Hi Ugo, We've added the pre-grasp and grasp posture to the ReactiveGrasp action goal, it will come out in the next release. However, we probably won't be able to release this for at least a few days. Can you get on to trunk? A rosinstall file you could use is: https://code.ros.org/svn/wg-ros-pkg/branches/trunk_cturtle/rosinstall_files/cturtle/pr2_manipulation-cturtle-pr2all-overlay-devel.rosinstall Matei On Fri, Mar 4, 2011 at 12:55 AM, Ugo Cupcic wrote: > Hi, > > Thanks for your answers. > > Having pre_grasp_posture and grasp_posture would in the ReactiveActionGoal > would be the best for me. I'm using unstable (and I'll be happy to make an > overlay if you want me to test one branches). > > Matei, I already implemented the first approach you described, but as a more > "static" approach: the approach is just checking against collisions when > computing the path it's going to take, then the hand is closing from > pre_graps_posture to grasp_posture and that's it. No going back if we have > some contact, etc... I was assuming that it was meant to be like this in > this case, so as to have an easy to use and relatively direct approach to > grasping an object. That's why I wanted to implement the reactive grasp / > approach separately, as I saw it in your packages. > > Cheers, > > Ugo > > On Thu, Mar 3, 2011 at 10:01 PM, Kaijen Hsiao wrote: >> >> Hi Ugo, >> Would it be sufficient for your purposes to add >> sensor_msgs/JointState pre_grasp_posture >> and >> sensor_msgs/JointState grasp_posture >> to the ReactiveActionGoal? >> (If you want, I can also make a new CompliantCloseAction that contains >> these two things, so you can parallel our code--I've meant to use such >> a thing for our code for awhile even, but there was never a need for >> it until now.  We are likely to want such a thing for future arm/hand >> ports, anyway.) >> Are you using the trunk or Diamondback or unstable version of our >> code, or something else? >> >> -Kaijen >> >> >> On Thu, Mar 3, 2011 at 9:41 AM, Matei Ciocarlie >> wrote: >> > Hi Ugo, >> > >> > There are two things that the hand needs to do: move from pre-grasp to >> > grasp, and then close the fingers. Our nomenclature is definitely less >> > than ideal, they are both referred to as "grasp" in parts of the >> > pipeline... >> > >> > Reactive grasping as defined by the ReactiveGrasp.action actually >> > combines both. It should be called "ReactiveApproachAndGrasp" or >> > something in the vicinity... The implementation we have is PR2 >> > specific for both the approach and the finger closing part. You are >> > right, as a module that is (also) responsible for closing the fingers, >> > it should take in the grasp posture as well (not just the pose). >> > >> > When not using reactive grasping, we actually do split it into two. >> > First, open-loop inerpolated IK is done to get the hand from pre-grasp >> > to grasp. Then, a call to a GraspHandPostureExecution.action is made. >> > This call does contain all the info about the grasp .We have a PR2 >> > implementation that simply closes the fingers in response to that call >> > in the >> > pr2_gripper_grasp_controller package. >> > >> > You could write a sh_gripper_grasp_controller package that responds to >> > GraspHandPostureExecution goals, either in a reactive or non-reactive >> > way. This would only refer to the finger closing part (not the >> > approach) but you could implement all the behaviors that you mentioned >> > in your email. >> > >> > Alternatively, if you prefer a "ReactiveApproachAndGrasp" all in one >> > shot, we would indeed need to modify the ReactiveGrasp call to contain >> > the grasp posture. That also seems like a reasonable thing to do. >> > >> > Best, >> > Matei >> > >> > On Thu, Mar 3, 2011 at 4:16 AM, Ugo Cupcic wrote: >> >> Hi, >> >> >> >> In the reactive_grasp, the compliant_close function is not using the >> >> grasp >> >> posture from the database. I understand that it can work for the >> >> gripper, >> >> but for a more complex hand such as ours, I believe it would be a good >> >> start >> >> to have access to this grasp posture here. >> >> >> >> What I wanted to do in the reactive grasp, was (as a first approach): >> >>  - interpolate between current posture of the hand and "closed posture" >> >> (read from the database), while checking for contacts. >> >>  - when I have a contact on one finger, I stop moving this finger. >> >>  - when all fingers are touching lightly the object, close until force >> >> > X >> >> >> >> Is it not the purpose of the reactive_grasp server? Should I do that in >> >> my >> >> standard static grasp? Do I need to query my databases in my >> >> reactive_grasp >> >> node to get the list of possible grasps, or would it be possible to >> >> extend >> >> the content of the ReactiveGraspGoal message, so as to include this >> >> information? >> >> >> >> I hope my questions make sense, otherwise feel free to ask me for more >> >> info! >> >> >> >> 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 >> >> >> >> >> > >> > >> > >> > -- >> > Matei Ciocarlie >> > Research Scientist >> > Willow Garage Inc. >> > 650-475-9780 >> > _______________________________________________ >> > 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 > > > > -- > 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 > > -- Matei Ciocarlie Research Scientist Willow Garage Inc. 650-475-9780