Dear Ruben, Are you using KDL::TreeIkSolverPos_NR_JL for the inverse position kinematics ? If it is the case, would you have an example? I can't find any on the web :S Cheers, Ugo On 07/04/10 12:08, Ruben Smits wrote: > On Wednesday 07 April 2010 12:48:23 Sachin Chitta wrote: > >> Hi Ugo, >> >> You can use KDL to do inverse kinematics using one of the inverse >> kinematics solvers in the package. These are numerical solvers that >> operate on a KDL chain. First use the kdl_parser package to create a KDL >> chain and then initialize an inverse kinematics solver for the chain. The >> solution tends to be dependent on the initial state you pass into the >> solver and can sometimes get stuck in local minima. Also, I am not sure >> about how well the solvers handle joint limits. I believe more advanced >> solvers are in the works but I will let the orocos folks comment on that. >> > > If you need inverse velocity kinematics, which is commonly the case in > a control application, KDL contains various implementations including > the use of (task and/or robot space weighted)pseudo-inverses of the > jacobian and (damped) least squares solutions of the inverse velocity > problem. More advanced (constraint-based) solvers are currently being > developed, but these are still at the velocity level. > > > If you need inverse position kinematics, KDL does currently not have a > perfect solution, at the moment we only have an implementation of a > Newton-Raphson integration on top of one of the inverse velocity > kinematic solvers. > > Ruben > > >> Have a look at the api page here >> http://orocos.org/kdl/UserManual/kinematic_solvers for more examples. >> > This page (sadly) does not cover all the existing solvers :( > > >> The other option is to write your own solver (we have one for the PR2 that >> takes in a hint for one of the joint angles and then computes the other 6 >> analytically - >> www.ros.org/wiki/pr2_arm_kinematics> tics>) >> >> Sachin >> >> On Wed, Apr 7, 2010 at 3:28 AM, Ugo Cupcic >> > wrote: Hi all, >> >> Is it possible to use robot_state_publisher or some other ROS stack to >> do reverse kinematic on my urdf model? >> Or do I need to implement my own using the "Coding a realtime Cartesian >> controller with KDL" tutorial ? >> >> Cheers, >> >> Ugo >> >> >> -- >> Ugo Cupcic | Shadow Robot Company | >> ugo@shadowrobot.com Software Engineer 251 >> Liverpool Road >> need a Hand? London N1 1LX | +44 20 7700 2487 >> http://www.shadowrobot.com/hand/ @shadowrobot >> >> _______________________________________________ >> ros-users mailing list >> ros-users@code.ros.org >> https://code.ros.org/mailman/listinfo/ros-users >> >> >> >> -- >> Sachin Chitta >> Research Scientist >> Willow Garage >> > _______________________________________________ > ros-users mailing list > ros-users@code.ros.org > https://code.ros.org/mailman/listinfo/ros-users > > -- Ugo Cupcic | Shadow Robot Company | ugo@shadowrobot.com Software Engineer 251 Liverpool Road need a Hand? London N1 1LX | +44 20 7700 2487 http://www.shadowrobot.com/hand/ @shadowrobot