Weeks 12-13: Gazebo Jazzy Simulation

Course Overview

Weeks 12 and 13 introduce Gazebo Jazzy, the next-generation robot simulator integrated with ROS2 Jazzy. Unlike legacy Gazebo Classic, Gazebo Jazzy (gz-sim) is built on a modular plugin-based architecture with physically accurate rendering and first-class ROS2 integration via ros_gz_bridge.

Week 12

World design, SDF environments, physics and wind simulation

Week 13

URDF/SDF robot modeling, sensors, drone & flight controller integration

Projects

Smart City Environment + Intelligent Quadcopter Drone with Vision

What is Gazebo Jazzy?

Gazebo Jazzy is the modern simulator release aligned with ROS2 Jazzy. It replaces legacy Gazebo Classic with a plugin-based architecture, offering improved performance, realistic sensors, and seamless ROS2 integration via ros_gz_bridge and ros_gz_sim.

Installation

Installing Gazebo Jazzy with ROS2 Jazzy

sudo apt update
sudo apt install -y \
  ros-jazzy-ros-gz \
  ros-jazzy-ros-gz-bridge \
  ros-jazzy-ros-gz-sim \
  ros-jazzy-ros-gz-interfaces \
  ros-jazzy-gz-ros2-control

# Verify
gz sim --version

Note: Ensure ~/.bashrc contains: source /opt/ros/jazzy/setup.bash

# Launch empty world to verify
gz sim empty.sdf

# Or via ROS2
ros2 launch ros_gz_sim gz_sim.launch.py gz_args:="empty.sdf"

Week 12 — World Building

Gazebo Jazzy Architecture

Key Components

Component	Description	Command
`gz sim`	Main simulator	`gz sim world.sdf`
`gz topic`	Inspect Gazebo topics	`gz topic -l`
`gz model`	Spawn/inspect models	`gz model -l`
`ros_gz_bridge`	Bridge ROS2 ↔ Gazebo	`ros2 run ros_gz_bridge parameter_bridge`
`ros_gz_sim`	Launch Gazebo from ROS2	`ros2 launch ros_gz_sim gz_sim.launch.py`
`gz fuel`	Online model library	app.gazebosim.org/fuel

# List all Gazebo topics
gz topic -l

# Echo a topic
gz topic -e -t /model/my_robot/pose

# List models in simulation
gz model -l

# Get model info
gz model -m my_robot -i

SDF World Design

Simulation Description Format (SDF)

SDF is the primary world format for Gazebo Jazzy. Every world contains physics, plugins, models, and lights inside a <world> tag.

Basic World Structure

<?xml version="1.0"?>
<sdf version="1.9">
  <world name="smart_city">

    <!-- Physics -->
    <physics name="1ms" type="ignored">
      <max_step_size>0.001</max_step_size>
      <real_time_factor>1.0</real_time_factor>
    </physics>

    <!-- Required plugins -->
    <plugin filename="gz-sim-physics-system"
            name="gz::sim::systems::Physics"/>
    <plugin filename="gz-sim-scene-broadcaster-system"
            name="gz::sim::systems::SceneBroadcaster"/>
    <plugin filename="gz-sim-user-commands-system"
            name="gz::sim::systems::UserCommands"/>
    <plugin filename="gz-sim-sensors-system"
            name="gz::sim::systems::Sensors">
      <render_engine>ogre2</render_engine>
    </plugin>

    <!-- Sun -->
    <light type="directional" name="sun">
      <cast_shadows>true</cast_shadows>
      <pose>0 0 10 0 0 0</pose>
      <diffuse>0.8 0.8 0.8 1</diffuse>
      <specular>0.2 0.2 0.2 1</specular>
      <direction>-0.5 0.1 -0.9</direction>
    </light>

