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Command System

Overview

The Command dataclass and CommandType enum define a standardised communication layer between input adapters (gesture, keyboard, etc.) and drone control adapters (AirSim, etc.).

A command represents an intent that an input system wants to execute. It is intentionally minimal to keep input systems decoupled from drone implementations.

New commands are added by extending the CommandType enum and implementing handling in DroneAdapter.execute() and corresponding concrete adapters.

CommandType Enum

Purpose

Defines all supported drone actions. Each enum value maps to a single operation in a DroneAdapter implementation.

Values

  • TAKEOFF
  • LAND
  • MOVE_UP
  • MOVE_DOWN
  • MOVE_LEFT
  • MOVE_RIGHT
  • MOVE_FORWARD
  • MOVE_BACKWARD
  • ROTATE_CW
  • ROTATE_CCW
  • HOVER
  • EMERGENCY_STOP

Priority Constants

These constants define execution priority levels for commands.

  • PRIORITY_NORMAL = 1
  • PRIORITY_HIGH = 10
  • PRIORITY_CRITICAL = 999

Higher values indicate higher priority. This is enforced by the handler.

Command Dataclass

Purpose

Represents a single immutable command to be executed by the drone control pipeline.

The optional payload can be used to configure custom commands, for instance subtly changing the speed and duration for more fluid or sensitive control.

Fields

type: CommandType

Required. Specifies the action to perform.

payload: dict[str, Any]

Optional dictionary of parameters that modify command behaviour.

Supported keys: - distance_m: movement distance - speed_ms: movement speed in metres per second - duration_s: duration of movement execution - degrees: rotation amount in degrees

It is up to the DroneAdapter to implement support for these keys as kwargs in their respective handlers.

priority: int

Execution priority of the command.

  • Higher value means higher priority
  • Default: PRIORITY_NORMAL
  • Automatically set to PRIORITY_CRITICAL for EMERGENCY_STOP commands

source: str

Identifier for the input system that created the command.

Used primarily for logging and debugging.

Default: "unknown"

Behaviour

Emergency Stop Priority Override

If the command type is EMERGENCY_STOP, the priority is automatically set to:

  • PRIORITY_CRITICAL

This is enforced in post_init.

Methods

post_init()

Automatically adjusts priority for emergency stop commands.

repr()

Returns a compact string representation of the command. Used for non-verbose logging.

Only includes: - type - payload (if present) - priority (if not default) - source (if not default)

Example output:

Command(type=MOVE_FORWARD, payload={'speed_ms': 2.0}, source='gesture')

Example Usage

Basic Takeoff

Command(type=CommandType.TAKEOFF, source="keyboard")

Move forward for 3m at a custom speed

Command(
    type=CommandType.MOVE_FORWARD,
    payload={"distance_m": 3.0, "speed_ms": 1.5},
    source="gesture",
)

Emergency Stop

cmd = Command(type=CommandType.EMERGENCY_STOP, source="keyboard")
assert cmd.priority == PRIORITY_CRITICAL