[ros-users] [Orocos-users] kdl::parser

Wim Meeussen meeussen at willowgarage.com
Sat Mar 5 21:23:09 UTC 2011

Shashank, (CC to ros-users)

> I have parsed a URDF model of my robot ( URDF includes joint limits ) via
> KDL parser to build a kdl::chain.
> This chain I want to use for doing inverse position kinematic solving using
> the KDL::ChainIkSolverPos_NR_JL class.
> This class requires joint limits. Now is it possible somehow to extract
> these values (joint limits from urdf) using the parser? Is there a better
> way to do it than hardcoding (defining it specifically) it?

A urdf tree contains joint limits, but a kdl tree/chain does not.  In
the kdl world the joint limits are not part of the model, but instead
are parameters to some of the solvers.  The best way to get access to
the joint limits is by using the urdf parser. You can pass the same
urdf file to both the urdf parser and the kdl parser (internally the
kdl parser uses the urdf parser before it converts the model to a kdl
format). The code api of the urdf model
<http://www.ros.org/doc/api/urdf/html/classurdf_1_1Model.html> should
help you find the joint limits.

Hope this helps,


Wim Meeussen
Willow Garage Inc.

More information about the ros-users mailing list