Vacuum/Magnetic Feet for a Walking Robot

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Hello GazeboSim,

I have a robot model similar to the image below (collision shown). This is a 10 linkage robot with 9 DOF, and I have already calculated joint angles required for walking through MoveIt! with a simulated robot. I am doing this with two robot models in my URDF, one for each foot fixed to the ground (one MoveIt! planning group for each robot model).

I am wondering if there is some way to load a new robot model (neither leg fixed to ground), and simulate walking with vacuum/magnetic feet.

I would pass the joint angle trajectories from MoveIt! with a simulated robot to the new robot model with the vacuum/magnetic feet. Gazebo would take care of which foot is in contact with the ground and plan the corresponding trajectory.

I have found the gazebo_ros_vacuum_gripper plugin, but have not been able to get this to work with ROS Indigo and Gazebo 2.2. Perhaps I am misunderstanding how to add this to my URDF. So far this has been my attempt:

world link
  floating joint (world->vacuum)
vacuum gripper
  fixed joint (vacuum->link1)
link1
...
link10
  revolute joint (link10->vacuum)
vacuum gripper

What I don't understand is contacting my robot base_link (link1) to world frame. If I do a revolute joint as specified in the plugin API, then the robot will never be able to lift it's foot off the ground. So I tried a floating joint, but did not have any success.

I have also tried using the ROS service /gazebo/apply_body_wrench/ instead of the vacuum plugin, but with no success either (for the same reason).

So my question comes down to is it possible to simulate a vacuum/magnetic foot for base_link through the URDF in which I can use it for walking?

Any help would be appreciated, thanks!