    <!-- Ground plane -->
    <model name="ground_plane">
      <static>true</static>
      <link name="link">
        <collision name="collision">
          <geometry><plane><normal>0 0 1</normal><size>500 500</size></plane></geometry>
        </collision>
        <visual name="visual">
          <geometry><plane><normal>0 0 1</normal><size>500 500</size></plane></geometry>
          <material><ambient>0.8 0.8 0.8 1</ambient></material>
        </visual>
      </link>
    </model>

  </world>
</sdf>

Buildings & No-Fly Zone Markers

<!-- Building block -->
<model name="building_1">
  <static>true</static>
  <pose>10 5 0 0 0 0</pose>
  <link name="link">
    <collision name="collision">
      <geometry><box><size>8 6 12</size></box></geometry>
    </collision>
    <visual name="visual">
      <geometry><box><size>8 6 12</size></box></geometry>
      <material><ambient>0.5 0.5 0.6 1</ambient><diffuse>0.6 0.6 0.7 1</diffuse></material>
    </visual>
  </link>
</model>

<!-- No-fly zone (red transparent cylinder) -->
<model name="no_fly_zone_1">
  <static>true</static>
  <pose>20 20 0 0 0 0</pose>
  <link name="link">
    <visual name="visual">
      <geometry><cylinder><radius>10</radius><length>0.1</length></cylinder></geometry>
      <material><ambient>1 0 0 0.4</ambient><diffuse>1 0 0 0.4</diffuse></material>
    </visual>
  </link>
</model>

Physics & Wind Simulation

Wind Plugin & Physics Tuning

<!-- Add inside <world> -->
<plugin filename="gz-sim-wind-effects-system"
        name="gz::sim::systems::WindEffects">
  <horizontal>
    <magnitude>
      <time_for_rise>10</time_for_rise>
      <sin>
        <amplitude_percent>0.05</amplitude_percent>
        <period>60</period>
      </sin>
      <noise type="gaussian"><mean>0</mean><stddev>0.0002</stddev></noise>
    </magnitude>
    <direction>
      <time_for_rise>30</time_for_rise>
      <sin><amplitude>5</amplitude><period>20</period></sin>
      <noise type="gaussian"><mean>0</mean><stddev>0.03</stddev></noise>
    </direction>
  </horizontal>
  <vertical>
    <noise type="gaussian"><mean>0</mean><stddev>0.03</stddev></noise>
  </vertical>
</plugin>

<wind>
  <linear_velocity>3 1 0</linear_velocity>
</wind>

<gravity>0 0 -9.8</gravity>
<magnetic_field>6e-06 2.3e-05 -4.2e-05</magnetic_field>

<physics name="1ms" type="ode">
  <max_step_size>0.001</max_step_size>
  <real_time_factor>1</real_time_factor>
  <real_time_update_rate>1000</real_time_update_rate>
</physics>

ROS2 ↔ Gazebo Bridge

ros_gz_bridge

# Bridge multiple topics
ros2 run ros_gz_bridge parameter_bridge \
  /clock@rosgraph_msgs/msg/Clock[gz.msgs.Clock \
  /model/drone/pose@geometry_msgs/msg/PoseStamped[gz.msgs.Pose \
  /lidar@sensor_msgs/msg/LaserScan[gz.msgs.LaserScan \
  /camera/image@sensor_msgs/msg/Image[gz.msgs.Image \
  /imu@sensor_msgs/msg/Imu[gz.msgs.IMU \
  /gps@sensor_msgs/msg/NavSatFix[gz.msgs.NavSat \
  /cmd_vel@geometry_msgs/msg/Twist]gz.msgs.Twist

