[ros-users] Actuating a wheeled robot URDF model in gazebo

[John Hsu]

Hi Dave,

can you post more of the console outputs?  The warning you posted is to be
expected; as there are no transmissions in the erratic setup in gazebo, it's
using the gazebo_ros_diffdrive to control a differential_position2d
controller.  I am only using mechanism control stack to publish fixed
transforms as commented in the urdf.  Assuming things compiled without
errors, the demo should bring up gazebo and rviz with an erratic in the wg
world.

In your urdf, some of the visual elements and collision elements are
inconsistent, was it done on purpose?  I've attached one with minor
adjustments.  Also, with the current setup, without a laser sensor publisher
you will not be able to drive the pioneer3dx model using 2dnav stack.

hope this helps,
John


On Fri, Jul 2, 2010 at 1:12 AM, David Feil-Seifer <
david.feilseifer at gmail.com> wrote:

> OK, I tried using the erratic model, with no luck. I got the following
> message:
>
> Node: /gazebo_1278058054452352000
> Time: 12.532000000
> Severity: Warn
> Location:
> ros/stacks/pr2_mechanism/pr2_mechanism_model/src/robot.cpp:RobotState::RobotState:170
> Published Topics: /rosout, /clock, /base_scan,
> /base_pose_ground_truth, /joint_states, /mechanism_statistics
>
> None of the joints in the robot desription matches up to a motor. The
> robot is uncontrollable.
>
> I tried adding a transmission, even though this was stated to be
> pr2-only on the wiki (see attached file), and that made the above
> error go away, but there was still no way to control the robot. While
> it was publishing a /base_pose_ground_truth topic, there was no
> subscription to anything other than /clock and /time. Is there some
> other way to defined motors in urdf for gazebo?
>
> A related question. The rear caster wheel is un-actuated. Is there any
> way for that joint to be published by default to a certain angle?
> Unless gazebo publishes an angle (which currently it will not without
> a transmission), the links will not show up in rviz. Obviously, this
> is not nearly as important, but a cosmetic issue.
>
> Thanks in advance,
> Dave
>
> On Tue, Jun 29, 2010 at 12:01 PM, John Hsu <johnhsu at willowgarage.com>
> wrote:
> > There is an erratic model in gazebo with 2dnav stack hooked up.
> > You'll need to get the unreleased wg-ros-pkg repository for this to work,
> >
> > svn co https://code.ros.org/svn/wg-ros-pkg/trunk wg-ros-pkg-unreleased
> >
> > The package is:
> >
> >
> /u/johnhsu/projects/cturtle_wg_all/wg-ros-pkg-unreleased/stacks/wg_robots_gazebo/erratic_gazebo
> >
> > This is an unreleased stack, but should be in working state:
> >
> > rosmake erratic_gazebo
> > roslaunch erratic_gazebo erratic_2dnav_demo.launch
> >
> > Let me know if you run into any issues.
> > John
> >
> >
> > On Tue, Jun 29, 2010 at 11:53 AM, David Feil-Seifer
> > <david.feilseifer at gmail.com> wrote:
> >>
> >> I am trying to make a urdf model for the pioneer 3dx robot that can be
> >> used in gazebo. The robot is a 2-wheeled diff drive robot with a singe
> >> rear caster.I have the robot visualizing correctly in rviz. However, I
> >> want this robot to be drivable. I am a little unclear from the wiki
> >> tutorials regarding gazebo and urdf on how to accomplish this? Is the
> >> GazeboRosDiffdrive node something that I could use for the pioneer as
> >> well as the erratic? What information do I need to have about the
> >> pioneer in order to make a urdf model work in gazebo?
> >> _______________________________________________
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> >
> >
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