[ros-users] move_arm tutorial - Moving the arm to a pose goal

Tue May 18 08:41:20 UTC 2010

Hi Adolfo,

The move_arm node relies on your controller to report back that the
final goal was achieved within the desired limits specified in the
goal message. The problems you are having on the robot could be due to
a steady-state error in your controller that prevents it from
converging to the goal. It could also be because you are setting the
convergence
limits too tight. Try and make them a little more lenient.

The first message that says "goal constraint violated" just refers to
the fact that you are at the starting point and not at the goal yet. I
will modify it to something more meaningful soon.

I am surprised by the report that the controllers do not converge in
simulation. I will check this out and let you know what's going on
soon. Are you using the latest versions of the simulator or are you
using the boxturtle versions?

Please keep me updated about your experiences with using the stack on
a different robot. We are currently in the process of updating and
adding more tutorials dealing with the collision map and collision
space representations and features for the stack.

Best Regards,
Sachin

2010/5/18 Adolfo Rodríguez Tsouroukdissian <adolfo.rodriguez at pal-robotics.com>:
>
>
> On Tue, May 18, 2010 at 9:46 AM, Ben Rudder <b.rudder382 at gmail.com> wrote:
>>
>> Hi All
>>
>> With the move_arm tutorials, I am always getting warnings that the current
>> position violates the goal constraints, which is pretty obvious, but it
>> often also misses a success message, or more frequently actually errors once
>> it has reached the goal (in each of the four functions) with 'trajectory
>> controller reports error'. Does this happen to everyone or should I check my
>> system for missing things?
>
> I have seen similar behavior as well on a PR2 simulation (as per the
> tutorials), the more common error being that the robot performs a motion
> that appears successful from visual inspection, but then waits in the goal
> configuration until it times out. I've also seen the warnings that the
> current position violates the goal constraints, but not on the PR2, but on
> one of our robots (so the error may be on my side and not on the ROS side).
> I'm still getting to grips with the internals of the arm_navigation stack
> (and making it work with our robots), and I wasn't going to post on the list
> until I had a more concise description of the problems I'm seeing, but now
> that you bring this up, I can confirm some of your issues.
> I'll get back to the list if I find out something meaningful.
>
> Best,
>
> Adolfo
>
>>
>> I am using the C++ versions.
>>
>> Also, in an effort to find out what was going wrong, I tried using the
>> CHOMP planner, which I still have not managed to make function at all for
>> planning...
>>
>> Thanks in advance
>> Ben
>>
>> On Tue, May 18, 2010 at 6:42 AM, Advait Jain <advait at cc.gatech.edu> wrote:
>>>
>>> Thanks Sachin.
>>>
>>> In case other people are also interested in using move_arm from
>>> python, my python equivalent for the MoveArmPoseGoalComplex
>>> tutorial is at -
>>>
>>>
>>> http://code.google.com/p/gt-ros-pkg/source/browse/trunk/hrl/hrl_simple_arm_goals/src/hrl_simple_arm_goals/move_arm_pose_goal.py
>>>
>>> It does the same thing as the C++ tutorial (in simulation).
>>>
>>> Advait
>>>
>>>
>>> On Mon, May 17, 2010 at 1:12 AM, Sachin Chitta <sachinc at willowgarage.com>
>>> wrote:
>>> > Hi Advait,
>>> >
>>> > Yes, the helper functions are only in C++ right now. You will be able
>>> > to address the move_arm node directly from both C++ or python using
>>> > the underlying action API. Have a look at this tutorial for how you
>>> > can specify pose goals directly without needing the extra helper
>>> > functions
>>> > (http://www.ros.org/wiki/move_arm/Tutorials/MoveArmPoseGoalComplex)
>>> >
>>> >  I don't have python tutorials but you should be able to follow the
>>> > python tutorials for actions
>>> >
>>> > (http://www.ros.org/wiki/actionlib_tutorials/Tutorials/Writing%20a%20Simple%20Action%20Client%20%28Python%29).
>>> >
>>> > I will be happy to accept a python version of the helper functions
>>> > though :-)
>>> >
>>> > Sachin
>>> >
>>> > On Sun, May 16, 2010 at 8:37 PM, Advait Jain <advait at cc.gatech.edu>
>>> > wrote:
>>> >> I am trying to replicate the functionality of this tutorial from a
>>> >> python node -
>>> >> http://www.ros.org/wiki/move_arm/Tutorials/MoveArmPoseGoal
>>> >>
>>> >> It isn't clear to me if there is a python equivalent for this
>>> >> function:
>>> >> move_arm_msgs::addGoalConstraintToMoveArmGoal(desired_pose,goalA);
>>> >>
>>> >> Am I missing something or do I need to write my own python
>>> >> versions for addGoalConstraintToMoveArmGoal (C+ code in
>>> >> move_arm_msgs/utils.h) and
>>> >> poseConstraintToPositionOrientationConstraints
>>> >> (motion_planning_msgs/convert_messages.h) to use the
>>> >> move_arm package from python?
>>> >>
>>> >>
>>> >> Advait
>>> >> _______________________________________________
>>> >> ros-users mailing list
>>> >> ros-users at code.ros.org
>>> >> https://code.ros.org/mailman/listinfo/ros-users
>>> >>
>>> >
>>> >
>>> >
>>> > --
>>> > Sachin Chitta
>>> > Research Scientist
>>> > Willow Garage
>>> > _______________________________________________
>>> > ros-users mailing list
>>> > ros-users at code.ros.org
>>> > https://code.ros.org/mailman/listinfo/ros-users
>>> >
>>> _______________________________________________
>>> ros-users mailing list
>>> ros-users at code.ros.org
>>> https://code.ros.org/mailman/listinfo/ros-users
>>
>>
>> _______________________________________________
>> ros-users mailing list
>> ros-users at code.ros.org
>> https://code.ros.org/mailman/listinfo/ros-users
>>
>
>
>
> --
> Adolfo Rodríguez Tsouroukdissian, Ph. D.
>
> Robotics engineer
> PAL ROBOTICS S.L
> http://www.pal-robotics.com
> Tel. +34.93.414.53.47
> Fax.+34.93.209.11.09
> 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 at code.ros.org
> https://code.ros.org/mailman/listinfo/ros-users
>
>

--
Sachin Chitta
Research Scientist
Willow Garage

-- 
Sachin Chitta
Research Scientist
Willow Garage