Sunday, June 19, 2011

Geeky stage props made easy

Currently I'm involved in building the stage and props for an amateur theater, the Brechtbau Theater at my university. We're currently preparing for an Agatha Cristie play, "And then there were none". As a great opportunity, we are able to perform this piece in the city's professional theater, the Landestheater Tübingen (LTT).
Needless to say, we're really excited about this. Of course having to build a stage for a 300 seat theater is a bit different to building a stage for the 80 seat theater we've got at university. Also, we only have about four hours to set up the stage, and after the last night, we have to clear out immediately. While the way to build a modular stage design probably is worth a blog post on it's own, I want to talk about the electronics behind stage a bit today.
Without wanting to spoil some of the surprises we have in store for our audience, we're working on a stage design with lots of big cogwheels and other moving parts. We will power some of these with the cheapest and most readily available power source we have available: actors. But some of the stage has parts that are just out of reach, or need to be positioned more precisely. For this, I'm currently planning to use a combination of stepper motors and hobby servos, run by an Arduino Uno.
I'm still heavy in the prototyping stage, but I just wanted to share my discovery on how easy it is to do stuff like this with the Arduino. My current test setup looks a bit like

Using an L293D (left) and an L293NE (right) IC, I'm running two Trinamic bipolar steppers, and I'm also controlling four servo motors. For making all of these move forwards and backwards, I had to write about 50 lines of code, including whitespace and some comments. Arguably, moving a couple of motors forward and backward in a loop isn't that intersting, but the amout of work the Arduino default libraries already take care of is just great.
Next, I'll have to figure out how to build a lamellar transport belt and move it with one of the steppers, while converting the circular movement of the other stepper to a linear movement. Never played with elaborate hardware stuff before, this is fun.

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