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First huge climb in AltHold flight mode

Hello,

I’m using Holybro Kakute F7 AIO and Arducopter 4.0.3 Quad.

When i fly first time in AltHold mode, with my throttle trigger, the copter climb approximately 5-6 meters although released the throttle stick.

But for second fly, without restart FC, there is no huge climbing. When i release the throttle stick, the copter keeps current altitude. If the FC restarted, the huge climb is happening again in first flight. Is there any bug?

My first flight log: https://drive.google.com/file/d/1GqB3pfk8NTQbOs6GswXvX3HjKZaRrhD-/view?usp=sharing

Go through this guide : https://ardupilot.org/copter/docs/tuning-process-instructions.html
and try again.

Hi @AGurel

I and other people may have the similar problem. A issue has been raised in https://github.com/ArduPilot/ardupilot/issues/11304

I am investigating this issue and suspect it may caused by sd card logging. Would you mind do a simple test? Start FC, arm and then disarm (do not take off), wait a few seconds and then arm again and take off. There should be ok this time. Thank you very much

I tried it but the problem continues.

Thank you very much @chobitsfan

I test it with your suggestion and it happened exactly as you said.

By the way, although I disabled logging, the problem continues.

Theorizing, based on log. Your GPS is still settling when you arming first time. The GPS altitude is 950m at first, and 930m at the second start. And it is decreasing as GPS finds more sats and gain more precision (Note, that you see only 5-7 GPS during your flight which means a crappy old GPS.)
This change of altitude creeps into EKF and generate a false negative climb, which FC tries to compensate. (hence the initial jump). After you are in the air and baro takes over, climb calculation stabilized. At the second takeoff your GPS already stabilized so no jump.

Set a Fence with radius and altitude and enable it, then you cant arm until there’s a valid 3D fix.
You have to disable the fence if your going to disable GPS checks and fly without a GPS fof some reason.

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