Safety¶

What stops the drone¶

1. The firmware, onboard. The Crazyflie supervisor handles arming, cuts the motors when the drone tumbles, disarms a drone left armed without taking off, and runs the emergency-stop watchdog. The host cannot override it. An emergency stop locks the motors off until the drone is power-cycled (cf-lab reboot does that).
2. The flying examples' host runners (mocap_waypoint, hover_neural_network):
   • SPACE sends an emergency stop.
   • Ctrl-C lands and disarms.
   • The runner does not arm unless mocap poses reached the drone while it settled.
   • Once armed, if no new pose reaches the drone for mocap.pose_timeout_s (1 s by default), the drone lands.
   • If sending poses to the drone fails, the runner sends an emergency stop.
   • The runner feeds the firmware's watchdog four times a second. After one second without it, for example when the radio link drops, the drone cuts its own motors.

The host keeps no geofence or attitude monitor of its own: limits like these belong onboard, where they survive a host or radio failure.

Preflight checks¶

cf-lab preflight runs read-only checks. Without --checks it only validates the config and does not touch the drone:

cf-lab preflight --list-checks
cf-lab preflight --checks configuration,firmware-self-test,supervisor-ready,battery,static-imu \
  --stop-on-failure

Run the drone checks with the drone still and disarmed.