# Hungry Vampire Display 2016



## Greg G (Nov 4, 2012)

A modestly small porch display of mine.
There is a flapping bat you can't see that's making that other noise in the video (besides the thunder and lightning)
I definitely need to use more background decorations to cover the house siding and window to have a better effect.

Greg

https://photos.google.com/share/AF1...?key=LWFtMk1OX3NJNktHc0VNWEJ6ekVEeEtSYXlQSW13

https://photos.google.com/share/AF1...?key=LWFtMk1OX3NJNktHc0VNWEJ6ekVEeEtSYXlQSW13


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## RoxyBlue (Oct 6, 2008)

Modestly small, yes, but a very effective use of the space. The head movement and sudden pop up of the vampire are what we technically refer to as "way cool":jol:


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## jdubbya (Nov 6, 2005)

Dang! That was great! I really like the movement and then when it pops up and looks around! Wow! Nice job!!


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## heresjohnny (Feb 15, 2006)

Very effective use of space. Can you tell us more about the vampire?


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## Greg G (Nov 4, 2012)

Thx everyone. 
heresjohnny, 
the vampire head is just a hollow prop head I got online that I thought looked pretty cool (can get at horrordome and many other places). I added LEDs in the eyes, 2 servo motors and a servo block for both horizon and vertical 180 degree head rotation, and a small but powerful speaker for audio (in the upper chest) along with a controllable mp3 player module loaded with the various audio clips I want to play. I made the outer body from skeleton parts from Walgreens, a ghoul costume, PVC pipes, and some round duct work. I have a wooden base structure with the body on a winging wood plank (about a bolt through it) hooked to a pneumatic cylinder, with a valve for control, that propels the body to its upright position I used a 6 Gallon electric pneumatic pump to supply the air pressure. All of these devices are controlled by an Arduino Mega micro controller using it's standard low level libraries and prop controller software I wrote (mainly as an exercise in doing this as I'm a software engineer by profession).
I wanted the vampire head to have a fairly large range of motion, be very quick in its movements, and be able to precisely control the position of the head, so I used 333 oz/in servos (a little more than 20 lbs/inch) servos for both the horizontal and vertical rotational motion and kept the rotational mass of the head as little as possible and as close to the center of the head as possible. I didn't add a third servo for head tilt as I wanted to keep things simple for this go around (plus space in the head was tight with the way I had things connected), and thought I could get pretty good motion with just those two. The horizontal head rotation is accomplished via a servo in the body that rotates the PVC pipe that is connected to the vertical servo in the head. I have the micro controller output settings every 1/10 second to all devices, and it just uses a software table that has the setting for each device as entries in the table (something very simple). The hardest part of all this was controlling the speed from bent over to upright position. Even with all the air speed controller valves I ended up having to use car bungee tie cords to reduce the speed at the fully upright and fully bent over points to keep the body from slamming into those positions too hard (possibly I'll switch to a linear servo for that but those are more expensive for the same kind of power). The other thing about the servos is that under stress they emit a high pitched noise as they hold their position. It's not loud but noticable and I covered it up by the munching, sucking sounds of the vampire when it was bent over (the vertical servo is holding the head parallel to the ground at that point). 

My next enhancement is adding a moving mouth controlled by a small servo.


Greg


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## Greg G (Nov 4, 2012)

In the prior post I meant oz-inches and lb-inches for the servos not oz/in and lb/in


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## Hairazor (Mar 13, 2012)

Great use of a small space and that Vampire is BOSS!


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