Intro To Physical Computing

Week 1 Week 2 Week 3

Class 1: Physical Interaction 02/09/2015

What is physical interaction?

Chris Crawford defines interaction as

“a cyclic process in which two actors alternately listen, think, and speak”.

which I always thought to be about as succint a definition as there could be. I first read this definition (with a slight difference in phrasing) in his book “…on Interactive Storytelling”  and now again recently for class in “The Art of Interactive Design”.

In that case what is physical interaction? In simplest terms, the aforementioned process but with the added inclusion of a physical body as the agent of either one of both of the parties’ actions.

Then what makes for good physical interaction? Some things that I think are important are believable feedback, haptic feedback, feedback and actions that lead to further interaction. e.g: Something that takes human capabilities into account to paraphrase Bret Victor. There is always careful thought and a long design process behind devices that feel “intuitive”. The ability to engineer it so that the user considers using your product “intuitive” is a valuable and hard learned / repeated skill.

His central point is summarised in the article’s postscript:

If you’re with me so far, maybe I can nudge you one step further. Look down at your hands. Are they attached to anything? Yes — you’ve got arms! And shoulders, and a torso, and legs, and feet! And they all move! …With an entire body at your command, do you seriously think the Future Of Interaction should be a single finger?

Bret argues for convincing, immersive interaction. Though centered on the primacy of the hand as the easiest and most obviously unexplored avenue of research for new interfaces, I believe that a policy of inclusion of the rest of our capabilities beyond the screen/interface or touchscreen paradigm is the way forward. I will see if I can put this into practice somehow in the coming weeks.

It was hard for me to think of an example of something completely devoid of interactivity. Perhaps, especially recently and with new media, it is something thought so intrinsic to human nature that we either strive to include it in our work or subconsciously do so anyway. The works of the video artist Bill Viola  can be said, in my opinion, to be devoid of interactivity.  Seen here in a gallery setting:



The work can be observed and can surely elicit an emotional response but at no point does the video respond to any of the actions the observer might take. It is scripted, it plays out the same way every time. This is no way subtracts from its merit but as an example of a digital work that is not interactive it serves its purpose.


Class 2: Switches and LED’s 10/09/2015

wanted to use FSR. Started with this blog

Modified the sketch to control more LED’s from each of Arduino’s PWM ports.

Arduino has only 6 pwm pins could solve using this

Need better adhesive than this tape.


Class 3: Digital and Analog Input / Output 10/09/2015


“Arcadeotron 5000”


Initial concept and playtesting :


We built a 16 x 16 LED matrix using Sparkfun button pads. It is a large version of an arduino based monome. Each LED is RGB, driven by TLC5940 IC’s and is capable of outputting a 16 x 16 downsampled version of a live camera feed. Each LED is also a button, we have used this feature to enable users to draw pixel art by pressing buttons to change their colour. The purpose of this project is to provide a novel interface that allows the user to perceive themselves in the context of the form that our device displays. Only large differences in colour or light are tracked resulting in a recognisable outline devoid of the finer detail that we are used to seeing and perhaps obsessing over when using a mirror. We display the basic form of a person, hopefully making people realise that image is primarily an issue of perception which varies from observer to observer.


User Testing

Issues and Questions

Use of LED Driver IC’s

In Summary

If I were to make this project again, knowing what I know now I have two solutions: Take the silicone button pads by themseleves, a strip of 256 neopixels and wire up a matrix of switches using a base of conductive fabric (the base of the buttons is conductive so this is all that’s needed to make a switch) with the same form / spacing that the Sparkfun button pads have. Most of the complexity of this project came from scale and driving the LED’s would have been completely solved by using individually adressable LED’s, eliminating a large part of our problem. A laser cut enclosure would be all that’s needed to hold the buttons in place. The Sparkfun pads even provide an illustrator file with the correct measurements as a starting point.

I enjoyed learning how to use the IC’s but they were not the quickest nor the easiest solution for this project. As Tom said during our second user testing they are essentially now outdated technology, the prominence and affordability of individually adressable LED’s today being a direct result of the popularity of the hobbyist electronics market.

The most elegant solution but one which I am currently listing as separate as I don’t know how to do so yet would be to replicate the sparkfun PCB but with connections designed for the through hole version of WS2812 (Neopixel) LED’s. This would be trivial to someone who knew what they were doing I’m sure. One thing we underestimated was the amount of wiring involved that increased with scale. This would solve both that and the LED problem, the two biggest bugbears of the project.

A word of warning to whoever goes down the path, like we did of trying to emulate an Arduinome or Chronome from FlipMu. They are great projects with a lot of careful and well thought out work and documentation gone into them but I will share some problems we had with trying to replicate their approach from an electronics novice standpoint:



  1. jonnie

    September 20, 2015 / Reply

    From Week 1 (comments were broken) Tom Igoe:

    define what you mean by “intuitive.” The way you’re using it in your post, it sounds like an important ideal to you. So make sure you can articulate what it is. If it’s something that’s necessary to the quality of a design for you, you should have a way of describing it in your own terms. Same goes for any other quality you consider central to evaluating design.

    I like this: "the user considers using your product “intuitive”” because it places the power of evaluation in the user’s hand, not the designer’s. But it also means that the designer needs to understand what the user thinks is “intuitive”, no? Listening to my mother talk about her confusion with her new iPhone this weekend made me question what “intuitive” means to her vs. what it means to Jonny Ive.

  2. Tom Igoe

    October 14, 2015 / Reply

    The LED brolley is a neat idea. What was the intended behavior of it? The videos give an indication that it worked, but a few lines of description would help to give some context. There are a number of possible behaviors I can imagine, and I'm wondering which you have in mind. I think it's an idea worth returning to as you get more of the electronics under your belt. There are some multi-channel PWM drivers that may help with it, among other things.

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