4b8198fd14
Add a host tool that replays a recorded .ulg through the real MotorFailureDetector
and prints the per-motor trip verdict, for validating and tuning the detector
offline (EKF2-replay style: the real library drives recorded data, not a
re-implementation).
Built on ulog_cpp (PX4's C++ ULog library, added as a git submodule and built for
the posix host target only), so it reads ESC current, motor command and arming
state by field name from the log's own format -- one binary replays logs of any
PX4 message version with no rebuild. The feed mirrors the runtime in escCheck:
evaluated only while armed, at the runtime's 10 Hz cadence, with the per-ESC
current-report startup latch and reset-on-disarm. Config comes from the log's
MOTFAIL_* parameters with a built-in calibration fallback, and --set
MOTFAIL_NAME=value overrides any knob for what-if retuning. Because the runtime's
exact 10 Hz sample phase cannot be reconstructed offline, a single pass over the log
drives several detector instances on staggered grid offsets and reports a per-motor
peak band and trip fraction rather than a single phase's verdict, flagging when the
result is phase-dependent.
batch_replay.sh runs the tool over a folder of logs and summarizes each verdict
(OK / FAIL / SKIP) from its exit code.
Off by default so it never enters the firmware build or CI: it is a posix-only,
EXCLUDE_FROM_ALL host executable gated behind the MFD_REPLAY_TOOL cache option.
Build it with:
cmake -DMFD_REPLAY_TOOL=ON build/px4_sitl_default
ninja -C build/px4_sitl_default mfd_replay
The autopilot stack the industry builds on.
About
PX4 is an open-source autopilot stack for drones and unmanned vehicles. It supports multirotors, fixed-wing, VTOL, rovers, and many more experimental platforms from racing quads to industrial survey aircraft. It runs on NuttX, Linux, and macOS. Licensed under BSD 3-Clause.
Why PX4
Modular architecture. PX4 is built around uORB, a DDS-compatible publish/subscribe middleware. Modules are fully parallelized and thread safe. You can build custom configurations and trim what you don't need.
Wide hardware support. PX4 runs on a wide range of autopilot boards and supports an extensive set of sensors, telemetry radios, and actuators through the Pixhawk ecosystem.
Developer friendly. First-class support for MAVLink and DDS / ROS 2 integration. Comprehensive SITL simulation, hardware-in-the-loop testing, and log analysis tools. An active developer community on Discord and the weekly dev call.
Vendor neutral governance. PX4 is hosted under the Dronecode Foundation, part of the Linux Foundation. Business-friendly BSD-3 license. No single vendor controls the roadmap.
Supported Vehicles
 Multicopter |
 Fixed Wing |
 VTOL |
 Rover |
…and many more: helicopters, autogyros, airships, submarines, boats, and other experimental platforms. These frames have basic support but are not part of the regular flight-test program. See the full airframe reference.
Try PX4
Run PX4 in simulation with a single command. No build tools, no dependencies beyond Docker:
docker run --rm -it -p 14550:14550/udp px4io/px4-sitl:latest
Open QGroundControl and fly. See PX4 Simulation Quickstart for more options.
Build from Source
git clone https://github.com/PX4/PX4-Autopilot.git --recursive
cd PX4-Autopilot
make px4_sitl
Note
See the Development Guide for toolchain setup and build options.
Documentation & Resources
| Resource | Description |
|---|---|
| User Guide | Build, configure, and fly with PX4 |
| Developer Guide | Modify the flight stack, add peripherals, port to new hardware |
| Airframe Reference | Full list of supported frames |
| Autopilot Hardware | Compatible flight controllers |
| Release Notes | What's new in each release |
| Contribution Guide | How to contribute to PX4 |
Community
- Weekly Dev Call — open to all developers (Dronecode calendar)
- Discord — Join the Dronecode server
- Discussion Forum — PX4 Discuss
- Maintainers — see
MAINTAINERS.md - Contributor Stats — LFX Insights
Contributing
We welcome contributions of all kinds — bug reports, documentation, new features, and code reviews. Please read the Contribution Guide to get started.
Citation
If you use PX4 in academic work, please cite it. BibTeX:
@software{px4_autopilot,
author = {Meier, Lorenz and {The PX4 Contributors}},
title = {{PX4 Autopilot}},
publisher = {Zenodo},
doi = {10.5281/zenodo.595432},
url = {https://px4.io}
}
The DOI above is a Zenodo concept DOI that always resolves to the latest release. For a version-pinned citation, see the Zenodo record or our CITATION.cff.
Governance
The PX4 Autopilot project is hosted by the Dronecode Foundation, a Linux Foundation Collaborative Project. Dronecode holds all PX4 trademarks and serves as the project's legal guardian, ensuring vendor-neutral stewardship — no single company owns the name or controls the roadmap. The source code is licensed under the BSD 3-Clause license, so you are free to use, modify, and distribute it in your own projects.
