1.4 MAVProxy Command Line Control¶

What You'll Learn¶

Master basic drone control through MAVProxy command line:

What MAVProxy is and why we use it
Launch SITL with map and console
Understand flight modes
Arm and disarm the vehicle
Perform takeoff and landing
Basic navigation using map
Monitor telemetry data

Time: 60-90 minutes

Prerequisites¶

Before starting, you must have completed:

✅ 1.1 Prerequisites and Setup
✅ 1.2 Environment Setup
✅ 1.3 ArduPilot SITL Installation
✅ SITL launches successfully
✅ Can arm/disarm vehicle

What is MAVProxy?¶

MAVProxy = MAVLink Proxy and Command Shell

It's a command-line ground control station that lets you:

Control drone through typed commands
Monitor telemetry in real-time
Load and execute missions
Visualize drone position on map

Why MAVProxy?

Lightweight and fast
Perfect for learning fundamentals
Scriptable and automatable
Works over SSH (no GUI needed)

Later we'll use: ROS2 for advanced control, but MAVProxy teaches the basics.

What is MAVLink?¶

MAVLink (Micro Air Vehicle Link) is the communication protocol that allows ground control stations to talk to drones.

Think of it as the language spoken between your computer and the flight controller:

Component	Role
MAVLink	The language/protocol (defines message formats)
MAVProxy	The translator (sends/receives MAVLink messages)
SITL	The drone brain (understands MAVLink commands)

What MAVLink handles:

Telemetry: GPS position, altitude, battery, attitude
Commands: Arm, disarm, takeoff, land, mode changes
Missions: Upload/download waypoint files
Parameters: Read/write flight controller settings

In this tutorial:

You won't write MAVLink messages directly. MAVProxy handles that for you. When you type arm throttle, MAVProxy converts it to the appropriate MAVLink message and sends it to SITL.

Later in Phase 2: MAVROS will bridge MAVLink to ROS2, letting you control drones programmatically with Python/C++.

Reference: Full MAVLink specification at mavlink.io

Launch SITL with Map and Console¶

Basic SITL Launch with Visualization¶

Instead of just text output, let's open map and console windows:

sim_vehicle.py -v ArduCopter --map --console

Note: We can run sim_vehicle.py from any directory because we added it to PATH in Section 1.3.

Command breakdown: - -v ArduCopter — Vehicle type (multirotor) - --map — Opens map window - --console — Opens console window

This takes: 10-20 seconds to launch all windows.

Expected Windows¶

Four windows will open:

Window	Name	Purpose
Top-Left	MAVProxy 2D Map	Shows drone position on satellite/terrain map with grid overlay
Top-Right	SITL Main Terminal	Command input (MAVProxy prompt), system messages
Bottom-Left	MAVProxy Console	Real-time telemetry (GPS, altitude, speed, battery, flight mode)
Bottom-Right	ArduCopter Console	ArduCopter initialization messages and system logs

SITL Launch Windows

✅ Success: All four windows open, see STABILIZE> prompt in main terminal

Understanding the Windows¶

SITL Main Terminal (Top-Right):

STABILIZE>

- Purpose: Enter commands here - Shows: MAVProxy prompt, system messages, command responses

MAVProxy 2D Map (Top-Left): - Drone icon: Green marker showing position - Heading: Arrow indicates drone orientation - Controls: Zoom (mouse wheel), pan (drag), right-click for commands

MAVProxy Console (Bottom-Left): - Real-time data displayed: - Mode, Armed status - Altitude, Speed - GPS status, Satellite count - Battery voltage, percentage - Heading, Attitude

ArduCopter Console (Bottom-Right): - Shows: System initialization, parameter loading, validation messages - Use: Monitor for errors or warnings during startup

Can't See Windows? (Headless/SSH Users)¶

If you're on SSH without display:

sim_vehicle.py -v ArduCopter

Skip map/console — Control via terminal only (works fine for learning).

Understanding Flight Modes¶

ArduCopter has different modes for different purposes:

Common Flight Modes¶

Mode	Purpose	When to Use
STABILIZE	Manual control, self-levels	Default mode, manual flying
GUIDED	Computer control via commands	Autonomous commands (takeoff, land)
AUTO	Follow pre-planned mission	Execute waypoint missions
LOITER	Hold position using GPS	Pause and hover in place
CIRCLE	Fly in circular pattern	Practice autonomous flight
RTL	Return to launch point	Emergency return home
LAND	Descend and land	Controlled landing

For this tutorial, we'll use:

GUIDED — For takeoff and landing
LOITER — Hold position
CIRCLE — Fly in circles
RTL — Return home

For a complete comparison of flight modes:

ArduCopter Flight Modes Comparison

Check Current Mode¶

At MAVProxy prompt:

mode

Expected output:

Check Current Mode

STABILIZE

Change Mode¶

mode GUIDED

Expected output:

Change Mode

GUIDED>

Notice the prompt changes to show current mode.

✅ Success: Mode changed, prompt shows GUIDED>

Arming and Takeoff¶

Pre-Arm Checks¶

Before arming, ArduPilot performs safety checks:

GPS lock (SITL has instant GPS)
Battery sufficient
No critical errors

In SITL, these pass automatically.

Arm the Vehicle¶

Switch to GUIDED mode first:

mode GUIDED

Then arm:

arm throttle

Expected output:

Arm the Vehicle

ARMED

Console window: Shows "ARMED" status

What happens:

Motors would spin up (if real drone)
Vehicle ready to fly
LEDs change (on real hardware)

✅ Success: Status shows ARMED

Important: 30-Second Rule¶

After arming, you have 30 seconds to takeoff.

If you don't send takeoff command within 30 seconds:

Vehicle automatically disarms (safety feature)
You'll see: DISARMED

This prevents: Leaving motors armed indefinitely.

Takeoff Command¶

Immediately after arming:

takeoff 10

Command breakdown:

takeoff — Takeoff command
10 — Target altitude in meters

Expected behavior:

Drone climbs to 10 meters
Console shows altitude increasing
Map shows altitude number changing

This takes: 10-20 seconds to reach altitude.

Watch console window: Altitude (Alt) climbs to ~10m

Takeoff Command

✅ Success: Altitude reaches 10 meters, drone hovers

Navigate Using Map (Easiest Method)¶

After takeoff, the easiest way to move the drone:

Right-click on the map where you want drone to go
Select "Fly to here" from the menu
Drone automatically flies to that position and holds

Practice:

Click different locations on the map
Watch drone move in real-time
Observe drone icon following your commands
Map updates position continuously

Takeoff Command

✅ This is the recommended way for beginners!

Hold Position (LOITER Mode)¶

To pause and hover in place:

mode LOITER
rc 3 1500

What happens:

Drone holds current GPS position
Maintains altitude (with rc 3 1500)
No drift (GPS position lock)

Use this to:

Pause during flight
Hold position while you plan next move
Emergency "stop and hover"

Note: The rc 3 1500 command sets throttle to maintain altitude in LOITER mode.

Practice: Fly in Circles¶

Make drone fly in circular pattern:

mode GUIDED
arm throttle
takeoff 15

# Set throttle to maintain altitude
rc 3 1500

# Switch to CIRCLE mode
mode CIRCLE

What happens:

Drone flies in circles around current center point
Radius: 10 meters (default)
Maintains 15m altitude (thanks to rc 3 1500)
Direction: Clockwise

Watch the map: Drone traces circular path

Return home:

mode RTL

Note: The rc 3 1500 command is necessary to maintain altitude in CIRCLE and LOITER modes. Without it, drone will lose altitude.

Landing¶

Land Command¶

When ready to land:

land

What happens:

Drone descends at controlled rate
Automatically disarms when on ground
Mode changes to LAND

This takes: 10-30 seconds depending on altitude.

Console window: Watch altitude decrease to 0

✅ Success: Altitude reaches 0, status shows DISARMED

Alternative: RTL (Return to Launch)¶

Return and land at start position:

mode RTL

What happens:

Drone flies back to start position
Climbs to RTL altitude (15m default)
Descends and lands at home

Useful for: Emergency return or end of mission.

Understanding Coordinate Frames¶

ArduPilot uses the NED (North-East-Down) coordinate system for navigation and telemetry:

NED Coordinate Frame

Axis	Direction	Positive Value
X	North	Moving northward
Y	East	Moving eastward
Z	Down	Moving toward ground

Why this matters:

When you see telemetry data, altitude appears as a negative Z value. This is normal behavior, not an error.

Real-world position	NED representation
10m above ground	Z = -10
50m North of home	X = +50
30m East of home	Y = +30

Example telemetry reading:

Position: X=50, Y=30, Z=-15

This means: 50m North, 30m East, 15m altitude above home.

Note: Some robotics systems use ENU (East-North-Up) where Z is positive upward. ArduPilot uses NED, so always remember: negative Z = altitude gain.

Reading Telemetry¶

Console Window Data¶

Key information displayed:

Mode: GUIDED
Armed: True
Alt: 10.5m
Spd: 2.3m/s
Hdg: 45°
GPS: 3D Fix (10 sats)
Bat: 12.6V (100%)

What each means:

Mode — Current flight mode
Armed — Motors armed/disarmed
Alt — Altitude above ground
Spd — Ground speed
Hdg — Heading (0° = North)
GPS — GPS status and satellite count
Bat — Battery voltage and percentage

MAVProxy Status Commands¶

Get GPS position:

status GPS_RAW_INT

Get attitude (roll, pitch, yaw):

status ATTITUDE

Get battery status:

status SYS_STATUS

Complete Flight Example¶

Video Demonstration¶

Watch the complete flight sequence in action:

Step-by-Step Flight¶

# 1. Start SITL with map
sim_vehicle.py -v ArduCopter --map --console

# 2. Change to GUIDED mode
mode GUIDED

# 3. Arm the vehicle
arm throttle

# 4. Takeoff to 10 meters
takeoff 10

# Wait for altitude to reach 10m (watch console)

# 5. Navigate using map
# Right-click on map and select "Fly to here"
# Watch drone move to selected position

# 6. Try LOITER mode
rc 3 1500
mode LOITER

# 7. Try CIRCLE mode
mode CIRCLE

# Watch drone fly in circles

# 8. Return to launch
mode RTL

# Wait for drone to return and land

# 9. Exit SITL
Ctrl+C

Complete this sequence to verify everything works.

✅ Success: Drone completes full flight, lands safely

🌍 Custom Location (Optional)¶

Why Change Location?¶

Default SITL location is in Australia. You can set your own location.

Add Custom Location¶

Create location entry:

echo "custom=YOUR_LAT,YOUR_LONG,ALT,HEADING" >> ~/simtofly_ws/ardupilot/Tools/autotest/locations.txt

Example (replace with your coordinates):

echo "myfield=37.7749,-122.4194,50,0" >> ~/simtofly_ws/ardupilot/Tools/autotest/locations.txt

Format:

Name = your location identifier
LAT = latitude (decimal degrees)
LONG = longitude (decimal degrees)
ALT = altitude MSL (meters)
HEADING = initial heading (0 = North)

Launch at Custom Location¶

sim_vehicle.py -v ArduCopter --map --console -L myfield

Replace myfield with your location name.

Map window: Shows your custom location.

Verification Checklist¶

Before moving to next section, verify:

All checked? You can control a simulated drone!

What You Accomplished¶

✅ Launched SITL with visualization (map + console)
✅ Understood different flight modes
✅ Armed and disarmed vehicle
✅ Performed takeoff to target altitude
✅ Navigated drone using map interface
✅ Used LOITER mode to hold position
✅ Used CIRCLE mode for autonomous flight
✅ Landed safely using RTL
✅ Read and understood telemetry data
✅ Completed full autonomous flight sequence

Next Steps¶

Continue to 1.5 Gazebo Simulation where we'll:

Install Gazebo Harmonic 3D simulator
Connect Gazebo to SITL
See realistic drone physics
Visualize sensors and environment

Common Questions¶

Q: Why use GUIDED mode instead of STABILIZE?¶

A:

GUIDED — Accepts autonomous commands (takeoff, land)
STABILIZE — Manual RC control only (no autonomous commands)

For autonomous missions, always use GUIDED or AUTO.

Q: What if I forget to takeoff within 30 seconds?¶

A: Vehicle disarms automatically. Just arm again and send takeoff command.

Q: Can I control multiple drones in SITL?¶

A: Yes! Use multiple SITL instances on different ports. We'll cover this in advanced topics.

Q: How do I make drone hold position?¶

A: Use one of these modes:

LOITER with rc 3 1500 — Holds current GPS position
Map "Fly to here" in GUIDED mode — Holds at clicked position
STABILIZE won't hold position (manual control only)

Q: Why do CIRCLE and LOITER need rc 3 1500?¶

A: These modes need throttle input to maintain altitude. Without it, the drone will lose altitude. The rc 3 1500 command sets throttle to middle position (hover).

Q: How do I stop a command mid-flight?¶

A: Send a new command (overrides previous) or change mode:

mode LOITER  # Stops and holds position

Troubleshooting¶

Map window doesn't open¶

Cause: Missing Python packages

Solution:

pip3 install --user wxPython matplotlib

Relaunch SITL.

"Bad mode" error when changing modes¶

Cause: Mode name typo

Solution: Mode names are case-sensitive. Use:

GUIDED (not "guided")
STABILIZE (not "stabilize")
LOITER (not "loiter")

Arm command rejected "PreArm: Need 3D Fix"¶

Cause: GPS not initialized (rare in SITL)

Solution: Wait 5-10 seconds, try arming again. SITL gets instant GPS fix.

Console shows negative altitude¶

Cause: Normal! NED frame uses negative Z for up.

Solution: Nothing to fix. Just remember:

Altitude 10m = Z of -10
Ground level = Z of 0

Takeoff command does nothing¶

Cause:

Not armed
Not in GUIDED mode
Already in air

Solution:

mode GUIDED
arm throttle
takeoff 10

In this exact order.

Drone loses altitude in CIRCLE or LOITER mode¶

Cause: Missing rc 3 1500 command

Solution:

rc 3 1500

Then switch to CIRCLE or LOITER mode.

"Failed to change mode" message¶

Cause: Some modes require certain conditions (e.g., GPS lock for LOITER)

Solution: Check console for reason, or use STABILIZE/GUIDED (always available).

← Back: 1.3 ArduPilot SITL | Next: 1.5 Gazebo Simulation →

1.4 MAVProxy Command Line Control¶

What You'll Learn¶

Prerequisites¶

What is MAVProxy?¶

What is MAVLink?¶

Launch SITL with Map and Console¶

Basic SITL Launch with Visualization¶

Expected Windows¶

Understanding the Windows¶

Can't See Windows? (Headless/SSH Users)¶

Understanding Flight Modes¶

Common Flight Modes¶

Check Current Mode¶

Change Mode¶

Arming and Takeoff¶

Pre-Arm Checks¶

Arm the Vehicle¶

Important: 30-Second Rule¶

Takeoff Command¶

Basic Navigation¶

Navigate Using Map (Easiest Method)¶

Hold Position (LOITER Mode)¶

Practice: Fly in Circles¶

Landing¶

Land Command¶

Alternative: RTL (Return to Launch)¶

Understanding Coordinate Frames¶

Reading Telemetry¶

Console Window Data¶

MAVProxy Status Commands¶

Complete Flight Example¶

Video Demonstration¶

Step-by-Step Flight¶

🌍 Custom Location (Optional)¶

Why Change Location?¶

Add Custom Location¶

Launch at Custom Location¶

Verification Checklist¶

What You Accomplished¶

Next Steps¶

Common Questions¶

Q: Why use GUIDED mode instead of STABILIZE?¶

Q: What if I forget to takeoff within 30 seconds?¶

Q: Can I control multiple drones in SITL?¶

Q: How do I make drone hold position?¶

Q: Why do CIRCLE and LOITER need rc 3 1500?¶

Q: How do I stop a command mid-flight?¶

Troubleshooting¶

Map window doesn't open¶

"Bad mode" error when changing modes¶

Arm command rejected "PreArm: Need 3D Fix"¶

Console shows negative altitude¶

Takeoff command does nothing¶

Drone loses altitude in CIRCLE or LOITER mode¶

"Failed to change mode" message¶