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Inertia again: significant figures

Hi.

I'm facing really bad bugs which seem to be related to inertia. I'm trying to understand the issue with Gazebo and found that the inertia tensors are [0] for the smaller parts:

image description

This is consistent with my bugs, since with the large arm parts, it works more or less, but with the gripper, that becomes crazy. The small parts of the arm and the gripper have 1e-4 values for the inertia tensor.

So I wonder how many figures are considered in Gazebo. What are the best practice for simulating this kind of robot? (we could imagine to use a simple kinematic simulation for this part of the body, as they have a low contribution to the overall behavior)

Any inputs will be helpful.

This question is related to:

http://answers.gazebosim.org/question/4372/the-inertia-matrix-explained/

Inertia again: significant figures

Hi.

I'm facing really bad bugs which seem to be related to inertia. I'm trying to understand the issue with Gazebo and found that the inertia tensors are [0] for the smaller parts:

image description

This is consistent with my bugs, since with the large arm parts, it works more or less, but with the gripper, that becomes crazy. The small parts of the arm and the gripper have 1e-4 values for the inertia tensor.

Here is a short video:

http://www.youtube.com/watch?v=3T2s96NkvFI

The joint 3 is moved to 1.0 rad, the next links should stay in line (at 0 rad), but they don't. If you stay long enough (several tenth of second), they finally go to there stable position.

So I wonder how many figures are considered in Gazebo. What are the best practice for simulating this kind of robot? (we could imagine to use a simple kinematic simulation for this part of the body, as they have a low contribution to the overall behavior)

Any inputs will be helpful.

This question is related to:

http://answers.gazebosim.org/question/4372/the-inertia-matrix-explained/