individual 3D printed parts are available for download below. They were created using the Fusion 360 software, and tested with Ultimaker 3 or 3X 3D printers using PLA or Tough PLA filament and a 0.4mm printcore.

The suction cup is a standard 20-mm diameter one, which generates a suction force of approximately 130 newtons.

The spring has 10 coils and is made of steel (AISI 304L stainless steel). It is 25mm-long when free, and 7mm-long when compressed. Inner diameter is 0.7mms, and outer diameter is 0.9mms.

The schema below details how to assemble the different parts into a WallToken.

Development Framework

Source code (C#) of our framework that transforms TUIO events into high-level token events: WallTokens.zip.
Read the paper and the README for more details.

Java TUIO WallToken client library (to be used with the above package): TUIOWT.zip.

Experimental Data