Altitude reset in flight

ArduPlane Plane 4.0
1

I need some help from the group. I’ve been using Arduplane for some time but this issue is beyond my knowledge level.

I was just out flying my F405-Wing with Arduplane 4.0.5 and had the altitude jump from an expected value (~100m) to a negative value in a short time. The attached images from the OSD show the messages that flashed up just prior to and after the reset.

Images are in reverse order, start at bottom and go up for chronological order.

Log file:

Altitude error step landed_no_lat_lon Altitude error step 3_no_Lat_lon Altitude error step 2_no_Lat_lon Altitude error step 1_no_Lat_lon

2

you’ve got ARMING_REQUIRE set to 0, which basically disables the whole arming process including prearm safety checks, as well as your ARMING_CHECKS bitmask set to 64 (RC_CHANNELS only). that’s why you didn’t notice you launched without a sufficient GPS fix and your EKF origin not set. you had a sufficient 3D lock not before about a minute into your flight, and that’s when your EKF finally settled and your altitude got reset.

image
image1920×1080 246 KB

it is quite favourable to leave the arming process enabled and your checks set to default (all = 1) to avoid things like this, see https://ardupilot.org/plane/docs/arming-your-plane.html for reference.

1 Like
3

Thanks. I normally don’t fly this model with a gcs. How do I know when all parameters are ok via osd? I waited until I had 7 Sats and icon was not blinking prior to take off.

Thanks

4

with the settings you’re using you actually don’t, that’s what i was trying to say. if you’d set ARMING_REQUIRE and ARMING_CHECKS back their default of 1, your OSD message panel will notify you respectively if any requirements for arming fail.
the most common reason to disable arming checks is missing basic mandatory setup steps, keeping your FC from arming in the field. while this might seem annoying at first glance, fundamentally solving your arming issues is a far better approach, as it will likely only take a couple of clicks while adding a lot of reliability to your setup. it might be useful to have a GCS at hand for these steps just once. once setup correctly, your OSD message panel is all you need on subsequent flights in the rare case something keeps you from arming. at least that’s how i usually do it, with good results so far.