Hi all.
I’m trying to rig and animate this landing leg but I’m having trouble getting the sliding bracket and piston to stay locked in the Z axis while the sliding bracket rotates with the leg to slide in the grove of the leg. I’ve tried various constraints and armatures but with only limit success.
Any help is most appreciated.
Here is what I take from what you are trying to do:
The vertical piston landing Leg (upper leg) stays vertical with the craft trough out landing. Is it extended for touch down and cushions (compresses) when landing? The sliding bracket, is it an additional cushioning device? Or is it just a slider to deploy the lower leg with 60 degrees tilt?
Hi ridix
Yes the piston and slider push down to deploy the leg. Here it is fully deployed with the foot.
OK I’ve had no luck in sorting this, I have googled the crap out of it tried all sorts of constraints and modifiers.
The only solution I’ve come up with is to animate it frame by frame which works but boy is it tedious.
have you looked for train piston constraint tracking?
thats how i did my avatars piston on his arm.
had to watch 3-4 videos to get it though.
if i could upload video i could show you.
Err where did that foot come from? It’s not apparent how it is supposed to move, and I’m guessing there is some sort of connection to a vehicle hull.
Hi PsychotropicDog.
Yeah I hid objects in the first pictures. I hope these will better explain what I’m trying to achieve.
parent the piston to cube 2
modeled this on my com and it works:)
you can use the cube 2 to move everyting
i’ll show you a pic when i get done
copy rotation of leg to bracket
Sometimes it’s hard to figure out a mechanical rig without running into cyclic dependencies or something just doesn’t want to track right. That’s when I’d cheat and use actions. (Also great if motions involved in a mechanical operation have an order to them.) Manuallly keyframe the animation for the operation sequence, save it as an action, then apply the action constraint to the objects. Moving the action controller then scrubs through the animation for the action, makes operating the rig whenever you want easy. (Not to mention less overhead and definite certainty in how it’ll work vs. the IK chain solver.)
Oh, you’ll have to use armatures (bones) to go with this approach. Might seem like a pain if you’re not used to it, but armatures opens up more options in terms of control. Also each bone serves the functionality of using two empties, and it forces you to consider heirarchy and define your pivot points.
Not sure if it’s the best option here given the description, but it’s something to keep in mind.
You have multiple mechanisms here: Piston, hinged landing strut,and Slider. Its simpler if you deal with them separately in the form of different object / rigging.
Here is simple slider. The hinge point of slider bracket travels in Z axis up and down. The slider on the bracket slides on groove along the slot on landing strut throughout the deployment. So the trick is to point the bracket along the landing strut and strut to point to bracket slider bone. I used Empty to each to track it. As for hinge bracket rotation I just copied bracket slider bone angle to hinge bracket rotation.
Now separate piston rig can be made to work by tracking hinge bracket hinge point.
Also (and quite-ruthlessly here …): “is this actually something that anyone is actually going to see?” If the answer happens to be “no,” then you don’t need to model it. If “yes,” then you need to restrict yourself only to the point(s)-of-view and camera angle(s) from which “the difference will actually make a meaningful, visually-discernible difference to the show.”
Sometimes, that’s a very hard call to make. I daresay most people “model first,” then try to figure out how they’re actually going to use the model. With intricate mechanics that can kill your schedule. “The good news is that the back of the building is beautiful. But the point is that it’s not the side that’s facing the road.” Lay out your shots and camera-angles first, then use that to tell you how to get the most bang for your buck.
Ridix would it be possible to get that .blend file?
Here is the file. http://www.pasteall.org/blend/31978
It works by grabbing Hinge bkt in pose mode, and moving it up and down in Z axis.
Thanks for the file Ridix.
Ok i had a go at replicating it, I can get everything to work but for the life of me i can’t get Hinge bkt to copy the rotation of Bkt slider.
I’ve tried all of the axis in the constraint menu but it either rotates in the wrong direction or not at all.
Here’s a version using IK. Move the IKTarget bone down and up in the Z-direction to control both the piston expansion and the leg/slider.
The ideal solution would instead have the rotation of the leg control everything, but that would need an IK tree instead of a single IK chain, and Blender IK trees don’t play nicely with stretches :(.
Best wishes,
Matthew
LegMechanism.blend (622 KB)
