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Is it possible to rig this robot with a telescopic arm?

Posted: Thu Oct 31, 2019 2:11 pm
by Gangster
I'm quite new to Duik and I'm very excited about this tool.
However, I need to rig a robot with a telescopic arm and I just don't get there. Is it even possible?

Please see my sketch attached. The lower arm is fixed (it should just rotate around the Y axis later on). The middle arm can rotate round the Z axis in both ends. And the four arms to the right should be telescopic (and not bend like a tail - it's always straight of course). As you change the position of the head, I want the telescopic arm to became longer or shorter, when the different arms should move equally in/out relative to eachother.


Best regards // Björn

Re: Is it possible to rig this robot with a telescopic arm?

Posted: Fri Nov 01, 2019 7:39 pm
by Duduf
Hi Björn,

I think this is doable with Duik and a few expressions.

Here what I would do:

- Create a structure with three parts
- add IK / autorig the two upper parts only (as the root won't move). You get your controller for animating the arm
- Create a new Structure with four parts
- Move it above the third part of the previous Structure, where the arm is telescopic. To make it easier with the expressions later, be careful to move and rotate only the first part of this new structure to align the whole structure to the arm. DO NOT manipulate the 2nd, 3rd and 4th part yet!
- Parent the first part to the arm
- Only then adjust the 2nd, 3rd and 4th part by changing ONLY the X position, keepin Y at 0.
- Separate the dimensions of the 2nd, 3rd and 4th part.
- Add an expression in their X position to move these parts.

The expression should be something like this (not tested)

Code: Select all

var controller = layer("controller");
var lowerArmLength = controller.effect("IK | Hand")("Upper length");
lowerArmLength = lowerArmLength + controller.effect("IK | Hand")("Upper stretch");
lowerArmLength * 0.25
You'd just have to change the multiplicator at the end, depending on the placement of the part you want. You could even replace it by a slider to be able to adjust it.

Re: Is it possible to rig this robot with a telescopic arm?

Posted: Sat Nov 30, 2019 8:42 pm
by Tracker115
Thanks for the explanation, this is pure gold to me! I was struggling to create a robotic-like animation and that will definitely help.