Hi every one,

I am really getting frustrated with this problem. I have a Gazebo simulation of a KUKA_KR6R900SIXX with a gripper and an object to grasp. The issue is that every time i try to grasp the object, it slips between the fingers of the gripper. I can see the contacts established in Gazebo (see video) but it is like there is no friction between the object and the gripper fingers. What parameters should i fix to make the cylinder stick the gripper. See video here : KukagripperGazebo_Sim

Here is my configuration :

1) The gripper fingers link xacro config :

  <joint
    name="Mors_prismatic1_joint"
    type="prismatic">
    <origin
      xyz="0.0014158 -0.020952 0.0995"
      rpy="1.5708 0 0.5236" />
    <parent
      link="${prefix}tool0" />
    <child
      link="Mors_prismatic1_Link" />
    <axis
      xyz="0 0 1" />
    <limit effort="1000" lower="0.0" upper="0.02" velocity="0.01" />
    <dynamics damping="0.7" />
    <dynamics damping="1" friction="1"/>
  </joint>

  <joint
    name="Mors_prismatic2_joint"
    type="prismatic">
    <origin
      xyz="0.017437 0.011702 0.0995"
      rpy="1.5708 0 2.618" />
    <parent
      link="${prefix}tool0" />
    <child
      link="Mors_prismatic2_Link" />
    <axis
      xyz="0 0 1" />
    <limit effort="1000" lower="0.0" upper="0.02" velocity="0.01" />
    <dynamics damping="0.7" />
    <dynamics damping="1" friction="1"/>
  </joint>

  <joint
    name="Mors_prismatic3_joint"
    type="prismatic">
    <origin
      xyz="-0.018853 0.00925 0.0995"
      rpy="1.5708 0 -1.5708" />
    <parent
      link="${prefix}tool0" />
    <child
      link="Mors_prismatic3_Link" />
    <axis
      xyz="0 0 1" />
    <limit effort="1000" lower="0.0" upper="0.02" velocity="0.01" />
    <dynamics damping="0.7" />
    <dynamics damping="1" friction="1"/>
  </joint>

2)The gripper fingers gazebo xacro config :

  <gazebo reference="Mors_prismatic1_Link">
    <material>Gazebo/Blue</material>
    <turnGravityOff>true</turnGravityOff>
    <implicitSpringDamper>1</implicitSpringDamper>
    <kp>100000.0</kp>
    <kd>1.0</kd>
    <mu1>10.0</mu1>
    <mu2>0.1</mu2>
    <fdir1>1 0 0</fdir1>
    <minDepth>0.01</minDepth>
  </gazebo>

  <gazebo reference="Mors_prismatic2_Link">
    <material>Gazebo/Blue</material>
    <turnGravityOff>true</turnGravityOff> 
    <implicitSpringDamper>1</implicitSpringDamper>
    <kp>100000.0</kp>
    <kd>1.0</kd>
    <mu1>10.0</mu1>
    <mu2>0.1</mu2>
    <fdir1>1 0 0</fdir1>
    <minDepth>0.01</minDepth>
  </gazebo>



  <gazebo reference="Mors_prismatic3_Link">
    <material>Gazebo/Blue</material>
    <turnGravityOff>true</turnGravityOff>
    <implicitSpringDamper>1</implicitSpringDamper>
    <kp>100000.0</kp>
    <kd>1.0</kd>
    <mu1>10.0</mu1>
    <mu2>0.1</mu2>
    <fdir1>1 0 0</fdir1>
    <minDepth>0.01</minDepth>
  </gazebo>

3)The object (cylinder) urdf :

<?xml version="1.0"?>
<robot
  name="Cylinder">
  <link
    name="cylinder_link">
    <inertial>
      <origin
        xyz="-2.27623991509391E-49 1.09168197518227E-17 0.0125"
        rpy="0 0 0" />
      <mass
        value="0.12556160438235" />
      <inertia
        ixx="0"
        ixy="0"
        ixz="0"
        iyy="0"
        iyz="0"
        izz="0" />
    </inertial>
    <visual>
      <origin
        xyz="0 0 0"
        rpy="0 0 0" />
      <geometry>
        <mesh
          filename="package://Cylinder/meshes/base_link.STL" />
      </geometry>
      <material
        name="">
        <color
          rgba="0.647058823529412 0.619607843137255 0.588235294117647 1" />
      </material>
    </visual>
    <collision>
      <origin
        xyz="0 0 0"
        rpy="0 0 0" />
      <geometry>
        <mesh
          filename="package://Cylinder/meshes/base_link.STL" />
      </geometry>
    </collision>
  </link>

