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120 lines
6.6 KiB
Markdown
120 lines
6.6 KiB
Markdown
# 비행 모드
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Modes ("flight modes", "drive modes", and so on) are special operational states that control how the autopilot responds to user input and controls vehicle movement.
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They are loosely grouped into _manual_, _assisted_ and _auto_ modes, based on the level/type of control provided by the autopilot.
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조종사는 리모콘 스위치를 사용하거나 지상 관제소를 사용하여 비행 모드를 전환할 수 있습니다.
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Modes can be implemented as [PX4 internal modes](#px4-internal-modes) running on the flight controller, or as [PX4 external (ROS2) modes](#px4-external-modes) running on a companion computer.
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From the perspective of a ground station (MAVLink), the origin of a mode is indistinguishable.
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This topic links to documentation for the supported modes, compares PX4 internal and external modes, provides implementation hints, and provides links to how PX4 modes can be used with MAVLink.
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## Supported Modes
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Not all modes are available (or makes sense), on all vehicle types, and some modes behave differently on different vehicle types.
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Mode documentation for the PX4 internal modes are listed below:
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- [Flight Modes (Multicopter)](../flight_modes_mc/index.md)
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- [Flight Modes (Fixed-Wing)](../flight_modes_fw/index.md)
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- [Flight Modes (VTOL)](../flight_modes_vtol/index.md)
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- [Drive Modes (Rover)](../flight_modes_rover/index.md)
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- [Basic Configuration > Flight Modes](../config/flight_mode.md)
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## Internal vs External Modes
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With some exceptions a mode can be implemented in either the FC or companion computer.
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The main considerations are listed below.
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PX4 external modes cannot be used in the following cases:
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- Modes that need to run on vehicles that don't have a companion computer.
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- Modes that require low-level access, strict timing, and/or high update rate requirements.
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For example, a multicopter mode that implements direct motor control.
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- Safety critical modes, such as [Return mode](../flight_modes_mc/return.md).
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- When you can't use ROS (for any reason).
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External modes should be considered for all other cases.
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They have the following benefits:
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- Easier to implement as there is no need to deal with low-level embedded constraints and requirements (such as restricted stack sizes).
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- Easier to maintain as the integration API is small, well defined, and stable.
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- Porting custom PX4 modes on the flight controller between PX4 versions can be much harder, as often flight modes use interfaces that are considered internal, and allowed to change.
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- Process termination of a ROS 2 mode results in a fallback to an internal flight mode (while termination of an internal mode may well crash the vehicle).
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- They can override existing modes to provide more advanced features.
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You can even override a safety-critical mode with a better versions: if the ROS 2 mode crashes the original mode will be engaged.
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- High-level functionality is available, including a better-feature programming environment, and many useful Linux and ROS libraries.
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- More available compute to do more advanced processing (e.g. computer vision).
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Note that the [PX4 ROS 2 Control Interface](../ros2/px4_ros2_control_interface.md) used to create external modes first appeared in PX4 v1.15 and is still considered experimental.
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There are still some limitations, but expect changes and ongoing enhancement.
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## PX4 External Modes
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PX4 external modes, are written in ROS 2 using the [PX4 ROS 2 Control Interface](../ros2/px4_ros2_control_interface.md) (see link for instructions).
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## PX4 Internal Modes
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<!--
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The specific control behaviour of a mode at any time is determined by a [Flight Task](../concept/flight_tasks.md).
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A mode might define one or more tasks that define variations of the mode behavior, for example whether inputs are treated as acceleration or velocity setpoints.
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The task that is used is normally defined in a parameter, and selected in [src/modules/flight_mode_manager/FlightModeManager.cpp](https://github.com/PX4/PX4-Autopilot/blob/main/src/modules/flight_mode_manager/FlightModeManager.cpp#L266-L285)
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Name the relevant modules in which code directly related to flight modes is defined.
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Name any base classes that modes must/should derive from
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Explain the core things you need to do to make a mode work
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Very high level architecture
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-->
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### Mode Restrictions
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Some modes only make sense only under specific pre-flight and in-flight conditions.
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For example, a manual control mode should not be used unless the system has a manual controller.
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PX4 modes can specify these conditions as _restrictions_.
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For internal modes the types of restrictions are listed in the [FailsafeFlags](../msg_docs/FailsafeFlags.md) uORB topic under "Per mode requirements" (duplicated below)
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```text
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# Per-mode requirements
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mode_req_angular_velocity
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mode_req_attitude
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mode_req_local_alt
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mode_req_local_position
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mode_req_local_position_relaxed
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mode_req_global_position
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mode_req_mission
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mode_req_offboard_signal
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mode_req_home_position
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mode_req_wind_and_flight_time_compliance # if set, mode cannot be entered if wind or flight time limit exceeded
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mode_req_prevent_arming # if set, cannot arm while in this mode
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mode_req_manual_control
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mode_req_other # other requirements, not covered above (for external modes)
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```
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If the condition of restriction is not met:
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- arming is not allowed, while the mode is selected
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- when already armed, the mode cannot be selected
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- when armed and the mode is selected, the relevant failsafe is triggered (e.g. RC loss for the manual control requirement).
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Check [Safety (Failsafe) Configuration](../config/safety.md) for how to configure failsafe behaviour.
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This is the corresponding flow diagram for the manual control flag (`mode_req_manual_control`):
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The requirements for all modes are set in `getModeRequirements()` in [src/modules/commander/ModeUtil/mode_requirements.cpp](https://github.com/PX4/PX4-Autopilot/blob/main/src/modules/commander/ModeUtil/mode_requirements.cpp#L46).
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When adding a new mode you will need to add appropriate requirements in that method.
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:::tip
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Readers may note that this image is from [PX4 ROS2 Control Interface > Failsafes and mode requirements](../ros2/px4_ros2_control_interface.md#failsafes-and-mode-requirements).
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The requirements and concepts are the same (though defined in different places).
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The main difference is that ROS 2 modes _infer_ the correct requirements to use, while modes in PX4 source code must explicitly specify them.
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:::
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## MAVLink Integration
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PX4 implements the MAVLink [Standard Modes Protocol](../mavlink/standard_modes.md) from PX4 v1.15.
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This can be used to discover all modes and the current mode, and to set the current mode.
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