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Space Robotics Challenge
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Arm controllers can get stuck in limit cycle #87

Open osrf-migration opened 7 years ago

osrf-migration commented 7 years ago

Original report (archived issue) by Steve Peters (Bitbucket: Steven Peters, GitHub: scpeters).

I've seen the arm controllers get stuck in a limit cycle when the elbow is straight. Bending it seems to help stop the oscillations.

https://vimeo.com/204599150

osrf-migration commented 7 years ago

Original comment by Steve Peters (Bitbucket: Steven Peters, GitHub: scpeters).

The following trajectory seems to induce the limit cycle with using the arm_traj_yaml.py script:

diff -r bce4512568c28b810de18fe90be63ab8591ece44 scripts/Traj_data.yaml
--- a/scripts/Traj_data.yaml    Fri Feb 17 17:48:30 2017 +0000
+++ b/scripts/Traj_data.yaml    Fri Feb 17 13:17:51 2017 -0800
@@ -93,6 +93,13 @@
   - [4.0, "right", "0 0 0 0 0 0 -0.4"]
   - [6.0, "left",  "0 0 0 0 0 0  0"]
   - [6.0, "right", "0 0 0 0 0 0  0"]
+armLimitCycle:
+  - [0.5, "left",  "-1 0  2 0 0 0 0"]
+  - [0.5, "right", "-1 0  2 0 0 0 0"]
+  - [1.5, "left",  " 1 0 -2 0 0 0 0"]
+  - [1.5, "right", " 1 0 -2 0 0 0 0"]
+  - [2.0, "left",  " 0 0  0 0 0 0 0"]
+  - [2.0, "right", " 0 0  0 0 0 0 0"]
 armDemo1:
   - [2.0, "left",  "0 0 0 0 0 0 0"]
   - [4.0, "left",  "0.1 -1.3 1.94 -1.18 0.0 -0.07 0.0"]
osrf-migration commented 7 years ago

Original comment by Steve Peters (Bitbucket: Steven Peters, GitHub: scpeters).

I've reproduced it with the dart physics engine also, so I don't think it's an artifact of ODE numerical issues:

osrf-migration commented 7 years ago

Original comment by Steve Peters (Bitbucket: Steven Peters, GitHub: scpeters).

Currently attempting to reproduce in scs...

osrf-migration commented 7 years ago

Original comment by Tom Tseemceeb Xiong (Bitbucket: Tom_Xiong).

Any luck?

osrf-migration commented 7 years ago

Original comment by Steve Peters (Bitbucket: Steven Peters, GitHub: scpeters).

I was unable to run scs in my docker container. If someone else wants to try:

roslaunch ihmc_valkyrie_ros ihmc_valkyrie_scs.launch
osrf-migration commented 7 years ago

Original comment by Erica Tiberia (Bitbucket: T_AL).

No luck, I get the same errors. Is there any way to go back to the version that was working?

osrf-migration commented 7 years ago

Original comment by Louise Poubel (Bitbucket: chapulina, GitHub: chapulina).

osrf-migration commented 7 years ago

Original comment by Jeremy White (Bitbucket: knitfoo).

Issue #145 was marked as a duplicate of this issue.