  <gazebo reference="cylinder_link">
    <implicitSpringDamper>1</implicitSpringDamper>
    <kp>100000.0</kp>
    <kd>1.0</kd>
    <mu1>10.0</mu1>
    <mu2>0.1</mu2>
    <fdir1>1 0 0</fdir1>
    <minDepth>0.01</minDepth>
  </gazebo>

</robot>

3)The gripper fingers controller :

gripper_controller:
  type: effort_controllers/JointTrajectoryController
  joints:
       - Mors_prismatic1_joint
       - Mors_prismatic2_joint
       - Mors_prismatic3_joint
  gains:
    Mors_prismatic1_joint:  {p: 50.0, d: 10.0, i: 0.01, i_clamp: 1.0}
    Mors_prismatic2_joint:  {p: 50.0, d: 10.0, i: 0.01, i_clamp: 1.0}
    Mors_prismatic3_joint:  {p: 50.0, d: 10.0, i: 0.01, i_clamp: 1.0}

4)The empty world configuration :

<?xml version="1.0"?>

<gazebo:world
  xmlns:xi="http://www.w3.org/2001/XInclude"
  xmlns:gazebo="http://playerstage.sourceforge.net/gazebo/xmlschema/#gz"
  xmlns:model="http://playerstage.sourceforge.net/gazebo/xmlschema/#model"
  xmlns:sensor="http://playerstage.sourceforge.net/gazebo/xmlschema/#sensor"
  xmlns:window="http://playerstage.sourceforge.net/gazebo/xmlschema/#window"
  xmlns:param="http://playerstage.sourceforge.net/gazebo/xmlschema/#param"
  xmlns:body="http://playerstage.sourceforge.net/gazebo/xmlschema/#body"
  xmlns:geo="http://willowgarage.com/xmlschema/#geo"
  xmlns:geom="http://playerstage.sourceforge.net/gazebo/xmlschema/#geom"
  xmlns:joint="http://playerstage.sourceforge.net/gazebo/xmlschema/#joint"
  xmlns:interface="http://playerstage.sourceforge.net/gazebo/xmlschema/#interface"
  xmlns:ui="http://playerstage.sourceforge.net/gazebo/xmlschema/#ui"
  xmlns:rendering="http://playerstage.sourceforge.net/gazebo/xmlschema/#rendering"
  xmlns:renderable="http://playerstage.sourceforge.net/gazebo/xmlschema/#renderable"
  xmlns:controller="http://playerstage.sourceforge.net/gazebo/xmlschema/#controller"
  xmlns:physics="http://playerstage.sourceforge.net/gazebo/xmlschema/#physics" >

  <thread>4</thread>
  <verbosity>5</verbosity>

  <!-- cfm is 1e-5 for single precision -->
  <!-- erp is typically .1-.8 -->
  <!-- here's the global contact cfm/erp -->
  <physics:ode>
    <stepTime>0.001</stepTime>
    <gravity>0 0 -9.8</gravity>
    <cfm>0.0000000001</cfm>
    <erp>0.2</erp>
    <quickStep>true</quickStep>
    <quickStepIters>10</quickStepIters>
    <quickStepW>1.3</quickStepW>
    <contactMaxCorrectingVel>100.0</contactMaxCorrectingVel>
    <contactSurfaceLayer>0.001</contactSurfaceLayer>
  </physics:ode>

  <geo:origin>
    <lat>37.4270909558</lat><lon>-122.077919338</lon>
  </geo:origin>

  <rendering:gui>
    <type>fltk</type>
    <size>480 320</size>
    <pos>0 0</pos>
    <frames>
      <row height="100%">
        <camera width="100%">
          <xyz>0.3 0 3</xyz>
          <rpy>0 90 90</rpy>
        </camera>
      </row>
    </frames>
  </rendering:gui>


  <rendering:ogre>
    <ambient>0.5 0.5 0.5 0.5</ambient>
    <sky>
      <material>Gazebo/CloudySky</material>
    </sky>
    <grid>false</grid>
    <maxUpdateRate>10.</maxUpdateRate>
    <shadowTechnique>none</shadowTechnique>
    <shadows>false</shadows>
  </rendering:ogre>

  <!-- ground plane -->
  <model:physical name="gplane">
    <xyz>0 0 0</xyz>    
    <rpy>0 0 0</rpy>
    <static>true</static>

