Milk Pixel at the Arnolfini

After a week of stress and late nights, Milk Pixel was up and running in the Arnolfini during Saturday and Sunday's uncurated open event unCraftivism. We kept the project more or less under wraps until the day so reactions were very interesting. Here are some pictures:

Milk Pixel is essentially a giant, interactive, 8x8 Red Green Blue LED array with each led pixel placed inside a plastic milk bottle. The textured plastic of the bottles diffuses the lights from the leds nicely to give some interesting colour combination.

The patterns of colours are generated from webcam and microphone input as well as number of manual controls. This means that the system responds to motion and sound. During the weekend the array was feeding off live musicians, projected films, games of tambourelli (badminton with tambourines) and anyone who happened to walk by during quiet moments. The Audio Visual driver software was written entierly in Processing. In the above photo the green parts of the array reflect movments of the brass instrument and player.

Here is the system with myself (center), Paul O'Dowd (left) and Thomas Burton (right). Jason Welsby is another memeber of the team that isn't in the photo.

Oh, and here's a video of it watching a movie while listening to a band. There are still some glitches that need to be ironed out so the representation of the audio / visual input is quite abstract at the moment...

If you were at craftivism and have any pictures of Milk Pixel I'd love to see them, leave a comment below...

Multiple LED pulsing via a 555 timer

UPDATE - The bug in the last schematic has been corrected. R2 had been incorrectly connected to Pin 7 and GND instead of Pin 7 and Pin 2.

I noticed awhile back that there were a few people in a few forums asking for simple ways to make LEDs pulse. During the summer I designed a circuit that pulsed a number of LEDs as part of a fancy dress costume. I was told that it looked great :-) Anyway, here is the circuit. It uses a single 555 timer in astable configuration to create a square wave. On the high part of the wave it triggers one LED, on the low part it triggers the other LED. The big capacitors cause the fading by charging and discharging the square wave into something more analog than digital.

Note: This is Version 3 of this circuit. A lot of people sent me messages saying that they were having a few issues building the circuit. There were a few problems with the previous schematics. The first was that the line connecting pin 2 and 6 could of been misinterpreted as also connecting to pin 7. I've now colour coded that line and put junction indicators (black dots) to show when two wires should be connected together. I recently realised that while making this correction I accidently connected R2 to GND instead of Pin 2. This is now fixed.
The other error was that the dotted line part had the led connected to ground after the capacitor instead of before it. As necro_nemisis pointed out this meant that LED1 was on a direct path from 5V to ground. I dread to think of all the dead leds that drawing mistake was responsible for!

Sorry it takes me so long to do corrections...

The effect is quite nice and you can add more capacitors in series to get several LEDs to light up in a chain. Here's a video where I had 4 sets of LEDs running from one 555 timer (shown at the end).



In addition, here's a photograph of how I wire up the 555 timer IC on some stripboard (with the strips running vertically from top to bottom). The only cut tracks are under the 555 chip. Note there is a red cable hidden from view behind the left capacitor which connects the other red cables together. I would only use this picture as a reference for the IC wiring, rather than the caps, as it is hard to see which track the capacitors are connected to.

Milk Pixel

Following the last post we (myself and some colleagues from BRL) have decided to attempt to create a low-cost, low-complexity, interactive installation for the Craftivism open event at the Arnolfini.
The project is to be called Milk Pixel. Reasons for the name will become evident in time. We don't want to release too many details of what we are up to at the moment, but details will be appearing on the Craftisism wiki closer to the event (11 - 13 December).

Open Event @ Arnolfini

I was recently approached by Rui Guerra of the V2 Institute for the Unstable Media who was looking for participants for an Open Event, 'Craftivism', to be held at the Arnolfini (Bristol) in December.

Rui has given everyone a huge amount of freedom in what they want to host as part of the event and my group (consisting of myself and other researchers from BRL) is no exception. Will keep posting as I know more.