Bridge via Launch File

# ros2_gz_bridge.launch.py
from launch import LaunchDescription
from launch_ros.actions import Node

def generate_launch_description():
    bridge = Node(
        package='ros_gz_bridge',
        executable='parameter_bridge',
        arguments=[
            '/clock@rosgraph_msgs/msg/Clock[gz.msgs.Clock',
            '/model/drone/pose@geometry_msgs/msg/PoseStamped[gz.msgs.Pose',
            '/lidar@sensor_msgs/msg/LaserScan[gz.msgs.LaserScan',
            '/camera/image_raw@sensor_msgs/msg/Image[gz.msgs.Image',
            '/camera/camera_info@sensor_msgs/msg/CameraInfo[gz.msgs.CameraInfo',
            '/imu/data@sensor_msgs/msg/Imu[gz.msgs.IMU',
            '/navsat@sensor_msgs/msg/NavSatFix[gz.msgs.NavSat',
            '/cmd_vel@geometry_msgs/msg/Twist]gz.msgs.Twist',
        ],
        output='screen',
    )
    return LaunchDescription([bridge])

Week 13 — Robot & Drone Modeling

URDF & SDF Modeling

Robot Description Formats

URDF

ROS2 native format
Used by robot_state_publisher
Xacro macros supported
Must convert to SDF for Gazebo

SDF

Gazebo Jazzy native format
Richer physics properties
Sensor plugins built-in
Preferred for simulation

Minimal URDF with Xacro

<?xml version="1.0"?>
<robot name="my_robot" xmlns:xacro="http://www.ros.org/wiki/xacro">
  <link name="base_link">
    <visual>
      <geometry><box size="0.5 0.3 0.1"/></geometry>
      <material name="blue"><color rgba="0.0 0.0 0.8 1.0"/></material>
    </visual>
    <collision><geometry><box size="0.5 0.3 0.1"/></geometry></collision>
    <inertial>
      <mass value="5.0"/>
      <inertia ixx="0.05" ixy="0" ixz="0" iyy="0.05" iyz="0" izz="0.05"/>
    </inertial>
  </link>

  <link name="left_wheel">
    <visual>
      <geometry><cylinder length="0.05" radius="0.1"/></geometry>
      <material name="black"><color rgba="0.1 0.1 0.1 1.0"/></material>
    </visual>
    <collision><geometry><cylinder length="0.05" radius="0.1"/></geometry></collision>
    <inertial><mass value="0.5"/><inertia ixx="0.001" ixy="0" ixz="0" iyy="0.001" iyz="0" izz="0.001"/></inertial>
  </link>

  <joint name="left_wheel_joint" type="continuous">
    <parent link="base_link"/>
    <child link="left_wheel"/>
    <origin xyz="0 0.175 -0.05" rpy="-1.5707 0 0"/>
    <axis xyz="0 0 1"/>
  </joint>
</robot>

Convert URDF → SDF

sudo apt install -y gz-tools2
gz sdf -p my_robot.urdf > my_robot.sdf
gz sdf --check my_robot.sdf

Sensor Simulation

LIDAR, Camera, IMU & GPS

2D LIDAR

<sensor name="lidar" type="gpu_lidar">
  <pose>0 0 0.2 0 0 0</pose>
  <update_rate>10</update_rate>
  <lidar>
    <scan>
      <horizontal>
        <samples>640</samples>
        <resolution>1</resolution>
        <min_angle>-3.14159</min_angle>
        <max_angle>3.14159</max_angle>
      </horizontal>
    </scan>
    <range><min>0.08</min><max>25</max><resolution>0.01</resolution></range>
    <noise type="gaussian"><mean>0</mean><stddev>0.01</stddev></noise>
  </lidar>
</sensor>

RGB Camera

<sensor name="camera" type="camera">
  <pose>0.25 0 0.1 0 0 0</pose>
  <update_rate>30</update_rate>
  <camera>
    <horizontal_fov>1.3962634</horizontal_fov>
    <image><width>640</width><height>480</height><format>R8G8B8</format></image>
    <clip><near>0.02</near><far>300</far></clip>
    <noise type="gaussian"><mean>0</mean><stddev>0.007</stddev></noise>
  </camera>
</sensor>

