Smile/Frown Mechanism for Canid/Wolf/Anthro Heads

Fe2O3

Hello, I have been working on an animatronic wolf head for some time now, but have hit a roadblock with the smiling/frowning mechanism. I am struggling to find a way to make the test fabric I'm using for fur move in the way I want it to. Despite me adjusting the length of the arms multiple times, It seems I either get too much range of motion, which causes the fur detach the servo arm, too little to actually convey the intended expression, or both simultaneously (where the fur is unable to pull into a smile or frown without binding. Can anyone recommend an  alternative solution/ share inspiration that might help.  My goal is to just raise or lower the corner of the lip, being able to pull it back or push it forward is an added benefit, but not necessary for the amount of additional mechanical complexity (I have run out of space on my current servo driver and have ditched the bottom smile servo).
Thanks
 

Here is a video link to the skull without fur running an animation loop: https://www.youtube.com/watch?v=LAXPD83Mm2Y

Alexander H

Looks great! I've also been printing mechanical parts, what material do you print from?

As for the fabric, I think I get what you're saying the trouble is, but if you have a video that might further help shine a light on the issue. I'm only new to animatronics but maybe with some visuals I or others may be able to identify where the problem is.

Is the fabric you use stretchy? Not sure if they make stretchy fur fabrics.

Fe2O3

Alexander H said:

Looks great! I've also been printing mechanical parts, what material do you print from?

As for the fabric, I think I get what you're saying the trouble is, but if you have a video that might further help shine a light on the issue. I'm only new to animatronics but maybe with some visuals I or others may be able to identify where the problem is.

Is the fabric you use stretchy? Not sure if they make stretchy fur fabrics.

Here is a link to the skull with fur: https://youtu.be/YbE857m1meg 
The material is ABS
right now I'm just using some felt to test how the armatures would affect the flexible skin, I should have considered that the foam used in stage animatronics is significantly stretchier. My guess right now is that the smile arm is placed too low to actually pull the face into a smile, since ive deleted the bottom arm.

Chris Ellerby

One thing that may help with the smile is having the smile servo pull a cable (similar to a bicycle brake cable) rather than being directly linked to the fur.   This way you can pull from any angle you like and make adjustments to get the smile just right.  You can get lightweight cables designed for RC airplanes that work great for animatronics.

You can also have a dimensional form (similar to what you have with your eyebrows) that sits under the fabric for the smile mech.  This would give the fabric and servo something to attach to, which would help you control how much motion you get. 

/Chris

Fe2O3

Chris Ellerby said:

One thing that may help with the smile is having the smile servo pull a cable (similar to a bicycle brake cable) rather than being directly linked to the fur.   This way you can pull from any angle you like and make adjustments to get the smile just right.  You can get lightweight cables designed for RC airplanes that work great for animatronics.

You can also have a dimensional form (similar to what you have with your eyebrows) that sits under the fabric for the smile mech.  This would give the fabric and servo something to attach to, which would help you control how much motion you get. 

/Chris

Thanks for the suggestion, however I'm still a bit hung up on how exactly I would implement that (cable placement, etc.). could you point me towards a good example for specifically the corner of the mouth? It seems like reusing the relatively common lip lifter cable (Like the one used on the puma guide) might not work the way I want it to. specifically I worry that when the mouth opens, it will always pull the face into a smile, because the distance between the top and bottom of the mouth naturally increase as the mouth opens (duh ;}). 

Chris Ellerby

Using a mech like in the Puma course should work for you, as opening the mouth does not generally increase the circumference of the mouth much, and the cable can adjust.  That said, every character will have its own unique challenges.  I would try to match the example in the Puma course and make adjustments where needed.

/Chris