px4 0.0.1

An interface to send trajectories to the PX4 flight controller

PX4 CLI Utility

A command-line interface for commanding PX4 quadrotors over MAVLink with support for agile trajectories and motion capture feedback.

Installation

pip install -e .

Or to build and install:

python3 -m build
pip install dist/px4-*.whl

Usage

Basic Command Structure

px4 {URL} {COMMAND} {TRAJECTORY} [OPTIONS]

Mandatory Arguments

• URL: PX4 connection URL (positional, required)

  • Format: udp:localhost:14540 or tcp:192.168.1.5:5760

• COMMAND: Command to execute (positional, required)

  • track: Track a trajectory (more commands may be added in the future)

• TRAJECTORY: Type of trajectory to execute (positional, required for track command)

  • lissajous: Figure-eight trajectory
  • circle: Circular trajectory
  • position: Hold a fixed position

Optional Arguments

General Options

• --mocap URL: Motion capture system URL (e.g., vicon:192.168.1.3)
• --takeoff HEIGHT: Takeoff to the specified height before executing the trajectory
  • If specified, trajectories are executed relative to the takeoff position
  • If not specified, trajectories are executed relative to the current position (must be flying with height > 0.5m)
• --iterations N: Number of times to repeat the trajectory (default: 5)

Trajectory Types and Parameters

Lissajous (Figure-Eight)

Optional keyword arguments:

• --A AMPLITUDE: Amplitude in X direction in meters (default: 1.0)
• --B AMPLITUDE: Amplitude in Y direction in meters (default: 0.5)
• --z HEIGHT: Target height in meters (default: 2.0)
• --duration SECONDS: Duration of one iteration in seconds (default: 10.0)
• --ramp-duration SECONDS: Time to ramp up/down in seconds (default: 3.0)

Example:

px4 udp:localhost:14540 track lissajous --mocap vicon:192.168.1.3 --A 1.5 --B 0.75 --z 2.5 --duration 10 --ramp-duration 3 --takeoff 1.0

This executes a lissajous trajectory with A=1.5m, B=0.75m, height=2.5m, duration=10s, ramp=3s, taking off to 1m first.

Circle

Optional keyword arguments:

• --radius METERS: Radius of the circle in meters (default: 1.0)
• --z HEIGHT: Target height in meters (default: 2.0)
• --duration SECONDS: Duration of one iteration in seconds (default: 6.5)
• --ramp-duration SECONDS: Time to ramp up/down in seconds (default: 1.0)

Example:

px4 tcp:192.168.1.5:5760 track circle --mocap vicon:192.168.1.3 --radius 1.5 --z 2.5 --duration 6.5 --ramp-duration 1.0

This executes a circular trajectory with radius=1.5m, height=2.5m, duration=6.5s, ramp=1s.

Position

Optional keyword arguments:

• --x METERS: X coordinate in meters (default: 0.0)
• --y METERS: Y coordinate in meters (default: 0.0)
• --z METERS: Z coordinate in meters (default: 2.0)

Example:

px4 udp:localhost:14540 track position --x 1.0 --y 0.5 --z 2.0 --takeoff 1.0

This takes off to 1m and then moves to and holds position (1.0, 0.5, 2.0).

Examples

With Takeoff (Starting from Ground)

# Lissajous trajectory with takeoff
px4 udp:localhost:14540 track lissajous --mocap vicon:192.168.1.3 --A 1.5 --B 0.75 --z 2.5 --duration 10 --ramp-duration 3 --takeoff 1.0

# Circle with takeoff, 3 iterations
px4 udp:localhost:14540 track circle --mocap vicon:192.168.1.3 --radius 1.0 --z 2.0 --duration 6.5 --ramp-duration 1.0 --takeoff 1.0 --iterations 3

# Hold position with takeoff
px4 udp:localhost:14540 track position --mocap vicon:192.168.1.3 --z 2.0 --takeoff 1.0

Without Takeoff (Already Flying)

# Lissajous from current position (must be > 0.5m high)
px4 tcp:192.168.1.5:5760 track lissajous --mocap vicon:192.168.1.3 --A 2.0 --B 1.0 --z 3.0 --duration 12 --ramp-duration 4

# Circle from current position
px4 udp:localhost:14540 track circle --mocap vicon:192.168.1.3 --radius 1.5 --z 2.5 --duration 7 --ramp-duration 1.5

Without Motion Capture

# Use onboard position estimation only (omit --mocap)
px4 udp:localhost:14540 track lissajous --A 1.0 --B 0.5 --z 2.0 --duration 8 --ramp-duration 2 --takeoff 1.0

Safety Features

• Minimum Height Check: If not using --takeoff, the current height must be > 0.5m to prevent accidental ground execution
• Gradual Position Changes: Position commands are ramped gradually
• Controlled Landing: After trajectory completion, the quadrotor hovers briefly then lands at the initial position

Behavior Details

With --takeoff Flag

1. Arms the quadrotor
2. Takes off to specified height
3. Moves to trajectory start position
4. Executes trajectory relative to takeoff position
5. Hovers for 2 seconds after completion
6. Lands at initial ground position

Without --takeoff Flag

1. Checks current height is > 0.5m (safety check)
2. Arms the quadrotor (if not already armed)
3. Moves to trajectory start position
4. Executes trajectory relative to current position
5. Hovers for 2 seconds after completion
6. Lands at initial ground position

Dependencies

• numpy: Numerical computing
• multirobot: Interface to PX4 and motion capture systems
  • Includes trajectory functions (lissajous, circle)
  • MAVLink communication
  • Vicon motion capture interface

Integration with Multirobot Package

This CLI uses the multirobot package for:

• Registry: Robot configuration management (multirobot.registry)
• MOCAP: Vicon motion capture system interface (multirobot.mocap.Vicon)
• Trajectories: Pre-defined trajectory functions (multirobot.trajectories.lissajous, multirobot.trajectories.circle)
• Client: Async client interface with methods like arm(), goto(), command()

Development

To install in development mode:

pip install -e .

To build for distribution:

./build.sh

License

MIT License - see LICENSE file for details

Author

Jonas Eschmann ([e-mail])