IMU Sensor

<sensor name="imu_sensor" type="imu">
  <always_on>1</always_on>
  <update_rate>100</update_rate>
  <imu>
    <angular_velocity>
      <x><noise type="gaussian"><mean>0</mean><stddev>0.0002</stddev></noise></x>
      <y><noise type="gaussian"><mean>0</mean><stddev>0.0002</stddev></noise></y>
      <z><noise type="gaussian"><mean>0</mean><stddev>0.0002</stddev></noise></z>
    </angular_velocity>
    <linear_acceleration>
      <x><noise type="gaussian"><mean>0</mean><stddev>0.017</stddev></noise></x>
      <y><noise type="gaussian"><mean>0</mean><stddev>0.017</stddev></noise></y>
      <z><noise type="gaussian"><mean>0</mean><stddev>0.017</stddev></noise></z>
    </linear_acceleration>
  </imu>
</sensor>

GPS / NavSat

<sensor name="navsat" type="navsat">
  <always_on>1</always_on>
  <update_rate>10</update_rate>
  <navsat>
    <position_sensing>
      <horizontal><noise type="gaussian"><mean>0</mean><stddev>0.001</stddev></noise></horizontal>
      <vertical><noise type="gaussian"><mean>0</mean><stddev>0.001</stddev></noise></vertical>
    </position_sensing>
  </navsat>
</sensor>

Drone Modeling & Flight Controllers

Quadcopter SDF Model & Control

Quadcopter SDF with Motor Plugin

<?xml version="1.0"?>
<sdf version="1.9">
<model name="quadcopter">
  <pose>0 0 0.2 0 0 0</pose>

  <link name="base_link">
    <inertial>
      <mass>1.5</mass>
      <inertia>
        <ixx>0.029125</ixx><ixy>0</ixy><ixz>0</ixz>
        <iyy>0.029125</iyy><iyz>0</iyz>
        <izz>0.055225</izz>
      </inertia>
    </inertial>
    <visual name="body_visual">
      <geometry><box><size>0.47 0.47 0.11</size></box></geometry>
      <material><ambient>0.1 0.1 0.1 1</ambient></material>
    </visual>
    <collision name="body_collision">
      <geometry><box><size>0.47 0.47 0.11</size></box></geometry>
    </collision>
    <sensor name="imu_sensor" type="imu">
      <always_on>1</always_on><update_rate>250</update_rate>
    </sensor>
    <sensor name="navsat" type="navsat">
      <always_on>1</always_on><update_rate>10</update_rate>
    </sensor>
    <sensor name="downward_camera" type="camera">
      <pose>0 0 -0.1 0 1.5707 0</pose>
      <update_rate>30</update_rate>
      <camera>
        <horizontal_fov>1.5707</horizontal_fov>
        <image><width>640</width><height>480</height></image>
        <clip><near>0.1</near><far>100</far></clip>
      </camera>
    </sensor>
  </link>

  <!-- Rotor 0 (front-right, CW) -->
  <link name="rotor_0">
    <pose>0.13 -0.22 0.023 0 0 0</pose>
    <inertial><mass>0.005</mass>
      <inertia><ixx>9.75e-7</ixx><ixy>0</ixy><ixz>0</ixz><iyy>0.000166704</iyy><iyz>0</iyz><izz>0.000167604</izz></inertia>
    </inertial>
    <visual name="rotor_0_visual">
      <geometry><cylinder><length>0.005</length><radius>0.1</radius></cylinder></geometry>
      <material><ambient>0 0 1 0.8</ambient></material>
    </visual>
  </link>
  <joint name="rotor_0_joint" type="revolute">
    <parent>base_link</parent><child>rotor_0</child>
    <axis><xyz>0 0 1</xyz><dynamics><damping>0.004</damping></dynamics></axis>
  </joint>

