Hello, Gazebo does provide a mechanism for actuator arrays. This will allow you to specify either speeds, or target angles for each joint.
If you have special equations then, you should write your own controller. -nate On Mon, Jan 26, 2009 at 10:53 AM, smonckton <simon.monck...@drdc-rddc.gc.ca> wrote: > > Thanks, Yes, I anticipated the controller solution...but that seemed awkward > to me. In effect I would be adding a series of (albeit simple) > constraint/controller equations to the system of equations rather than > supplying data directly to ODE's integrator. I haven't written controllers > for Gazebo before, but I would assume that they have to exploit existing > joint types rather than (for example) a generic 6DOF joint and controller > that simply assigns 6 position/velocity values. > > If I have to use existing joint types, I suppose I will have to build (an > invisible) a serial manipulator to move the object around the world (a > 3-prismatic, 3-revolute joint for example) and accompanying controllers. > > Comments? > > > Nate Koenig wrote: >> >> If you want to pass 3D poses to Gazebo, and have Gazebo move the model >> to each of these points then you will get snapping - unless the >> relative differences between the 3D poses is small. You could write a >> controller that interpolates between 3D poses, kind of like >> keyframing. This will produce a smooth motion. >> >> -nate >> >> On Tue, Jan 13, 2009 at 3:30 PM, smonckton >> <simon.monck...@drdc-rddc.gc.ca> wrote: >>> >>> Well, after being away from this for awhile I'm back at this project >>> trying >>> to get an aircraft (driven by an external simulator) to render in gazebo >>> (svn version). Of course everything has changed so I'm trying to figure >>> out >>> the best way of doing this. I can see how a custom (invisible) controller >>> could be used to move an aircraft model around the 'world' ...is there a >>> better way? If I use simIface, I can only set modelPose and thus get the >>> snapping effect I encountered in my earlier experience in 0.7.0. >>> >>> Suggestions? >>> >>> >>> smonckton wrote: >>>> >>>> Hmmm, I tried this before (and I tried it again just to be sure). Using >>>> only SetPose (or the other Sets) snaps the model from point to point. >>>> Ok, >>>> I can understand that, I'm only updating the model at 3 Hz and no >>>> velocities are set. So if I then add the velocities put out by the >>>> external simulator the results are smoother...but still odd. I think I >>>> may >>>> have some coordinate transform issues here! In any case tracking the >>>> results is hard since the UAV moves out of the rendered area very >>>> quickly. >>>> Is there a way to enlarge the rendered volume w.r.t. the ObserverCam? >>>> >>>> Simon >>>> >>>> Nathan Michael wrote: >>>>> >>>>> Hi Simon, >>>>> >>>>> Try: >>>>> >>>>> this->body->SetPose(GzPose pose) >>>>> >>>>> or >>>>> >>>>> this->body->SetPosition(GzVector pos) >>>>> this->body->SetRotation(GzQuatern rot) >>>>> >>>>> See: >>>>> >>>>> http://playerstage.sourceforge.net/doc/Gazebo-manual-0.7.0-html/ >>>>> classBody.html#a6d32b9b81d5e09ebaec8bc852184837 >>>>> >>>>> Nate >>>>> >>>>> On Aug 27, 2007, at 3:24 PM, smonckton wrote: >>>>> >>>>>> >>>>>> Hello All, >>>>>> >>>>>> I'm a newbie to libgazebo and trying to figure out the best way of >>>>>> driving >>>>>> an aircraft model in gazebo through an external aviation simulator. >>>>>> I'm not >>>>>> using player, since we use (IMHO) a more flexible device server >>>>>> (MIRO, for >>>>>> those that are interested), so I'm talking directly to libgazebo. >>>>>> I've tried >>>>>> a few experiments setting positions, which works...sort of. If I set >>>>>> position directly, I get odd results that makes me think I'm >>>>>> fighting ODE. >>>>>> Basically, I just want to feed the aircraft state directly to a plugin >>>>>> model. I noticed that in the AvatarHeli model, the following >>>>>> approach is >>>>>> used in AvatarHeli::PositionGetCmd(): >>>>>> void AvatarHeli::PositionGetCmd() >>>>>> { >>>>>> gz_position_lock(this->position, 1); >>>>>> >>>>>> this->cmdLinVel = GzVectorSet(this->position->data->cmd_vel_pos[0], >>>>>> this->position->data->cmd_vel_pos[1], >>>>>> this->position->data->cmd_vel_pos[2]); >>>>>> >>>>>> this->cmdAngVel = GzVectorSet(this->position->data->cmd_vel_rot[0], >>>>>> this->position->data->cmd_vel_rot[1], >>>>>> this->position->data->cmd_vel_rot[2]); >>>>>> >>>>>> gz_position_unlock(this->position); >>>>>> >>>>>> return; >>>>>> } >>>>>> >>>>>> and then in Update(): >>>>>> this->PositionGetCmd(); >>>>>> // Rotate velocities into global cs >>>>>> pose = this->GetPose(); >>>>>> lv = GzCoordPositionAdd(this->cmdLinVel, GzVectorSet(0, 0, 0), >>>>>> pose.rot); >>>>>> av = GzCoordPositionAdd(this->cmdAngVel, GzVectorSet(0, 0, 0), >>>>>> pose.rot); >>>>>> >>>>>> // Dumb controller >>>>>> this->body->SetLinearVel(lv); >>>>>> this->body->SetAngularVel(av); >>>>>> >>>>>> >>>>>> ...which is a 'back door' method of setting the state. Over the >>>>>> long haul >>>>>> the position within the external simulator and gazebo would diverge >>>>>> using >>>>>> this method. A similar technique is used in Blimp. So the question >>>>>> is: " Is >>>>>> there a way of directly setting the state of an actor in libgazebo >>>>>> other >>>>>> than through derivative terms?" >>>>>> >>>>>> Simon >>>>>> -- >>>>>> View this message in context: http://www.nabble.com/External- >>>>>> simulators-and-Gazebo-tf4337753.html#a12355928 >>>>>> Sent from the playerstage-gazebo mailing list archive at Nabble.com. >>>>>> >>>>>> >>>>>> ---------------------------------------------------------------------- >>>>>> --- >>>>>> This SF.net email is sponsored by: Splunk Inc. >>>>>> Still grepping through log files to find problems? Stop. >>>>>> Now Search log events and configuration files using AJAX and a >>>>>> browser. >>>>>> Download your FREE copy of Splunk now >> http://get.splunk.com/ >>>>>> _______________________________________________ >>>>>> Playerstage-gazebo mailing list >>>>>> Playerstage-gazebo@lists.sourceforge.net >>>>>> https://lists.sourceforge.net/lists/listinfo/playerstage-gazebo >>>>> >>>>> >>>>> ------------------------------------------------------------------------- >>>>> This SF.net email is sponsored by: Splunk Inc. >>>>> Still grepping through log files to find problems? Stop. >>>>> Now Search log events and configuration files using AJAX and a browser. >>>>> Download your FREE copy of Splunk now >> http://get.splunk.com/ >>>>> _______________________________________________ >>>>> Playerstage-gazebo mailing list >>>>> Playerstage-gazebo@lists.sourceforge.net >>>>> https://lists.sourceforge.net/lists/listinfo/playerstage-gazebo >>>>> >>>>> >>>> >>>> >>> >>> -- >>> View this message in context: >>> http://www.nabble.com/External-simulators-and-Gazebo-tp12355928p21446949.html >>> Sent from the playerstage-gazebo mailing list archive at Nabble.com. >>> >>> >>> ------------------------------------------------------------------------------ >>> This SF.net email is sponsored by: >>> SourcForge Community >>> SourceForge wants to tell your story. >>> http://p.sf.net/sfu/sf-spreadtheword >>> _______________________________________________ >>> Playerstage-gazebo mailing list >>> Playerstage-gazebo@lists.sourceforge.net >>> https://lists.sourceforge.net/lists/listinfo/playerstage-gazebo >>> >> >> ------------------------------------------------------------------------------ >> This SF.net email is sponsored by: >> SourcForge Community >> SourceForge wants to tell your story. >> http://p.sf.net/sfu/sf-spreadtheword >> _______________________________________________ >> Playerstage-gazebo mailing list >> Playerstage-gazebo@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/playerstage-gazebo >> >> > > -- > View this message in context: > http://www.nabble.com/External-simulators-and-Gazebo-tp12355928p21671265.html > Sent from the playerstage-gazebo mailing list archive at Nabble.com. > > > ------------------------------------------------------------------------------ > This SF.net email is sponsored by: > SourcForge Community > SourceForge wants to tell your story. > http://p.sf.net/sfu/sf-spreadtheword > _______________________________________________ > Playerstage-gazebo mailing list > Playerstage-gazebo@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/playerstage-gazebo > ------------------------------------------------------------------------------ This SF.net email is sponsored by: SourcForge Community SourceForge wants to tell your story. http://p.sf.net/sfu/sf-spreadtheword _______________________________________________ Playerstage-gazebo mailing list Playerstage-gazebo@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/playerstage-gazebo
