PX4 오토파일럿 사용자 설명서

# 항공 사고 방지: ADS-B/FLARM

PX4는 ADS-B (opens new window) 또는 FLARM (opens new window) 트랜스폰더를 사용하여 임무에서 간단한 항공 시고 방지를 지원할 수 있습니다. 잠재적인 충돌이 감지되면 PX4는 NAV_TRAFF_AVOID의 값에 따라 경고, 즉시 착륙 또는 귀환 할 수 있습니다.

# 지원 하드웨어

PX4 사고방지는 MAVLink ADSB_VEHICLE (opens new window) 메시지를 사용하여 트랜스폰더 데이터를 제공하는 ADS-B 또는 FLARM 제품에서 작동합니다.

다음 장치들로 테스트되었습니다:

# 하드웨어 설정

두 장치 모두 비행컨트롤러의 직렬 포트에 연결할 수 있습니다. 가장 일반적으로 TELEM2에 연결됩니다 (다른 용도로 사용되지 않는 경우).

# PingRX

PingRX MAVLink 포트는 아래와 같이 핀아웃이있는 JST ZHR-4 메이팅 커넥터를 사용합니다.

핀 신호 전압
1 (red) RX (IN) +5V tolerant
2 (blk) TX (OUT)
3 (blk) Power +4 to 6V
4 (blk) GND GND

PingRX에는 mRo Pixhawk의 TELEM2 포트 (DF13-6P)에 직접 연결가능한 커넥터 케이블이 함께 제공됩니다. 다른 포트나 보드의 경우 자체 케이블이 필요합니다.

# FLARM

FLARM에는 mRo Pixhawk와 동일한 핀아웃을 가진 온보드 DF-13 6 핀 커넥터가 있습니다.

핀 신호 전압
1 (red) VCC +4V to +36V
2 (blk) TX (OUT) +3.3V
3 (blk) RX (IN) +3.3V
4 (blk) - +3.3V
5 (blk) - +3.3V
6 (blk) GND GND

Note

비행 컨트롤러의 TX 및 RX는 FLARM의 RX 및 TX에 각각 연결되어야 합니다.

# 소프트웨어 설정

# 포트 설정

Flarm/PingRX는 다른 MAVLink 주변기기와 동일한 방식으로 설정됩니다. 유일한 특정 설정은 포트 전송 속도가 57600 및 저 대역폭 프로필 (MAV_X_MODE)로 설정되어야 한다는 것입니다.

장치를 TELEM2 포트에 연결했다고 가정하고 다음과 같이 매개 변수를 설정합니다.

기체를 재부팅합니다.

이제 57600으로 설정하여야 하는 SER_TEL2_BAUD라는 새 매개변수를 찾을 수 있습니다.

# 사고 방지 설정

아래의 매개변수를 사용하여 잠재적 충돌시의 동작을 설정합니다.

매개변수 설명
NAV_TRAFF_AVOID 교통 회피 모드 활성화는 회피 대응을 지정합니다. 0 : 비활성화, 1 : 경고 만, 2 : 귀환 모드, 3 : 착륙 모드.
NAV_TRAFF_A_HOR Horizonal radius of cylinder around the vehicle that defines its airspace (i.e. the airspace in the ground plane).
NAV_TRAFF_A_VER Vertical height above and below vehicle of the cylinder that defines its airspace (also see NAV_TRAFF_A_HOR).
NAV_TRAFF_COLL_T Collision time threshold. Avoidance will trigger if the estimated time until collision drops below this value (the estimated time is based on relative speed of traffic and UAV).

# 구현

아래의 매개변수를 사용하여 잠재적 충돌 발생시 기체의 동작을 설정합니다.

If a valid transponder report is received, PX4 first uses the traffic transponder information to estimate whether the traffic heading and height indicates there will be an intersection with the airspace of the UAV. The UAV airspace consists of a surrounding cylinder defined by the radius NAV_TRAFF_A_HOR and height NAV_TRAFF_A_VER, with the UAV at it's center. The traffic detector then checks if the time until intersection with the UAV airspace is below the NAV_TRAFF_COLL_T threshold based on the relative speed. If the both checks are true, the Traffic Avoidance Failsafe action is started, and the vehicle will either warn, land, or return.

The code can be found in Navigator::check_traffic (/src/modules/navigator/navigator_main.cpp (opens new window)).

MAVLink 인스턴스에 대해 구성된 경우 PX4는 트랜스폰더 데이터도 GCS로 전달합니다 (권장됨). GUID의 마지막 10 자리로 드론을 식별합니다.

# Testing/Simulated ADSB Traffic

You can simulate ADS-B traffic for testing. Note that this requires that you Build PX4.

Note

Simulated ADS-B traffic can trigger real failsafe actions. Use with care in real flight!

To enable this feature:

  1. Uncomment the code in AdsbConflict::run_fake_traffic()(AdsbConflict.cpp (opens new window)).
  2. Rebuild and run PX4.
  3. Execute the navigator fake_traffic command in the QGroundControl MAVLink Shell (opens new window) (or some other PX4 Console or MAVLink shell, such as the PX4 simulator terminal).

The code in run_fake_traffic() is then executed. You should see ADS-B warnings in the Console/MAVLink shell, and QGC should also show an ADS-B traffic popup.

By default run_fake_traffic() publishes a number of traffic messages (it calls AdsbConflict::fake_traffic() to emit each report). These simulate ADS-B traffic where there may be a conflict, where there won't be a conflict, as well as spamming the traffic buffer.

DETAILS

Information about the test methods

The relevent methods are defined in AdsbConflict.cpp (opens new window).

# run_fake_traffic() method

The run_fake_traffic() method is run when the navigator fake_traffic command is called.

The method calls the fake_traffic() method to generate simulated transponder messages around the current vehicle position. It passes in the current vehicle position, and information about the simulated traffic, such as callsign, distances, directions, altitude differences, velocities, and emitter types.

The (commented out) code in run_fake_traffic() simulates a number of different scenarios, including conflicts and non-conflicts, as well as spamming the traffic buffer.

# fake_traffic() method

AdsbConflict::fake_traffic() is called by the run_fake_traffic() to create individual ADS-B transponder reports.

This takes several parameters, which specify the characteristics of the fake traffic:

  • callsign: Callsign of the fake transponder.
  • distance: Horizontal distance to the fake vehicle from the current vehicle.
  • direction: Direction in NED from this vehicle to the fake in radians.
  • traffic_heading: Travel direction of the traffic in NED in radians.
  • altitude_diff: Altitude difference of the fake traffic. Positive is up.
  • hor_velocity: Horizontal velocity of fake traffic, in m/s.
  • ver_velocity: Vertical velocity of fake traffic, in m/s.
  • emitter_type: Type of fake vehicle, as an enumerated value.
  • icao_address: ICAO address.
  • lat_uav: Lat of this vehicle (used to position fake traffic around vehicle)
  • on_uav: Lon of this vehicle (used to position fake traffic around vehicle)
  • alt_uav: Altitude of the vehicle (as reference - used to position fake traffic around vehicle)

The method creates a simulated transponder message near the vehicle, using following steps:

  • Calculates the latitude and longitude of the traffic based on the UAV's position, distance, and direction.
  • Computes the new altitude by adding the altitude difference to the UAV's altitude.
  • Populates a TransponderReport topic with the simulated traffic data.
  • If the board supports a Universally Unique Identifier (UUID), the method retrieves the UUID using board_get_px4_guid and copies it to the uas_id field of the structure. Otherwise, it generates a simulated GUID.
  • Publishes the simulated traffic message using orb_publish.

# 추가 정보

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