PX4 Autonomous Takeoff-Hover-Land Mission in GPS Denied Environment

This project customizes the PX4 commander module to include a new command called mission_start, enabling fully autonomous drone behavior in GPS Denied Environments: arm → takeoff → hover → monitor → land.

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Important Notes

• This firmware is designed for Gazebo-Classic (ROS1) and Gazebo-Harmonic (ROS2) simulations.

• Ignore inbuilt PX4 failsafe messages that may appear in the PX4 console during simulation.

• Clone the repo using:

  git clone https://github.com/avianbob/PX4-Autonomous-Mission.git

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What This Command Does

When you run:

commander mission_start

The drone performs the following:

1. Arms the drone
2. Switches to AUTO mode
3. Takes off to a predefined altitude (default 5m)
4. Hovers in place for a set duration (default 40s)
5. Logs sensor and flight data every few seconds (default 3s)
6. Monitors for battery low or RC signal loss
7. Lands and disarms when mission ends or safety triggers occur

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Code Location

1. The logic can be found at:

Codes/Commander.cpp

2. The logic is to be implemented at:

PX4-Autopilot/src/modules/commander/Commander.cpp

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Mission Flow Breakdown

1. Takeoff Preparation

Sets parameters for:

• MIS_TAKEOFF_ALT = 5.0 meters
• hover_time = 40.0 seconds
• print_interval = 3.0 seconds

2. Arm and Wait

Sends arming command and blocks until drone is armed:

send_vehicle_command(VEHICLE_CMD_COMPONENT_ARM_DISARM, ARMING_ACTION_ARM);

3. Switch to AUTO Mode

send_vehicle_command(VEHICLE_CMD_DO_SET_MODE, 1, 2);

Mode 2 = AUTO

4. Initiate Takeoff

send_vehicle_command(VEHICLE_CMD_NAV_TAKEOFF);

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5. Hover and Monitor

While hovering:

• Logs position, velocity, battery, and angular rate every few seconds
• Records home position

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6. Monitors for Conditions to Land

It will trigger landing if any of these happen:

Condition	Trigger
Battery below BAT_LOW_THR	Lands
RC Signal Lost	Lands
Time Elapsed > Hover Duration	Lands

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7. Detect Landing and Disarm

Monitors:

vehicle_land_detected_s.landed == true

Then safely disarms:

send_vehicle_command(VEHICLE_CMD_COMPONENT_ARM_DISARM, ARMING_ACTION_DISARM);

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Logged Data

Every 3 seconds, prints:

• Position: X, Y, Height
• Velocity: Vertical, Horizontal
• Battery: % Remaining, Current
• Angular Velocity: Roll, Pitch, Yaw