UTC Time Delay in Auto Missions

General
1

Hi all,

I don’t have a deep background in GPS signals and such, but in the past I’ve been able to use the UTC delay command in Mission Planner with Arducopter to coordinate the auto missions of multiple copters to be “synchronized”. I don’t use this for light shows or anything like that, but it’s usually a fun visual and good exercise in mission planning for some of my students towards the end of the term. However, yesterday we tried this and had multiple failures where the copters seemed to miss a command at the precise UTC delay time and then would of course just sit waiting for that UTC time to come again in 24 hours. This happened even on the initial takeoff command to start the mission when the copters were already “at” the position they needed to be at for the next command. (they weren’t flying and just not getting to a new position fast enough)

I am aware of the AUTO_OPTIONS parameter and had that enabled to allow arming in auto and allow takeoff without raising throttle. In the past we were able to enable those AUTO_OPTIONS for the flight, temporarily disable the DISARM_DELAY and then arm the copters in auto a minute or so before the scheduled takeoff time. The copters would then sit with motors idling until the UTC time arrived and takeoff onto the pre-planned missions simultaneously. It is quite fun to watch.

Unfortunately this didn’t work yesterday after multiple attempts and resets and the one main variable that has changed from the last time we did this that I can think of is the GPS modules themselves. We were using Walksnail M181 GPS modules this time where in the past we’ve typically used Matek GPS’s. The Walksnail modules are definitely a cheaper module, which is why they’re nice in an educational setting, but I’m wondering if there’s something about them that affects clock timing or something similar, causing them to continually miss the UTC time “checkpoints” and to then start the wait for 24 hours until the UTC time comes around again.

Is there a key feature of higher quality GPS modules that would affect things in this way? Any insight would be appreciated!

2

This is interesting to me. Do you have a logfile from a couple of the aircraft showing this behaviour?

3

Hi @CraigElder thanks for taking a look! Here’s one of the log-files. I’m trying to round up the others (there were 3 total) from the students.

GroupFlight1.bin

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4

Here is another log @CraigElder . I’m only going to be able to get 2 of the 3 logs, unfortunately. One of the students left for break and didn’t take his aircraft with him, so no way to access the log until August/Sept.

GroupFlight2.bin

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