ASV Simulator

This package contains plugins and models for the simulation of surface vessels in Gazebo.

Dependencies

• A working installation of Gazebo Garden or later including development symbols.

Ubuntu

• Ubuntu 22.04 (Jammy)
• Gazebo Sim, version 7.1.0 (Garden)

macOS

• macOS 12.6.2 (Monterey)
• Gazebo Sim, version 7.1.0 (Garden)

Installation

Create a workspace

mkdir -p gz_ws/src

Clone and build the package

Clone the asv_sim repository:

cd ~/gz_ws/src
git clone https://github.com/srmainwaring/asv_sim.git

Compile the package:

Ubuntu

colcon build --symlink-install --merge-install --cmake-args \
-DCMAKE_BUILD_TYPE=RelWithDebInfo \
-DBUILD_TESTING=ON \
-DCMAKE_CXX_STANDARD=17

Source the workspace:

source ./install/setup.bash

macOS

colcon build --symlink-install --merge-install --cmake-args \
-DCMAKE_BUILD_TYPE=RelWithDebInfo \
-DBUILD_TESTING=ON \
-DCMAKE_CXX_STANDARD=17 \
-DCMAKE_MACOSX_RPATH=FALSE \
-DCMAKE_INSTALL_NAME_DIR=$(pwd)/install/lib

Source the workspace:

source ./install/setup.zsh

Usage

Set environment variables

# for future use - to support multiple Gazebo versions
export GZ_VERSION=garden

# not usually required as should default to localhost address
export GZ_IP=127.0.0.1

# ensure the model and world files are found
export GZ_SIM_RESOURCE_PATH=$GZ_SIM_RESOURCE_PATH:\
$HOME/gz_ws/src/asv_sim/asv_sim_gazebo/worlds

# ensure the system plugins are found
export GZ_SIM_SYSTEM_PLUGIN_PATH=$GZ_SIM_SYSTEM_PLUGIN_PATH:\
$HOME/gz_ws/src/asv_sim/install/lib

Anemometer Sensor

The package includes a custom Anemometer sensor to measure wind speed and direction.

Usage

Add the SDF for the sensor to a <link> element of your model.

<sensor name="anemometer" type="custom" gz:type="anemometer">
  <always_on>1</always_on>
  <update_rate>30</update_rate>
  <topic>anemometer</topic>
  <gz:anemometer>
    <noise type="gaussian">
      <mean>0.2</mean>
      <stddev>0.1</stddev>
    </noise>
  </gz:anemometer>
</sensor>

Published Topics

1. ~/anemometer (gz::msgs::Vector3d)

• header.stamp (gz::msgs::Time)
  The simulation time of the observation.

• x, y, z (double)
  The apparent wind velocity components at the sensor origin in the world frame (i.e. true wind adjusted for the link velocity).

Parameters

1. <always_on> (bool, default: false)
   Standard <sensor> parameter. See SDF documentation for details.

2. <update_rate> (double, default: 0)
   Standard <sensor> parameter. See SDF documentation for details.

3. <topic> (string, default: ~/anemometer)
   Standard <sensor> parameter. See SDF documentation for details.

Anemometer Example

To run the example:

gz sim -v4 -s -r anemometer.sdf

The system plugin is registered with the simulation in the world file using:

<plugin filename="asv_sim2-anemometer-system"
  name="gz::sim::systems::Anemometer">
</plugin>

You should see a world containing a single block at the origin. The figure below shows the block falling to demonstate the effect of motion on apparent wind:

When the block is at rest with axis aligned with the world frame, the true and apparent wind should be the same.

% gz topic -e -t /anemometer -n 1
header {
  stamp {
    sec: 61
    nsec: 369000000
  }
  data {
    key: "frame_id"
    value: "anemometer::base_link::anemometer"
  }
  data {
    key: "seq"
    value: "61368"
  }
}
x: -5
y: 1.4381672343972489e-17
z: -0.00099989893750004975

When the block is in motion, for instance by setting the z pose to 100 and letting it fall, the apparent wind will be adjusted for the object's motion.

gz topic -e -t /anemometer -n 1
header {
  stamp {
    sec: 58
    nsec: 596000000
  }
  data {
    key: "frame_id"
    value: "anemometer::base_link::anemometer"
  }
  data {
    key: "seq"
    value: "58595"
  }
}
x: -5
y: 1.959765959893313e-16
z: 25.675000101061269

License

This is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This software is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.