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Liftoff - Drone Telemetry

Av JuniorDiscart och 2 medverkande

Liftoff: FPV Drone Racing allows you to stream drone telemetry data to external locations. That way, you can analyze flights, or diagnose issues with external programs that interface with Liftoff.

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JuniorDiscart
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Kasper
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LuGus Studios
Online

Kategori: Modding or Configuration

Languages: English

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14 feb, 2024 @ 3:07

27 jan @ 12:01

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Guideindex

Överblick

Introduction

Who is this for?

Setup

Configuring the telemetry data

Modifying the configuration while in-game

Example configurations

Kommentarer

Introduction

Liftoff: FPV Drone Racing allows you to stream drone telemetry data to external locations. This way you can analyze flights or diagnose issues with external programs that interface with Liftoff.

Who is this for?

The Drone Telemetry feature is not something the average Liftoff: FPV player will find a use for. It is however, useful to players wanting some extremely detailed feedback or researchers interested in analyzing a drone's behavior, to plot out data in other software, or to train certain data models for A.I.

Setup

The Drone Telemetry feature can be enabled by placing a file in a specific directory. This location depends on the operating system running Liftoff:

Windows:
C:\Users\%userprofile%\AppData\LocalLow\LuGus Studios\Liftoff\
macOS:
~/Library/Application Support/LuGus Studios/Liftoff/
Linux:
~/.config/unity3d/LuGus Studios/Liftoff/
Linux (when Steam is installed as a flatpak):
~/.var/app/com.valvesoftware.Steam/.config/unity3d/LuGus Studios/Liftoff

Within this directory, create a new file named TelemetryConfiguration.json to enable the drone telemetry.

Currently there is no way to enable or configure this feature from within Liftoff itself. This might be added in a future update.

Configuring the telemetry data

The Drone Telemetry data stream is configured using the TelemetryConfiguration.json file. We'll go over each of the parameters in this section. The example configurations section below provides a few practical examples.

Before diving into the different configuration possibilities, first let's define the types of data you can expect to receive on the data stream. Each component will state what type of value it will be. This will be important for when you parse the data on your end. So let's sum them up below:

float - a single precision floating point number, 4 bytes long.
int - an integral number, 4 bytes long.
byte - a single byte.

There are two main parameters that can be configured:

The data end point: all telemetry data are sent over a UDP packet stream. The EndPoint value allows you to configure where it is sent to. This value is formatted in IP end point notation, e.g. 127.0.0.1:9001, where you specify the intended IP address and port number.
The stream format: you can configure which telemetry data points you're interested in, as well as the sequence in which they are sent. The StreamFormat string array defines the sequence. The supported data points and their data layout are listed below. Note: Liftoff uses a left-handed, Y-Up coordinate system: the positive x-axis points to the right, the positive y-axis points up, and the positive z-axis points forward.
- Timestamp (1 float) - current timestamp of the drone's flight. The unit scale is in seconds. This value is reset to zero when the drone is reset.
- Position (3 floats) - the drone's world position as a 3D coordinate. The unit scale is in meters. Each position component can be addressed individually as PositionX, PositionY, or PositionZ.
- Attitude (4 floats) - the drone's world attitude as a quaternion. Each quaternion component can be addressed individually as AttitudeX, AttitudeY, AttitudeZ and AttitudeW.
- Velocity (3 floats) - the drone's linear velocity as a 3D vector in world-space. The unit scale is in meters/second. Each component can be addressed individually as SpeedX, SpeedY, or SpeedZ. Note: to get the velocity in local-space, transform it[math.stackexchange.com] using the values in the Attitude data stream.
- Gyro (3 floats) - the drone's angular velocity rates, represented with three components in the order: pitch, roll and yaw. The unit scale is in degrees/second. Each component can also be addressed individually as GyroPitch, GyroRoll and GyroYaw.
- Input (4 floats) - the drone's input at that time, represented with four components in the following order: throttle, yaw, pitch and roll. Each input can be addressed individually as InputThrottle, InputYaw, InputPitch and InputRoll.
- Battery (2 floats) - the drone's current battery state, represented by the remaining voltage, and the charge percentage. Each of these two can be addressed individually with the BatteryPercentage and BatteryVoltage keys. Note - these values will only make sense when battery simulation is enabled in the game's options.
- MotorRPM (1 byte + (1 float * number of motors)) - the rotations per minute for each motor. The byte at the front of this piece of data defines the amount of motors on the drone, and thus how many floats you can expect to find next. The sequence of motors for a quadcopter in Liftoff is as follows: left front, right front, left back, right back.

Note that this data stream is only available for drones that are actively being simulated by Liftoff. It won't work for drones being spectated in multiplayer or during a replay session.

Modifying the configuration while in-game

Each time the drone is reset, Liftoff will check whether the telemetry configuration file has been changed, and reload it if so. This allows you to tweak and change parameters without restarting Liftoff.

