6 legged robot slips on the ground, not able to move forward, what could be the problem?

edit

I made a 6 legged robot using a fork of this repo: https://github.com/utra-robosoccer/Tu...

Here is my fork: https://github.com/dfszabo/Tutorials-...

I tried a lot of stuff like setting minDepth, specifying mu1 and mu2 and the friction vector etc but still it slips.

I leave some snippets here, but It might be better to just check the repo.

the leg which touches the ground: <link name="${prefix}_leg_link_3">

<collision>
  <origin xyz="${leg_width/2 + axel_offset} 0 ${-leg_height/2 + leg_width/2}" rpy="0 0 0"/>
  <geometry>
      <box size="${leg_width} ${leg_width} ${leg_height}"/>
  </geometry>
  <surface>
    <friction>
      <ode><mu>100000.0</mu><mu2>100000.0</mu2></ode>
    </friction>
            <contact>
              <ode><min_depth>0.003</min_depth></ode>
            </contact>
  </surface>
</collision>

<visual>
  <origin xyz="${leg_width/2 + axel_offset} 0 ${-leg_height/2 + leg_width/2}" rpy="0 0 0"/>
  <geometry>
      <box size="${leg_width} ${leg_width} ${leg_height}"/>
  </geometry>
  <material name="orange"/>
</visual>

<inertial>
  <origin xyz="${leg_width/2 + axel_offset} 0 ${-leg_height/2 + leg_width/2}" rpy="0 0 0"/>
  <mass value="${mass}"/>

  <inertia
  ixx="${mass / 12.0 * (leg_width*leg_width + leg_height*leg_height)}" ixy="0.0" ixz="0.0"
  iyy="${mass / 12.0 * (leg_height*leg_height + leg_width*leg_width)}" iyz="0.0"
  izz="${mass / 12.0 * (leg_width*leg_width + leg_width*leg_width)}"/>
</inertial>

</link>

Another properties for the leg: <gazebo reference="${prefix}_leg_link_3"> <kp>1000000.0</kp> <kd>100.0</kd> <mu1>10000.0</mu1> <mu2>10000.0</mu2> <fdir1>1 0 0</fdir1> <maxVel>1.0</maxVel> <minDepth>0.0001</minDepth> <material>Gazebo/Orange</material> </gazebo>

To run it just use the launch command used in the README.md also you can find the command to run the program which moves the program here as well.