The Enactive Torch was presented at V2 by my colleague Tom Froese in February 2008.

RiderSpoke

I recently took part in Rider Spoke which is currently being held in Bristol (with the Arnolfini as the hub) an event that combines Ubiquitous computing with cycling. As a cyclist and geek I was in.

Here is a blurb from the Blast Theory website:

'The audience can take part either either on their own bike or borrow one supplied by Blast Theory. Following a short introduction and a safety briefing you head out into the streets with a handheld computer mounted on the handlebars. You are given a question and invited to look for an appropriate hiding place where you will record your answer. The screen of the device acts primarily as a positioning system, showing where you are and whether there are any hiding places nearby. The interface employs imagery drawn from Mexican votive painting, sailor tattoos and heraldry: swallows flutter across the screen to show available hiding places, prefab houses indicate places where others have hidden.'

I thought the game was enjoyable but it could of done with some context, and I seemed to come across quite a dark set of questions and answers compared to my girlfriend, which probably affected my enjoyment of the experience. We tried the game on it's first few days after opening (such things book up quickly in Bristol) but it would be nice to try it again at the end of the week when more answers have been recorded.

The novely of having a little Nokia computer on your handlebars is very cool too (though it's only held onto it's bracket with velcro - I was convinced it would fall off or get stolen).

Paper in Springer Book

My first PhD paper "Robotic Implementation of Realistic Reaching Motion Using a Sliding Mode/Operational Space Controller" has been published the Springer book beries 'Lecture Notes in Computer Science' and may be found on Google Scholar (though I don't know if can be downloaded outside an institution with a Springer License).

If you would really like to read it (the paper, not the book) drop me a line and I can email you a copy.

Conference Tour

I recently (well, relatively recently) returned from two robotics conferences where I presented some work from my PhD in synthesising human motion for robotic application.

At the International Conference of Social Robotics in Incheon, South Korea, I presented a paper titled 'Implementation of Realistic Reaching Motion Using a Sliding Mode/Operational Space Controller' abstract. This work described a controller that mimics the shoulder and elbow motions of a human for 2-dimensional reaching motion and then uses a sliding mode controller to allow this method to be applied to practical systems. This paper is to be published in the Springer proceedings 'Advances in Robotics'.

At TAROS (Towards Autonomous Robotic Systems), which was held in Londonderry, Northen Ireland, I presented an extension of the above paper which augmented the robot's concept of posture 'effort' to include limits of motion abstract. This is analogous to the discomfort felt by a human when stretching muscles or holding uncomfortable poses. Again the benefit of this work lies in the application to physical robots, where the limits of motion prevent mechanical damage to the system.

At both conferences my work was recieved well and there were some very interesting comments and suggestions. Of course it was also a pleasure to visit South Korea and Northern Ireland both as a tourist and as a robotics researcher. The image below was taken from the drinks reception at the Derry robotics lab and shows a research platform modified to distribute party snacks.



I don't think I can host .pdfs on blogspot otherwise I would make the papers available for download. Here are the full references if you wish to do your own search:

Spiers, A., Herrmann, G., Melhuish, C., Pipe, A. and Lenz, A. (2009) Robotic Implementation of Realistic Reaching Motion Using a Sliding Mode/Operational Space Controller. In: S. Ge, U. Witkowski, D., Kim, J., Kim, U., Rückert, D., Sandberg, M., Wahde, C., Cho, J. Cabibihan, Y. Pan, eds. In: Advances in Robotics - FIRA RoboWorld Congress 2009, Incheon 16th-20th August 2009. Heidelberg: Springer, 1980, pp. 230-238.

Spiers, A., Melhuish, C. and Herrmann, G. (2009) Implementing 'Discomfort' in Operational Space: Practical Application of a Human Motion Inspired Robot Controller. In: 10th Anniversary of TAROS - Towards Autonomous Robotic Systems, Londonderry 31st August – 3rd September 2009.