PID clarification for new setup

Hello, just a stupid question. I’ve a new setup with Tarot 650sport with 17 propellers and Turnigy 4112 320kv motors, pixhawk FC, 6S.

After the first flight, the quad flight decently but it needs of course a bit of tuning. The purpose of this quad should be aerial filming, the most used flight mode will be loiter and auto.

Basic and advanced PID tuning explained in the docs, influence also the loiter mode or are just related to non GPS mode?

The reason of my question is that there are also specific tuning fo loiter only and I don’t know if I need to focus on these parameter only.

Thanks for the help

The Rate and Stabilize loops are active any time you are in modes that are not acro. In acro, just the Rate loop is used. There are a couple of loiter tuning parameters but for most copters they work OK. Tune your copter first then see how the loiter performance is. I recommend running an autotune, it should work very well on that frame and power train setup.

Hello Matt, thank you for the support. I will try autotune.

Just for info, after some additional flight, reduction of the Throttle out parameter was required (about 300 instead of 500) to reach the stick mid position. Same story for the Roll and Rate PID (current value 0.1). Currently the most important issue to solve is that, in loiter and Alt-Hold, when the copter brake, it’s not able to remain at the same altitude. It loose about 1 or 2 meters. When it’s back in hovering, it regain the correct position. In hovering the hold of altitude is correct.

Do you have an idea where the issue can be?

Thanks again.

You can do a search around here for similar symptoms. The key search is air bubble effect on the barometer and can be minimized/eliminated with a good isolation of the barometer chip on the flight controller.

Thankyou Luis for the info. I will try to fix the problem in this direction.

Just to update about the bubble effect. The problem is solved mounting the Tarot 680 canopy which fit also on the 650. No more altitude issues. I suppose the barometer is no more influenced by the propellers. Still remain some tuning to do regarding PID’s but the copter fight has been improved significantly.

Thats good to hear.

Would you please post your PID setup here so that others may learn from your experience?