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Initial joint angles

asked 2015-08-24 11:14:53 -0600

Samper-Esc gravatar image

updated 2015-08-28 11:04:49 -0600

Hi,

Is there anyway to set the initial joint angles of the robot ? After reading a lot of pages and some packages of several robots, I have seen that it can be done by adding some args to the spawning node. However, I haven't been able to make it work for me. Right now, what I am doing is:

<node name="arm_base_spawn_urdf" pkg="gazebo_ros" type="spawn_model" args="-urdf -param robot_description -model schunk_lwa4p_and_base 
    -J schunk_lwa4p_and_base::J_foldingSupport 0.075 
    -J schunk_lwa4p_and_base::J1_PowerBall -1.5607 
    -J schunk_lwa4p_and_base::J2_PowerBall -0.3817"
    respawn="false" output="screen" />

The robot is a lwa4p mounted over a mobile platform. For doing that, I am using xacros, being the robot schunk_lwa4p_and_base the union of all the xacros.

I would really appreciate if you can help me. Thank you in advance,

JLuis Samper

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Do you need that from config file? Or would just setting defaults in the URDF be sufficient?

dornhege gravatar image dornhege  ( 2015-08-24 11:57:43 -0600 )edit

Setting defaults is sufficient

Samper-Esc gravatar image Samper-Esc  ( 2015-08-24 13:05:57 -0600 )edit
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answered 2017-02-08 17:53:27 -0600

bsaund gravatar image

Start gazebo paused, then have spawn_model unpause gazebo.

<include file="(find gazebo_ros)/launch/empty_world.launch">
   ...
   <arg name="paused" value="true">
</include>

<node name="arm_base_spawn_urdf" pkg="gazebo_ros" type="spawn_model" args="-urdf -param robot_description -model schunk_lwa4p_and_base 
    -J schunk_lwa4p_and_base::J_foldingSupport 0.075 
    ...
    -unpause 
    ..."/>

If this does not work, you can make your own version of "spawn_model", where you can pause gazebo, set the configuration, reset your joint controller, then unpause gazebo.

Some links I found helpful:

https://github.com/ros-simulation/gaz... https://github.com/ros-simulation/gaz...

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This odd little workaround works for me. Thank you, bsaund :) Can anyone explain what's going on here in detail? I assume the controllers are somehow seeing different initial joint states if Gazebo is paused during initialization. Is there any plan to implement a more elegant solution? I might be able to make this contribution if I can better understand the problem.

mogumbo gravatar image mogumbo  ( 2019-03-21 19:54:05 -0600 )edit
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Asked: 2015-08-24 11:14:53 -0600

Seen: 2,792 times

Last updated: Aug 28 '15

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