Hi, I have seen that in bipedal humanoid robots a contact model for the feet is specified in robot.gazebo.xacro file:

   <gazebo reference="LFoot">
 <kp>1000000.0</kp>
 <kd>100.0</kd>
 <mu1>1.0</mu1>
 <mu2>1.0</mu2>
 <fdir1>1 0 0</fdir1>
 <maxVel>1.0</maxVel>
 <minDepth>0.00</minDepth>
 <cfmDamping>1</cfmDamping>

I was wondering if I have to do the same for hands/grippers

Thank you.