Prototype animatronic head
October 7, 2012
Well my boss is involved in organizing a robot head building contest in China and asked me to make an example to inspire the contestants. I know many will just be made from cardboard and wood but I decided that if I was going to spend time on this project then I wanted to make the most of it and develop a new product.
Some of the animatronic heads I've seen on Youtube are very advanced with custom machined metal parts and 20 -30 servos. I decided to try and make this design flexible. It can work with as little as 4 servos or as many as 11 and all servos have magnetic clutches to protect the gears. The head is intended to have a rubber halloween mask fitted to it.
Two servos are used for the mouth with flexible spring wire lips. This allows the mouth to open, close, smile, frown or grimace. A third servo can be mounted behind the lips to move bottom teeth up/down or a tongue in and out.
The eyes can be controlled with as little as 2 servos (up/down and left/right) but adding another 2 servos will allow the eyes to pan individually for "cross eyes" and blink assuming I can find 40mm table tennis balls to go over the 38mm eyeballs. It seems most table tennis balls in China are 38mm these days.
The eyebrows can be driven by 2 servos for basic movements (up or down can express sad, angry or even curious) or 4 servos for a full range of human expression.
To control these servos, there is room inside the head for a DAGU Mini Driver. Although this board can only drive 8x servos directly from the battery, it's 5V regulator is rated for 1A and can drive a couple of extra servos from the analog inputs (D14-D19) as long as they are lightly loaded.
The Mini Driver has a dual "H" bridge which need not go to waste. 1 motor can be a shaker like they used in some game console hand controllers. This will let the head shiver when it is cold. The other motor output can be used to drive bi-colour LEDs for the eyes. Another option would be a small fan inside the head so it can blow out a candle.
The head will be assembled from 4mm thick, clear acrylic plates held together with small steel 90° brackets and screws. The base can accept a 6mm or ¼ inch bolt or it can be mounted on a heavy duty servo.
Once I get the prototype working I will post it as a robot project.
I am told the laser cut parts will arrive either 9th or 10th of Octoberand my company has bought a small sample of rubber masks to experiment with.
The Clown mask will probably work best with the eybrows but I must admit I think the gorilla would be fun.