# Gazebo Simulation :::warning Gazebo was previously known as "Gazebo Ignition" (while *Gazebo Classic* was previously known as Gazebo). See the [official blog post](https://www.openrobotics.org/blog/2022/4/6/a-new-era-for-gazebo) for more information. ::: [Gazebo](https://gazebosim.org/home) is an open source robotics simulator. It supersedes the older [Gazebo Classic](https://px4.gitbook.io/px4-user-guide/development/simulation/sim_gazebo_classic) simulator, and is the only supported version of Gazebo for Ubuntu 22.04 and onwards. **Supported Vehicles:** Quadrotor, Plane, VTOL @[youtube](https://youtu.be/eRzdGD2vgkU) :::note See [Simulation](https://px4.gitbook.io/px4-user-guide/development/simulation) for general information about simulators, the simulation environment, and simulation configuration (e.g. supported vehicles). ::: ## Installation (Ubuntu Linux) Gazebo is installed by default on Ubuntu 22.04 as part of the development environment setup: [Ubuntu Dev Environment Setup > Simulation and NuttX (Pixhawk) Targets](https://px4.gitbook.io/px4-user-guide/getting_started/dev_env/dev_env_linux_ubuntu#simulation-and-nuttx-pixhawk-targets) If you want to use Gazebo on Ubuntu 20.04 you can install it manually after following the normal setup process (installing `gz-garden` will uninstall Gazebo-Classic!): ```sh sudo wget https://packages.osrfoundation.org/gazebo.gpg -O /usr/share/keyrings/pkgs-osrf-archive-keyring.gpg echo "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/pkgs-osrf-archive-keyring.gpg] http://packages.osrfoundation.org/gazebo/ubuntu-stable $(lsb_release -cs) main" | sudo tee /etc/apt/sources.list.d/gazebo-stable.list > /dev/null sudo apt-get update sudo apt-get install gz-garden ``` ## Running the Simulation Gazebo SITL simulation can be conveniently run through a `make` command as shown below: ```bash cd /path/to/PX4-Autopilot make px4_sitl gz_x500 ``` This will run both the PX4 SITL instance and the Gazebo client. Note that all gazebo make targets have the prefix `gz_`. The supported vehicles and `make` commands are listed below. | Vehicle | Command | `PX4_SYS_AUTOSTART` | | -------------------------------------------------------------------------------------------------------------------------------------------------------- | -------------------------------- | ------------------- | | [Quadrotor(x500)](https://px4.gitbook.io/px4-user-guide/development/simulation/gazebo_vehicles#x500-quadrotor) | `make px4_sitl gz_x500` | 4001 | | [Quadrotor(x500) with Depth Camera](https://px4.gitbook.io/px4-user-guide/development/simulation/gazebo_vehicles#x500-quadrotor-with-depth-camera) | `make px4_sitl gz_x500_depth` | 4002 | | [Quadrotor(x500) with Vision Odometry](https://px4.gitbook.io/px4-user-guide/development/simulation/gazebo_vehicles#x500-quadrotor-with-visual-odometry) | `make px4_sitl gz_x500_vision` | 4005 | | [VTOL](https://px4.gitbook.io/px4-user-guide/development/simulation/gazebo_vehicles#standard-vtol) | `make px4_sitl gz_standard_vtol` | 4003 | | [Plane](https://px4.gitbook.io/px4-user-guide/development/simulation/gazebo_vehicles#rc-cessna) | `make px4_sitl gz_rc_cessna` | 4004 | The commands above launch a single vehicle with the full UI. *QGroundControl* should be able to automatically connect to the simulated vehicle. In order to run the simulation without running the Gazebo gui, use the `HEADLESS=1` flag: ```bash HEADLESS=1 make px4_sitl gz_x500 ``` ## Usage/Configuration Options The startup pipeline allows for highly flexible configuration. In particular, it is possible to: * Start a new simulation with an arbitrary world or attach to an already running simulation. * Add a new vehicle to the simulation or link a new PX4 instance to an existing one. These scenarios are managed by setting the appropriate environment variables. ### Syntax The startup syntax takes the form: ```bash ARGS ./build/px4_sitl_default/bin/px4 ``` where `ARGS` is a list of environment variables including: * `PX4_SYS_AUTOSTART` (**Mandatory**): Sets the [airframe autostart id](https://px4.gitbook.io/px4-user-guide/development/hardware/dev_airframes/adding_a_new_frame) of the PX4 airframe to start. * `PX4_GZ_MODEL_NAME`: Sets the name of an *existing* model in the gazebo simulation. If provided, the startup script tries to bind a new PX4 instance to the Gazebo resource matching exactly that name. * The setting is mutually exclusive with `PX4_GZ_MODEL`. * `PX4_GZ_MODEL`: