On Fri, Jan 13, 2012 at 11:17 AM, Armin Hornung wrote: > Hi Thomas! > > I edited in the description of the base_footprint with some minor > adjustments to keep it more general, and added a a rationale why this should > be as described (I think this makes it easier to understand). I added > another sentence to l/r_sole. What I don't fully understand are "It is > recommended to choose the origin as the projection of the body center on the > contact surface." for sole and toe. Is this the same as the sentence I added > afterwards? Then I would suggest to change "body center" into "support body > origin" or "support body link origin". (I am posting your mail back to the ml so that anyone can take part in the discussion) Yes this is right, I made the modification. > I also changed the frame hierarchy into a tree-format, what do you think? It is better, I fixed it to be valid rst. Is it not as nice as your tree, but I did not find any way to do a better formatting job... > You're right about the ankle, I haven't thought of non-rigid feet. I guess > I'm too fixed to our Nao's which are all rigid and have no toes. Thinking > about toes, I think there should be also room for an intermediate frame. In > URDF there will be a frame at the toe link which is a child of the ankle or > sole. Only then does the toe link follow (rigid or non-rigid like > ankle->sole, is this correct? Yes, this is correct. > Concerning Tully's comments on the mailing list I tend to agree. Torso also > sounds less medical or biological than chest (but that might only be my own > preference since I've used "Torso" more often than "Chest"). I like "hand" > more as it's more general than the "gripper" (which on the other hand is > very specific to the PR2) but afaik the whole grasping / arm_navigation code > in ROS is already using this convention. I switched to torso and gripper to follow PR2 naming scheme. I do not have any preference but we have to keep in mind that it would not be sufficient to use the PR2 arm navigation directly as PR2 frame names are l_gripper_* and not l_gripper directly. I it also a chance as it means that it is straight forward to add a fixed joint in the PR2 model to define the l_gripper / r_gripper as proposed in this REP. @Tully: IMHO adding a "strict" hierarchy will make the REP much more complex to follow when dealing with mobile robots. I think that humanoid robotos mechanical structure will evolve a lot in the future. It will be much easier to extend it when needed and complete it than freezing the whole thing right now. As far as I'm concerned, I use task space control so as long as I can identify the robot hands, I can generate a command which will move them at the appropriate position without having any knowledge regarding the intermediary frames and the real robot structure. Therefore, I would recommend not standardizing intermediary frames unless you find it is crucial to do so. The updated REP is here: - online version: http://laas.github.com/rep-coordinate-frames-for-biped-robots/rep-0120.html - git repository / sources: https://github.com/laas/rep-coordinate-frames-for-biped-robots Best, -- Thomas Moulard