Boules

Flight plan processing has now been moved to a new autopilot process ultimately with the aim of feeding Sweep object detection into the autopilot, which in turn swaps from the current flight plan to an ’emergency landing’ flight plan, updating the main process to hover and descend to ground. This flight proves the autopilot feed works, though does raise other problems, primarily the drift over the course of a 3 second takeoff, 5 second hover and 4 second land.

I suspect the drift is caused by video processing: it was processing the 10Hz output at 7Hz, leading to lag.  This reduced processing speed may be caused by overheating of the RPi CPU, causing it to throttle back.

I’d set

force_turbo=1

in /boot/config.txt to make sure the CPU runs at fully speed always, rather than when it ‘thinks’ it’s busy.  This, combined with the fact the temperature today is 24° in the shade may well be enough for the CPU to throttle back due to overheating instead.  Certainly just a few days ago when the outdoor temperature was in the mid-teens and a cool breeze was blowing, there was no drift.  The CPU has a heatsink, but it is a case.  I may have to either remove the case (exposing it to the elements) or add a cooling fan to the case.  If possible, the latter would be better as the case is there to provide a constant temperature to IMU temperature drift.  I’ve found this one which might just fit in.

Note the kids’ pétanque kit is deliberately on the ground to provide weighty contrasting areas that the grass no longer supplies to the video.  Off to mow the lawn now.

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