inaccurate timestamps after a few days?

[rmackay9]

There's a report here that says we have a problem with timestamps becoming inaccurate over time.

This was brought up in this discussion

And PR #26104 apparently resolved the issue in Linux

FYI @geofrancis

[rmackay9]

We had a good discussion about this on the dev call and we're looking forward to seeing logs

We think that AP should be able to run for many days and we have reports from at least two developers who are successfully running autopilots for months which suggests that the issue could be hardware specific. In particular we know that some autopilots suffer from severe clock drift.

Still, it's an important issue because we are looking forward to AP being used on boats crossing oceans

[geofrancis]

is there any documentation on the clock drift issue with ardupilot?

[geofrancis]

Based on the report that there are some controllers that have been on a desk running for extended periods of time the only things I can think of that could be different would be temperature and how much data is consuming if those controllers don't have a GPS connected.

I have an omnibusf4 set to offline logging at 1hz with a 32gb sd card in it. its plugged into a phone charger and il just leave it for a week. I have a clone pixhawk and a matekh743 I will also test with but i need to get more memory cards .

If that doesnt do anything then I will do the same test but with a GPS attached in case it has some effect on it.

To test for clock drift issues, I have ordered a TEC cooler to build a thermal cycling setup to take the controller from 0c to 60c repeatedly , hopefully that can highlight some issues if there is temperature related clock or gyro drift.

[geofrancis]

I now have the omnibusf4 and the pixhawk clone flashed with latest stable rover and the h743 on my 9 inch quad running arducopter as im currently working on my other rovers. I have set offline logging enabled at 1hz with a 32gb sd card on all of them and they are placed next to a window to get some variable temperatures so barring any power cuts I should have logs in a week,.

This is from the locarb solar boat
https://www.locarbftw.com/the-build-in-review/

LOCARB navigation is based on open source Ardupilot software with a Pixhawk 2.4.8 flight controller as its hardware base. The pixhawk controls the GPS, compass, telemetry, IMU, and rudder servo. Being an Ardupilot based navigation system, freely available ground control software (such as Mission Planner) makes for creating way-points “simple,” and allows for easy two-way communication with the autopilot.

If I was to build another boat, I would most definitely not use this platform again. It introduces too many unknowns into the navigation process, has too many frivolous settings required to get it operating correctly, requires another hard to understand Arduino library to control it, and is unreliable.

When powered on for 1 week durations with no reset, the autopilot fails to respond to new waypoint commands without having to be rebooted first. It also loses control of the rudder randomly and requires a power cycle to get the rudder operational again. It seems to lose track of the heading over time, and just introduces too many unknowns in the way the boat navigates because it is generally unstable. I just couldn’t trust it to do what it was told so was left second guessing why the boat was behaving as it did (was it the wind/currents pushing the boat or the autopilot?). With the limited amount of data available during the journey, it was problematic trying to troubleshoot. I say stay away from these solutions.

[rmackay9]

@geofrancis,

I posted over in this discussion but for anyone else reading this issue here are my comments again

It’s too bad that the LOCARB person had such a bad experience. There’s no log to analyse and so it’s just a guess but it seems like his vehicle had estimation issues (e.g. EKF and/or DCM) and he struggled with AP’s complexity.

I’m keen to help anyone who wants to create a boat to cross a sea or travel around the world and I think AP can do it.

[rmackay9]

@geofrancis,

I think it's OK for us to close this issue now right? According to the discussion I think you tested for a few days and saw no issues

I'll go ahead and close this but I'm happy to re-open if we can reproduce it