Sunday, June 14, 2015

My first AutoTune (Testing Only)

Here are the docs for AutoTune , and here is a thread about it. Remember that this procedure is completely optional and that the Default PIDs should be fine for 90% of quads (so say the developers). If you want to try it manually instead, here is the guide for that, and also read this.

And some Auto-Tune videos AutoTune and AutoTrim Video , Video-2, Video-3 .

Now would be a good time to do a Auto-Trim if you haven't already. While not as vital for Auto-Tune, Auto-Trim should be done in windless environment.

How to invoke AutoTune
1. Set up one flight mode switch position to be AltHold.
2. Set the Ch7 Opt or Ch8 Opt to AutoTune to allow you to turn the auto tuning on/off with the ch7 or ch8 switch.
3. Ensure the ch7 or ch8 switch is in the LOW position.
4. Wait for a calm day and go to a large open area.
5. Arm in Stabilize and Take off and put the copter into AltHold mode at a comfortable altitude (7 meters or 20 ft).
6. Set the ch7/ch8 switch to the HIGH position to engage auto tuning:
  •  You will see it twitch about 20 degrees left and right for a few minutes, then it will repeat forward and back.
  •  Use the roll and pitch stick at any time to reposition the copter if it drifts away (it will use the original PID gains during repositioning and between tests).  When you release the sticks it will continue auto tuning where it left off.
  •  Move the ch7/ch8 switch into the LOW position at any time to abandon the autotuning and return to the origin PIDs.
  •  Make sure that you do not have any trim set on your transmitter or the autotune may not get the signal that the sticks are centered.
7. When the tune completes (about 4 minutes) the copter will change back to the original PID gains.
8. Put the ch7/ch8 switch into the LOW position then back to the HIGH position to test the tuned PID gains.
9. Put the ch7/ch8 switch into the LOW position to fly using the original PID gains.
10. If you are happy with the autotuned PID gains, leave the ch7/ch8 switch in the HIGH position, land and disarm to save the PIDs permanently.

If you DO NOT like the new PIDS, switch ch7/ch8 LOW to return to the original PIDs. The gains will not be saved when you disarm.

In summary, the position of the AutoTune switch when you Dis-Arm will determine what PIDs are saved or used for next flight.

First AutoTune Flight:

Ok, so my first attempt of AutoTune worked fine in big field.

SuperSimple-Mode was already assigned to a switch on Taranis. All I did for this setup, was to temporarily swap SuperSimple-Mode on CH7 for AutoTune in Mission-Planner (no other changes were required). So, it turns out that on ArduCopter 3.1.5, there is no indication in MP or Tower that it is actually engaged. To me, it seems more like a Mode-Modifier like Simple-Mode. In a flight, the only indication is observing the aircraft and controls. I was not able to simulate it or test switch settings on the bench.

It was a bit windy and AutoTune took a good 7 minutes to complete. Almost couldn't finish on full-charged 2700 lipo. Battery usually lasts longer ... really stressed it and it was Puffy-McPuffers and hot when finished.

I'm not using these Auto-Tuned PIDs at this time. Instead, I'm still running the last PIDs from the bottom of my v3.1.5 page. I recently found out that gimbal should have been removed (and it's weight added back) or disconnected and "blocked/isolated". Pretty sure it "threw-off" my Auto-Tune process and resulting PIDs. It was also pretty windy, so I don't think that helped.

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