I have not posted in a while. I have been in school getting my Electronics Engineering Technology degree. But I have been working on this and a Predator costume in my spare time.
Well, I came up with the cheapest way I could think of. I attached a video of what I have so far.
Here's the breakdown:
A cheap plastic squirtgun from Wal-Mart. Repainted....if you want paint plastic, I suggest using a Self-Etching primer then any spray paint will stick. I spent many hours trying to paint plastic (even using that paint for plastics) until I found this primer works the best. It is usually in the AutoBody section of department stores and dries within about a day.
Arduino Uno. I love this open sourced board. You get the compiler program free with tons of examples to understand how to program the arduino (RadioShack $30). You will need to buy the cable to reprogram and power it up until you get the design set up. $10
2 ea. Hitec 322HD servos.($10 ea, eBay)
Wii NunChuck controller ($5 to $20...cheapest on eBay). For the price you can't beat getting a built in accelerometer, Joystick and buttons.
With my current code (which is not perfect but works for now) the x axis and y axis servos respond to the Nunchuck's internal Accelerometers tilt when powered up (Auto Mode). If the Nunchuck's Z button is pressed and held, then Nunchuck's Joystick commands the servos (Manual Mode). When the C button is pressed I have two interesting things happen; I slowly ramp up a bright LED (you can't see in the video) and quickly power a laser pointer for a short time. I did this to simulate the shoulder cannon ramping up and firing. I'm just using a cheap Wal-Mart laser pointer and superbright red LED.
To power it, I'm currently using my computer via USB but I plan on using 6 ea 1.5 vdc rechargable batteries. The batteries will put out 9vdc at 1250 or better mAh (milliamp hours) and the Arduino with servos and LEDs will draw about 60 mA per hour (rough estimate). But when the amperage is reduced about 25% it may shut down the Arduino (opertaing range is from 7.5 to 12 vdc) so 1250 / 60 = 20.83 x 0.25 ( or 25%) = about 5.2 hours until it drains enough to shut down. It could be more as these are rough estimates.
There are only two issues I'm trying to work out with the code: The jitter when the servos are waiting for movement when in Auto Mode (accelerometers) and the delays for the laser and LED stop servo commands. If I can work them out, it will be that much better.
Another thing to mention is you have to tilt your head to turn (somewhat naturally). The Wii Nunchuck has no yaw accelerometer. But I did recently learn the "Wii Remote Motion Plus" does have yaw (rotation CW / CCW) sensing so I may experiment with one to see if I can use it.
If anyone is interested, I do not mind sharing the code. If anyone wants it, just reply and I'll post it. It took me a long time ot get the code this far but it may help others save some time. Plus I enjoy helping other prop builders. Just please keep me cited in the code. As soon as I can, I will create some schematics and post. Enjoy the brief video and any feedback is welcomed.
I tried to attach the video but it was loading too slow. So try and use this link for Youtube:
http://youtu.be/o10z1t4lcQA