# 오프보드 제어

:::warning
[Offboard control](../flight_modes/offboard.md) is dangerous.
오프보드 비행전에 적절한 준비, 테스트 및 안전 예방 조치를 취하여야 합니다.
:::

오프보드 제어의 아이디어는 자동조종장치 외부에서 실행되는 소프트웨어를 사용하여 PX4를 제어하는 것입니다.
This is done through the MAVLink protocol, specifically the [SET_POSITION_TARGET_LOCAL_NED](https://mavlink.io/en/messages/common.html#SET_POSITION_TARGET_LOCAL_NED) and the [SET_ATTITUDE_TARGET](https://mavlink.io/en/messages/common.html#SET_ATTITUDE_TARGET) messages.

## 오프보드 제어 펌웨어 설정

오프보드 개발전에 펌웨어에서 두 가지를 설정하여야 합니다.

### Enable RC Override

In _QGroundControl_ you can set the [COM_RC_OVERRIDE](../advanced_config/parameter_reference.md#COM_RC_OVERRIDE) parameter to automatically switch from offboard mode (or any mode) to Position mode if the RC sticks are moved.
This is the best way to ensure that an operator can easily take control of the vehicle and switch to the safest flight mode.

### RC 스위치를 오프보드 모드 활성화에 매핑

In _QGroundControl_ you can set the [RC_MAP_OFFB_SW](../advanced_config/parameter_reference.md#RC_MAP_OFFB_SW) parameter to the RC channel that will be used to activate offboard mode.
This can be used to switch between offboard mode and the mode set by the mode switch ([RC_MAP_MODE_SW](../advanced_config/parameter_reference.md#RC_MAP_MODE_SW)).
You can also switch into offboard mode using a GCS/MAVLink so this is not "mandatory".

Note also that this mechanism is not as "safe" as using [RC Override](#enable-rc-override) to switch out of offboard mode, because the mode you switch to is unpredictable.

### 보조 컴퓨터 인터페이스 활성화

Enable MAVLink on the serial port that you connect to the companion computer (see [Companion Computers](../companion_computer/index.md)).

## 하드웨어 설정

일반적으로 오프보드 통신을 설정하는 방법에는 세 가지가 있습니다.

### 직렬 라디오

1. 하나는 자동조종장치의 UART 포트에 연결합니다.
2. One connected to a ground station computer

   Example radios include:

   - [Digi International XBee Pro](https://www.digi.com/products/embedded-systems/digi-xbee/rf-modules/sub-1-ghz-rf-modules)

[![Mermaid graph: mavlink channel](https://mermaid.ink/img/eyJjb2RlIjoiZ3JhcGggVEQ7XG4gIGduZFtHcm91bmQgU3RhdGlvbl0gLS1NQVZMaW5rLS0-IHJhZDFbR3JvdW5kIFJhZGlvXTtcbiAgcmFkMSAtLVJhZGlvUHJvdG9jb2wtLT4gcmFkMltWZWhpY2xlIFJhZGlvXTtcbiAgcmFkMiAtLU1BVkxpbmstLT4gYVtBdXRvcGlsb3RdOyIsIm1lcm1haWQiOnsidGhlbWUiOiJkZWZhdWx0In0sInVwZGF0ZUVkaXRvciI6ZmFsc2V9)](https://mermaid-js.github.io/mermaid-live-editor/#/edit/eyJjb2RlIjoiZ3JhcGggVEQ7XG4gIGduZFtHcm91bmQgU3RhdGlvbl0gLS1NQVZMaW5rLS0-IHJhZDFbR3JvdW5kIFJhZGlvXTtcbiAgcmFkMSAtLVJhZGlvUHJvdG9jb2wtLT4gcmFkMltWZWhpY2xlIFJhZGlvXTtcbiAgcmFkMiAtLU1BVkxpbmstLT4gYVtBdXRvcGlsb3RdOyIsIm1lcm1haWQiOnsidGhlbWUiOiJkZWZhdWx0In0sInVwZGF0ZUVkaXRvciI6ZmFsc2V9)

<!-- original mermaid graph
graph TD;
  gnd[Ground Station] --MAVLink-- > rad1[Ground Radio];
  rad1 --RadioProtocol-- > rad2[Vehicle Radio];
  rad2 --MAVLink-- > a[Autopilot];
-->

### 온보드 프로세서

A small computer mounted onto the vehicle, connected to the autopilot through a serial port or Ethernet port.
There are many possibilities here and it will depend on what kind of additional on-board processing you want to do in addition to sending commands to the autopilot.
Some examples are provided in [Companion Computers](../companion_computer/index.md#companion-computer-options).