Sets the name of a new Gazebo model to be spawned in the simulator. If provided, the startup script looks for a model in the Gazebo resource path that matches the given variable, spawns it and binds a new PX4 instance to it. * The setting is mutually exclusive with `PX4_GZ_MODEL_NAME`. :::note If both `PX4_GZ_MODEL_NAME` and `PX4_GZ_MODEL` are not given, then PX4 looks for `PX4_SIM_MODEL` and uses it as an alias for `PX4_GZ_MODEL`. However, this prevents the use of `PX4_GZ_MODEL_POSE`. ::: * `PX4_GZ_MODEL_POSE`: Sets the spawning position and orientation of the model when `PX4_GZ_MODEL` is adopted. If provided, the startup script spawns the model at a pose following the syntax `"x,y,z,roll,pitch,yaw"`, where the positions are given in metres and the angles are in radians. * If omitted, the zero pose `[0,0,0,0,0,0]` is used. * If less then 6 values are provided, the missing ones are fixed to zero. * This can only be used with `PX4_GZ_MODEL` (not `PX4_GZ_MODEL_NAME`). * `PX4_GZ_WORLD`: Sets the Gazebo world file for a new simulation. If it is not given, then [default](https://github.com/PX4/PX4-Autopilot/blob/main/Tools/simulation/gz/worlds/default.sdf) is used. * This variable is ignored if an existing simulation is already running. * This value should be [specified for the selected airframe](#adding-new-worlds-and-models) but may be overridden using this argument. * `PX4_SIMULATOR=GZ`: Sets the simulator, which for Gz must be `gz`. * This value should be [set for the selected airframe](#adding-new-worlds-and-models), in which case it does not need to be set as an argument. The PX4 Gazebo worlds and and models databases [can be found on Github here](https://github.com/PX4/PX4-Autopilot/tree/main/Tools/simulation/gz). They are added to the Gazebo search `PATH` by [gz\_env.sh.in](https://github.com/PX4/PX4-Autopilot/blob/main/src/modules/simulation/gz_bridge/gz_env.sh.in) during the simulation startup phase. :::note `gz_env.sh.in` is compiled and made available in `$PX4_DIR/build/px4_sitl_default/rootfs/gz_env.sh` ::: ### Examples Here are some examples of the different scenarios covered above. 1. **Start simulator + default world + spawn vehicle at default pose** ```sh PX4_SYS_AUTOSTART=4001 PX4_GZ_MODEL=x500 ./build/px4_sitl_default/bin/px4 ``` 2. **Start simulator + default world + spawn vehicle at custom pose (y=2m)** ```sh PX4_SYS_AUTOSTART=4001 PX4_GZ_MODEL_POSE="0,2" PX4_GZ_MODEL=x500 ./build/px4_sitl_default/bin/px4 ``` 3. **Start simulator + default world + link to existing vehicle** ```sh PX4_SYS_AUTOSTART=4001 PX4_GZ_MODEL_NAME=x500 ./build/px4_sitl_default/bin/px4 ``` ## Adding New Worlds and Models New worlds files can simply be copied into the PX4 Gazebo [world directory](https://github.com/PX4/PX4-Autopilot/tree/main/Tools/simulation/gz/worlds). To add a new model: 1. Add an **sdf** file in the PX4 Gazebo [model directory](https://github.com/PX4/PX4-Autopilot/tree/main/Tools/simulation/gz/models). 2. Define an [airframe configuration file](https://px4.gitbook.io/px4-user-guide/development/hardware/dev_airframes/adding_a_new_frame). 3. Define the default parameters for Gazebo in the airframe configuration file (this example is from [x500 quadcopter](https://github.com/PX4/PX4-Autopilot/blob/main/ROMFS/px4fmu_common/init.d-posix/airframes/4001_gz_x500)): ``` PX4_SIMULATOR=${PX4_SIMULATOR:=gz} PX4_GZ_WORLD=${PX4_GZ_WORLD:=default} PX4_SIM_MODEL=${PX4_SIM_MODEL:=} ``` * `PX4_SIMULATOR=${PX4_SIMULATOR:=gz}` sets the default simulator (Gz) for that specific airframe. * `PX4_GZ_WORLD=${PX4_GZ_WORLD:=default}` sets the [default world](https://github.com/PX4/PX4-Autopilot/blob/main/Tools/simulation/gz/worlds/default.sdf) for that specific airframe. * Setting the default value of `PX4_SIM_MODEL` lets you start the simulation with just ```bash PX4_SYS_AUTOSTART= ./build/px4_sitl_default/bin/px4 ``` :::note As long as the world file and the model file are in the Gazebo search path `IGN_GAZEBO_RESOURCE_PATH` it is not necessary to add them to the PX4 world and model directories. However, `make px4_sitl gz__` won't work with them. ::: ## Multi-Vehicle Simulation Multi-Vehicle simulation is supported on Linux hosts. For more information see: [Multi-Vehicle Simulation with Gazebo](https://px4.gitbook.io/px4-user-guide/development/simulation/sim_gazebo_gz/multi_vehicle_simulation) ## Further Information * [px4-simulation-ignition](https://github.com/Auterion/px4-simulation-ignition)