飞行模式
Flight Modes define how the autopilot responds to user input and controls vehicle movement. They are loosely grouped into manual, assisted and auto modes, based on the level/type of control provided by the autopilot. 飞手使用遥控器上的开关或者 ground control station 在飞行模式之间进行切换。
需要注意的是并非所有类型的飞机都具备全部的飞行模式，同时部分模式在不同类型的飞机上的行为模式也不相同（见下文）。 Finally, some flight modes make sense only under specific pre-flight and in-flight conditions (e.g. GPS lock). 系统只会在特定条件下才能进行一些模式之间的切换。
The sections below provide an overview of the modes, followed by a flight mode evaluation diagram that shows the conditions under which PX4 will transition into a new mode.
INFO
User-facing flight mode documentation can be found in:
飞行模式概要
Manual Flight Modes
"Manual" modes are those where the user has direct control over the vehicle via the RC control (or joystick). Vehicle movement always follows stick movement, but the level/type of response changes depending on the mode. For example, experienced fliers can use modes that provide direct passthrough of stick positions to actuators, while beginners will often choose modes that are less responsive to sudden stick-position changes.
Rovers / Boats:
- MANUAL/STABILIZED/ACRO: The pilot's control inputs (raw user inputs from RC transmitter) are passed directly to control allocation.
Fixed-wing aircraft:
- MANUAL: The pilot's control inputs (raw user inputs from RC transmitter) are passed directly to control allocation.
- STABILIZED: The pilot's pitch and roll inputs are passed as angle commands to the autopilot, while the yaw input is sent directly via control allocation to the rudder (manual control). If the RC roll and pitch sticks are centered, the autopilot regulates the roll and pitch angles to zero, hence stabilizing (leveling-out) the attitude against any wind disturbances. However, in this mode the position of the aircraft is not controlled by the autopilot, hence the position can drift due to wind. With nonzero roll input the vehicle does a coordinated turn to achieve zero sideslip (the acceleration in y-direction (sidewards) is zero). During a coordinated turn, the rudder is used to control the sideslip and any manual yaw input is added to that.
- ACRO: The pilot's inputs are passed as roll, pitch, and yaw rate commands to the autopilot. 反之，飞手的操作输入会作为滚转和俯仰<1>角度</1>指令和偏航<1>角速率</1> 指令。 Throttle is passed directly to control allocation.
Multirotors:
STABILIZED (MANUAL also selects this mode): The pilot's inputs are passed as roll and pitch angle commands and a yaw rate command. Throttle is passed directly to control allocation. The autopilot controls the attitude, meaning it regulates the roll and pitch angles to zero when the RC sticks are centered, consequently leveling-out the attitude. However, in this mode the position of the vehicle is not controlled by the autopilot, hence the position can drift due to wind.
INFO
For Multirotors, Manual and Stabilized modes are the same.
:::
- ACRO: The pilot's inputs are passed as roll, pitch, and yaw rate commands to the autopilot. The autopilot controls the angular rates, but not the attitude. Hence, if the RC sticks are centered the vehicle will not level-out. This allows the multirotor to become completely inverted. Throttle is passed directly to control allocation.
辅助飞行模式
"Assisted" modes are also user controlled but offer some level of "automatic" assistance - for example, automatically holding position/direction, against wind. Assisted modes often make it much easier to gain or restore controlled flight.
ALTCTL (Altitude Control)
- Fixed-wing aircraft: When the roll, pitch and yaw (RPY) RC sticks are all centered (or less than some specified deadband range) the aircraft will return to straight and level flight and keep its current altitude. 飞机的的 X 和 Y 方向的位置会随风漂移。
- Multirotors: Roll, pitch and yaw inputs are as in Stabilised mode. 油门输入会令飞机按照预定的最大速率爬升或下降。 油门的输入有很大的死区。 油门居中表示保持当前高度。 飞控程序仅控制高度，所以飞机的 X、Y 位置会随风漂移。
POSCTL (Position Control)
- Fixed-wing aircraft: Neutral inputs (centered RC sticks) give level flight and it will crab against the wind if needed to maintain a straight line.
- Multirotors Roll controls left-right speed, pitch controls front-back speed over ground. 偏航与手动控制模式一样，控制的是偏航角速率。 油门与定高模式 模式一样控制飞机的爬升/下降速率。 这意味着当滚转、俯仰和油门杆居中时，飞控程序会在任意风的干扰下稳定地保持飞机的X、Y、Z 位置。
自动飞行模式
"Auto" modes are those where the controller requires little to no user input (e.g. to takeoff, land and fly missions).
AUTO_LOITER (Loiter)
- Fixed-wing aircraft: The aircraft loiters around the current position at the current altitude (or possibly slightly above the current altitude, good for 'I'm losing it').
- Multirotors: The multirotor hovers / loiters at the current position and altitude.
AUTO_RTL (Return to Launch)
- Fixed-wing aircraft: The aircraft returns to the home position and loiters in a circle above the home position.
- Multirotors: The multirotor returns in a straight line on the current altitude (if the current altitude is higher than the home position + RTL_RETURN_ALT) or on the RTL_RETURN_ALT (if the RTL_RETURN_ALT is higher than the current altitude), then lands automatically.
AUTO_MISSION (Mission)
- All system types: The aircraft obeys the programmed mission sent by the ground control station (GCS). 如果没有收到任务, 飞机将会在当前的的位置上停留/盘旋。
- OFFBOARD (Offboard) In this mode the position, velocity or attitude reference / target / setpoint is provided by a companion computer connected via serial cable and MAVLink. The offboard setpoint can be provided by APIs like MAVSDK or MAVROS.
飞行模式评估图
