[ros-users] urdf: multiple movements at the same joint

John Hsu johnhsu at willowgarage.com
Sat Jun 26 00:36:32 UTC 2010


Hi Grace,
I wanted to add that unfortunately our current simulation platform does not
allow chained joints.  We are looking into ways to make this happen.
John

On Wed, Jun 23, 2010 at 8:02 PM, Wim Meeussen <meeussen at willowgarage.com>wrote:

> Grace Lee,
>
> The best way to create joints with multiple DOF is to chain multiple 1
> DOF joints together. The links between the 1 DOF joints can just be
> empty placeholders that only have a name, but don't have an inertia
> etc. So, for example, if you want to create a 2 DOF link between
> 'link1' and 'link2', you can use:
>
> <link name="link1" />
>
> <joint name="joint1">
>  <parent link="link1"/>
>  <child link="link_virtual" />
> </joint>
>
> <link name="link_virtual" />
>
> <joint name="joint2" >
>  <parent link="link_virtual" />
>  <child link="link2" />
> </joint>
>
> <link name="link2" />
>
>
> Wim
>
>
>
> On Wed, Jun 23, 2010 at 5:33 PM, Yeon Grace Lee <yeongrace.lee at gmail.com>
> wrote:
> > Hello!
> >
> > I am writing an urdf for a human model and I am looking for the
> > cleanest way of allowing rotation along multiple axis. For example,
> > human head can tilt and pan- I plan to model this by making two
> > revolute joints - but only one joint is allowed between two links? I
> > am considering making a new set of links for each movement but I have
> > doubts as to whether this is the most optimal way. And I am not quite
> > sure where to place these new links (should I hide them inside
> > overlapping set of links?). Please let me know if you know a better
> > way of allowing multiple movements between two links.
> >
> > Thank you in advance!
> >
> > Grace Lee
> > _______________________________________________
> > ros-users mailing list
> > ros-users at code.ros.org
> > https://code.ros.org/mailman/listinfo/ros-users
> >
>
>
>
> --
> --
> Wim Meeussen
> Willow Garage Inc.
> <http://www.willowgarage.com)
> _______________________________________________
> ros-users mailing list
> ros-users at code.ros.org
> https://code.ros.org/mailman/listinfo/ros-users
>
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