Dear Quad Doctors
Noticed strange behaviour with my quad. With Version 2.6 , Logs were not working, presumably due to the dataflash issue. Now with 2.7, I notice large magnitude GPS noise.
Background: From logs (in May back at v2.5.5) I notice smooth GPS graph and log below:
Now, with V 2.7 I notice noisy GPS signal , flying in my usual flying field, with the graph abut the same scale.... see log file and graph below:2012-07-29%2021-23%203.log
I think the noisy " sawtooth" position is driving the navigation PID crazy because the quad is a bit twitchy and RTL will not land. Could I have a faulty GPS?
GPS: MediaTek MT3329
Here is the flight above, (my latest flight ) at the field shown in APM Visualizer 1.3.4
I've noticed the same thing, and I noticed a couple of others have too.
See log file from this afternoon where I took my quad for a car ride with motors on but without props so no vibration. If you open log in APM visualizer, you can see quad is pitched up because it's on my car back seat.
Also attach a kmz.
I think gps is very jittery!
The jittery GPS is not really a problem. The GPS is run through a lag filter to deal with the MTEKs almost 1.2 seconds of lag. This is only used to judge things like are we there yet? If you are flying home at 6m/s you will overshoot home by over 20feet in RTL with an MTEK. This filter prevents that. It's not used to judge speed which is the main thing you're complaining about with jitters. It also only works in XY and not Z so it wouldn't have anything to do with landing.
One issue is the logging should use the straight GPS output and not the filtered output.
Try and lower your nav_P if you have jitteriness in the air.
Thanks Jason. I'll try lowering Nav_P. For the jitters.
I'm still wondering why I got smooth GPS graphs in May but noisy graphs in July. Could this be a problem with my MTEK? Or perhaps there were changes to logging between v 2.5.5 and 2.7 so I'm now seeing unfiltered GPS with 2.7 and the filtered output with 2.5.5?
Hi Jason! How this lag filter actually works and is it somehow adjustable? I see about twice bigger jitter in latitude direction, could it be because i live in north hemisphere [Finland] ?