Hi, this is Rong-Hao from TU Eindhoven. I'm presenting NFCSense, a data-defined
rich-ID motion-sensing technique We realized fluent, hot-swappable
tangible interaction using a single commodity NFC tag reader.
By leveraging physical constraints, the system supports various hands-off,
multi-tag inputs and can be used as a wearable.
First of all, NFC systems are passive tagging systems that support non-line-of-sight sensing.
They have been embedded in many devices, but they also have been limited to a discrete,
hands-on interaction style, using one tag at a time,
because they can not solve the collisions of multiple tags, efficiently.
Previous works make NFC tags more interactive
by modifying the tag circuitry, using multiple tags,
or using sensor fusion, but these systems make the deployment more complex.
They also focused on sensing the static states like the location and orientation.
On the other hand, we focused on sensing the transient states
like the speed and frequency of a motion, and require only a single commodity reader
and unmodified tag. It’s fairly easy to deploy.
An unmodified commodity reader can recognize a tag at above 300 reads per second,
so it can reliably resolve the frequency of a rotation.
Ideally, linear motions can be derived from the path length
and time duration of a tag activation as well.
Unfortunately, the tag activation behavior is hard to predict,
because it depends on the tag and reader's location, orientation, and antenna designs.
Therefore, we directly observed the tag activation maps using a 3D printer regarding
the tag-to-reader distance, tag-to-reader angle, tag-to-tag distance, with various types of tags.
and then, we define a set of guidelines for designing the physical form of tagged tokens,
physical constraints, algorithms and a lookup table of motion speed with the data.
In the following 100 seconds, we showcase the hot-swappable interactivity in one take.
The black spinner attached 1 tag allows the system to resolve its frequency of spinning.
The white spinner attached 3 tags allows the system
to resolve the spinning frequency and direction based on tag presence order.
Now, we put a swing on the reader.
The system resolves the motion frequency of the swing hanging on the rack
based on the ID of the tag attached to the bottom, and reports a correct frequency.
Now, let's add a track as a linear constraint.
The boat attached a tag on the top allows the system to resolve the speed of a boat
sliding on the track from the pulse width of the square wave.
The figurine attached a tag at the bottom further allows the system to recognize
whether it is walked or jumped along the track from the tag presence signal patterns.
The car with a tilted tag allows the system to
recognize whether it is moved backward or forward when sliding on the track.
The trolley with a pair of tags allows the system to recognize its
movement direction from the tag presence order.
Now, let's further use gravity to get an object sensed by an effortless release.
Based on the tag's ID, the system identifies which set of algorithms to use
when the user interchanges the hardware components on-the-go.
Physical constraints can extend the input space,
like the multiplexer allowing an NFC coin to roll along and get identified from various tracks.
The sorter preserves a tag order in this educational application.
The user release the sorter to resolve a linear order of the blocks.
The funnel allows the user to throw tags into it and get each tag through.
The modulator further allows the user to throw a handful of tags into the container with one hand,
and to resolve jams using another hand, rocking the handle before the tags being read.
By hooking up a custom finger-worn NFC reader antenna,
the user can use the spinner in a mobile context and perform bodily inputs.
A three-coil, non-planar antenna array can reliably capture the speed
of a tag-embedded marble rolling on the track.
Summary, NFCSense enables rapid-prototyping
fluent tangible interaction using simple hardware. We’ve shown and tested the data-defined designs
with existed objects like lego bricks in the time of pandemic.
We further discuss design implications, study limitations, and research directions in our paper.
We’d invite you to check the tutorial, try the source codes, and check our other projects on
Rich-ID interactivity. Thanks you so much!