Carl wrote up a post about our 500 Clock Project, or at least what we completed before temporarily shelving it. Here’s a brief description of the project from his site:

…a robotic kinetic sculpture that would wirelessly receive stock market data and update itself throughout the market day. Five aluminum columns would raise and lower indicating the current position of the market in accordance to one stock index.

He has some nice photos and videos of the mechanical work he did, which are worth checking out. Here’s a video I found of the completed and working prototype shield I built:

For those interested, there are a few more details after the jump.

What you are seeing is an Arduino accessing a very basic web service to get some numbers to “display” by moving the servos. Trust me, the display would be much more impressive if it were connected to Carl’s sculpture. For the purposes of this demo, the web service is just returning random numbers with each request. In production, the numbers would, of course, be more meaningful.

The main components:

  • Arduino
  • Roving Networks RN-134 wifi SuRF Board
  • Micro Servos
  • Webservice (written in Ruby)

Most of the time went into working with the wifi board. Today, there are better options for Arduino wifi connectivity than when we were working on this project. I’d probably opt of an Arduino Yún, which has built-in wifi (among other things).

I did have some minor issues with power. My original prototype used the same power for the servos, Arduino and the wifi module. This was fine when I was testing with one servo, but with five, it failed spectacularly. This was solved by using some power regulators to separate the power for the servos from the control electronics.

Finally, for this project, servos are not a great choice. When we pick this up again, we should probably look into using stepper motors to drive the sculpture. They have more torque, finer control and run much quieter than the servos.

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