Thread: Animating Bucky Arms

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I want to animate our Coachman's arms this year. I have some of the mechanics of it pictured in my mind but as heavy as the bucky arms are, I want to make sure I have plenty of power to drive things. Wiper motors seem to be the least expensive for the lifting power they offer and I want to be able to control them using VSA. I've read some posts about Pololu motor control boards and still have some questions and concerns. We have used wiper motors in other props and they ran one direction. Will the Pololu board enable me to control 2 wiper motors and will I be able to run them back and forth like a I do a 180 degree HiTec servo in VSA?

buckaneerdude, I think this thread will help Wiper Motor servo It shows how to convert a regular wiper motor into a servo motor and where to get the necessary parts/electronics. Keep us posted on your progress as this is something I am interested in.

Hey bd, something that might help as well, is to change the material of the arms.

Foam, with wire sub-structure, and a fiberglass resin coating, will give you bones that are much, much lighter than the resin bones of a Bucky, and are strong enough to take a fair amount of abuse from moving around.

My "flying skeleton" has arms like that, which I made in '05, and he flies for a few weeks every Halloween season, banging around in the wind, and his arms are still in great shape.
I am willing to bet that repetitive movement for your routine wouldn't be much more wear and tear.

If you can lighten the hands and arms a bit, you'll get better movement out of your motors, and not wear them out so quickly either.

That's a good thread and the cost of building that is hard to beat. I'm still wondering about those Pololu boards. If I remember right they will run 12vdc to the motor which would give maximum torque. If they will let me run the motor backward and forward I'm thinking I'll have more torque and perhaps more speed and I won't have the reliability worries that convinced Dr. Morbius to wire power to the slow terminals on his motor.

I like the idea too of maybe building lighter arms. Actually, Grimsley, our coachman, wears a long coat so I don't have to worry about reproducing every arm bone.

Originally Posted by buckaneerdude

That's a good thread and the cost of building that is hard to beat. I'm still wondering about those Pololu boards. If I remember right they will run 12vdc to the motor which would give maximum torque. If they will let me run the motor backward and forward I'm thinking I'll have more torque and perhaps more speed and I won't have the reliability worries that convinced Dr. Morbius to wire power to the slow terminals on his motor.

I like the idea too of maybe building lighter arms. Actually, Grimsley, our coachman, wears a long coat so I don't have to worry about reproducing every arm bone.

Just to clarify, Reliability isn't the reason I wired the motor to 5V. the reason is the Parallax Hbridge circuit can only handle up to 6VDC. This can be worked around by using a MOSFET power amp configuration to get 12V DC to the motor without burning up the Hbridge. The Polulu boards are great, but are almost 100 bucks each. If you're willing to spend the bucks, then go for it! If you want to save, then you will have to do some soldering.

I have used the EFX-TEC prop-1 controller board (EFX-TEK :: Prop-1 Controller) and the Parallax HB-25 DC motor controller (HB-25 Motor Controller) to control my wiper motor powered prop. The HB-25 allows connection of direct 12 volt power, independent of the controller board, so your motor can use its full torque capability. Prop-1 programming allows you to control speed and direction of the motor. Works great!

Originally Posted by Dr Morbius

Just to clarify, Reliability isn't the reason I wired the motor to 5V. the reason is the Parallax Hbridge circuit can only handle up to 6VDC. This can be worked around by using a MOSFET power amp configuration to get 12V DC to the motor without burning up the Hbridge. The Polulu boards are great, but are almost 100 bucks each. If you're willing to spend the bucks, then go for it! If you want to save, then you will have to do some soldering.

Thanks for the clarification. I get a little nervous about reliability. I've spent many hours futzing with props and such that stop working right when I should have spent the evening having fun.

Since I'm looking at running two motors, the Pololu board gets even more expensive. I think what frightens me about the method you used is the importance of the potentiometer and the way it is mounted. I worry about the epoxy cracking. I would guess that the pot would have to be perfectly centered on the axis of the motor or it would put stress on the epoxy. How did you ensure it was on center or was close good enough or did it matter?

Originally Posted by thisain'tmayberry

I have used the EFX-TEC prop-1 controller board (EFX-TEK :: Prop-1 Controller) and the Parallax HB-25 DC motor controller (HB-25 Motor Controller) to control my wiper motor powered prop. The HB-25 allows connection of direct 12 volt power, independent of the controller board, so your motor can use its full torque capability. Prop-1 programming allows you to control speed and direction of the motor. Works great!

The price of this controller seems more reasonable as far as price goes. It says it works with most anything that will generate a servo pulse so I'm fairly safe that VSA through an SSC32 board will work with it. What I don't see is a 3 pin terminal like is found on the SSC32 board. Would that be because it is powered separately from the SSC32 and only needs the pulse and ground connection? Sorry to be so dumb about this stuff!

The HB-25 is powered separately from the controller board. It uses a standard servo (3 pin) connection to the controller board. Here is a pretty good picture of the servo wire hook up- http://www.scary-terry.com/wipmtr/hb25demo.jpg. I would not power the HB-25 this way though as the wiper motor pulls too much current and the Wall wart can't power it.

I think I'm going to try something similar to what Bob did. I like how he has the horizontal axis at the shoulder and the left & right motion that adds. It's much more natural. Thanks for posting the link. I hadn't seen that before.