Hello all! Okay, so I'm working on a personal project that involves an "enchanted book". Basically it's going to be a book with an eyeball on the front cover that looks around and blinks with the help of some servos that will be hidden inside the book's cover. Now, I'm still working out the kinks with my servo sketch; but what's really nagging me is how to place/set up the servos so that they can move the eye the way that I want them to.
I've spent a lot of time looking on YouTube and anywhere else that I can find examples of animatronic eyes, but all of the examples show mechanisms where the servos are placed behind the eyes, on a horizontal plane- so that the eyes are looking forward, like they would in a skull. My final project is meant to look like a book that was made out of a dragon: so there's only going to be one eye on the book's cover, looking up at you, on a vertical plane (think of the spell-book from Hocus Pocus, if that provides any reference). That being said, the placement of the servos is very important to how the eye will move.
In a typical eye mechanism the setup would have the servos controlling the eyes and lid with long wires or rods on a square surface; but my final project will basically look like a book with an eye. Based on the setup of the second image, the servos are going to have to placed in a sideways position, right underneath the eyeball. I just want to know is if there's any additional space I should make for the servos. I'm also open to any setup suggestions or advice on how/where to place the servos to get them to work properly. Thanks in advance, and let me apologize if I went on for too long 
I do not know how thick your cover will be.
But liner servos have a fairly small profile.
Aliexpress has them for about $6 each.
@Brainfart14, can you provide a diagram that illustrates what you are trying to do? And maybe another diagram showing what would not be acceptable.
...R
Nice! I dont believe I have ever saw a linear servo before..
do they behave the same hobby servos then? they 'know' their position.. have (roughly) 0-180 degrees of travel? (how does that equate to the linear motion.. just mapped out?)
What is the torque on these linear type servos? (this may fit perfect for a project where I need to push/lift something vertically!)
Those particular linear servos are tiny, weighing only 1.5 gram. They are driven like standard hobby servos (1 to 2ms pulses with 1.5 the centre) but obviously the travel is from one end to the other not any number of degrees. They might lift about 20 grams but probably not much more.
Steve
I'm not sure what 20 grams equals to as far as 'force' (I'm trying to use it for pressing/pushing an optics measure for liquor bottles)
the small seems to have the right 'footprint'... just not sure if the torque if up to par for the task.
vinceherman:
I do not know how thick your cover will be.
But liner servos have a fairly small profile.
Aliexpress has them for about $6 each.
Wow! Why have I never seen/heard of these!? I'll definitely be looking for them in the future. Thanks for the suggestion!
xl97:
I'm not sure what 20 grams equals to as far as 'force'
approx. 28 gms to the ounce. These are micro servos used in very small limited applications. Been around almost since r/c was invented.
With a standard servo, the force is usually quoted as grams per centimeter gm/cm as it is rotational but with a linkage attached it becomes almost linear, and this almost linear I think would be sufficient for your needs.
Most mini metal geared servos will push around 1.8kg on 4.8v...cheap and small.
Servo could be mounted inside the eyeball itself with linkage to the outer rim.
With the advent of quad cameras, plenty to see.
Actually with 2 servos on a gimbal it covers an x-y axis.
Not a bad project really as it could be expanded to include many different sensors with Arduino such as auto tracking or joystick control via radio link as well as many other.
Perhaps look at gimbal mechanisms so you can get a bit of a sense of direction for your mechanical setup.
With the advent of quad cameras, plenty to see.
Other than that try to work out why a 2d painting eyes follow you around the room.
I think I've figured out how to set up the eye and it's movement range. I had always considered using a ball joint or something similar. So I was gonna set up a makeshift ball joint, consisting of two bowl-like cups (bare with me, I made them myself so my description of them is probably going to sound kind of weird haha) and between them I'm going to place a ball. The bottom bowl will be place on the inner binder's cover and the top bowl till be placed on the underside of the eye. With the ball in between the two bowls it will kind of be like a sandwich. Then there will be 1 servo on the side of the eye to control the UP/DOWN movements, and a servo on the adjacent side of the eye, controlling its LEFT/RIGHT movements. Hopefully, this will give it those 4 basic movements, while still letting it sort of roll thanks to the ball.
As for the blink, that's still a bit of a head-scratcher. But that'll have to take a back seat for now, because until I can get my sketch to work for the eye movement, the blink isn't important.