Making-of: Trapper 0.1

Trapper is a costume&&instrument for sound performances. It is made for the performance of “Trapped in a Loop“, the Swedish duo band by Magdalena Ågren and Richard Widerberg.
This post is the on-going process of making and experimenting the “Trapper 0.1”. Hopefully in the future, this becomes a fully functioning Trapper 1.0 that can be used on the stage.

Here is the first version design. This version was made in rather a quick way at the Swedish school of textiles. The stretch sensor was knit with double bed hand knitting machine with Bekinox 50/2 (2 yarn) + elastane (stretchy yarn). The knitting pattern is a simple 1X1 rib.

The control unit (Lilypad + Xbee + battery) is placed on the back of the pants in a small detachable pocket.

The sensors on the shirt is connected to the pants via poppers placed around the waist.

The pants’ pattern is based on a pants I have and modified. The shirt pattern is from a book called “Pattern Magic: Stretch Fabrics” by Tomoko Nakamichi.

We did a quick rehearsal in November with Magdalena and Richard at their studio in Goteborg Sweden. Here is the footage from the rehearsal.

The Trapper has 4 knitted stretch sensor embedded, on the elbow part and the back of the knees. In this rehearsal, the sensor calibration (size of the pull-up register) is not well done. You can see Magdalena is having hard time controlling the samples. Also, I am not super sure if this interaction (bending knees/ elbow) is the best choice for their performance. This needs to be further explored.

So, I made some changes. One of the reasons for the arm stretch sensor to be not sensitive was because the knit was double layered (It is too conductive for a sensor in this way). So, I made it into single layer and used t-shirt material for the back. The pull-up registers are replaced to the suitable size now.

I also wanted to replace the Lilypad on the control unit to Lilypad simple, because I use only 4 Analog input, and on simple, there are onboard lipo plug and switch.

But, after I completed the alteration, I noticed the Xbee is not working.. why?!
After some google search, I realized the “NOTE” on the very bottom of the Sparkfun page.. it says “Note: Because of the added battery charging circuitry the Simple is unable to power a device from the FTDI header meaning that the Bluetooth Mate, for instance, is no longer plug’n’play compatible.”
.. So, I sew back the normal lilypad and added extra switch on the cable connection between the battery and the lilypad. Now everything works fine.

Here is the switch!

The pull-up resistors are placed on the back of the base fabric (neoprene) of the control unit

With these modifications, it works much better now.
Here is how it looks, and the footage from the trial with a simple max patch (it play out different frequency)

While the first version is gone to Mag and Richard for testing, I have already started to work on the second version. There were few of the things to change from the first version:
– Try different kind of interaction rather than bending elbows or knees
– The design of the shirt needs to change. It looks too tight

So, I started this new shirt now. The pattern comes from Pattern Magic 2. (It is really a great book!)

In this trial, I am using a conductive knit I made at the Swedish School of Textiles. It is made out of bekinox 50/2 and elastarn with industrial circular knitting machine. The gray stripe is the conductive yarn and the white is just elastane. It is very stretchy, and it contracts very well when it is not stretched. The gray stripes are electrically not connected. To connect them, I added stitches with conductive thread running vertical (against stripes).

In this pattern, under the arm is a separate patch. I am replacing this piece with conductive knit mentioned above.

I made some adjustments (shorter sleeves, stretch end on the waist part of the shirt to stay down) and now adding conductive traces to it for the connections.

And here is the outcome. The popper connectors are not placed yet. It will be ready for use when I place poppers

This was made with Toile fabric. I will make the real version with these fabric. (what do you think Mag?)

Bellow images are the process of making the isolation layer for the conductive traces.
The fabric is cut as bias to gain the flexibility.

And here is how the finished shirt look like

Now, it is time to make the shirt for Richard.
I used sloper pattern of M size man’s shirt. As it is quite loose fit, it should be ok.

And here is the finished shirt. The under-arm stretch sensor was too loose, so I am currently making some revision.

The circuit for the both shirt is basically the same (“basically” because the pull-up resistor value is different for each shirt, so you can not really swap the circuit)

Here is the pull-up value:
Analog Pin 2 >> Left Armpit >> 47K ohm
Analog Pin 3 >> Left Elbow >> 2.2K ohm
Analog Pin 4 >> Right Armpit >> 47K ohm
Analog Pin 5 >> Right Elbow >> 1.5K ohm

Analog Pin 2 >> Left Elbow >> 1.5K ohm
Analog Pin 3 >> Left Armpit >> 10K ohm
Analog Pin 4 >> Right Elbow >> 1.5K ohm
Analog Pin 5 >> Right Armpit >> 10K ohm

The finished image of ver 2.0






Collaborator of this project

Trapped in a Loop / Magdalena Ågren, Richard Widerberg