[![Mermaid diagram: Companion mavlink](https://mermaid.ink/img/eyJjb2RlIjoiZ3JhcGggVEQ7XG4gIGNvbXBbQ29tcGFuaW9uIENvbXB1dGVyXSAtLU1BVkxpbmstLT4gdWFydFtVQVJUIEFkYXB0ZXJdO1xuICB1YXJ0IC0tTUFWTGluay0tPiBBdXRvcGlsb3Q7IiwibWVybWFpZCI6eyJ0aGVtZSI6ImRlZmF1bHQifSwidXBkYXRlRWRpdG9yIjpmYWxzZX0)](https://mermaid-js.github.io/mermaid-live-editor/#/edit/eyJjb2RlIjoiZ3JhcGggVEQ7XG4gIGNvbXBbQ29tcGFuaW9uIENvbXB1dGVyXSAtLU1BVkxpbmstLT4gdWFydFtVQVJUIEFkYXB0ZXJdO1xuICB1YXJ0IC0tTUFWTGluay0tPiBBdXRvcGlsb3Q7IiwibWVybWFpZCI6eyJ0aGVtZSI6ImRlZmF1bHQifSwidXBkYXRlRWRpdG9yIjpmYWxzZX0)

<!-- original mermaid graph
graph TD;
  comp[Companion Computer] --MAVLink-- > uart[UART Adapter];
  uart --MAVLink-- > Autopilot;
-->

### On-board processor and wifi link to ROS (**_Recommended_**)

A small computer mounted onto the vehicle connected to the autopilot through a UART to USB adapter while also having a WiFi link to a ground station running ROS.
This can be any of the computers from the above section coupled with a WiFi adapter.

[![Mermaid graph: ROS](https://mermaid.ink/img/eyJjb2RlIjoiZ3JhcGggVERcbiAgc3ViZ3JhcGggR3JvdW5kICBTdGF0aW9uXG4gIGduZFtST1MgRW5hYmxlZCBDb21wdXRlcl0gLS0tIHFnY1txR3JvdW5kQ29udHJvbF1cbiAgZW5kXG4gIGduZCAtLU1BVkxpbmsvVURQLS0-IHdbV2lGaV07XG4gIHFnYyAtLU1BVkxpbmstLT4gdztcbiAgc3ViZ3JhcGggVmVoaWNsZVxuICBjb21wW0NvbXBhbmlvbiBDb21wdXRlcl0gLS1NQVZMaW5rLS0-IHVhcnRbVUFSVCBBZGFwdGVyXVxuICB1YXJ0IC0tLSBBdXRvcGlsb3RcbiAgZW5kXG4gIHcgLS0tIGNvbXAiLCJtZXJtYWlkIjp7InRoZW1lIjoiZGVmYXVsdCJ9LCJ1cGRhdGVFZGl0b3IiOmZhbHNlfQ)](https://mermaid-js.github.io/mermaid-live-editor/#/edit/eyJjb2RlIjoiZ3JhcGggVERcbiAgc3ViZ3JhcGggR3JvdW5kICBTdGF0aW9uXG4gIGduZFtST1MgRW5hYmxlZCBDb21wdXRlcl0gLS0tIHFnY1txR3JvdW5kQ29udHJvbF1cbiAgZW5kXG4gIGduZCAtLU1BVkxpbmsvVURQLS0-IHdbV2lGaV07XG4gIHFnYyAtLU1BVkxpbmstLT4gdztcbiAgc3ViZ3JhcGggVmVoaWNsZVxuICBjb21wW0NvbXBhbmlvbiBDb21wdXRlcl0gLS1NQVZMaW5rLS0-IHVhcnRbVUFSVCBBZGFwdGVyXVxuICB1YXJ0IC0tLSBBdXRvcGlsb3RcbiAgZW5kXG4gIHcgLS0tIGNvbXAiLCJtZXJtYWlkIjp7InRoZW1lIjoiZGVmYXVsdCJ9LCJ1cGRhdGVFZGl0b3IiOmZhbHNlfQ)

<!-- original mermaid graph
graph TD
  subgraph Ground  Station
  gnd[ROS Enabled Computer] --- qgc[qGroundControl]
  end
  gnd --MAVLink/UDP-- > w[WiFi];
  qgc --MAVLink-- > w;
  subgraph Vehicle
  comp[Companion Computer] --MAVLink-- > uart[UART Adapter]
  uart --- Autopilot
  end
  w --- comp
-->