Tutorial 04: Takeoff and Land

Overview

This tutorial demonstrates fundamental drone flight operations using MAVROS commands. It covers the complete flight cycle: arming, takeoff to a target altitude, hovering, and landing with automatic disarm detection.

Learning Objectives

• Send MAV_CMD_NAV_TAKEOFF command via MAVROS
• Set GUIDED mode before takeoff (required)
• Monitor altitude during takeoff sequence
• Execute landing sequence with AUTO.LAND mode
• Detect automatic disarm after landing

Key Concepts

• MAV Commands: MAVLink protocol commands for drone control
• GUIDED Mode: Flight mode required for autonomous takeoff
• Altitude Monitoring: Tracking relative altitude during flight
• Auto-Disarm: Automatic motor disarm after landing detection

Prerequisites

• Active TensorFleet VM with MAVROS running
• Simulation restarted (as described in Preparation)
• Understanding of connection, telemetry, and arming from previous tutorials

Running the Tutorial

After mastering arming/disarming, this tutorial introduces the complete flight cycle. The script handles all necessary steps automatically.

To run the takeoff and land tutorial:

bun run src/tutorials/04_takeoff_land.js

Expected Output Example

When running the tutorial, you should see output similar to:

[INFO] Connected to ROS Bridge
[INFO] Target altitude: 3m

[INFO] Drone is not armed. Arming...
[ARM] Sending arm command...
[ARM] Arm command sent successfully
[ARM] Waiting for arm confirmation...
[ARM] Drone is now armed!

[TAKEOFF] Setting GUIDED mode...
[TAKEOFF] GUIDED mode set
[TAKEOFF] Sending takeoff command to 3m...
[TAKEOFF] Takeoff command sent
[TAKEOFF] Monitoring altitude...
[TAKEOFF] Current altitude: 0.5m / 3.0m
[TAKEOFF] Current altitude: 1.2m / 3.0m
[TAKEOFF] Current altitude: 2.1m / 3.0m
[TAKEOFF] Current altitude: 2.8m / 3.0m
[TAKEOFF] Target altitude reached!

[SUCCESS] Takeoff complete! Drone is hovering at altitude.
[INFO] Drone will remain in AUTO.LOITER mode.
[INFO] Waiting 2 seconds before landing...

[INFO] Landing drone...
[LAND] Sending land command...
[LAND] Land command sent
[LAND] Monitoring descent...
[LAND] Current altitude: 2.5m
[LAND] Current altitude: 1.8m
[LAND] Current altitude: 0.9m
[LAND] Current altitude: 0.2m
[LAND] Waiting for disarm...
[LAND] Drone has landed and disarmed!

[SUCCESS] Drone has landed and disarmed!
[EXIT] Closing connection...

How It Works

The tutorial demonstrates a complete autonomous flight cycle:

1. Connection: Establish ROS Bridge connection and wait for telemetry
2. Arming: Automatically arm the drone if not already armed
3. Takeoff: Set GUIDED mode and send takeoff command
4. Altitude Hold: Monitor altitude until target is reached
5. Landing: Send land command and monitor descent
6. Disarm: Wait for automatic disarm after landing

Code Analysis

Setup and Auto-Arm

const ros = await connectToDrone(rosbridgeUrl);
const { telemetry } = await waitForTelemetry(ros);

// Arm if not already armed
if (!telemetry.state.armed) {
    console.log("[INFO] Drone is not armed. Arming...\n");
    await armDrone(ros, telemetry);
} else {
    console.log("[INFO] Drone already armed");
}

The script automatically handles arming if the drone isn't already armed.

Takeoff Sequence

const TARGET_ALTITUDE = 3.0; // meters

await takeoffToAlt(ros, telemetry, TARGET_ALTITUDE);

The takeoffToAlt utility:

1. Sets GUIDED mode (required for autonomous takeoff)
2. Sends MAV_CMD_NAV_TAKEOFF command
3. Monitors altitude until target is reached
4. Transitions to AUTO.LOITER for stable hover

Landing Sequence

await landDrone(ros, telemetry);

The landDrone utility:

1. Sends MAV_CMD_NAV_LAND command
2. Monitors altitude during descent
3. Waits for automatic disarm confirmation

Flight Modes During Tutorial

Phase	Mode	Description
Pre-flight	STABILIZE	Default ground mode
Takeoff	GUIDED	Autonomous takeoff mode
Hover	AUTO.LOITER	Position hold after takeoff
Landing	AUTO.LAND	Autonomous landing mode
Post-landing	STABILIZE	Auto-disarm triggers

Safety Considerations

• Auto-Arm: The script arms automatically - ensure area is clear
• Target Altitude: Default is 3m - adjust TARGET_ALTITUDE for your environment
• Landing Zone: Drone lands at current position - ensure clear landing area
• Auto-Disarm: Motors automatically disarm after landing detection

Common Issues

• Takeoff Fails: Check GPS lock and pre-arm checks
• Altitude Not Reached: Verify telemetry is updating correctly
• Landing Timeout: May occur if ground detection is slow
• No Auto-Disarm: Flight controller may require manual disarm in some modes

Next Steps

After mastering takeoff and landing, you're ready for:

• OFFBOARD mode and velocity control
• Waypoint navigation
• Mission planning

Navigation

• Previous: Tutorial 03: Arm/Disarm
• Next: Tutorial 05: OFFBOARD Hover

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The takeoff and land sequence is fundamental to all autonomous drone operations. Master this before attempting more complex flight maneuvers.