Skweezee Technical FAQ

In demonstrating Skweezee at academic conferences and in public venues, we have encountered frequently asked questions. We grouped these questions and formulated answers below. If you have additional questions, don't hesitate to contact us and we are happy to make some time addressing these!

Overview

 


 

Can you make Skweezee wireless?

Yes, you can! We have developed some custom shields ourselves in the past with wireless functionality, but there is a more convenient option: we developed the Skweezee shield to connect to the Arduino platform, and created Skweezees on Arduino without shields. The Arduino Uno allows you to stack shields, in order to add functionality. We suggest you use available wireless shields such as a Bluetooth or WiFi shield to add wireless functionality to Skweezee. Due to the bulky UTP connector, you might want to put the Skweezee shield on top.

Note that the conductive material acts as a Faraday cage, blocking your wireless communication if you place your antenna within the wool.

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Can I make a battery powered Skweezee?

Yes. We have created demos using 9V batteries that lasted long enough. Depending on your project, you might want to use rechareable batteries.

We have used Voltaic IoT Battery Packs in the past, as these power banks have an Always On feature.

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Why a UTP cable? Can I use another cable and connector?

We agree that the UTP connector is bulky, and their clips break easily. Still, we decided to keep using UTP cables as it is widely available, and is an affordable way to have multiple wires in one cable, a UTP cable has 8.

Using the two multiplexers on our sensing shield for Arduino, we need 1 analog input pin and 7 digital pins to control the multiplexers while allowing 28 unique pairs of wires (n*(n-1)/2), with n = 8). With a standard Arduino Uno or Micro, that leaves plenty of remaining pins for additional functionality (for example to connect a NeoPixel).

Taking into account the availability of a UTP cable, the number of wires in the cable, the needed pins on a microcontroller to make it work, and resulting dimension, we argue that the UTP cable is an appropriate choice for the Skweezee project. However, following the published Skweezee code, you should be able to adapt to your desired cable and connector.

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What is the biggest Skweezee you can build?

The bigger the Skweezee, the better it works. At least, in the range of sizes we experimented with (that is up to a radius of 1 meter). The limiting factor that has restricted us from going bigger was the availability of conductive material. In theory, full-body or wall-sized Skweezees should definitely be possible, especially when expanding the dimensions of the system (see question below).

We are curious too, so let us know if you have made some! In the meantime, we are dreaming of a room-sized Skweezee.

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What is the smallest Skweezee you can build?

We suggest to create at least hand-sized objects (with a radius of ~10 cm), when you want to make use of the full functionality Skweezee provides. Below 10cm, the signal stability drops significantly. For example squeeze recognition becomes very limited to impossible.

However, in specific use cases, up to finger sized Skweezees have been made (with a radius of ~1 cm).

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What is the maximum dimension?

A single sensing shield for Arduino results in a 28-dimensional squeeze vector.

We have connected four sensing shields for Arduino in parallel in the past, and could create a 112 dimensional Skweezee with minimal effort. The control pins of the Arduino were connected in parallel, while the analog input was connected to A0–A3.

The Arduino Uno has 6 analog input pins, so in theory, you could create 168 dimensional Skweezee. With an Arduino Mega, which has 16 analog input pins, you could go up to 448.

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Can you make a controller with multiple objects?

Yes. There are multiple ways of achieving this:

  1. Electrically connect the objects (for example by connecting a wire to the objects), so it becomes a single object from an electrical point of view.
  2. Distribute wires between the objects, and create subvectors for each object. This method does sacrifice quite some data (and thus stability).
  3. Connect a sensing shield per object, and connect these shields in parallel.
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Does it work in VR?

Oh yes it does! On our GitHub, we have published our Sailing Skweezee game. The game was developed in Unity, and demonstrated with an Oculus Rift at CHI Play 2019. Read more about the game in our academic paper.

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My platform isn’t listed, can I make a Skweezee on my preferred platform?

We have developed the Arduino shield, Arduino code, and Processing library. On our GitHub, you can find additional examples in Unity.

The Skweezee toolkit contains background information, technical resources on the mentioned platforms, and detailed instructions of how to use these resources. We believe that this enables makers to find solutions to make Skweezee work on their preferred platforms. However, if you have any technical question regarding your preferred setup let us know!

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Where can I get the conductive wool?

The conductive wool we use is Bekinox W12/18 from Bekaert. It is a B2B product, used for example in anti-static clothing. You can contact Bekaert in case you are interested in buying the product, but with a minimum order quantity of 30 kg it is not very accessible to makers. Contact us if you are interested in using conductive wool in your project.

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More info on Skweezee: skweezee.net