Question about small object and penetration

[chao0716]

Hi, I am new to pybullet. I am trying to use Franka Emika Panda at panfranka_panda/panda.urdf to grasp a small object (1cm2cm2cm). modified from pybullet_data/cube_small

When the object size is (3cm5cm5cm), the system looks fine. But when I decrease the object size to 1cm2cm2cm. The object becomes very easy to jump out of the gripper, and sometimes the gripper and the object penetration。

Is pybullet not supporting physical simulation with such small objects? or is there any way to improve it?

Some people say to adjust the timestep, but the tutorial says that it should not be changed at will.

The system looks like:

The urdf file of the object:
`

</contact>
<inertial>
  <origin rpy="0 0 0" xyz="0 0 0"/>
   <mass value="0.1"/>
   <inertia ixx="1" ixy="0" ixz="0" iyy="1" iyz="0" izz="0"/>
</inertial>
<visual>
  <origin rpy="0 0 0" xyz="0 0 0"/>
  <geometry>
			<mesh filename="cube.obj" scale=".005 .04 .04"/>
  </geometry>
   <material name="white">
    <color rgba="1 1 1 1"/>
  </material>
</visual>
<collision>
  <origin rpy="0 0 0" xyz="0 0 0"/>
  <geometry>
 	<box size=".005 .04 .04"/>
  </geometry>
</collision>

`

[olliejday]

I've got the same issue