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how to increase move_arm action speed ?

asked 2011-04-07 20:30:16 -0500

Guido gravatar image

updated 2014-01-28 17:09:30 -0500

ngrennan gravatar image

Hi all,

I'm currently testing on PR2, with the "move_arm to joint position" client, the motion's stability when stopping. In order to find the highest speed which ensure a smooth stop, I need to change arm's speed. Does anyone knows how to do that ?

Guido

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answered 2011-04-08 05:19:18 -0500

Sachin Chitta gravatar image

Hi Guido,

pr2_arm_navigation/pr2_arm_navigation_config/config/joint_limits.yaml contains the actual velocity and acceleration limits that are used. If you are using the trajectory filter (which you will be if you are using the launch files in pr2_3dnav), it will use these values to determine the maximum velocities and set appropriate times for each waypoint in the trajectory so that these limits are always obeyed.

The "Moving the arm through a Cartesian pose trajectory" tutorial does not use the trajectory filter though. It assigns the times to each waypoint individually. It computes the time between waypoints assuming a linear segment between waypoints.

The behavior of the underlying joint trajectory controller is described here: http://www.ros.org/wiki/robot_mechanism_controllers/JointSplineTrajectoryController

Hope this helps,

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Thank you for your answer, this is what I needed to know. By the way, I don't think it is worth a new question so i post it in this comment: why does the left arm have smaller velocity and acceleration values than the right arm ?
Guido gravatar image Guido  ( 2011-04-10 20:55:43 -0500 )edit
Probably because one of us changed it for the right and forgot to make the corresponding changes for the left :-)
Sachin Chitta gravatar image Sachin Chitta  ( 2011-04-13 12:58:13 -0500 )edit
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answered 2011-04-07 20:38:56 -0500

Ugo gravatar image

Hi,

If you're using the pr2 arms, I think those limits should be in the joint_limits.yaml file. Not sure which of those 3 is used but you should be able to check which one is loaded in your launch file. - trajectory_filters/trajectory_filter_server/config/joint_limits.yaml - pr2_arm_navigation/pr2_arm_navigation_tutorials/config/joint_limits.yaml - pr2_arm_navigation/pr2_arm_navigation_config/config/joint_limits.yaml

Cheers,

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Thank you for your answer. These files describe the speed limits, but is the PR2 always trying to reach maximum speed ? For exemple, in the "Moving the arm through a Cartesian pose trajectory" tutorial, speed is regulated by giving a time to reach each position fo the trajectory.
Guido gravatar image Guido  ( 2011-04-07 21:23:44 -0500 )edit

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Asked: 2011-04-07 20:30:16 -0500

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Last updated: Apr 08 '11