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How to fix pr2_kinect_empty_world broken when collision?

asked 2012-04-02 00:14:30 -0500

sam gravatar image

When I add a box,and drag it to make a collision with pr2, sometimes caused gazebo to crash.

Here is the crash picture:

image description

And here is the crash error messages:

  [ERROR] [1333361033.522978054, 165.891000000]: TF_NAN_INPUT: Ignoring transform for child_frame_id "torso_lift_link" from authority "/robot_state_publisher" because of a nan value in the transform (-nan -nan -nan) (0.000000 0.000000 0.000000 1.000000)

How to fix it?

Thank you~

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answered 2012-04-02 07:47:48 -0500

hsu gravatar image

What you are seeing is probably the physics solver destabilizing, leading to NaN's in link velocities and eventually segmentation fault of the simulator. For objects with deep interpenetration, there is no known cure in ODE/Gazebo right now.

There is, however, something I am experimenting with that may potentially reduce or eliminate these types of numerical "explosion" by using a type of pose projection correction for interpenetrating bodies. You can see the improved interpenetration correction behavior in the following videos for simple shapes in collision and PR2 in collision. Unfortunately, there is no free lunch in this case, in complex dynamical scenarios for PR2, completely removing the original ODE interpenetration correction introduces limit cycles and errors in overall dynamic behavior of the robot: i.e. see PR2 drift backwards in first 3 seconds of this video. Any comments or suggestions are welcome here.

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So pose projection correction will solve the problem I have met?

sam gravatar image sam  ( 2012-04-02 20:59:15 -0500 )edit

maybe, it's experimental, so I wouldn't hold my breadth for it. But for now try not to spawn models that overlaps each other.

hsu gravatar image hsu  ( 2012-04-07 09:14:08 -0500 )edit

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Asked: 2012-04-02 00:14:30 -0500

Seen: 374 times

Last updated: Apr 02 '12