  <!-- Multicopter motor model -->
  <plugin filename="gz-sim-multicopter-motor-model-system"
          name="gz::sim::systems::MulticopterMotorModel">
    <robotNamespace>quadcopter</robotNamespace>
    <jointName>rotor_0_joint</jointName>
    <linkName>rotor_0</linkName>
    <turningDirection>cw</turningDirection>
    <maxRotVelocity>1000</maxRotVelocity>
    <motorConstant>8.54858e-6</motorConstant>
    <momentConstant>0.016</momentConstant>
    <commandSubTopic>command/motor_speed</commandSubTopic>
    <motorNumber>0</motorNumber>
  </plugin>

  <!-- Velocity control -->
  <plugin filename="gz-sim-multicopter-control-system"
          name="gz::sim::systems::MulticopterVelocityControl">
    <robotNamespace>quadcopter</robotNamespace>
    <commandSubTopic>cmd_vel</commandSubTopic>
    <enableSubTopic>enable</enableSubTopic>
    <comLinkName>base_link</comLinkName>
    <velocityGain>2.7 2.7 2.7</velocityGain>
    <attitudeGain>2 3 0.15</attitudeGain>
    <angularRateGain>0.4 0.52 0.18</angularRateGain>
  </plugin>

</model>
</sdf>

ROS2 Drone Controller

#!/usr/bin/env python3
import rclpy
from rclpy.node import Node
from geometry_msgs.msg import Twist
from std_msgs.msg import Bool

class DroneController(Node):
    def __init__(self):
        super().__init__('drone_controller')
        self.enable_pub = self.create_publisher(Bool, '/quadcopter/enable', 10)
        self.cmd_pub = self.create_publisher(Twist, '/quadcopter/cmd_vel', 10)
        self.state = 'arming'
        self.timer = self.create_timer(1.0, self.run)
        self.get_logger().info('Drone controller ready')

    def run(self):
        if self.state == 'arming':
            msg = Bool(); msg.data = True
            self.enable_pub.publish(msg)
            self.state = 'takeoff'
        elif self.state == 'takeoff':
            cmd = Twist(); cmd.linear.z = 2.0
            self.cmd_pub.publish(cmd)
            self.state = 'hover'
        elif self.state == 'hover':
            self.cmd_pub.publish(Twist())  # zero = hover

def main(args=None):
    rclpy.init(args=args)
    rclpy.spin(DroneController())

if __name__ == '__main__':
    main()

PX4 / ArduPilot Integration:

For full flight stack integration, use PX4 SITL with the uXRCE-DDS bridge (native ROS2), or ArduCopter SITL with MAVROS. Both connect to Gazebo Jazzy via the ros_gz packages.

ArduPilot SITL Setup

# Terminal 1 - ArduCopter SITL
cd ~/ardupilot
./Tools/autotest/sim_vehicle.py -v ArduCopter --console --map

# Terminal 2 - Launch Gazebo world
ros2 launch ros_gz_sim gz_sim.launch.py gz_args:="smart_city.sdf"

# Terminal 3 - MAVROS bridge
ros2 launch mavros apm.launch fcu_url:=udp://:14550@127.0.0.1:14555

# Terminal 4 - Check topics
ros2 topic list | grep mavros

Week Projects

Week 12 Project: Smart City Environment with No-Fly Zones

Build a realistic urban simulation world in Gazebo Jazzy featuring buildings, roads, wind, and clearly marked no-fly zones.

Deliverables:

SDF world file with at least 5 buildings of varying heights
Road network and open areas
3 no-fly zones marked with red transparent cylinders
Wind configured at 3–5 m/s with Gaussian noise
Directional lighting
ROS2 launch file that starts Gazebo + ros_gz_bridge

# smart_city.launch.py
from launch import LaunchDescription
from launch.actions import IncludeLaunchDescription
from launch.launch_description_sources import PythonLaunchDescriptionSource
from launch_ros.actions import Node
from ament_index_python.packages import get_package_share_directory
import os

def generate_launch_description():
    pkg = get_package_share_directory('my_simulation')
    world = os.path.join(pkg, 'worlds', 'smart_city.sdf')

    gz = IncludeLaunchDescription(
        PythonLaunchDescriptionSource([
            get_package_share_directory('ros_gz_sim'), '/launch/gz_sim.launch.py'
        ]),
        launch_arguments={'gz_args': world}.items()
    )

    bridge = Node(
        package='ros_gz_bridge', executable='parameter_bridge',
        arguments=['/clock@rosgraph_msgs/msg/Clock[gz.msgs.Clock'],
        output='screen'
    )
    return LaunchDescription([gz, bridge])

Week 13 Project: Intelligent Quadcopter Drone with Vision

Model a complete quadcopter, spawn it in the Smart City world, and implement autonomous vision-based navigation.

