Invisible collision with lego_vhacd.obj [video]

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ianstahli
Posts: 1
Joined: Mon Nov 12, 2018 1:27 pm

Invisible collision with lego_vhacd.obj [video]

Post by ianstahli » Mon Nov 12, 2018 1:51 pm

Hello

I am training a neural net to learn to grasp objects. I use the provided lego.urdf as the object to pick up with a YuMi robot.

With the provided lego object I noticed quickly that a lot of slipping is happening. Changing the friction and force values of the gripper did not help against slipping.

Then I found the lego_vhacd.obj file that is also provided in the bullet3 repository and changed the collision part in the lego.urdf to make use of it.

Code: Select all

    <collision>
      <origin rpy="1.570796 0 0" xyz="-0.016 -0.016 -0.0115"/>
      <geometry>
	 <mesh filename="lego_vhacd.obj" scale=".1 .1 .1"/>
      </geometry>
    </collision>
With this change the object does not slip from the gripper that much, but another problem occurs: when the gripper is close to the object it will "sidestep" as though it collided with an invisible object. Here is a video of the situation and also how it looks like with the standard lego.urdf: https://drive.google.com/open?id=1xXUne ... eIEb4BeRzz.

Do you know why this occurs and how it could be solved?

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