Society of Robots - Robot Forum

Mechanics and Construction => Mechanics and Construction => Topic started by: gamilus7 on January 13, 2009, 12:11:12 PM

Title: animatronic groundhog
Post by: gamilus7 on January 13, 2009, 12:11:12 PM

I have a fake groundhog and I have a fake tree stump. making his eyes and mouth move are not a problem. I have halloween prop hacks for that. what i want to do is make this little guy rise up from the stump on groundhogs day turn180 degrees , see his shadow (projected on my house with floodlight) turn back to original position and go back down in stump. I'm thinking 12 volt gear motor with gear reduction chain for up and down motion. however making it stop and turn at top is problem. I have limited prop building skills. any help is appreciated.

Title: Re: animatronic groundhog
Post by: airman00 on January 13, 2009, 03:52:28 PM

how heavy is the groundhog?

Title: Re: animatronic groundhog
Post by: ArcMan on January 13, 2009, 03:57:54 PM

As airman00 is asking, the weight could be an issue.  But if it's not too heavy, you could mount it to a hobby server which could turn it 180 degrees and back.  A 1/4 scale servo could probably handle an actual groundhog.

Title: Re: animatronic groundhog
Post by: gamilus7 on January 13, 2009, 04:12:31 PM

hi. groundhog is light. about 1.5 pounds. thanks

Title: Re: animatronic groundhog
Post by: Dscrimager on January 14, 2009, 08:55:59 AM

A short pneumatic cylinder to raise and lower with a platform mounted on top (inside character possibly) with a continuous rotation servo. Use some limit switches or something to tell positioning and stop at each station.

See MonsterGuts.com for very good prices on cylinders and accessories.

Title: Re: animatronic groundhog
Post by: bukowski on January 14, 2009, 11:36:35 AM

Or a linear actuator. They are pricey tho. Check servocity.com, they have a range of strokes, but expect to spend a couple hundred. No need for the continuous rotation servo either.

Title: Re: animatronic groundhog
Post by: airman00 on January 14, 2009, 05:02:38 PM

Quote from: bukowski on January 14, 2009, 11:36:35 AM

Or a linear actuator. They are pricey tho. Check servocity.com, they have a range of strokes, but expect to spend a couple hundred. No need for the continuous rotation servo either.

or make your own linear actuator, its pretty simple
(http://www.engineersedge.com/hydraulic/images/linear-actuator-animation.gif)

Title: Re: animatronic groundhog
Post by: frodo on January 14, 2009, 05:05:46 PM

nice diagram airman. where did you find that?