Simulated Sensors

name: simulated-sensors description: 'Simulate sensors in Gazebo. Use when configuring simulated IMU, lidar, camera, depth camera, GPS, or contact sensor noise models.'

Simulated Sensors in Gazebo Harmonic

Sensor System Architecture

All sensors in Gazebo Harmonic require the gz-sim-sensors-system world plugin. Individual sensor types may need additional system plugins (e.g., gz-sim-imu-system for IMU). Sensors attach to links via <sensor> elements inside <gazebo reference="link_name"> blocks.

Critical principle: simulated sensor parameters must match real hardware—same FOV, resolution, update rate, and realistic noise levels. Mismatched sensor characteristics cause sim-to-real transfer failures where algorithms that work in simulation fail on the physical robot.

IMU — Inertial Measurement Unit

Requires: gz-sim-imu-system + gz-sim-sensors-system

Realistic noise parameters for a typical MEMS IMU (e.g., BNO055):

<sensor name="imu_sensor" type="imu">
  <always_on>true</always_on>
  <update_rate>100</update_rate>
  <topic>imu/data</topic>
  <imu>
    <angular_velocity>
      <x>
        <noise type="gaussian">
          <mean>0.0</mean>
          <stddev>0.0002</stddev>        <!-- rad/s, ~0.01 deg/s -->
          <bias_mean>0.0000075</bias_mean>  <!-- Slow gyro drift -->
          <bias_stddev>0.0000008</bias_stddev>
          <dynamic_bias_stddev>0.00000002</dynamic_bias_stddev>
          <dynamic_bias_correlation_time>400</dynamic_bias_correlation_time>
        </noise>
      </x>
      <y><noise type="gaussian"><mean>0.0</mean><stddev>0.0002</stddev>
        <bias_mean>0.0000075</bias_mean><bias_stddev>0.0000008</bias_stddev>
      </noise></y>
      <z><noise type="gaussian"><mean>0.0</mean><stddev>0.0002</stddev>
        <bias_mean>0.0000075</bias_mean><bias_stddev>0.0000008</bias_stddev>
      </noise></z>
    </angular_velocity>
    <linear_acceleration>
      <x>
        <noise type="gaussian">
          <mean>0.0</mean>
          <stddev>0.017</stddev>           <!-- m/s², typical accelerometer -->
          <bias_mean>0.1</bias_mean>
          <bias_stddev>0.001</bias_stddev>
          <dynamic_bias_stddev>0.0001</dynamic_bias_stddev>
          <dynamic_bias_correlation_time>175</dynamic_bias_correlation_time>
        </noise>
      </x>
      <y><noise type="gaussian"><mean>0.0</mean><stddev>0.017</stddev>
        <bias_mean>0.1</bias_mean><bias_stddev>0.001</bias_stddev>
      </noise></y>
      <z><noise type="gaussian"><mean>0.0</mean><stddev>0.017</stddev>
        <bias_mean>0.1</bias_mean><bias_stddev>0.001</bias_stddev>
      </noise></z>
    </linear_acceleration>
    <!-- Enable gravity reference for orientation -->
    <enable_orientation>true</enable_orientation>
  </imu>
</sensor>

The noise model is Gaussian with additive bias drift. dynamic_bias_stddev and dynamic_bias_correlation_time model slowly-varying bias using a first-order Gauss-Markov process. These parameters should come from your IMU's datasheet (noise density × √bandwidth).

Lidar

Requires: gz-sim-sensors-system (the sensors system handles rendering-based sensors including gpu_lidar)

Use gpu_lidar for performance; lidar uses CPU raycasting and is much slower.

