Frequently Asked Questions¶
I need help, where can I get support?¶
Please keep in mind that this is a volunteer effort, so try to be nice.
I want to help, how can I get involved?¶
That being said, it’s always a good idea to post to the godrone mailing to discuss things before getting started.
Additionally help with the documentation and answering questions on the mailing list would be really appreciated.
Where can I report bugs or propose features?¶
Features are usually best discussed on the mailing list and added to the tracker once there is consensus.
What happens if the drone goes out of WiFi range?¶
It could theoretically go up forever (To infinity, and beyond!). So don’t let that happen. Fly indoors until we’ve implemented a fail-safe of some sort.
Does GoDrone provide any features not provided by the official firmware?¶
Not a lot at this point, but being able to control the drone with a gamepad using your web browser is nice. It also seems that the official firmware puts some limits on speed, especially vertically, so you may find that GoDrone will help you with crashing your drone in more spectacular ways : ).
What are the goals of the project?¶
The project was started as a personal challenge to write a firmware for the Parrot AR Drone in Go. Now that this is achieved, there are many possibilities, and it will really depend on whatever users and contributors are most interested in. Here are a few ideas:
- Improved stabilization and control algorithms (kalman filter, optical flow, etc.)
- Video drivers and support for streaming video to the HTML client
- Compatibility with the various mobile apps and NodeCopter.
- Improved HTML client, e.g. usability, design, graphs, WebGL, support for mobile devices
- More aggresive flight, faster vertical speed, and additional tricks.
- GPS support, including the ability to plan missions in the HTML client on a map
- 3G support, to allow controlling the drone over cellular networks
- Education, e.g. a specialized HTML client to demonstrate quadcopter physics
- Research, GoDrone could make it incredible easy and cheap to reproduce quadcopter research anywhere in the world.
- Mounting the AR Drone electronics on custom frames, attaching custom sensors, and maybe even using different motors.
- Encourage vendors such as Parrot to embrace a full open source strategy.
Why is the firmware written in Go?¶
Originally to see if a firmware like this could be written in a high level garbage collected language.
Go seemed like a good choice because it has great support for cross-compiling, concurrency, systems programming and is just a very pleasant language to work with.
Isn’t Go unsuitable for real-time applications like this?¶
This question is one of the reasons this project exists. Go uses a stop-the-world garbage collector that does not provide any real-time guarantees , so it’s certainly not a perfect fit for a flying robot.
However, for all practical purposes the GC just needs to keep up with the stabilization loop which runs at 200 Hz. This means that GC pauses below 5ms have no impact on performance. Longer pauses will degrade stabilization performance, but the tolerance threshold may be up to a second depending on altitude and the situation.
Considering that stabilization cannot be guaranteed due to environmental factors to begin with, it will be interesting to see if drone vendors will make similar compromises for reducing the costs of software development, or if governments will provide detailed software architecture regulations for commercial drones.
Given that the AR Drone is a very light weight toy that has an extremely low chance of causing direct harm, the GoDrone project will continue to use the current approach for now. However, if problems are observed, or the project becomes more popular than expected, the plan is to rewrite the stabilization loop in C, run it on a separate thread with strong scheduling guarantees, and use some form of IPC to communicate with it.
Why aren’t you building on existing projects?¶
This project is about exploring what it would be like to build a drone firmware using a high level language, and embracing web technologies for providing a portable user interface.
Other projects are certainly more mature at this point, and e.g. Paparazzi already has support for the AR Drone 2. However, they are significantly more difficult to run and work with, written in C/C++, and use rather archaic UI technology.
Where can I get the source code?¶
The source code is available on GitHub: https://github.com/felixge/godrone
What license is GoDrone released under?¶
GoDrone is licensed under the AGPLv3 license.
This basically means that any derived software products will have to be licensed under the same license, and that their source code needs to be made available.
The license was chosen to ensure that the GoDrone will always remain free software. Contributors are not asked to sign a CLA, so there will be no dual licensing model in the future.
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