Although there are many gains that can be tuned in APM:Copter to get optimal performance, the most critical is the Rate Roll and Pitch P values which convert the desired rotation rate into a motor output. This alone will likely get it flying reasonably well at least in Stabilize mode.
Some general advice on how to tune this parameter:
- Too high and the copter will oscillate quickly in roll and/or pitch
- Too low and the copter will become sluggish
- High powered copter should use a lower gain, under powered copters are a higher gain
Rate Roll P and Rate Pitch P can be tuned in flight using your transmitter’s channel 6 tuning knob by following these instructions:
- Connect your APM/Pixhawk/PX4 to the Mission Planner
- On the mission planner, select Config/Tuning >> APM:Copter Pids
- Set the CH6 Opt to “Rate Roll/Pitch kP”
- Set Min to 0.08, Max to 0.20 (most copters ideal gain is within this range although from a small number of copter the Max can be as high as 0.25)
- Push the “Write Params” button
- Turn your transmitter’s CH6 tuning knob to the minimum position, press the “Refresh Params” button and ensure that the Rate Roll P and Rate Pitch P values become 0.08 (or something very close)
- Turn the CH6 knob to it’s maximum position, press “Refresh Params” and ensure the Rate Roll P moves to 0.20
- Move the CH6 knob back to the middle
- Arm and fly your copter in Stabilize mode adjusting the ch6 knob until you get a copter that is responsive but not wobbly
- After the flight, disconnect your lipo battery and reconnect the APM to the mission planner
- With the CH6 knob in the position that gave the best performance, return to the ArduCopter Pids screen and push the “Refresh Params” button
- In the Rate Roll P and Rate Pitch P fields re-type the value that you see but just slightly modified so that the mission planner recongises that it’s changed and resends to the APM/PX4 (Note: if you re-type exactly the same number as what appears in Rate Roll P it won’t be updated). So for example if the Rate Roll P appears as “0.1213” make it “0.1200”
- Set Ch6 Opt back to “None” and push “Write Params”
- Push the Disconnect button on the top right, and the Connect
- Ensure that the Rate Roll P value is the value that you retyped in step #12
Note: while you are moving the tuning knob the values update at 3 times per second. The need to press the Refresh button in the mission planner in steps #6 and #7 above is just because the APM:Copter is not sending the updates to the mission planner in real-time.
Video of in-flight tuning
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