安全性
PX4有许多安全功能，可以在发生故障时保护并恢复您的机体：
遥控器上的安全开关可用于在出现问题时立即制动电机或使机体返航。
故障保护动作
每种故障保护措施都定义有自己的一组动作。 部分较为常见的故障保护措施如下：
QGroundControl 安全设置
The QGroundControl Safety Setup page is accessed by clicking the QGroundControl Gear icon (Vehicle Setup - top toolbar) and then Safety in the sidebar). This includes the most important failsafe settings (battery, RC loss etc.) and the settings for the return actions Return and Land.
低电量故障保护
The low battery failsafe is triggered when the battery capacity drops below one (or more warning) level values.
The most common configuration is to set the values and action as above (with Warn > Failsafe > Emergency). With this configuration the failsafe will trigger warning, then return, and finally landing if capacity drops below the respective levels.
It is also possible to set the Failsafe Action to warn, return, or land when the Battery Failsafe Level failsafe level is reached.
The settings and underlying parameters are shown below.
遥控信号丢失故障保护
The RC Loss failsafe is triggered if the RC transmitter link is lost in manual modes (RC loss does not trigger the failsafe in automatic modes - e.g. during missions).
The settings and underlying parameters are shown below.
数据链路丢失故障保护
The Data Link Loss failsafe is triggered if a telemetry link (connection to ground station) is lost when flying a mission.
The settings and underlying parameters are shown below.
地理围栏故障保护
The Geofence Failsafe is a "virtual" cylinder centered around the home position. If the vehicle moves outside the radius or above the altitude the specified Failsafe Action will trigger.
PX4 separately supports more complicated GeoFence geometries with multiple arbitrary polygonal and circular inclusion and exclusion areas: Flying > GeoFence.
The settings and underlying geofence parameters are shown below.
The following settings also apply, but are not displayed in the QGC UI.
返航设置
Return is a common failsafe action that engages Return mode to return the vehicle to the home position. This section shows how to set the land/loiter behaviour after returning.
The settings and underlying parameters are shown below:
降落模式设置
Land at the current position is a common failsafe action that engages Land Mode. This section shows how to control when and if the vehicle automatically disarms after landing. For Multicopters (only) you can additionally set the descent rate.
The settings and underlying parameters are shown below:
其他故障保护设置
This section contains information about failsafe settings that cannot be configured through the QGroundControl Safety Setup page.
位置（GPS）丢失故障保护
The Position Loss Failsafe is triggered if the quality of the PX4 position estimate falls below acceptable levels (this might be caused by GPS loss) while in a mode that requires an acceptable position estimate.
The failure action is controlled by COM_POSCTL_NAVL, based on whether RC control is assumed to be available (and altitude information):
0：遥控控制可用。 如果高度估计值可用，则切换到定高模式，否则为自稳模式。1：遥控控制不可用。 如果高度估计值可用，则切换到降落模式，否则进入飞行终止。
Fixed Wing vehicles additionally have a parameter (NAV_GPSF_LT) for defining how long they will loiter (circle) after losing position before attempting to land.
The relevant parameters for all vehicles shown below (also see GPS Failure navigation parameters):
Parameters that only affect Fixed Wing vehicles:
Offboard 中断故障保护
The Offboard Loss Failsafe is triggered if the offboard link is lost while under Offboard control. Different failsafe behaviour can be specified based on whether or not there is also an RC connection available.
The relevant parameters are shown below:
任务故障保护
The Mission Failsafe checks prevent a previous mission being started at a new takeoff location or if it is too big (distance between waypoints is too great). The failsafe action is that the mission will not be run.
The relevant parameters are shown below:
交通规避故障保护
The Traffic Avoidance Failsafe allows PX4 to respond to transponder data (e.g. from ADSB transponders) during missions.
The relevant parameters are shown below:
自适应 QuadChute 故障安全
Failsafe for when a pusher motor fails (or airspeed sensor) and a VTOL vehicle can no longer achieve a desired altitude setpoint in fixed-wing mode. If triggered, the vehicle will transition to multicopter mode and enter failsafe Return mode.
The relevant parameters are shown below:
故障检测器
The failure detector allows a vehicle to take protective action(s) if it unexpectedly flips, or if it is notified by an external failure detection system.
During flight, the failure detector can be used to trigger flight termination if failure conditions are met, which may then launch a parachute or perform some other action.
During takeoff the failure detector attitude trigger invokes the lockdown action if the vehicle flips (lockdown kills the motors but, unlike flight termination, will not launch a parachute or perform other failure actions). Note that this check is always enabled on takeoff, irrespective of the CBRK_FLIGHTTERM parameter.
The failure detector is active in all vehicle types and modes, except for those where the vehicle is expected to do flips (i.e. Acro mode (MC), Acro mode (FW), and Manual (FW)).
姿态触发器
The failure detector can be configured to trigger if the vehicle attitude exceeds predefined pitch and roll values for longer than a specified time.
The relevant parameters are shown below:
外部自动触发系统（ATS）
The failure detector, if enabled, can also be triggered by an external ATS system. The external trigger system must be connected to flight controller port AUX5 (or MAIN5 on boards that do not have AUX ports), and is configured using the parameters below.
应急开关
Remote control switches can be configured (as part of QGroundControl Flight Mode Setup) to allow you to take rapid corrective action in the event of a problem or emergency; for example, to stop all motors, or activate Return mode.
This section lists the available emergency switches.
急停开关
A kill switch immediately stops all motor outputs (and if flying, the vehicle will start to fall)! The motors will restart if the switch is reverted within 5 seconds. After 5 seconds the vehicle will automatically disarm; you will need to arm it again in order to start the motors.
解锁/上锁开关
The arm/disarm switch is a direct replacement for the default stick-based arming/disarming mechanism (and serves the same purpose: making sure there is an intentional step involved before the motors start/stop). It might be used in preference to the default mechanism because:
这种机制偏向于切换动作而不是持续运动。
这种机制可以避免因为某种意外误触而引发的飞行期间解锁/上锁。
这种机制没有延迟（立即作出反应）。
The arm/disarm switch immediately disarms (stop) motors for those flight modes that support disarming in flight. This includes:
手动模式
特技模式
自稳模式
For modes that do not support disarming in flight, the switch is ignored during flight, but may be used after landing is detected. This includes Position mode and autonomous modes (e.g. Mission, Land etc.).
返航开关
A return switch can be used to immediately engage Return mode.
其他安全设置
超时自动上锁
You can set timeouts to automatically disarm a vehicle if it is too slow to takeoff, and/or after landing (disarming the vehicle removes power to the motors, so the propellers won't spin).
The relevant parameters are shown below:
更多信息
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