Park Life

I took Phoebe for a play in the village park just now – it was a huge amount of fun for us both!  When the local kids are at school, it’s empty, and there’s a football pitch sized area of just grass.  It’s also just a few meters higher than our garden (we’re at the lowest point in the village), so while our lawn is currently somewhere between a quagmire and a lake, the park just had soft grass to land on, which, it turned out, is a very good thing!

The only downside is our garden has 6 – 10′ stone walls around it shielding it from the worst of any wind; the park is next to an open field, and today a 20mph wind was blowing.  So I sat, back to the wind and let her rip.  Off she flew at probably 20mph and reached the other side of the pitch in no time at all.  Her wind-drift protection wasn’t engaged so that’s actually what I’d expected (which is why I sat where I did), but I was surprised at how effective the wind was!

She did takeoff at a tilt and self corrected as the complementary filter started kicking in.  With dlpf set to 5Hz, I think I should be able to pull in the accelerometer much quicker.  I got it down to 10ms but I suspect I could go lower still.

And best of all, it was fun – there was nobody and nothing other than me that Phoebe could harm, meaning I could just watch the details of the flight and the change of behaviour as I tweak the config – very satisfying!

I’ll definitely be back there next time it’s not raining – Monday’s forecast is looking promising, and the wind is only expected to be just 14mph!

P.S. After reviewing the stats from the final flight, something useful has come from the 20mph flights too:  I’d been tuning the DLPF / complementary filter the wrong way round.  Under the belief that a low DLFP cuts out noise, I’d been reducing the fraction of time that accelerometer Euler angles became dominant.  But as a result, the stats showed I was tuning out the integrated gyro data.  This meant long term stability was fine, but Phoebe lacked the ability to react to the initial tilt she took off with.  So Tuesday’s priority is to see the net effect of the changes I’ve made – to allow more accelerometer data through (DLPF @ 10Hz rather than 5Hz), but then take longer to allow it through the complementary filter (0.2s rather than 0.01s).  Looking forward to seeing the result.

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