View Full Version : Mechanical rigging problems.

07 July 2011, 03:05 PM
Hello everyone.

I'm Houdini user and right now I'm fighting with two rigs. I'm totally noob in rigging.

1. --------------------------------------------------------------------------------------

I'm working on Cain model (replica of Robocop 2). Model is not finished yet but I started to make rigging tests to solve problems I may encounter.

I hit the wall with pistons. This robot can move them in many directions and also rotates them. Their lengths can also vary indepedently on each. When you combine all this you need a lot more flexible piston than standard one.

it needs to allow move left and right hinges on both ends and orient automatically orient them to math angle change of main body of the piston. On attached picture you can see it under number (1.). As you can see it breaks but while I know how to solve this, if I do it I will lose other possibilities that I will explain below.

additionaly to moving left and right each hinge it needs to allow rotate each hinge (with pivot point placed in the base of each hinge) atleast 45 degrees in left and right (see point (2.) on attached picture). This causes another problem with main body and hinges not alligning properly. Again, I know how to solve this to and have points (a.) and (b.) accomplished in one rigg BUT I can't do this and have point (c.) that I will describe below also in this rigg.

on attached picture in point (3.) you can see that it also needs to allow rotate each hinge front-back with pivot in moddle of hinge atleast 90 deegres.

I attched also short film that presents all problems.

adding this last part to this rigg causes poin (a.) and (b.) to show up and I don't know how to solve it.

I can share asset and piston if you need.
Below you can download picture and video I mentioned.


2. --------------------------------------------------------------------------------------

Second rig I'm working on is Hexapod Phoenix. It's based in around 95% on small spider like robot models than can be bough and assembled by yourself.

I hit the wall with it's legs.

Watch this video ( ). I got three tests and in each I solved some problems but not all. Especially one is very troublesome. When you rotate it's body, foots stays in place but the rest of the leg just orbits around and reacts by changing angle. This is the biggest problem. When I try to rotate root of my leg, just like if his body rotated, leg just completely breaks (forget about orbiting at all).

Below you can download video that shows three of my tests. I can share scene with leg geometry and my tests if you need it.

First test doesn't follow properly hight changes from root HOOK that will be attached to main body. It just moves all leg up/down. It also breaks geometry when you try to rotate it simulating body orbiting like you can see on you tube film when the ant moves it's body ( once back is up and front is down and then switches).

Second also breaks when you try to simulate main body orbiting. It also breaks earlier when you move foot front-left (since his legs are moving doing circles I need around 150-180 degrees working good without flipping geometry).

Third test gives a little better results than second one. But it also fails miserably when you try to mimic main body orbiting.

From all three test only first allow to offset leg rotation so I can reuse it for all legs. And only second and third reacts correctly on main body hight change (foot stays on ground and leg straightens) while i first all leg follows body just like with normal FK solution.


Thanks in advance

07 July 2011, 01:09 AM
Weee, I made some progress.

Piston problem is Solved. You can watch test video:

I made also some nice progress with leg but still not everything works as should.

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07 July 2011, 01:09 AM
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