Quad 450 dual GPS

Hello friends,
today I made a flight with my quad 450 and dual GPS.
Setup: Arducopter 3.6.11, Pixhawk 4, 9055 gemfan propellers, 2,8 kg weight.
Overall, I can be satisfied. I only see some uncertainty in maintaining the Loiter position.
I have not proceeded with Autotune yet.
I attach my log to get your opinion.
In your opinion, with these performances is it necessary to proceed with autotune?

Size (kb) 11551.138671875
No of lines 133943
Duration 0:06:30
Vehicletype ArduCopter
Firmware Version V3.6.11
Firmware Hash f0d59294
Hardware Type
Free Mem 0
Skipped Lines 0
Test: Autotune = UNKNOWN - No ATUN log data
Test: Brownout = GOOD -
Test: Compass = GOOD - mag_field interference within limits (5.05%)

Test: Dupe Log Data = GOOD -
Test: Empty = GOOD -
Test: Event/Failsafe = GOOD -
Test: GPS = GOOD -
Test: IMU Mismatch = GOOD - (Mismatch: 0.24, WARN: 0.75, FAIL: 1.50)
Test: Motor Balance = GOOD - Motor channel averages = [1519, 1529, 1487, 1516]
Average motor output = 1512
Difference between min and max motor averages = 42
Test: NaNs = FAIL - Found NaN in CTUN.DSAlt

Test: OpticalFlow = FAIL - FAIL: no optical flow data

Test: Parameters = FAIL - ‘THR_MIN’ not found
Test: PM = GOOD -
Test: Pitch/Roll = GOOD -
Test: Thrust = GOOD -
Test: VCC = UNKNOWN - No CURR log data

Thank’s to all friends
@smartdave @xfacta

It is always a good idea to run autotune to fine tune a craft.

Out of curiosity, why are you using an old Arducopter build? Are you able to upgrade to 4.0.3?

In looking at your logs I would say it needs it. It may feel ok but the logs are showing a different story.

In the following chart you can see the craft is not tightly following the commands given. An autotune will tighten this up.

You vibrations are excellent

You might also want to set these per the tuning guide


Hope that helps

Thank you for your answer @smartdave .
I thought I would proceed step by step and update to AC 4.3 after getting a good set of PID values.
I thought of proceeding manually and not with autotune as I have read about some cases in which a crash can occur.
All your advice is welcome and thank you.
Dual GPS is set as “Use the best”. Although the GPS are not the same both use an ublox M8N chip and I have observed that their accuracies are comparable (obviously the default Holybro GPS is better). Do you think that if for some reason the second GPS is better and the control unit considers it instead of the first GPS there could be problems in flight?

P.S. ATC_ACCEL they were already set as tuning guide :slight_smile:

For all my dual GPS crafts I have selected “use best”

I would upgrade before you put all the effort into tuning

Hi @smartdave,
i attach autotune changement valor of PID roll axis.
Very different from default valor.
Reponse of roll axis is very better after autotune.
But difference is very big i think.

What do you think about it?

Thank’s to all my friends

Looks good to me. I have found the auto-tune numbers to be way different than stock pids all the time

Very thank’s @smartdave
I am glad to hear this.
I also proceeded with the pitch autotune and the values ​​are even higher than the roll.

The quad seems to respond well.
I will also do other tests and maybe some videos.

Dont forget to do the yaw autotune.
If the PIDs are already fairly good (from other Autotunes or manual tuning) then subsequent Autotunes seem to be much quicker - you’ll be able to run all axis at once.

Certainly as soon as possible I will also carry out the PID of the YAW.
I decided to go one axis at a time for more security.
Thanks for your advice @xfacta :slight_smile:

Hello friends,
I also completed the autotune on the yaw axis and I must say that the quad responds very well and I am satisfied with this.

Your help and support has been crucial in this process.
I would like to ask you one more question. My gear is retractable and I wonder if, having autotune with the gear lowered, the moment I retract it for the flight it will significantly change my attitude. Did you happen to face this question?
Thanks to all friends @xfacta @smartdave

You are welcome, glad it worked out well for you