Deliverables:

Complete quadcopter SDF with IMU, GPS, camera, and LIDAR
ROS2 controller: arm → takeoff → hover → waypoint navigation
Downward camera feed bridged to ROS2 and shown in RViz2
No-fly zone detector node (GPS-based)
Telemetry node publishing altitude and GPS coordinates
Emergency land service: ros2 service call /emergency_land std_srvs/srv/Trigger "{}"

#!/usr/bin/env python3
# no_fly_zone_detector.py
import rclpy, math
from rclpy.node import Node
from sensor_msgs.msg import NavSatFix
from std_msgs.msg import String

class NoFlyZoneDetector(Node):
    ZONES = [
        (31.9522, 35.9107, 50.0),
        (31.9530, 35.9120, 30.0),
        (31.9510, 35.9095, 40.0),
    ]
    def __init__(self):
        super().__init__('no_fly_zone_detector')
        self.sub = self.create_subscription(NavSatFix, '/navsat', self.cb, 10)
        self.pub = self.create_publisher(String, '/no_fly_zone_alert', 10)

    def haversine(self, la1, lo1, la2, lo2):
        R = 6371000
        p1, p2 = math.radians(la1), math.radians(la2)
        dp, dl = math.radians(la2-la1), math.radians(lo2-lo1)
        a = math.sin(dp/2)**2 + math.cos(p1)*math.cos(p2)*math.sin(dl/2)**2
        return R * 2 * math.atan2(math.sqrt(a), math.sqrt(1-a))

    def cb(self, msg):
        for i, (clat, clon, r) in enumerate(self.ZONES):
            d = self.haversine(msg.latitude, msg.longitude, clat, clon)
            if d < r:
                alert = String()
                alert.data = f'WARNING: No-fly zone {i+1}! Dist={d:.1f}m'
                self.pub.publish(alert)
                self.get_logger().warn(alert.data)

def main(args=None):
    rclpy.init(args=args)
    rclpy.spin(NoFlyZoneDetector())

if __name__ == '__main__':
    main()

Weeks 12–13 Summary

Topic	Week 12	Week 13
Focus	World building & environments	Robot/drone modeling
Format	SDF world files	URDF + SDF model files
Key tools	`gz sim`, SDF editor	Xacro, `gz sdf`
Sensors	Lighting, wind, physics	LIDAR, Camera, IMU, GPS
ROS2 integration	ros_gz_bridge, clock	Sensor topics, cmd_vel
Project	Smart City + no-fly zones	Quadcopter with vision
Flight stack	—	Gazebo motor plugin / PX4 / ArduPilot

Weeks 12–13: Gazebo Jazzy Simulation

Contents

Course Overview

Week 12

Week 13

Projects

Installation

Gazebo Jazzy Architecture

SDF World Design

Basic World Structure

Buildings & No-Fly Zone Markers

Physics & Wind Simulation

ROS2 ↔ Gazebo Bridge

Bridge via Launch File

URDF & SDF Modeling

URDF

SDF

Minimal URDF with Xacro

Convert URDF → SDF

Sensor Simulation

2D LIDAR

RGB Camera

IMU Sensor

GPS / NavSat

Drone Modeling & Flight Controllers

Quadcopter SDF with Motor Plugin

ROS2 Drone Controller

ArduPilot SITL Setup

Week Projects

Deliverables:

Deliverables: