RDC_Simulation/docs/drone_guide.md

Drone Controller Guide

Overview

The drone controller (src/drone_controller.py) provides a simple interface for flying the drone in simulation.

Usage

Command Line

source ~/venv-ardupilot/bin/activate
cd ~/RDC_Simulation

# Fly a square pattern
python scripts/run_ardupilot.py --pattern square

# Options
python scripts/run_ardupilot.py --help

Options

Option	Default	Description
--pattern	square	Flight pattern: square, circle, hover
--altitude	5	Flight altitude in meters
--size	5	Pattern size (side length or radius)
--connection	tcp:127.0.0.1:5760	MAVLink connection string

Examples

# Fly a 10m square at 8m altitude
python scripts/run_ardupilot.py --pattern square --size 10 --altitude 8

# Fly a circle with 5m radius
python scripts/run_ardupilot.py --pattern circle --size 5

# Just hover (useful for testing)
python scripts/run_ardupilot.py --pattern hover

Python API

Basic Usage

from src.drone_controller import SimpleDroneController

# Create and connect
drone = SimpleDroneController()
if not drone.connect():
    print("Connection failed")
    exit(1)

# Takeoff
drone.set_mode("GUIDED")
drone.arm()
drone.takeoff(5.0)

# Fly
drone.fly_square(size=5, altitude=5)

# Land
drone.land()

Class: SimpleDroneController

Connection

drone = SimpleDroneController(connection_string="tcp:127.0.0.1:5760")
drone.connect(timeout=30)  # Returns True/False

State

drone.armed      # bool: Is the drone armed?
drone.mode       # str: Current flight mode
drone.altitude   # float: Current altitude (m)
drone.position   # dict: {"x": float, "y": float, "z": float}

Commands

drone.set_mode("GUIDED")       # Set flight mode
drone.arm()                    # Arm motors (force arm)
drone.takeoff(5.0)             # Takeoff to altitude
drone.goto(x, y, z)            # Go to position (NED frame)
drone.fly_to_and_wait(x, y, alt)  # Go and wait until reached
drone.land()                   # Land

Patterns

drone.fly_square(size=5, altitude=5)    # Square pattern
drone.fly_circle(radius=5, altitude=5)  # Circle pattern

Coordinate System

ArduPilot uses NED (North-East-Down):

• X: North (positive forward)
• Y: East (positive right)
• Z: Down (negative is up!)

# Go 5m north, 3m east, at 10m altitude
drone.goto(5, 3, -10)  # Z is negative for altitude

Flight Modes

Mode	Description
GUIDED	Accept external commands
LAND	Automatic landing
LOITER	Hold position
RTL	Return to launch
STABILIZE	Manual control

Sequence Diagram

┌─────────┐      ┌──────────┐      ┌─────────┐
│ Gazebo  │      │   SITL   │      │ Script  │
└────┬────┘      └────┬─────┘      └────┬────┘
     │                │                  │
     │ Physics data   │                  │
     │ ◄──────────────│                  │
     │                │                  │
     │ Sensor JSON    │                  │
     │ ───────────────►                  │
     │                │   Connect        │
     │                │ ◄────────────────│
     │                │                  │
     │                │   Set GUIDED     │
     │                │ ◄────────────────│
     │                │                  │
     │                │   Arm            │
     │                │ ◄────────────────│
     │                │                  │
     │                │   Takeoff        │
     │                │ ◄────────────────│
     │                │                  │
     │ Motor commands │                  │
     │ ◄──────────────│                  │
     │                │                  │
     │ Drone moves    │                  │
     │                │                  │

Troubleshooting

Drone doesn't move

1. Check Gazebo is running
2. Check SITL shows telemetry (not "No JSON sensor message")
3. Check drone is armed

Timeout waiting for altitude

• Increase takeoff timeout
• Check for pre-arm failures in SITL console

Connection refused

# Check SITL is running
nc -z 127.0.0.1 5760 && echo "SITL is ready" || echo "SITL not running"