The ExternalWrench is a Gazebo model_plugin. It is used to apply external wrenches on any of the links of the model (to which this plugin is added).

Usage

The plugin takes gazebo_icub_robotname.ini as the configuration file. Add the following lines to the sdf model.

<plugin name='externalwrench' filename='libgazebo_yarp_externalwrench.so'>
      <yarpConfigurationFile>model://icub/conf/gazebo_icub_robotname.ini</yarpConfigurationFile>
</plugin>

On launching the model in Gazebo, the rpc port will be opened e.g. /<model>/applyExternalWrench/rpc:i. Connect to this port and type help to know the available commands.

Responses:
  The default operation mode is with single wrench
  Insert [single] or [multiple] to change the operation mode
  Insert a command with the following format:
  [link] [force] [torque] [duration]
  e.g. chest 10 0 0 0 0 0 1
  [link]:     (string) Link ID of the robot as specified in robot's SDF
  [force]:    (double x, y, z) Force components in N w.r.t. world reference frame
  [torque]:   (double x, y, z) Torque components in N.m w.r.t world reference frame
  [duration]: (double) Duration of the applied force in seconds
  Note: The reference frame is the base/root robot frame with x pointing backwards and z upwards.

The plugin will operate in single wrench operation mode by default. Users can switch to multiple wrenches operation mode. To change the operation mode of the plugin enter single or multiple in the rpc terminal. Every time the operation mode is changed the wrenches present at the moment will be cleared. To apply external wrenches enter the command format [link] [force] [torque] [duration] e.g. l_hand 10 0 0 0 0 0 10 which applies an external wrench of pure force with 10 N magnitude for a duration of 10 seconds. Resetting Gazebo world will clear all the existing wrenches and change the operation mode of the plugin to default option i.e. single.