Society of Robots - Robot Forum

Mechanics and Construction => Mechanics and Construction => Topic started by: HopWorks on August 12, 2013, 04:29:17 PM

Title: Not necessarily a bot - Halloween props and decorations
Post by: HopWorks on August 12, 2013, 04:29:17 PM
I Googled active robotics forums and this forum came up first, and seemed very active. That's really good! I want to be where there are a lot of people interested in things that interest me! =)

I think I have most of what I want to do figured out, and I believe that if you post asking a question, you should tell people why and what it's for.

I have an idea for Halloween this year that is creepy and totally doable via microcontrollers and robotic mechanics. I want to ask for advice on this here though because I have never bought a servo before, let alone control them, and my project is very specific on action.

I have 4 cute dolls and I plan to remove their heads from their bodies, and place the head on a servo with a large wheel that is a diameter equal to the severed circumference. I will mount the servo on a pole that will be placed in the ground next to my home's entry pathway. This is so I can rotate the head to face newly discovered trick or treat prey. But that isn't enough...

I want to animate the doll's eyes as well. I figured mini servo's are great for this. SO I am looking at 4 standard servo's (torque isn't important) and 8 mini servos for all the eyes.

For the eyes that are stationary in the stock head, I thought that if I can remove them, I can mount them on the mini servo's to make them turn left and right. Lateral movement is all I am looking for. Up and down is overkill, but possible, say, for tall parents that are looking at my doll heads.

I plan to put a camera in their mouth. This camera will feed a raspberry pi running Debian and a facial recognition app. Yeah, I know what you're thinking. That means 4 RPi's, one for each doll head.

What I need advice on is EYES! I need eyeballs. A wide selection to pick from. And maybe a servo controller capable of handling 8 mini servos and 4 standard servos also. A single raspberry pi is totally capable of handling all the servos through such a controller, but the camera feeds for facial recognition might not be able to be demultiplexed.

So to summarized, I need eyeballs, servos (8 mini, 4 standard), and maybe a controller for all of those servos. I don't need to worry about torque I think. The controlled object will be mounted on top and should be very light.

Any thoughts, questions, insults, whatever are anxiously anticipated! And I sincerely thank you for your time!

Gary (Hop)

EDIT! I almost forgot what it will do! The doll head detects movement, asks "Want some candy" through a speaker in the head, and morphs the audio to something more demonic with time. The head and eyes track the trick or treat prey through camera object recognition. Once the "prey" leaves, the heads scream with white flashing eyes, and then laugh independently. They reset, then wait for the next prey.
Title: Re: Not necessarily a bot - Halloween props and decorations
Post by: jwatte on August 12, 2013, 08:35:17 PM
Cheap servos:

Servo controllers: Pololu Maestrol speaks USB. If you have four Pi:s, you may want four Mini Maestros (the mini does 6 servos) so each doll is truly independent. You'll need some power supply, too.

Eyes: No idea. Ask someone in a theater prop department, perhaps? Or, if these are bigger heads, try ping pong balls and paint the eyes on them.
Title: Re: Not necessarily a bot - Halloween props and decorations
Post by: HopWorks on August 13, 2013, 02:11:38 PM
That would be too big but that's a great idea for a larger model! Awesome! Thanks for the advice on the servos and controller!