It is in radio failsafe right now
What ArduPilot says:
- PreArm: Radio failsafe on
ArduPilot had the receiver and lost it: no valid frames for longer than RC_FS_TIMEOUT (1 s by default), or a throttle below FS_THR_VALUE, or the receiver's own failsafe flag. It will not arm while that lasts.
What to do, most likely first
The transmitter was switched off, or its battery died, after the flight controller started.
FixSwitch the transmitter on; the failsafe clears as soon as frames arrive again.
The receiver lost power or a wire while the flight controller kept running.
CheckThe receiver's LED, and its connector at both ends.
FixFix the wiring before flying: a link that drops on the bench will drop in the air.
The throttle stick's lowest position is below
FS_THR_VALUE.CheckIf the failsafe comes on only when you pull the throttle down, this is it.
FixCalibrate the radio and set
FS_THR_VALUEat least 10 µs belowRC3_MIN.
Parameters to look at
| Parameter | What it is |
|---|---|
FS_THR_ENABLE | Throttle Failsafe Enable |
FS_THR_VALUE | Throttle Failsafe Value |
RC_FS_TIMEOUT | RC Failsafe timeout |
Where to do it:Failsafe ExplainerSetup & Tuning Guide
The code that sends it
PreArm: Radio failsafe on
libraries/AP_Arming/AP_Arming.cpp AP_Arming::manual_transmitter_checks() · Open in ArduPilot Copter-4.7.1