    <body:plane name="plane">
      <geom:plane name="plane">
        <laserRetro>2000.0</laserRetro>
        <mu1>50.0</mu1>
        <mu2>50.0</mu2>
        <kp>1000000000.0</kp>
        <kd>1.0</kd>
        <normal>0 0 1</normal>
        <size>51.3 51.3</size>
        <segments>10 10</segments>
        <uvTile>100 100</uvTile>
        <material>Gazebo/GrayGrid</material>
      </geom:plane>
    </body:plane>
  </model:physical>

<!--
  <model:physical name="walls">
    <include embedded="false">
      <xi:include href="tests/willow-walls.model" />
    </include>
  </model:physical>
-->
<!--
  <model:physical name="willow_map">
   <xyz>-25.65 25.65 1.0</xyz>  
   <rpy>180 0 0</rpy>
   <static>true</static>
   <body:map name="willow_map_body">
     <geom:map name="willow_map_geom">
       <image>willowMap.png</image>
       <threshold>200</threshold>
       <granularity>1</granularity>
       <negative>false</negative>
       <scale>0.1</scale>
       <offset>0 0 0</offset>
       <material>Gazebo/Rocky</material>
     </geom:map>
   </body:map>
  </model:physical>
-->

  <!-- White Point light -->
  <model:renderable name="point_white">
    <xyz>0.0 0.0 8</xyz>
    <enableGravity>false</enableGravity>
    <light>
      <type>point</type>
      <diffuseColor>0.5 0.5 0.5</diffuseColor>
      <specularColor>.1 .1 .1</specularColor>
      <attenuation>0.2 0.1 0</attenuation>
      <range>10</range>
    </light>
  </model:renderable>

</gazebo:world>

5)My Gazebo Launch file :

    <?xml version="1.0"?>
<launch>
    <arg name="paused" default="false"/>

  <!-- remap topics to conform to ROS-I specifications -->
  <remap from="/arm_controller/follow_joint_trajectory" to="/joint_trajectory_action" />
  <remap from="/arm_controller/state" to="/feedback_states" />
  <remap from="/arm_controller/command" to="/joint_path_command"/>

  <!-- startup simulated world -->
  <include file="$(find gazebo_ros)/launch/empty_world.launch">
    <arg name="world_name" value="$(find kuka_kr6_gazebo)/worlds/empty.world"/>
    <arg name="gui" value="true"/>
    <arg name="paused" value="true"/>
  </include>

  <!-- urdf xml robot description loaded on the Parameter Server, converting the xacro into a proper urdf file-->
  <include file="$(find kuka_kr6_gazebo)/launch/load_kr6r900sixx.launch" />

  <!-- push robot_description to factory and spawn robot in gazebo -->
  <!-- <node name="kuka_kr6r900sixx_spawn" pkg="gazebo_ros" type="spawn_model" output="screen" args="-urdf -param robot_description -model kuka_kr6r900sixx" />-->
  <node name="kuka_kr6r900sixx_spawn" pkg="gazebo_ros" type="spawn_model" output="screen" args="-urdf -param robot_description -model kuka_kr6r900sixx -J joint_a1 0.0 -J joint_a2 -0.8915 -J joint_a3 1.4187   -J joint_a4 -0.0535   -J joint_a5 1.2381   -J joint_a6 0.0 -unpause" />


  <node name="cylinder_spawn" pkg="gazebo_ros" type="spawn_model" output="screen" args="-urdf -param cylinder_description -model cylinder -x 0.65 -y 0 -z 0.01" />


  <!-- convert joint states to TF transforms for rviz, etc -->
  <node name="robot_state_publisher" pkg="robot_state_publisher" type="robot_state_publisher"
  output="screen">
  </node>


  <!-- init and start Gazebo ros_control interface -->
  <include file="$(find kuka_kr6_gazebo)/launch/kr6r900sixx_control.launch"/> 


</launch>

6)The applied forces to open and close the gripper :

<group_state name="open_gripper" group="gripper">
    <joint name="Mors_prismatic1_joint" value="1000" />
    <joint name="Mors_prismatic2_joint" value="1000" />
    <joint name="Mors_prismatic3_joint" value="1000" />
</group_state>

<group_state name="close_gripper" group="gripper">
    <joint name="Mors_prismatic1_joint" value="-1000" />
    <joint name="Mors_prismatic2_joint" value="-1000" />
    <joint name="Mors_prismatic3_joint" value="-1000" />
</group_state>

Can you please tell me what i am doing wrong, i red every topic on the subject but no proposed solution helped. I am on Gazebo 9.8 and Ubuntu 16.04.

Thank you in advance.