PDA

View Full Version : robot arm (Maya) - separate twist and bend joints

 swimtrunx10-22-2010, 01:11 AMHi, I have next to no rigging experience, but a rush job requires me to rig an industrial robot arm. This arm has six joints, beginning with a twist-only joint, followed by a 1-axis bend, then a second twist-only, second bend, then a third twist and then bend. I've tried creating the rig with the joints already rather bent or twisted, but it doesn't help much... Maya makes the rig very stiff. A coworker suggested that I do separate 2-joint IK rigs, but then what would control the twisting between these rigs? With this six-joint setup, the twist is definitely a part of the solution for the bends, if that makes sense. Thanks for any help Scott
swimtrunx
10-22-2010, 02:21 AM
Actually, I may have figured it out, but still have a question on using constraints. The robot rig acts basically the same as your arm if you were to group all your fingers together and point them out flat from your palm. Each segment can twist (pretend that your shoulder allowing your upper arm to twist is actually a twist joint in the middle of your arm), and I plan to manually control the orientation of what would be the wrist.

So then it's really simple - just a basic 2-joint rig, like shoulder to wrist.

I'll use constraints to control the movement of my model, and in order to get the parts to twist in the right locations, I'll use some aim constraints in the twisting sections, but this is where I run into problems with the aim constraints.

I can never get Maya to create an aim constraint that rotates an object only on its Y axis, (with the other axes turned off) but always points at the target. For some reason, as the target object moves around, the constrained object seems to drift away from properly pointing at it.

So if my target object has moved around to where the constrained object should rotate 180 degrees, the constrained object seems to rotate only up to about 45 degrees. Anybody know how to fix this?

thanks
Scott

CGTalk Moderation
10-22-2010, 02:21 AM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.