An old drone build going crazy after V1? The culprit might not what you expect!
With the release of V1, many aspects of Liftoff have been updated. Among the most important changes were the introduction of “physics 3.0” and adjustments to all drone parts available in the game. These changes mean that pre-V1 drone builds might perform very differently from before.
If you want to use an old build from before V1, you should at least re-tune its PID gains. A bad PID tuning can generate the following problems:
- General oscillations
- Unwanted amounts of acceleration at low throttle (after a hard throttle punch, non-convergence, or very slow convergence of the PID regulators with violent overshooting and overcompensation)
- Unpredictable behaviour after a collision
This is not an exhaustive list. To assess the quality of your PID tuning, you can press F9 in-game to display your gyro rates on screen. Let’s have a look at the following examples:
On the left, this kind of oscillation is a sign of very bad tuning (especially on the yellow yaw axis, with far too much P and maybe not enough D for example).
On the right, you can see a fast convergence to the input rate, and little to no oscillation. This is what decent PID tuning should look like.
Since Liftoff uses actual PID controllers (as opposed to a simple simulation) for its flight controller, real-life PID tuning resources also work in-game. Some really good resources are Oscar Liang’s introductive guide to PID or Joshua Bardwell’s guide from YouTube . Note that the gain won’t be exactly the same as in Betaflight in real life, but the way to tune them is the same.
As always, if you are not comfortable with PID tuning, you can always use blueprints or ask experienced players for their build and PID gains!
Another consequence of the changes brought on by V1 is the hover point of some drone builds. The hover point is the amount of throttle (given no other input) that is required for a drone to fly at a fixed altitude. The hover point is where the thrust generated by the drone is equal to its weight. The higher the thrust-to-weight ratio, the lower hover point will be.
If the hover point of your current drone build doesn’t fit your flight style, these are possible changes that could help you fine-tune it:
To obtain a higher hover point, you can:
- Reduce the power of your build by using lower pitch propellers, or less powerful motors
- Increase the weight of your build by using different parts
- Use the “Additional weight” feature in the workbench, under Frame part > Edit part to tweak the weight of your build
- Modify the throttle curve on your controller or in the flight controller settings.
To obtain a lower hover point, you can:
- Increase the power of your build by using higher pitch propeller, or more powerful motors
- Decrease the weight of your build by using lighter parts
- Modify the throttle curve on your controller or in the flight controller settings
Help us help you!
If you are sure that your PID Gains are fine (clean gyro rate graph), and if the problem you have is not about hover point, you can always contact us via our Liftoff Steam forums or via Liftoff’s official community group on Facebook or by sending an email to firstname.lastname@example.org
In order for us to help you with the troubleshooting, please explain your issues in detail, mentioning your drone setup and your flight controller settings. If you can link a short video of you demonstrating the issue, that often also makes things much easier. It lets us know exactly what problem to look for, and thus makes it easier for us to help you.
We hope that with this information, you will be able to fine-tune your quadcopters to fit your flight style. If you are happy with one of your build, don’t hesitate to share it on the Steam Workshop and on Liftoff’s community group on Facebook!