finani/storm_gazebo_ros_magnet

a Gazebo plugin that computes the force and torque between multiple magnets.

Add compatibility with gazebo9 and change it to an capture module

capture and gazebo9 branches by finani

• The default branch is 'capture' which is capturing something with the capture module. The model is a position-velocity, angle-angular velocity dynamic model with a P-P control loop.
• The 'gazebo' branch is simulating dipole magnets in gazebo9, but it is unstable because of the magnet model.
• I recommend using 'capture' branch.

1. gedit ~/.bashrc

export GAZEBO_PLUGIN_PATH=$HOME/catkin_ws/build/storm_gazebo_magnet:$GAZEBO_PLUGIN_PATH

2. roslaunch storm_gazebo_magnet storm_gazebo_ros_magnet.launch

3. rostopic pub /magnet_weebee/cmd std_msgs/Bool "data: true"

true : false, -r 10

• source ~/.bashrc

• gedit dipole_magnet.world

<plugin name="dipole_magnet" filename="libstorm_gazebo_dipole_magnet.so">
  <bodyName>magnet</bodyName>
  <xyzOffset>0 0 0.2</xyzOffset>
  <rpyOffset>1.5707962368 0 0</rpyOffset>
  <xyzRange>0.5 0.5 10.0</xyzRange>
  <xyzVelLimit>5 5 10</xyzVelLimit>
  <debug>false</debug>
  <!-- Set to false if not using ROS -->
  <controllable>true</controllable>
  <topicNs>magnet_weebee</topicNs>
</plugin>

<plugin name="dipole_magnet" filename="libstorm_gazebo_dipole_magnet.so">
    <bodyName>magnet</bodyName>
    <debug>true</debug>
    <controllable>false</controllable>
</plugin>

This is a Gazebo model plugin that uses the magnetic dipole-dipole model to compute the force and torque between multiple magnets. The plugin is enabled per model and looks for other models in the gazebo world that have the same plugin. It only simulates magnetic interactions between magnets (not other materials).

The plugin requires the bodyName tag specifying which link is the actual magnet and dipole_moment which is a vector specifying the dipole moment of said magnet.

Example:

  <plugin name="dipole_magnet" filename="libgazebo_dipole_magnet.so">
    <bodyName>magnet</bodyName>
    <dipole_moment>0 0 1.26</dipole_moment>
  </plugin>

The magnitude of dipole moment of a cylindrical magnet can be computed using the formula:

    dm_mag = B_max * 4*pi * (h/2)^3/(2*mu_0) 

Where B_max is the remanence of the magnet, h is the height and mu_0=4*pi*1e-7 is the permeability constant.

Building the plugin

The plugin is a ros package so the build process is the same as any other package.

$ cd ~/catkin_ws/src
$ git clone https://github.com/vustormlab/storm_gazebo_ros_magnet.git
$ catkin_make -C ~/catkin_ws

Running Example

To run the example in the worlds/ directory run

$ rosrun gazebo_ros gazebo dipole_magnet.world

Citing This Work

If you use this work, please cite our RSS 2016 paper:

@INPROCEEDINGS{Taddese-RSS-16, 
    AUTHOR    = {Addisu Z. Taddese AND Piotr R. Slawinski AND Keith L. Obstein AND Pietro Valdastri}, 
    TITLE     = {Closed Loop Control of a Tethered Magnetic Capsule Endoscope}, 
    BOOKTITLE = {Proceedings of Robotics: Science and Systems}, 
    YEAR      = {2016}, 
    ADDRESS   = {AnnArbor, Michigan}, 
    MONTH     = {June}, 
    DOI       = {10.15607/RSS.2016.XII.018} 
}