> ## Documentation Index
> Fetch the complete documentation index at: https://bedrockdynamics.studio/docs/llms.txt
> Use this file to discover all available pages before exploring further.
# Simulation
> Launch and manage robotics simulations directly from the IDE.
Substrate integrates simulation into your development workflow. Launch Software-In-The-Loop (SITL) environments, monitor system readiness, and iterate on your code without leaving the editor.
## Launching a Simulation
Open the **SITL Launcher** panel from the left sidebar. Select a simulation stack, robot model, and world, then click **Launch**. Substrate pulls the container image, allocates ports, and starts the environment automatically.
Pre-configured environments that bundle a physics engine, controller software, and the Substrate bridge into a single Docker image.
Built-in worlds (empty, warehouse, outdoor terrain), custom SDF files, or Gazebo Fuel worlds referenced by name.
Each simulation runs in its own container. Substrate manages image pulls, port allocation, and container lifecycle.
Spawn multiple instances in a shared world. Ports are allocated automatically to avoid conflicts.
## Readiness Monitoring
The readiness panel tracks each subsystem as it comes online. Indicators transition from red to green so you know exactly what is ready and what is still initializing.
The checks are evaluated against the running system, not hardcoded to a single platform:
| Check | What It Monitors | Applies To |
| -------------------- | -------------------------------------------------------- | ---------------------------------- |
| **Heartbeat** | Controller communication link and system status | MAVLink vehicles |
| **State Estimation** | Estimator convergence and innovation flags | Vehicles with inertial navigation |
| **Localization** | GPS fix, satellite count, or alternative position source | Vehicles requiring global position |
| **System Status** | Overall controller health | All connected systems |
Readiness checks run continuously. If state estimation diverges or a sensor feed drops during operation, the indicator reverts to a warning state.
***
## Robot Categories
Substrate organizes simulations into categories based on the type of system you are building. Each category maps to one or more simulation stacks.
**Quadcopters, fixed-wing aircraft, and VTOL hybrids.**
Aerial vehicles use MAVLink for communication and are supported by the PX4 and ArduPilot stacks. Available PX4 models include `x500` (quadrotor), `rc_cessna` (fixed-wing), and `standard_vtol` (hybrid).
| Stack | Controller | Models |
| ------------------ | -------------- | --------------------------------------------- |
| PX4 + Gazebo | PX4 v1.16.1 | x500, x500\_depth, rc\_cessna, standard\_vtol |
| ArduPilot + Gazebo | ArduPilot SITL | Copter, Plane, QuadPlane |
**Multi-vehicle**: Spawn up to 10 vehicles in a shared world. Each instance runs a separate autopilot with Y-axis offset spacing and independent MAVLink ports.
**Flight commands**: Arm, takeoff, land, go-to waypoint, return to launch, and mode switching are available through the AI assistant and the command palette. See [Flight Modes & Commands](/substrate/reference/flight-modes).
For PX4 stacks, use spawn mode (`PX4_MODEL=x500`). Do not set `PX4_GZ_MODEL_NAME` -- it enables attach mode, which skips sensor spawning and prevents the state estimator from converging.
**Rovers, wheeled vehicles, and tracked platforms.**
Ground vehicles use MAVLink and are supported by the PX4 and ArduPilot stacks. The PX4 rover model is `r1_rover`.
| Stack | Controller | Models |
| ------------------ | --------------- | -------------------- |
| PX4 + Gazebo | PX4 v1.16.1 | r1\_rover |
| ArduPilot + Gazebo | ArduPilot Rover | Various rover frames |
Ground vehicles use the same readiness monitoring, telemetry, and AI assistant tools as aerial vehicles. Localization checks apply when GPS is available; indoor rovers may rely on alternative position sources.
**Robot arms, grippers, and humanoid robots.**
Manipulators and humanoid robots use ROS 2 control interfaces and are supported by the MoveIt + Gazebo stack.
| Stack | Controller | Examples |
| --------------- | ---------------------- | -------------------------------- |
| MoveIt + Gazebo | MoveIt2 + ROS 2 Humble | UR5, Franka, Kinova, custom URDF |
These systems use joint-state topics and tf2 transforms instead of MAVLink telemetry. The 3D viewer renders joint positions, collision geometry, and sensor data in real time.
The MoveIt + Gazebo stack is registered in the launcher but its container image is not yet published. See the [Roadmap](/substrate/roadmap) for status.
**Underwater ROVs, AUVs, and surface vessels.**
Marine vehicles can use MAVLink (BlueROV, ArduSub) or ROS 2 depending on the platform. The PX4 stack includes a `boat` model for surface vehicles.
| Stack | Controller | Models |
| ------------------ | ----------- | --------------- |
| PX4 + Gazebo | PX4 v1.16.1 | boat |
| ArduPilot + Gazebo | ArduSub | BlueROV2 frames |
Localization checks adapt to the available position source -- GPS for surface vehicles, DVL or pressure-based depth for underwater systems.
**User-provided URDF or SDF models.**
Load your own robot description and simulate it in Gazebo without a specific autopilot stack. Custom models use Gazebo physics directly and can optionally connect a ROS 2 controller.
Provide your model via:
* A local URDF/SDF file loaded through the [Model Browser](/substrate/features/scene-authoring)
* A Gazebo Fuel model referenced by name
* A custom SDF world file mounted into the container
See the [Custom Models](/substrate/guides/custom-models) guide for details.
## Docker Requirements
Simulations require Docker to be installed and running on your machine. Substrate will display a clear error if Docker is not available. See the [Docker Image Reference](/substrate/reference/docker-image) for container details.