If the configuration file contains an error, Liftoff will display a popup message after the drone has been reset. Fix the error, reset the drone again, and the new telemetry configuration will be loaded.

Example configurations

Some example configurations of the TelemetryConfiguration.json file.

Everything

A configuration that will send over all telemetry data to a local end point.

{ "EndPoint": "127.0.0.1:9001", "StreamFormat": [ "Timestamp", "Position", "Attitude", "Velocity", "Gyro", "Input", "Battery", "MotorRPM" ] }

The total size of each data frame being sent would be 97 bytes.

Horizontal position over time

A configuration that will only send the position of the drone in the XZ-plane, along with the timestamp, to an end point in the local network.

{ "EndPoint": "192.168.1.6:6808", "StreamFormat": [ "Timestamp", "PositionX", "PositionZ" ] }

The total size of each data frame being sent would be 12 bytes.

From input to gyroscope

A configuration that correlates input axes to the drone's gyroscope, without a timestamp.

{ "EndPoint": "127.0.0.1:9001", "StreamFormat": [ "InputPitch", "GyroPitch", "InputRoll", "GyroRoll", "InputYaw", "GyroYaw" ] }

The total size of each data frame being sent would be 24 bytes.

35 kommentarer

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Mara Huldra 25 sep @ 0:44

This is absolutely great. Wish more sim games had this, it really increases immersion to be able to do this kind of tinkering interfacing with things outside the game.

Some suggestions for additional telemetry values that would be nice to have:
- CameraAngle
- CameraFOV
- Damage values (i guess this is per rotor)

Recursive_Dreams 3 jul @ 7:53

Hello all, I am a researcher interested in collecting FPV telemetry data for a training study I am working on. While I have significant data analytics experience, I am not familiar with networking or server setup. Could anyone provide some examples or point me to a good tutorial for setting up a local server for collecting the telemetry data stream? I'm on Windows 11 and have the TelemetryConfiguration.json file in the right location, but I don't have an endpoint IP and port setup to point it to. Thank you very much in advance!

Eloi Stree 30 apr @ 4:36

Your team is amazing ! Thank for that tool.
If someone need a python or Unity3D of this, I will write one for a contest in the coming week:
https://github.com/EloiStree/2025_04_26_LiftoffTelemetryPyUnity

Tobyo 18 feb @ 3:09

I was able to receive the data, and they are indeed 4 bytes per float, but how to I translate them back to a float? What is the formula or the method to turn those 4 bytes from unity/liftoff into a float (using Pd, Max/MSP, or Javascript)

FahD 16 feb @ 18:07

@juniorDiscart well, thats kinda sad :(

@Poison Dart Frag i just think about this eresterday, the problem is that i need it to fly continously in a track. opening a GUI would hinder the performance by a lot. i wonder if i can bind the PID change to a button or some sort?

Poison Dart Frag 13 feb @ 1:39

If there's no direct API to change values on-the-fly (pun not intended), perhaps you might need a more clunky solution like using something like https://pypi.org/project/PyAutoGUI-ng/ to input fake keyboard and mouse inputs to change things in the menu and reset the flight after saving each change to load them.

Dunno if there's a platform independent equivalent for emulating analog inputs via scripts; on Linux you could use something like https://pypi.org/project/evdev/ I think.

I have not tested either of those modules with Liftoff yet, no idea if there will be any obstacles. And to be honest, I have no idea if that would be the best approach in the first place. Really, I don't have much idea what I'm talking about; this is mostly just stuff I had bookmarked for some projects I never got around starting.

JuniorDiscart [skapare] 13 feb @ 0:39

@FahD This is an output-only stream. It's not possible to feed data to the drone.

FahD 12 feb @ 18:06

Hi, im currently developing an adaptive algorithm (AI) to tune the PIDs automatically. i already able to get the telemetry data through this. My question is, is there any way that my python/matlab code could change the in game PID value in realtime??

ponadto 1 feb @ 9:17

My bad!
netcat uses TCP by default, I should have called:

netcat -ul 127.0.01 9001

Now it works like a charm!

ponadto 31 jan @ 14:19

This looks awesome!

Alas, I tried adding this TelemetryConfiguration.json file:

{
"EndPoint": "127.0.0.1:9001",
"StreamFormat": [
"Timestamp",
"Position",
"Attitude",
"Velocity",
"Gyro",
"Input",
"Battery",
"MotorRPM"
]
}

and saved it in my ~/.config/unity3d/LuGus Studios/Liftoff/ directory (I'm running Steam on Ubuntu 22.04), but after I launch Liftoff and listen on the port:

netcat -l 127.0.0.1 9001

I don't get any data :(

I was looking for any clues in my Player.log file, but no info about the TelemetryConfiguration.json file being loaded.

Any hints on how to get this working / How to debug it?

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