• The behavior of the models and the environment of VRX is generated by a set of Gazebo Model Plugins.
• The current models used in these plugins are described in the Documentation Wiki: Gazebo Plugins.
• The model parameters (USV drag coefficient, wind speed, etc.) can be changed through the use of SDF configuration files.
• Changing these parameters allows users to test their solutions under a variety of conditions.

This tutorial describes the organization of the base parameter files in this repository, and gives examples explaining how to change wind, wave, fog and ambient lighting parameters.

Description	File Location	Notes
Hydrodynamic parameters (drag, added mass, etc.)	wamv_gazebo/urdf/dynamics/wamv_gazebo_dynamics_plugin.xacro	Current parameters based on FAU Publication https://doi.org/10.1016/j.oceaneng.2016.09.037
Wave characteristics (peak period, gain, direction, etc.)	wave_gazebo/world_models/ocean_waves/model.xacro	See current version of the VRX Technical Guide for the envelope of values used in the VRX challenge.
Propulsion characteristics (linear or nonlinear mapping and force limits)	wamv_gazebo/urdf/thruster_layouts/wamv_gazebo_thruster_config.xacro	Nonlinear mapping is based on experimental results from FAU https://doi.org/10.1016/j.oceaneng.2016.09.037
Windage coefficients of WAM-V	vrx_gazebo/worlds/sydneyregatta.world.xacro OR vrx_2019/worlds/sandisland.world.xacro	Windage coefficients from same FAU report https://doi.org/10.1016/j.oceaneng.2016.09.037
Wind velocity (mean speed, gust speed and direction)	vrx_gazebo/worlds/xacros/usv_wind_plugin.xacro	Windage coefficients from same FAU report https://doi.org/10.1016/j.oceaneng.2016.09.037
Fog and Ambient visual conditions	vrx_gazebo/worlds/sydneyregatta.world.xacro OR vrx_2019/worlds/sandisland.world.xacro	See current version of the VRX Technical Guide for the envelope of values which used in the VRX challenge.

These tutorials walk through examples for changing parameters of major environmental factors.