broken link on prismatic robot

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Hi everyone,

I am currently trying to simulate an entirely cartesian prismatic handling robot as part of a thesis. I have had significant trouble with links disconnecting and moving their link origins inline with the global origin when I click play in gazebo.

I have finally got it down to a single broken link where the rest appear to be connected properly. Only my x direction joint will disconnect now when I click play in gazebo as you can see bellow:

It appears to float up and down in the y (with respect to its own origin not the global)

I have tried alot of different things and spent a significant ammount of time testing inertias and other variables but I cannot seem to get it to stay in place. This problem occurs with or without controllers connected and I have tested it without the child links as well as without some parent links to no prevail. If anybody could offer some advice it would be an absolute god sent as I am having a terrible time trying to solve this.

Attached below is an exert from my URDF containing the link as well as its parent and child link.

<link name="vertical_bearing_movement_link"> <inertial> <origin xyz="2.964694 -0.004890 0.084615" rpy="0 0 0"/> <mass value="34.463419"/> <inertia ixx="0.106131" ixy="0.000180" ixz="0.000205" iyy="131.223893" iyz="0.036326" izz="131.265729"/> </inertial> <visual> <origin xyz="0 0 0" rpy="0 0 0"/> <geometry> <mesh filename="package://cartesian_pharmacist_description/meshes/vertical_bearing_movement_link.dae"/> </geometry> <material name=""> <color rgba="0.75294 0.75294 0.75294 1"/> </material> </visual> <collision> <origin xyz="0 0 0" rpy="0 0 0"/> <geometry> <mesh filename="package://cartesian_pharmacist_description/meshes/vertical_bearing_movement_link.dae"/> </geometry> </collision> </link>

<gazebo reference="vertical_bearing_movement_link"> <kp>10000.0</kp> <kd>21.0</kd> <mu1>10.0</mu1> <mu2>10.0</mu2> <selfcollide>true</selfcollide> </gazebo>

<joint name="vertical_bearing_movement_joint" type="prismatic"> <origin xyz="0 0 0.017925" rpy="0 0 0"/> <parent link="vertical_guide_rail_link"/> <child link="vertical_bearing_movement_link"/> <axis xyz="0 0 1"/> <limit lower="0" upper="1.7741" effort="10000" velocity="0.89207"/> </joint>

<link name="horizontal_guide_bearing_link"> <inertial> <origin xyz="-0.071227 0.034973 -0.125114" rpy="0 0 0"/> <mass value="3.352575"/> <inertia ixx="0.011593" ixy="-0.001125" ixz="0.006331" iyy="0.017635" iyz="-0.000832" <br=""> izz="0.010935" /> </inertial> <visual> <origin xyz="0 0 0" rpy="0 0 0"/> <geometry> <mesh filename="package://cartesian_pharmacist_description/meshes/horizontal_guide_bearing_link_two.dae"/> </geometry> <material name=""> <color rgba="0.75294 0.75294 0.75294 1"/> </material> </visual> <collision> <origin xyz="0 0 0" rpy="0 0 0"/> <geometry> <mesh filename="package://cartesian_pharmacist_description/meshes/horizontal_guide_bearing_link_two.dae"/> </geometry> </collision> </link>

<gazebo reference="horizontal_guide_bearing_link"> <kp>10000.0</kp> <kd>10.0</kd> <mu1>10.0</mu1> <mu2>10.0</mu2> <selfcollide>true</selfcollide> </gazebo>

<joint name="horizontal_guide_bearing_joint" type="prismatic"> <origin xyz="0.20235 0.0299 0.12043" rpy="1.5708 0 1.5708"/> <parent link="vertical_bearing_movement_link"/> <child link="horizontal_guide_bearing_link"/> <axis xyz="0 0 ... (more)