we are developing a drone for a time critical application. Currently it takes around 45s till our autonomous drone takes off. This is OK, but I think it could be shorter.
Our setup consists of a Pixracer running Copter 3.6 (ChibiOS) with an ublox NEO-M8N. Additionally there is a raspberry Pi companion computer controlling the system.
The “boot” time for the drone is around 7-8s, then I can fly manually in Stabelize mode. The Raspberry currently takes around 17s to boot. I thought this would be the bottle neck, but I can tell that after the boot the raspberry waits for the drone to become ready.
Now, I know that for Guided mode I need a good GPS fix. But according to the ublox datasheet a warm start should take only 1s and a cold start should take 26s… so the question is, why does the drone take so “long” to take off? The GPS module actually has blue status LED indicating if it has a fix or not, and this more or less matches the data sheet description (depending on how good the view of the sky is).
What could be preventing the drone from immediately taking off, once there is a good GPS fix?