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ur5 robot wrist splits with collision

asked 2018-04-03 07:13:51 -0600

tseco gravatar image

Hello,

We are working with an UR5 robot and gazebo 7.0.

We move the robot with a ps3 joy. When there is a collision between the robot and for example a table, the wrist3 splits from the previous joint. We would like to avoid this effect. We played around with the effort values, friction and damping without success.

We would like to grasp an objetct using the vacuum gripper, but at the very moment when the wrist contacts with the object the last joint of the arm (wrist3) splits.

Find attached two pictures, one before the collision and the other with the table collision. Any suggestions?

Thanks in advance,

C:\fakepath\ur5_before_collision.png C:\fakepath\ur5_collision_table.png

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Hi, any suggestions about this issue?

tseco gravatar imagetseco ( 2018-05-03 02:43:17 -0600 )edit

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answered 2018-10-29 02:35:20 -0600

jalfonso gravatar image

updated 2018-10-29 02:36:25 -0600

See the response of raequi link text to similar question.

The cause behind this unrealistic interaction (that is, this lack of friction) is the use of PositionJointInterface for the UR10 joints. Here's a decent explanation of the phenomenon:

... using 'set position' or 'set velocity' in gazebo forces the physics simulation to try and accomplish this, which results in strange behavior. It's actually preferable, according to the Gazebo team members I'm working with, to always use 'set force' in Gazebo because that allows a more normal interaction when the commanded force of an arm joint puts the arm in contact with the environment.

Following an example, I made local changes to the universal_robot package to use EffortJointInterface instead. Some gain values from ARIAC provide decent performance. Thanks to everyone who contributed suggestions!

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Asked: 2018-04-03 07:13:51 -0600

Seen: 172 times

Last updated: Oct 29