Robotic arms hierarchy

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ik-123
Posts: 10
Joined: 26 Jan 2020, 13:39

Robotic arms hierarchy

Post by ik-123 »

Hi,

I have noticed in most of the robotic arms models (ie KUKA, UR ,..) that the hierarchy of the arm had 2 shapes of links: xxx_link1 , xxx_link1_visible. due to that, I have some questions:

1-could you please explain the need for each one.
2- can I remove this shape (xxx_link1 ) from the hierarchy? and how it would affect the simulation?
3- in the example scene (motionPlanningDemo1) the KUKA arm(LBR4p) used had a different hierarchy than the similar on the model browser, so is that a bug (old model) and if I used the arm in the model browser do that will affect the functionality?

thank you in advance,

coppelia
Site Admin
Posts: 10375
Joined: 14 Dec 2012, 00:25

Re: Robotic arms hierarchy

Post by coppelia »

Hello,

best is probably to have a read through this tutorial, but basically:

If your robot needs to be dynamically enabled (i.e. simulated by the physics engine), then you often want to use simplified shapes for dynamics (e.g. primitive shapes, convex shapes, or a compound of convex shapes). This way dynamics is more stable and operates also faster. But at the same time, you maybe want nice and appealing visuals, or use a different, more precise version of that shape for proximity sensor detection, distance calculation, etc.
So typically, you will have two versions of the same robot link: one dynamic, simplified (hidden), and one visible, more precise, attached on the first shape.

Read also more on this page.

Cheers

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