飞行终止配置
The Flight termination failsafe action may be triggered by a safety check (e.g. RC Loss, geofence violation, etc. on any vehicle type or in any flight mode), or by the Failure Detector.
INFO
Flight termination may also be triggered from a ground station or companion computer using the MAVLink MAV_CMD_DO_FLIGHTTERMINATION command. This is sent, for example, when you call the MAVSDK Action plugin terminate() or terminate_async() methods.
When Flight termination is activated, PX4 simultaneously turns off all controllers and sets all PWM outputs to their failsafe values.
根据所连接的设备，PWM 故障保护输出可以用来完成以下动作：
- Deploy a parachute.
- 伸展可伸缩起落架。
- 将连接了 PWM 的云台移动到安全的方向（或将它回收）以保护摄像机。
- 触发一个可充气的装置，如安全气囊。
- 触发警报。
飞行终止是无法取消的。 在飞行终止触发后，您应尽快拔下电池。 您需要在重启载具或重新上电后才能再次使用。
TIP
PX4 does not know what safety devices are attached - it just applies a predefined set of PWM values to its outputs.
TIP
Failsafe values are applied to all outputs on termination. 无法配置电机或特定安全装置为独立的特定时间（或其他方式）触发。
INFO
This is not an independent Flight Termination System. 如果断电或者自驾仪完全失控，失效保护设备则不会触发。
硬件配置
Any safety device(s) (e.g. a parachute) that can be triggered by changing a PWM value can be used, and may be connected to any free PWM port (both MAIN and AUX).
INFO
If you're using Pixhawk-series board you will have to separately power the servo rail (i.e. from a 5V BEC, which is often also available from your ESC).
软件配置
The Safety topic explains how to set the flight termination as the failsafe action to be performed for particular failsafe check.
The Failure Detector can also (optionally) be configured to trigger flight termination if the vehicle flips (exceeds a certain attitude) or if failure is detected by an external automatic trigger system (ATS):
- Enable the failure detector during flight by setting CBRK_FLIGHTTERM=0.
- Safety > Failure Detector > Attitude Trigger explains how to configure the attitude limits that trigger Flight termination.
INFO
During takeoff excessive attitutes will trigger lockdown (kill motors, but not launch parachute) rather than flight termination. This is always enabled, irrespective of the value of
CBRK_FLIGHTTERM.
:::
- Safety > External Automatic Trigger System (ATS) explains how to configure an external trigger system.
对于每个与安全装置相连的 MAIN 输出，其中“n”指 PWM 端口号，设置：
- PWM_MAIN_DISn to the device's "OFF" PWM value.
- PWM_MAIN_FAILn to the device's "ON" PWM value.
对于每个与安全装置相连的 AUX 输出，其中“n”指 PWM 端口号，设置：
- PWM_AUX_DIS1 to the device's "OFF" PWM value.
- PWM_AUX_FAILn to the device's "ON" PWM value.
Finally, set the PWM_AUX_FAILn and PWM_MAIN_FAILn PWM values for any motors.
逻辑图解
下图显示了飞行终止的逻辑流程。
