I don’t think this is a problem.
I would try contacting UBlox for custom configuration/firmware. They are your best bet.
Thanks, I never thought of that. I’ll give it a go.
(The red trace is the XKF4/SV data, the green the GPS glitch and yellow is the number of satellites)
I’m still getting problems with the EKF becoming unstable. I’ve set things up so that there is only one External compass. There are two IMUs, but only one GPS (in this case an M10 Beitian BE-450). I understand that better GPS units will help.
However, I really can’t understand why the EKF becomes unstable for 5 MINUTES. The instability lasts as long as the GPS Glitch is set to 1. Looking at the GPS Logs, the number of satellites drops from 15 to 0 to 15 in 300ms and then remains above 15 satellites for the rest of the EKF instability. GPS/hDop does the same peak and recovery.
So if the GPS has recovered, why isn’t the GPS glitch being reset and why does the EKF continue to be unstable? Is this a bug in system?
Are there any settings that would help the EKF recover in this scenario? (EK3_GLITCH_RAD, EKF_POSNE_M_NSE, EKF_POS_I_GATE ?)
https://drive.google.com/file/d/1zKExoafYzDrjS-4vTN__vOL6EL1DykyP/view?usp=sharing
No, it can be that you have too many constellations and that the update rate is slower than 200ms.
Not a bug. Just a missconfiguration.
OK, so what configuration changes would improve the situation?
So you haven’t done anything since the previous posting? Try setting some explicit Constellations instead if leaving it at default. Like GPS & GLONASS or GPS, SBAS& GLONASS.
LOL, The weather is rubbish in the UK at the moment, so testing is not proceeding very quickly. I have three different configurations in test.
I’ve not come across the concept of reducing the constellations before. Just been reading up on the issues of update rate,etc. I’ll be giving this a try.
Looks like this BE-450 has upto 5 constellations. GPS, BDS, GALILEO (QZSS and SBAS) and the HolyBro micro 10 has up to 4.
At the moment I have:
GPS_GNSS_MODE = 0
GPS_RATE_MS = 200
GPS_AUTO_CONFIG = 1
GPS_SAVE_CFG = 2
GPS_TYPE = 1
I’ll try GPS_GNSS_MODE = 5 (GPS and Galileo) or 65 (GPS and GLONAS)
Should I leave GPS_RATE_MS = 200 (5Hz) or try pushing it up 125ms (8Hz)
and GPS_AUTO_CONFIG = 1 ?
That would make things worse. Leave it at 5Hz
OK, I’ll just try the 2 satellites. Thanks for your time.
Constellations and other settings would have been correct had you used ArduPilot methodic configurator software.
I’ve not come across that configurator before. I’ll run through it and see if there’s anything else I’ve missed.
Gps utc time for instance
I’ll check out the GPS time.
I believe that the compass calibration will be a problem if I move the “flight recorder” from one aircraft to another (which is a likely scenario). Would I be better off disabling the compass completely? What would be the issues associated with that?
I can’t find anything about “gps utc time”, what do you mean?
You can disable the compass with Plane. For your purposes it might be OK if you don’t need heading information. I guess I wonder why it’s a concern to have error messages. iI’s not flying the plane why do you care?
OK, I might try some flights with the compass turned off completely and see. I assume that I’ll still get yaw from the GPS and IMU data.
I’m not concerned about error messages, it’s the fact that the flight path from the log jumps all over the place. I’ve written some software that displays the flight path allowing aerobatic pilots to see what they actually did in the flight. Like FlightCoach but for “real” airplanes.
OK, that’s all GPS. Think you really need better hardware.
I hear you about the better hardware, I’m trying to get the settings as optimal as possible. I’ve got enough information to do some meaningful tests. Thank you everyone for the help.