PX4-Autopilot/docs/ko/simulation/hardware.md

Hardware Simulation

PX4 can run simulation directly on a real flight controller, replacing real sensors with simulated data, while otherwise executing the full flight stack on actual autopilot hardware.

:::info Simulating PX4 on flight controller hardware exercises more flight stack code than SITL, and tests more of your hardware integration. It can surface issues with running PX4 that might hidden when running on a desktop OS and hardware, or even a different flight controller board. :::

Two simulation approaches are available, controlled by the SYS_HITL parameter:

• HITL Simulation (SYS_HITL=1): An external simulator (Gazebo Classic or jMAVSim) runs physics on a companion computer and sends sensor data to the flight controller via MAVLink HIL messages. Requires a USB/UART connection and simulator setup.
• SIH on Hardware (SYS_HITL=2): A C++ physics model runs directly on the flight controller itself. No external simulator, no companion computer, no MAVLink sensor data. Just set the parameter and reboot.

HITL vs SIH

	HITL (SYS_HITL=1)	SIH (SYS_HITL=2)
Physics model	External simulator (Gazebo Classic, jMAVSim)	Internal C++ module
Communication	MAVLink HIL messages	uORB (internal)
External process	Required	Not required
Setup complexity	Higher	Lower
Sensor simulation	Camera, lidar, etc. (via simulator)	IMU, GPS, baro, mag, airspeed only
Vehicle types	Quadcopter, Standard VTOL	Quad, Hex, FW, VTOL Tailsitter, Standard VTOL, Rover

When to Use Which

• Use SIH if you want the simplest possible setup. No external dependencies.
• Use HITL if you need an external physics engine, 3D visualization from Gazebo Classic, or camera/lidar sensor simulation that SIH does not provide.