Setting contact coefficients

edit

We have designed our own magnetic gripper for a pick and place application. I was successfully able to import this and visualize the inertias in Gazebo.

But when I visualize the contacts, the vector keeps on moving frantically. Even though the movements of the arm itself is very smooth, when it comes in contact with another object, it starts vibrating. https://youtu.be/eP29QGYoQhY

I dug into PR2 gripper because it behaves very realistically when it is in contact with other objects and tried to implement the contact coefficients

Attempt 1 :

<surface>
  <friction>
    <ode>
      <mu>0.01</mu>
      <mu2>0.01</mu2>
      <fdir1>0 0 1</fdir1>
      <slip1>0.0</slip1>
      <slip2>0.0</slip2>
    </ode>
  </friction>
  <contact>
    <ode>
      <min_depth>0.005</min_depth>
      <kp>1e8</kp>
    </ode>
  </contact>
</surface>

Attempt 2 : This is exactly like the PR2 gripper

<gazebo reference="gripper_link">
  <turnGravityOff>true</turnGravityOff>
  <selfCollide>false</selfCollide>
  <mu1 value="${finger_tip_mu}" />
  <mu2 value="${finger_tip_mu}" />
  <kp  value="10000000.0" />
  <kd  value="1.0" />
</gazebo>
<gazebo reference="gripper_joint">
  <stopKd value="${finger_stop_kd}" />
  <stopKp value="${finger_stop_kp}" />
  <fudgeFactor value="${finger_fudge_factor}" />
  <provideFeedback value="true"/>
</gazebo>

This is my entire gripper xacro file :

<?xml version="1.0"?>
<robot xmlns:xacro="http://www.ros.org/wiki/xacro">

  <xacro:macro name="gripper_link" >
  <link name="gripper">    
    <inertial>
      <mass value="0.6" />
      <origin xyz="-0.02 0 0.04" />
      <inertia ixx="0.0003" ixy="0.0"  ixz="0.0"
               iyy="0.0009" iyz="0.0"
               izz="0.0008"/>
    </inertial>
    <visual>
       <origin xyz="-0.02 0 0.04" />
      <geometry>
        <mesh filename="package://ur5_pnp/meshes/gripper.stl" scale="0.01 0.01 0.01"/>
      </geometry>
    </visual>
    <collision>
       <origin xyz="-0.02 0 0.04" />
      <geometry>
        <mesh filename="package://ur5_pnp/meshes/gripper.stl" scale="0.01 0.01 0.01"/>
      </geometry>
       <surface>
      <friction>
        <ode>
          <mu>0.01</mu>
          <mu2>0.01</mu2>
          <fdir1>0 0 1</fdir1>
          <slip1>0.0</slip1>
          <slip2>0.0</slip2>
        </ode>
      </friction>
      <contact>
        <ode>
          <min_depth>5</min_depth>
          <kp>1e8</kp>
        </ode>
      </contact>
    </surface>
    </collision>
  </link>
  <gazebo reference="my_gripper">
    <material>Gazebo/Blue</material>
  </gazebo>

  </xacro:macro>
</robot>

But both the times I get the exact same behaviour. Is it something to do with friction or is it some other issue? This is my gripper's stl file

Edit 1: This gripper has no moving parts which is to simulate a magnetic gripper.

Edit 2: Updated link for STL file