비행 과업

Flight Tasks are used within Flight Modes to provide specific movement behaviours: e.g. follow me, or flight smoothing.

개요

A flight task is a class in the flight task framework derived from the base class FlightTask. 목표는 각 작업이 특정 모드의 기체 동작을 구현하는 임의의 입력 데이터에서 콘트롤러에 대한 설정값을 생성하는 것입니다. Programmers typically override the activate() and update() virtual methods by calling the base task's minimal implementation and extending with the implementation of the desired behavior. The activate() method is called when switching to the task and allows to initialize its state and take over gently from the passed over setpoints the previous task was just applying.

update() is called on every loop iteration during the execution and contains the core behavior implementation producing setpoints.

By convention tasks are contained in a subfolder of PX4-Autopilot/src/modules/flight_mode_manager/tasks named after the task, and the source files are named with the prefix "FlightTask".

INFO

Video overviews from PX4 developer summits are provided below.

비행 작업 생성

The instructions below might be used to create a task named MyTask:

1. Create a directory for the new flight task in PX4-Autopilot/src/modules/flight_mode_manager/tasks. By convention the directory is named after the task, so we will call it /MyTask.

   mkdir PX4-Autopilot/src/lib/flight_tasks/tasks/MyTask

2. Create empty source code and cmake files for the new flight task in the MyTask directory using the prefix "FlightTask":

   • CMakeLists.txt
   • FlightTaskMyTask.hpp
   • FlightTaskMyTask.cpp

3. Update CMakeLists.txt for the new task

   • Copy the contents of the CMakeLists.txt for another task - e.g. Orbit/CMakeLists.txt

   • Update the copyright to the current year

     ############################################################################
     #
     #   Copyright (c) 2021 PX4 Development Team. All rights reserved.
     #

   • Modify the code to reflect the new task - e.g. replace FlightTaskOrbit with FlightTaskMyTask. The code will look something like this:

     px4_add_library(FlightTaskMyTask
         FlightTaskMyTask.cpp
     )
     
     target_link_libraries(FlightTaskMyTask PUBLIC FlightTask)
     target_include_directories(FlightTaskMyTask PUBLIC ${CMAKE_CURRENT_SOURCE_DIR})

4. Update the header file (in this case FlightTaskMyTask.hpp): Most tasks reimplement the virtual methods activate() and update(), and in this example we also have a private variable.

   #pragma once
   
   #include "FlightTask.hpp"
   
   class FlightTaskMyTask : public FlightTask
   {
   public:
     FlightTaskMyTask() = default;
     virtual ~FlightTaskMyTask() = default;
   
     bool update();
     bool activate(const trajectory_setpoint_s &last_setpoint) override;
   
   private:
     float _origin_z{0.f};
   };

5. cpp 파일을 적절하게 업데이트 합니다. This example provides as simple implementation of FlightTaskMyTask.cpp that simply indicates that the task methods are called.

   #include "FlightTaskMyTask.hpp"
   
   bool FlightTaskMyTask::activate(const trajectory_setpoint_s &last_setpoint)
   {
     bool ret = FlightTask::activate(last_setpoint);
     PX4_INFO("FlightTaskMyTask activate was called! ret: %d", ret); // report if activation was successful
     return ret;
   }
   
   bool FlightTaskMyTask::update()
   {
     PX4_INFO("FlightTaskMyTask update was called!"); // report update
     return true;
   }

6. Add the new task to the list of tasks to be built in PX4-Autopilot/src/modules/flight_mode_manager/CMakeLists.txt.

   ...
    list(APPEND flight_tasks_all
      Auto
      Descend
      ...
      ManualPositionSmoothVel
      Transition
      MyTask
    )
   ...

   TIP

   The task added above will be built on all boards, including those with constrained flash such as Pixhawk FMUv2. If your task is not indended for use on boards with constrained flash it should instead be added to the conditional block shown below (as shown).

   ...
   if(NOT px4_constrained_flash_build)
      list(APPEND flight_tasks_all
        AutoFollowTarget
        Orbit
        MyTask
      )
    endif()
   ...

:::

7. 작업이 호출되도록 비행 모드를 업데이트합니다. 일반적으로, 매개변수는 특정 비행 작업을 사용해야 하는 시기를 선택합니다.

   For example, to enable our new MyTask in multicopter Position mode:

   • Update MPC_POS_MODE (multicopter_position_mode_params.c) to add an option for selecting "MyTask" if the parameter has a previously unused value like 5:

     ...
      * @value 0 Direct velocity
      * @value 3 Smoothed velocity
      * @value 4 Acceleration based
      * @value 5 My task
      * @group Multicopter Position Control
      */
     PARAM_DEFINE_INT32(MPC_POS_MODE, 5);

   • Add a case for your new option in the switch for the parameter FlightModeManager.cpp to enable the task when _param_mpc_pos_mode has the right value.

     ...
     // manual position control
     ...
     switch (_param_mpc_pos_mode.get()) {
       ...
       case 3:
          error = switchTask(FlightTaskIndex::ManualPositionSmoothVel);
          break;
       case 5: // Add case for new task: MyTask
          error = switchTask(FlightTaskIndex::MyTask);
          break;
     case 4:
     ....
     ...

신규 비행 작업 테스트

비행 작업을 테스트하려면, 작업이 활성화된 상태에서 기체를 실행하여야 합니다. For the example above, this means setting the parameter MPC_POS_MODE to 5, taking off, and switching the vehicle to Position mode.

INFO

The task defined above should only be tested on the simulator. 코드는 실제로 설정값을 생성하지 않으므로 기체는 비행하지 않습니다.

Build SITL simulation (gazebo-classic)

make px4_sitl gazebo-classic

Open QGroundControl (if not open, no message information will be printed out). In the console, takeoff and switch to Position mode:

pxh> commander takeoff
pxh> commander mode posctl

The console will continuously display: INFO [FlightTaskMyTask] FlightTaskMyTask update was called!. If you want to change to another flight mode, you can type a command to change the mode, such as commander mode altctl.

비디오

다음 비디오는 PX4의 비행 작업에 대한 개요를 제공합니다. 첫 번째는 PX4 v1.9의 비행 작업 프레임워크 상태를 다룹니다. 두 번째는 PX4 v1.11의 변경 사항을 다루는 업데이트입니다.

PX4 Flight Task Architecture 개요(PX4 개발자 회의 2019)

PX4 v1.9의 비행 모드 작동 방식 설명(Dennis Mannhart, Matthias Grob).

센서에서 모터에 이르는 멀티콥터 제어 개요(PX4 가상 개발자 회의 2020)

The relevant section of this video is an update of flight tasks in PX4 v11.1 at (9min 20sec). The slides can be found here (PDF) - Slides 9 and 12 are relevant.