Working with the robot gripper

The gripper of the robot is designed for the picking and placing of blocks; the gripper is in the simple linkage category. There are two joints for the gripper, and each joint is prismatic. Here is the joint definition of one gripper joint:

   <joint name="finger_joint1" type="prismatic"> 
    <parent link="gripper_roll_link"/> 
    <child link="gripper_finger_link1"/> 
    <origin xyz="0.0 0 0" /> 
    <axis xyz="0 1 0" /> 
      <limit effort="100" lower="0" upper="0.03" velocity="1.0"/> 
      <safety_controller k_position="20" 
                         k_velocity="20" 
                         soft_lower_limit="${-0.15 }" 
                         soft_upper_limit="${ 0.0 }"/> 
    <dynamics damping="50" friction="1"/> 
  </joint> 

Here, the first gripper joint is formed by gripper_roll_link and gripper_finger_link1, and the second joint is formed by gripper_roll_link and gripper_finger_link2.

The following graph shows how the gripper joints are connected in gripper_roll_link: