I was pretty pleased with how my last project turned out, so I’ve started working on another idea with a different friend, for her to wear to another party in late Jan. I’m glad to have a little more time on this one, because it’s looking like it will be a little more complex! The image below is the result of a few hours of brainstorming in SketchUp, and will also be one of the few electro-mechanical projects that I have done.

Some people have a passion for a certain something. Mine is building things. My friend’s passion is fairies… It’s an odd set to combine, but I think I can come up with something pretty cool here. She want’s a set of fairy wings to take to this party. Sure, you can buy wings from costume shops, but that’s no fun! I want to design something a bit more special then that! So, I sat down and thought of what would give that special something to the design.

I like LED lighting, so there will definitely be some of that involved. I had originally planned to use EL wire, for it’s unique appearance, but I got tired of looking for small-footprint solutions for reliably powering the EL strings. Besides, it’s somewhat fixed in it’s colour output, and that can be quite restrictive! I’ll explain what I’m using instead later on.

That’s not the final touch though. Shortly after the lighting, I got to thinking, can I get these wings moving? What you see above is the base of that idea. Using a couple of RC servos, and some ball bearings, it should be possible! I’m going to be working on finalizing the design over Christmas, which will leave me most of January to order and build.

I’ll be keeping track of the work here, so check back for more updates!

Rough Concept

What’s on the shopping list this time?

  • 2 x Turnigy MG90S Metal Gear Servo 1.8kg / 13.4g / 0.10sec
      • These are some tiny R/C servos, that can give a fair bit of pull!
  • “Sideglow” Optical Fibre
    • Looks a lot like EL wire, but much more appealing, for several reasons, discussed later. Think of it as “lossy” optical fiber, that emits light perpendicular to the axis of the fiber.

“Edgeglow” Fiber

  • Small Ball Bearings
    • We want a smooth movement to the wings, so it can look as natural as possible. If the travel of the wings is jerky, it will ruin the effect.
  • Various bits of carbon fibre tube, rod + plate, and some Acetal, for the framework and wings.
    • Carbon fiber is lightweight, flexible and strong!
  • And the usual mix of AVR’s, RGB LED’s and Li-Po Cells, as of yet to be confirmed. Likely running the setup off an ATMEGA328, for the 6 PWM channels, with spare I/O for the servos
I’ve asked her for a image of the profile that she’d like the wings to have. I got given this, and a quick jump back into SketchUp gives me a rough idea of the scale of what we’re going for.
That little servo pack looks a lot smaller now! Approximate span from tip to tip (open, as shown) is just under a meter. I might scale this down a little, as that could get quite uncomfortable in crowded spaces.
Here’s revision 2, a bit more fairy-like, as per request.
And here’s a spin around the frame in 3D space, just to give a feel for the mounting angle of the wings. It’s also worth noting that at this point, I’ve also decided to completely re-work the servo plate, for a more simplistic operation. Hence why it’s (barely) visibly different in the video below.

Electronics

So within the electronic specification, I’m after the ability to drive 2 servos, and vary the duty cycle on (probably) 6 PWM outputs, to give me 2 RGB channels. Some tinkering with an Arduino Mega board and a copy of the Servo library has produced exactly what I’m after, with the example Servo sketch modified into a function that accepts an integer number of “flaps”.  All I have to do now is recycle some of my older code, to deal with the RGB light changes in an interrupt-based fashion.