wave_params_tutorial

Adjusting the Waves

• Parameters for the wavefield are broadcast to the /vrx/wavefield/parameters topic by a Publisher plugin attached to the world.
• An instance of the wavefield plugin, which reads from this topic, must be attached to all objects affected by the wavefield.
• The parameters used by the publisher are stored in individual world files, found in vrx_gz/worlds.
• In this tutorial we will use the sydney_regatta world as an example.

Steps

Step 1: Modify Parameters

• Open vrx/vrx_gz/worlds/sydney_regatta.sdf and edit the values for direction, gain, period and steepness listed in the publisher plugin message:

      <!-- The wave field -->
      <plugin filename="libPublisherPlugin.so" name="vrx::PublisherPlugin">
        <message type="gz.msgs.Param" topic="/vrx/wavefield/parameters"
                 every="2.0">
          params {
            key: "direction"
            value {
              type: DOUBLE
              double_value: 0.0
            }
          }
          params {
            key: "gain"
            value {
              type: DOUBLE
              double_value: 0.3
            }
          }
          params {
            key: "period"
            value {
              type: DOUBLE
              double_value: 6.0
            }
          }
          params {
            key: "steepness"
            value {
              type: DOUBLE
              double_value: 0.0
            }
          }
        </message>
      </plugin>
  

For example, try changing the gain to 0.8.

Step 2: Rebuild

Recompile your workspace:

cd <VRX_WS>
colcon build --merge-install

Step 3: Test

Launch the simulation:

ros2 launch vrx_gz competition.launch.py world:=sydney_regatta

You should observe your WAM-V slowly moving due to the wind and bigger waves impacting the WAM-V.