System Design

A project log for Crochet Cthulhu Mask, Arduino controlled tentacles

A Crochet Cthulhu mask for my 4 year old's halloween costume with arduino controlled writhing tentacles.

GriffGriff 08/13/2014 at 18:140 Comments

Ok, so I am in my last 2 weeks of school to get my degree and so wont have time to really start working on this until im done with that, but i have been thinking about the design between work, homework and watching the kids. These are some of my ideas on how it will work (and a I added a system design to my sketches literally on the back of an envelope for the hackaday prize)

If you Google 'crochet Cthulhu' or 'Chulhu mask' you will see the basic design I am going for which I have sketched here. I will vaguely follow a pattern if I find a good one or the pictures I found online, but I will make changes as I go to accomodate the arduino, servos and battery as well as specific requests from my son. "It has to have red eyes like this" *showing me his Cthulhu plush toy we got from the local comic book store*.

A common way to make (tentacles) curl with yarn is essentially a very basic long shape, e.g. a rectangle or tube, which is tighter on one side, which makes it curve, and gravity makes it spiral.  I think if I can make the shape mostly straight, then feed a wire through one side, I can use a servo to pull the wire tight and the tentacle will curl up. I could have wires to different tentacles on opposite sides of each servo arm so they will curl/uncurl alternately and then if I have 3-5 servos going at different times I will get the creepy writhing effect I am looking for.

The system design for the arduino simply shows it controlling the servos and I think I'm going to connect it via Bluetooth to my phone. I am a little concerned the batteries won't last long with continuous movement, so I need a way to turn it on and off. Anyone who has tried to press an off button on something held or worn by a 4 year old all hopped up on candy will understand why controlling it from my phone will be much easier.