<sensor name="lidar" type="gpu_lidar">
  <always_on>true</always_on>
  <update_rate>10</update_rate>
  <topic>scan</topic>
  <visualize>true</visualize>
  <lidar>
    <scan>
      <horizontal>
        <samples>720</samples>          <!-- Match real lidar: LD19 = 160-320/rev -->
        <resolution>1</resolution>      <!-- 1 = use all samples -->
        <min_angle>-3.14159</min_angle>  <!-- -180 deg -->
        <max_angle>3.14159</max_angle>   <!--  180 deg -->
      </horizontal>
      <vertical>
        <samples>1</samples>            <!-- 2D lidar = 1 vertical sample -->
        <resolution>1</resolution>
        <min_angle>0</min_angle>
        <max_angle>0</max_angle>
      </vertical>
    </scan>
    <range>
      <min>0.12</min>                   <!-- Match real minimum range -->
      <max>12.0</max>                   <!-- Match real maximum range -->
      <resolution>0.01</resolution>     <!-- Range resolution in meters -->
    </range>
    <noise type="gaussian">
      <mean>0.0</mean>
      <stddev>0.01</stddev>             <!-- 1cm stddev, typical for budget lidars -->
    </noise>
  </lidar>
</sensor>

For 3D lidars (e.g., simulating Velodyne), increase vertical samples and set appropriate vertical angles.

Camera

<sensor name="camera" type="camera">
  <always_on>true</always_on>
  <update_rate>30</update_rate>
  <topic>camera/image_raw</topic>
  <camera>
    <horizontal_fov>1.2</horizontal_fov>  <!-- ~69 degrees, typical webcam -->
    <image>
      <width>640</width>
      <height>480</height>
      <format>R8G8B8</format>
    </image>
    <clip>
      <near>0.1</near>
      <far>100</far>
    </clip>
    <noise type="gaussian">
      <mean>0.0</mean>
      <stddev>0.007</stddev>
    </noise>
    <distortion>
      <k1>0.0</k1><k2>0.0</k2><k3>0.0</k3>
      <p1>0.0</p1><p2>0.0</p2>
      <center>0.5 0.5</center>
    </distortion>
  </camera>
</sensor>

Depth Camera / RGBD

For OAK-D simulation, use rgbd_camera which publishes both color and depth:

<sensor name="oakd" type="rgbd_camera">
  <always_on>true</always_on>
  <update_rate>15</update_rate>
  <topic>oakd</topic>
  <camera>
    <horizontal_fov>1.20428</horizontal_fov>  <!-- OAK-D: ~69 deg -->
    <image>
      <width>640</width>
      <height>480</height>
    </image>
    <clip><near>0.2</near><far>10.0</far></clip>
    <depth_camera>
      <clip><near>0.2</near><far>10.0</far></clip>
    </depth_camera>
    <noise type="gaussian">
      <mean>0.0</mean>
      <stddev>0.005</stddev>
    </noise>
  </camera>
</sensor>

This produces topics: oakd/image (color), oakd/depth_image (depth), oakd/points (point cloud), oakd/camera_info.

Contact Sensor

Detects physical collisions—useful for bumper simulation:

<gazebo reference="bumper_link">
  <sensor name="bumper_contact" type="contact">
    <always_on>true</always_on>
    <update_rate>30</update_rate>
    <topic>bumper/contact</topic>
    <contact>
      <collision>bumper_link_collision</collision>
    </contact>
  </sensor>
</gazebo>
<gazebo>
  <plugin filename="gz-sim-contact-system" name="gz::sim::systems::Contact"/>
</gazebo>

NavSat (GPS)

<sensor name="gps" type="navsat">
  <always_on>true</always_on>
  <update_rate>1</update_rate>
  <topic>gps/fix</topic>
  <navsat>
    <position_sensing>
      <horizontal><noise type="gaussian"><mean>0</mean><stddev>1.5</stddev></noise></horizontal>
      <vertical><noise type="gaussian"><mean>0</mean><stddev>3.0</stddev></noise></vertical>
    </position_sensing>
    <velocity_sensing>
      <horizontal><noise type="gaussian"><mean>0</mean><stddev>0.1</stddev></noise></horizontal>
      <vertical><noise type="gaussian"><mean>0</mean><stddev>0.1</stddev></noise></vertical>
    </velocity_sensing>
  </navsat>
</sensor>

Requires <spherical_coordinates> in the world SDF to define the reference lat/lon.

Sim-to-Real Checklist