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two degree of freedom

asked 2012-02-17 09:19:02 -0600

manang gravatar image

Hi, I'm Angelo. How I can do a joint with two degree of freedom? If I do two time the joint, a first time for first degree of freedom, and a second time for second degree of freedom, with axis xyz="1 0 0" and xyz="0 1 0" respectively,and if i try to set any value on rpy in the first and second joint I see with rviz only the effect of the last join. thank you very mich Angelo

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What? This question doesn't make any sense.

Mac gravatar image Mac  ( 2012-03-28 09:53:53 -0600 )edit

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answered 2013-07-25 05:16:04 -0600

TabStock gravatar image

updated 2013-07-25 22:35:15 -0600

felix k gravatar image

Hello! I am assuming you mean in URDF. If so continue reading! I had the exact same problem with a hip joint the other day.

In order to get two degrees of freedom, make TWO revolute joints in the same location connected via a dummy link.

Example in Pseudo XML:

link thigh_link
link leg_link

link placeholder
 origin="0 0 0" //NOTE: this link has no change in location nor any geometry

joint hip_joint_x type="revolute"
 parent = "thigh_link"
 child = "placeholder"
 axis xyz="1 0 0"

joint hip_joint_y type="revolute"
 parent = "placeholder"
 child = "leg_link"
 axis xyz="0 1 0"

Hope this helps!

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Asked: 2012-02-17 09:19:02 -0600

Seen: 467 times

Last updated: Jul 25 '13