On Wed, Jun 5, 2013 at 4:09 PM, Mrinal Kalakrishnan wrote: > Let me correct that. We actually don't use a specific > "CartesianTrajectory" msg any more. Instead, we have a generic > "Trajectory" msg, which has a list of dimension names and > TrajectoryPoints - which makes it very similar to a JointTrajectory > msg. We then agree upon a naming scheme, like "r_hand_cart_x", > "r_hand_cart_force_x", and "r_hand_cart_gain_x" and so on. This allows > us to synchronize the execution of cartesian positions, forces and > gains (impedances), on multiple end-effectors if needed. We can also > send joint trajectories (or null-space joint posture trajectories) > through the same interface. > > Maybe this is not how you want the CartesianTrajectory msg to look, > but I just thought I'd mention where we ended up after a few > iterations, to have all the functionality we needed. > Interesting that you bring this up. The JointTrajectory and JointTolerance messages are in fact applicable to non-joint data, albeit their name. Furthermore, the de facto consumer of these messages, the JointTrajectoryActionController is largely a spline interpolator, and joint specifics appear in very localized places such as when interfacing with its inputs/outputs, or to determine whether a joint is continuous (by reading the URDF). It makes a lot of sense in my mind to have a more generic interpolator message and code that leverages it. As an obvious non-joint usecase, we have some RGB led arrays, and it would be just great to reuse a generic nD trajectory interpolator to control them. @Mrinal, does your implementation provide a mechanism for specifying custom interpolation functions for certain fields?; for example one might want to interpolate orientation data represented by quaternions, whose components are best not interpolated independently, but using slerp. Cheers, Adolfo. > - Mrinal > > On Wed, Jun 5, 2013 at 11:56 AM, Adolfo Rodríguez Tsouroukdissian > wrote: > > > > > > > > On Wed, Jun 5, 2013 at 11:39 AM, Mrinal Kalakrishnan > > wrote: > >> > >> We use a simple Cartesian trajectory msg internally at USC. The one > >> additional thing we have is accelerations at each > >> CartesianTrajectoryPoint. This allows us to use quintic splines in > >> cartesian space, for continuous accelerations between segments > >> (similar to the JointTrajectory msg). > > > > > > +1 for accelerations in the message specification. Also, the more > > parallelisms we can make with the JointTrajectory msg the better. If > you're > > used to the look& feel of one, it should be straightforward to use the > > other. > > > > Adolfo. > >> > >> > >> - Mrinal > >> > >> On Wed, Jun 5, 2013 at 3:53 AM, Jonathan Bohren > >> wrote: > >> > > >> > On Tue, Jun 4, 2013 at 9:09 PM, Edwards, Shaun M. > >> > wrote: > >> >> > >> >> Are you aware if anybody is currently using a cartesian trajectory > >> >> (this > >> >> definition or any other)? > >> > > >> > > >> > There's an old repository of Stu's here: > >> > > >> > > https://bitbucket.org/sglaser/pr2_controllers_exp/src/02aa61c12b4b/jt_traj_controller_msgs/msg > >> > > >> > I think at one point there was something similar in ros_control or > >> > moveit, > >> > too. I put together a minimal cartesian trajectory message which was > >> > just an > >> > array of Poses and Twists with associated durations, but I think it > >> > should > >> > have some of the features that the aforementioned review describes. > >> > Other > >> > than that I don't know. > >> > > >> > -- > >> > Jonathan Bohren > >> > Laboratory for Computational Sensing and Robotics > >> > http://dscl.lcsr.jhu.edu/People/JonathanBohren > >> > > >> > > >> > _______________________________________________ > >> > ros-users mailing list > >> > ros-users@code.ros.org > >> > https://code.ros.org/mailman/listinfo/ros-users > >> > > >> _______________________________________________ > >> ros-users mailing list > >> ros-users@code.ros.org > >> https://code.ros.org/mailman/listinfo/ros-users > > > > > > > > > > -- > > Adolfo Rodríguez Tsouroukdissian > > Senior robotics engineer > > adolfo.rodriguez@pal-robotics.com > > http://www.pal-robotics.com > > > > PAL ROBOTICS S.L > > c/ Pujades 77-79, 4º4ª > > 08005 Barcelona, Spain. > > Tel. +34.93.414.53.47 > > Fax.+34.93.209.11.09 > > Skype: adolfo.pal-robotics > > Facebook - Twitter - PAL Robotics YouTube Channel > > > > AVISO DE CONFIDENCIALIDAD: Este mensaje y sus documentos adjuntos, pueden > > contener información privilegiada y/o confidencial que está dirigida > > exclusivamente a su destinatario. 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