Multirotor simulator

The multirotor simulator simulates the physics of a multirotor without a 3D world or graphics. It starts in a second, runs on any machine including macOS through Pixi, and is the simulator the Quickstart uses. It's the fastest way to test missions, behaviors and controllers before moving to Gazebo or a real drone.

It ships with Aerostack2 in the as2_platform_multirotor_simulator package, built on the multirotor_simulator library.

What it simulates

The simulator models the drone's dynamics, its motors and an internal flight controller, so it accepts every common control mode, from body rates up to full trajectories. It also takes off and lands by itself when the platform plugins are used.

It also simulates a gimbal, commanded on platform/gimbal/gimbal_command, for testing the point gimbal behavior. There's no camera or other perception sensor, since there's no world to see.

Launch

ros2 launch as2_platform_multirotor_simulator as2_platform_multirotor_simulator.launch.py \
  namespace:=drone0 \
  config_file:=config/config.yaml \
  uav_config:=config/uav_config.yaml \
  world_config:=config/world.yaml

Every file is optional. The package's defaults are always loaded first, so your files only need the values you change.

Several drones

Launch the platform once per drone with a different namespace and the same world file. The world file can set values for every drone and override them per namespace, such as the start pose:

/**:
  platform:
    ros__parameters:
      gps_origin:
        latitude: 40.4405287
        longitude: -3.6898277
        altitude: 100.0

drone0:
  platform:
    ros__parameters:
      vehicle_initial_pose:
        x: 0.0
        y: 0.0

drone1:
  platform:
    ros__parameters:
      vehicle_initial_pose:
        x: 2.0
        y: 0.0

With the rest of the stack

For the state estimator, use the ground_truth plugin with the simulator's own twist for a perfect state, or raw_odometry on sensor_measurements/odom to fly on imperfect odometry, closer to a real drone. Both the PID speed and the differential flatness controllers work with it.

/**:
  state_estimator:
    ros__parameters:
      plugin_name: "ground_truth"
      ground_truth:
        twist_sub_topic: "ground_truth/twist"

The project_as2_multirotor_simulator repository has a complete setup with every component, a ground station and example missions.

Simulated time

The simulator runs in real time by default. To run faster or slower, start the clock publisher and launch every node with use_sim_time:=true. Its rtf parameter sets the real-time factor.

ros2 launch as2_platform_multirotor_simulator sim_clock_publisher.launch.py