On Wed, Jun 5, 2013 at 4:09 PM, Mrinal Kalakrishnan <
kalakris@usc.edu>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
> <adolfo.rodriguez@pal-robotics.com> wrote:
> >
> >
> >
> > On Wed, Jun 5, 2013 at 11:39 AM, Mrinal Kalakrishnan <kalakris@usc.edu>
> > 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
> >> <jonathan.bohren@gmail.com> wrote:
> >> >
> >> > On Tue, Jun 4, 2013 at 9:09 PM, Edwards, Shaun M. <sedwards@swri.org>
> >> > 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. Si usted recibe este mensaje y no es el
> > destinatario indicado, o el empleado encargado de su entrega a dicha
> > persona, por favor, notifíquelo inmediatamente y remita el mensaje
> original
> > a la dirección de correo electrónico indicada. Cualquier copia, uso o
> > distribución no autorizados de esta comunicación queda estrictamente
> > prohibida.
> >
> > CONFIDENTIALITY NOTICE: This e-mail and the accompanying document(s) may
> > contain confidential information which is privileged and intended only
> for
> > the individual or entity to whom they are addressed. If you are not the
> > intended recipient, you are hereby notified that any disclosure, copying,
> > distribution or use of this e-mail and/or accompanying document(s) is
> > strictly prohibited. If you have received this e-mail in error, please
> > immediately notify the sender at the above e-mail address.
> >
> > _______________________________________________
> > 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
>
(text/plain)