IKFast and collision-aware IK

[Zdeněk Materna]

Hi all,

I just tried to replace KDL with IKFast for UR5 arm. IK works (I can set end effector pose in RViZ) but it seems that KDL generates collision free solutions (when possible) while IKFast doesn't care about collisions at all. Is this some problem with my configuration, or known "feature"? Is it possible to get collision-aware MoveIT+IKFast? Thanks in advance.

Zdenek

[robert.walenta]

Hi Zadenek,

unfortunately i don't have any info to your problem, because i wasnt able to create the ikfast plugin for the ur5. Can you maybe explain me how you get to the ikfast plugin?

In the past i tried the tutorial but i couldn't create the ikfast_output_file.cpp. Hoped then that it would be possible to work with the cpp file that is stored in the ur_kinematics directory of the repo but
i didn't worked ether to create a plugin.

Would also be happy for any advice.

Robert



 

[Dave Coleman]

As far as I know the kinematics solver you use should not really effect whether you get collision free solutions - MoveIt's IK interface does not include any concept of collision. Collision checking occurs after an IK solver produces a solution, in the scope of MoveIt! (robot_state, to be specific). If it is in collision, it is discarded I believe. 

Dave C

[Zdeněk Materna]

Hi Dave,

thanks for your notes. You are right. But I would expect that IK produces more solutions and then MoveIT will choose one without collision - this is how I understand collision-aware IK. Maybe I'm wrong so feel free to correct me. But it seems that in case of IKFast this doesn't work (at least for me). Maybe IKFast returns just one solution... But this is only my speculation, I need to check it somehow.

Zdenek

[Felix Meßmer]

Hello,

just wanted to point to a currently pending PR that provides analytic IK for UR5/UR10:
https://github.com/ros-industrial/universal_robot/pull/83

I haven't used it myself yet.
A feedback to the PR is appreciated.

Best,
Felix