Altitude Hold Problem v2.3

[nicky]

Hello MultiWii experts,

I'm new in multi-rotors. Its my first project - DIY Quad X450. The flight controller is Arduino Leonardo(+IMU: gyro, acc, baro, mag) with Multiwii 2.3 on it. I managed to get it flying quite well in HORIZON mode. However it tends to drift up and down, so now I also want to get the BARO mode working.

I do the following:
1. First I enable the HORIZON mode only in order to arm
2. Then I take off in ~2m
3. Finally I switch to HORIZON + BARO for stable altitude hold

The result of this procedure is automatic landing - e.g. motors start spinning at lower frequency.
I tried different PID values for ALT, but it didn`t make a difference.
I want to note that on the dry tests the behavior looks correct. When I push the quad down it resists(increases throttle), when I raise it up it decreases throttle.

Do you have an idea what could be the cause of this undesired landing? I think it could be something related to the switch from HORIZON to HORIZON + BARO, but apart from that I have no good ideas left.

Any help is appreciated, thanks!

[Arakon]

Your throttle stick has to be centered at around 1500, and centered when you switch to althold if you want it to stay at that height. Below 1450 or above 1550, it will go down or up.

[nicky]

Thanks! I'll give it a try

[Commando]

I have the same problem About PID altitude mode I have no difference after set. Let me know if you find it, . as I do if I find it first. Cheers

[nicky]

The problem was exactly what Arakon proposed. The throttle stick has to be centered when you switch on the BARO mode.
Now I have a different problem: when at ~1500 throttle, then quad copter elevates quite fast, e.g. my natural hovering throttle seems to be ~1400. Is there a good way shift it in multiwii, or should I calibrate my ESC differently?

[FengShuiDrone]

.

[Arakon]

MIDRC changes the values for ALL channels.
Since you only want to change the THR channel, use the Throttle Mid option in the multiwii GUI. Try i.e. 0.45 there to see if things improve.