24 hours til DAWN!

A day closer to DAWN. Another quick update.
The official Multimba poster has been released!!!



Moving on to more complex matters. On setting up Multimba in the exhibition space today, it 'dawned' (had to be done) on me that the threshold level set,(between 100 and 200) was not dependable. After further testing I realised that most of the sensors rise to the maximum level of 1023 when pressed. This results in a very dependable response when a sensor is pressed, plus it removes the multiple hits problem. Only downside is that sufficient force must be given, a force lacking in the soft leather bags of our mallets. Nevertheless this is only a prototype. I'm currently tweaking the electronics so that each sensor frequency value can reach the maximum.

Other than that, the exhibition layout is good and graphics look great on projector screens.

2 days til DAWN!

The countdown is on to the DAWN exhibition. Here's an update on progress. Final prototype is complete, bar some fine tuning of electronics. After fastening hinges and applying logo vinyl, here's some pics of Multimba. After many days and nights of preparing the circuitry, many key points were notes. Firstly, the original wires should never have been removed from the sensors. Instead of spending hours on end soldering and resoldering, it would have been much more worthwhile to have just extended the wires. Forgive me, I'm an electronics virgin. Secondly, I have should have kept those breadboards that come with the Arduinos in the bag. Way too small and figity. Finally got myself some decent ones. Also, on the night of previous blog I thought I had cracked the undesired hits problem. I had one arduino working perfectly without any leakage(excuze my made-up terminology). No matter how much I tried this could not be replicated throughout. Explored many avenues of manipulating the Arduino code but to no avail. Finally decided not to use resistors. Set a threshold between 100 and 200. This plays a sound only when a player uses sufficient force(like any instrument) and fingers crossed my debounce time will prevent multiple hits. Still needs a bit of fine tuning. Some sensors seem to be misbehaving. Probably part due to the fact that the sensors used are so cheap and low quality. Something to think about for next project. Here's a short video of the underbelly of this fantastic prototype.

Evaluation sessions will take place at the DAWN exhibition.

1st Arduino Working!!!

Here's a vid of the first Arduino working.

Now to do this 3 more times and attach to instrument.

Physical Prototype Complete!

After a couple of weeks of liasing with an expert carpenter, the physical prototype is complete, alomost exactly to spec!

The box measures 1000mm (length) x 300mm (width) x 100mm (depth).
The top and bottom of the box, and the instrument board is 100mm wide plywood.
The sides are 200mm white deal.
It is coated with a matt black finish.

Open, the instrument looks like this.

The instrument board that sits inside measures 800mm x 280mm.
Underneath the board lies 4 arduino boards and their cables.
Placed on the board are 24 sensors.
A 5mm holes was drilled through the board for each sensor's wires.
Each hole was placed 65mm apart, and the side holes were placed 57mm from the edge.
They then had to be countersunk with a 10mm drill bit to accommodate the solder underneath each sensor.
A white sticker is placed over each sensor.

Finally a 16mm hole was placed at the back of the box to accommodate the usb cables.

Building the Prototype

This week we hope to have the instrument built.

We decided that the most practical and accessible design would be to incorporate the instrument into a hinged box.
The below figure demonstrates this idea.


The main piece of timber that will contain the piezos needs to be solid and firmly attached to the box without any rattling (so as not to trigger the wrong sensor).

I've arranged for a carpenter to build box.
Below are dimensions I'll be providing him.


Stay tuned for more...

Pressure detected!

After our meeting with Mikael last Thursday, we decided it would be best to use Piezo transducers rather than force sensitive resistors. Firstly, the ones that Mikael had were wire-free, complicated to connect to an arduino. Secondly Marc McLoughlin used piezos on his bodybeats project last year and he may be helpful if we encounter difficulties. Also, after testing the Piezos on an oscilliscope we feel they should be more than sufficient for the sensitivity we are looking for.

And onwards we went. On connecting to the Arduino I realised that a threshold of 250 was good to detect sufficient force on the sensor. On successfully connecting numerous sensors, we began looking at how we could interface this with PD to output synthesized sounds. To create the sounds we needed to use the modal partial frequencies of our 2 octaves.
One resource that can give us information on this is Rossings 'The Science of Sound'.

Next: compose and output sounds using Pure Data
PDuino firmware downloaded and installed, the Simple Message System will be used to read the arduino

Chris H

Let's get started!

Recently we began building the prototype. I obtained an arduino kit from the IDC and ran a simple LEdBlink program to test it worked on my MacBook.

Waiting to get my hand on some force sensing resistors, I decided to test out Piezos sensors using a simple Knock program that gives back a reponse when the sensor is hit.

In total we will need 3 arduino - 3 x 8 analog inputs - 24 bars = 2 octaves

As soon as we have fsrs connected we will interface arduino with Pure Data using PDuino. PDuino download can be found at http://www.arduino.cc/playground/Interfacing/PD

Also in the mix at the moment is the physical construction of the prototype. We are looking at a wooden base and foam pads for the bars.
Stay tuned for more...

Chris H

Projectors

According to Mikael, it's probably best to use three projectors rather than trying to split one projection(loss of quality). The choice of projectors comes down to DLP(Digital Light Processing) or LCD(Liquid Crystal Display) - DLP is cheaper for equal power outputs, with better blacks but worse with moving images. LCd has better resolution but is more expensive and the blacks are not as deep.

Screens

Our original idea was to have three rectangular screens located infront of the performance. currently we are thinking of a semi-dome shaped enclosure. '
Audio-Visual art & VJ Culture'(Faulkner M) warns not to fall into the trap of always using traditional 4:3 or 16:9 screens in a front of the classroom arrangement. If you build your own screens you can experiment with polygons or other shapes, and even create 360 degree immersive environments. Almost any flat reflective material can be used for the screen but screen fabrics will normally give you the best reflectance and good viewing angles.

Arduino

Eoin Brazil gave us a lecture on Arduino today - an open source physical computing platform. It's a simple i/o board and a development environment. It can be used with C, Flash, Processing, PD, Max/MSP, Ruby. Doesn't work with Director. IDC has twenty of these on order.
Slides Attached