My 4 year old son wants to be Cthulhu for halloween (A very proud moment when he told us this). We had a quick look online at costume ideas and one that he really liked was a crochet mask which is awesome because I took up crochet a couple of years ago, so this seemed a great and easy idea.
Then something clicked and I realized I could combine my newest hobby of Arduino with the mask to make the tentacles curl and uncurl in the most creepy yarn based halloween costume ever!!! This should be fairly simple in terms of arduino programming as it just needs to be moving slowly.
Well, it has taken a lot longer than I expected, but I am very happy to say the crochet part of this project is finished. I am most excited because as much as I want to make the tentacles move etc, at least I have this much done and he has a pretty cool Halloween costume. Making the tentacles move on their own is just an added bonus if I can finish that in 2 days.
Before I add the picture, a quick reminder that this is a Cthulhu cushion that he got for Christmas because he loved playing with the display one at the local comic book store (Borderlands in Greenville, SC).
He was very specific to say it needed to look exactly like this, so that's why I made the eyes match as well as I could.. he still wanted to know why I didn't put black in the middle of the eyes and was only partially happy my answer that he wouldn't be able to see.
So now all I need to do is solder up the servos and electronics and attach them to the tentacles. My original idea of 4-6 servos attached at 2-4 arms each and turning the full 180 degrees to get a lot of movement of tentacles is probably too ambitious as I write this just 2 days before Halloween. I am thinking 3 servos attached to 1 or 2 tentacles each and just attached and fed through a few turns so they will make the tentacles move a little. (Just enough to make people pause and be slightly confused). This is the first animatronic costume I have made, and I am happy with a very minor success. By next year, I will be hopefully be able to do a lot more.
Thank you Hack A Day!! for featuring my project on the main page. I am still working on this, but life kind of slowed things down. Another good reason why I started so early.
I have been mainly working on the crochet mask and tentacles, this is the basic mask shape.
These are some of the tentacles... if you have been following, you will notice that these are already curled, after more testing I realized it was easier to make them curl more if already curled than doing al the curling with wires. There was just too much friction and they wouldn't straighten out again.
I am nearly done now with the crochet part of this, the tentacles should cover the arduino, servos and Bluetooth module. the arduino code is super simple and even the wiring should not be too hard. I will probably just move one servo at a time since I don't need super fast moving tentacles, and so a single 9V battery should power the whole thing long enough for trick-or-treating.
Then I "just" need to hook it all up and I should be done. Hopefully I will be posting again soon once the crochet part of this is done.
So I realised that I have been focusing mostly on the mechanical aspect of making the tentacles move and I should probably at least start looking at making the mask itself. I was going to write this up yesterday, but suddenly realized I needed to record a video for entry into the hackaday prize, so that took priority.
This is a free crochet pattern I found for the mask itself. This is going to be my starting point although I know I have a number of changes to make, so won't be able to follow the pattern very closely. I will be posting the final pattern I make on Ravelry and linking from here even though I suspect it won't be ideal for many people. Hopefully, it should at least give some ideas on how to integrate electronics into crochet patterns and point people in the right direction. When I thought of this idea, I did some Googling and found absolutely nothing in terms of combining servos and crochet. It almost makes me want to crochet a robot, but that's another project for another time.
1. Make it smaller - This is for my four year old son, so I will need to make the shape of the head a bit smaller to fit him snugly.
2. I will need to alter the pattern to get closer around the eyes and to give a nose and eyebrows shape to match his pillow. He has a very specific idea of what Cthulhu looks like based on the pillow he got for Christmas. He told me that he needs red eyes and the lighter green for the area around the eyes and nose. My wife took him to the craft store and they picked out the yarn, so at least I'm one step closer in that direction.
3. Hiding the electronics. This is the part that I know isn't going to be easy. I have an Arduino Pro Mini which will be controlling everything and the HC-06 bluetooth module will both be small enough to hide easily, but the servos are a bit bulky and more difficult. I know I will have space behind the tentacles, and the servos will need to go here, but I don't want him to feel like he can't talk or breathe. If possible, I also want him to be able to move the tentacles aside so he can eat and drink while wearing the costume. We live in South Carolina, so even in October it can get quite warm, and with the mask and the rest of the costume, he needs to be able to take a drink without removing the whole mask.
After seeing the tentacles curl when I pulled on the wire I was very happy and confident that the servo would be strong enough to do the same. I needed to do the test to see it working, and I had two concerns when setting it up. The first is that I want to keep things easy and use the servo arms included with the servos and I don't know if they will have enough movement to make a significant difference to the tentacles. The second concern is about feeding the wire back into the tentacle. I found this was doable when pushing carefully straight down, but a little awkward. I need to test with a servo to see that it can feed the wire back to make the tentacle uncurl without the wire just bunching up. As described in my last post, I used the "Knob" arduino tutorial http://arduino.cc/en/Tutorial/Knob This was the easiest thing to set up to have manual control of the servo for testing.
Well, it is definitely a success, but shows I have more work to do. The servo was able to make the tentacle move as I want it to and it was able to curl and uncurl the tentacle as needed. Getting the servo to feed the wire back into the tentacle, however, was a little tricky and you can see my finger helping guide the wire back in. I kept my finger still for the most part, but towards the end of the video when I turned the servo all the way it bunched up, so I will need to work on the design to have some way to help feed the wire back into the crochet tentacle.
The first step, before I spent too much time thinking about and working on this, is to show the proof of concept. Specifically, the one part of this that I haven't done before and haven't seen anywhere online is to make a tentacle curl and uncurl by pulling on a wire. Assuming that works, it's easy to attach the wire to a servo and have that controlled by the Arduino.
This first picture is a small tentacle made as a simple chain (about 20 stitches) then a single crochet in each st going back with more tension and tied at the end. Because of the increased tension, this tentacle has curled all on it's own. That is the effect I am going for, only creating tension with the wire.
This is a longer chain (about 50 stitches) and again, I have done a chain and then a single crochet in each stitch to the end and tied off, but tried to keep the tension even all the way. I have then threaded a wire through one side of each stitch. You can see the wire sticking out at the top and I tied it off at the bottom. (Ignore the extra strands at the bottom, I couldn't be bothered to sew them in or cut them off just for this test).
I tried pulling on the wire and the tentacle did move, but not in the way I wanted. After a little experimenting, I realized a slightly curled tentacle will work better as a starting point. These 2 pictures are taken one after the other and I am using my spare fingers to pull on the wire. You can see that the tentacle has curled up very nicely just by pulling on the wire.
This is exactly the effect I was hoping for and I am getting very excited that this project could actually work and be easier than I was expecting. If I have 8-10 tentacles curling like that on the mask this is going to look awesome!
I also spent a little time seeing if the process is reversible, and this is a bit harder, I needed 2 hands to push the wire back in carefully in order for the tentacle to straighten, and it was difficult to hold my phone to take pictures at the same time. I can see where this is going to be a challenge in the final mask, but I think I can get it to work.
The next step is to set up a simple breadboard circuit to test if the servo can curl and uncurl a tentacle directly and repeatedly. (I think I will use the tutorial project on the Arduino site to control a servo from a potentiometer to give me manual control for testing). I will try to upload a video of that test as soon as I can. Then I guess I should get started on making the main shape of the actual mask and see if I can figure out where to include al the electronics and the battery etc.
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.