We have a platform that is currently flying well with Arducopter V3.5.7 but we want to migrate over to PX4.Is it possible to convert the values PID values to get a starting point to tune from?
The PID values don’t only depend on the airframe but also on the mixer and the low pass filtering on the sensor data. Different cutoff frequencies give different delays to your data and this has an impact on your pid gains. I think ardupilot has low cutoff frequencies for accel and gyro data (20 or 30 Hz). I would start by checking what you have set for these cutoffs and set them also in px4. The parameters to set these cutoffs are IMU_ACCEL_CUTOFF and IMU_GYRO_CUTOFF. Then if your pid gains are higher than the px4 default ones I would start with the default ones and gradually increase them towards your gains from ardupilot (every time checking the stability). If your gains are lower than the px4 default ones then decrease the default gains and test it. For fine tuning you can then check the px4 guide https://docs.px4.io/en/config_mc/pid_tuning_guide_multicopter.htmlLet me know if you have any other questions.