Dragon ISS Docking Autopilot in Go
Autopilot written in Go and executed as WebAssembly for docking the SpaceX Dragon capsule in the official simulator.
I never used Go and WebAssembly together before. This seemed like a nice and small excercise and I also got to refresh controller algorithms.
Using this autopilot
- Compile the autopilot and serve the files.
go run ./cmd/autopilot-server
- Open the SpaceX ISS docking simulator: https://iss-sim.spacex.com
- Open the developer console of your browser (eg. right click > Inspect in Chrome)
- Paste the following code into the console to load the autopilot:
const s = document.createElement("script"); s.setAttribute("src", "http://localhost:8000/loader.js?t="+ new Date().getTime()); document.body.appendChild(s);
If you want to make modifications to
autopilot.go, restart the
autopilot-server, refresh the simulator page and paste the above
The main controller algorithm is the
correct() method in
At first the current rate is calculated using the previous time and offset
and dampened over some cycles
Then a correction factor
Correction is used to calculate the target rate.
This target rate is limited based on the offset and
RateFactor but kept
The difference between target and current rate is then added to a clicks accumulator. Full clicks are then subtracted from the accumulator and returned from the function.
Play around with the
ios configuration to get different controller behavior.
If you improved this autopilot or added a new feature, don't hesitate to open a PR. I'm looking forward to see what you will do with it.
Built by @mbertschler