Task Manager: State Machine¶

The primary control loop is the state machine in the task manager node. This state machine is described in the diagram below:

stateDiagram
   direction TB

   accTitle: State machine diagram for Open Drone Core

   classDef system fill:var(--md-default-bg-color),stroke:#555,color:var(--md-default-fg-color)

   [*] --> INITIALIZING:::system
   INITIALIZING --> PREFLIGHT_CHECKS:::system
   PREFLIGHT_CHECKS--> READY:::system : if ready to arm
   READY --> PREFLIGHT_CHECKS : if not ready to arm

   READY --> MANUAL : on pilot takes off
   MANUAL --> COMPLETE:::system : on arm -> disarm
   COMPLETE --> PREFLIGHT_CHECKS

   READY --> TAKING_OFF : on accepted mission
   TAKING_OFF --> MISSION : on altitude reached
   MISSION --> MISSION : on new mission accepted
   MISSION --> RTL_88 : on mission complete

   RTL_88 --> LANDING : on reached home
   LANDING --> COMPLETE : on arm -> disarm

States¶

States are defined by the TaskManager::Task enum and include the following:

• INITIALIZING
  The system is powering up and performing initial setup.

• PREFLIGHT_CHECKS
  Pre-flight checks are performed by the onboard flight controller to ensure the system is ready for operation.

• READY
  The system is ready to arm and begin flight operations.

• MANUAL_FLIGHT
  The drone is under direct manual control by the pilot.

• PAUSE
  The mission or flight is temporarily paused by the user.

• MISSION
  The drone is executing an autonomous mission.

• RTL_88
  Return-to-launch sequence is active (RTL). RTL_88 uses the obstacle-aware path planner and DEM when available, in contrast to the PX4/ArduPilot RTL methods.

• TAKING_OFF
  The drone is in the process of taking off.

• LANDING
  The drone is landing.

• FAILSAFE_LANDING
  The drone is performing a failsafe landing due to an error or safety trigger.

• COMPLETE
  The flight or mission has ended, and the system is disarmed.

Events¶

Events cause the state machine to change states.

• FLIGHT CONTROLLER CHECKS PASS/FAIL
  The onboard flight controller checks pass, then the state moves to READY. If they fail, the state is PREFLIGHT_CHECKS.

• FRONTEND MISSION RECEIVED
  If a mission is received and all the correct Task Manager integration is complete, MISSION state is activated.

• AUTONOMY ALTITUDE REACHED
  Missions can only be activated after takeoff once the user-defined altitude volume is reached.

• PILOT TAKEOFF
  The drone detects takeoff without a mission, not in guided mode.

• FRONTEND EMERGENCY BUTTON
  The 3 frontend emergency buttons result in 3 separate possible states: PAUSE, RTL_88, and FAILSAFE_LANDING.

• MISSION COMPLETE
  On completing the mission (e.g., setpoint reached, lawnmower points all completed), the drone enters hover mode and sets state to READY.

• AUTOMATIC FAILSAFE TRIGGERED
  Any of the failsafes can be automatically detected and interrupt a lower priority state, moving to FAILSAFE_LANDING.