Reading real flight logs

Advanced, for developers

These are research scripts in the Lothal repository, not features of the app. The app’s Studio reads only flights recorded in Lothal. The scripts need Python 3 and NumPy and a copy of the repository.

The scripts exist to check one guessed number in Lothal: the frequency a frame’s arms ring at, which every frame’s vibration figure is scaled from. Each one says in its own header what it does, why, and what it found. Read the header before running one.

Script	What it reads	What it is for
resonance_analysis.py	A Lothal flight-log CSV, or a Betaflight blackbox log already decoded to CSV with blackbox_decode	Look for a frame’s first bending mode in a gyro trace and compare it with Lothal’s model.
impact_analysis.py	A tap-test recording: a WAV from a phone microphone, a Betaflight log, or a Lothal log	Measure an arm’s ringing frequency and its damping from a tap on the arm, with nothing flown.
inav_log.py	INAV blackbox logs	Read INAV’s log dialect, which records the unfiltered gyro directly. Used by the other scripts.
campbell_analysis.py	A set of logs from one aircraft	Look for a frame mode across many flights at different hover throttles, when no single flight sweeps the throttle.

Running them

resonance_analysis.py and impact_analysis.py have command-line options; run either with --help from the tools/ folder. Both need the arm length (hub to motor centre) and the mass at the arm tip, measured on the real aircraft. inav_log.py and campbell_analysis.py are modules used by the others and by their self-tests, not stand-alone commands.

For the tap test, follow impact_test_protocol.md exactly. It lists what to measure and weigh before you start, because some of it cannot be done once the drone is reassembled.

What to expect

Normal flying rarely produces a log in which a frame’s resonance can be measured: the motor speed moves too much within each moment of the log. The scripts are written to say so rather than report a number they cannot support. A null result is a real result.