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Quadcopter Flight Controller
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Altitude Hold with Laser Rangefinder Feedback Loop #13

Closed RoboTechie closed 7 years ago

RoboTechie commented 8 years ago

I tested the most recent firmware release today, and while the barometric pressure and PING))) altitude hold modes perform well, using the SF11/C Laser Rangefinder causes an oscillatory feedback "loop", whereby as soon as the laser-assisted altitude hold is enable, the ELEV-8 begins to oscillate vertically (moves down vertically, then back up, then back down), and the magnitude of the oscillations (distance up/dwn) quickly increases with time.

I had wireless telemetry set up during the tests. Here is the graph of distance to ground over time, showing the oscillations osc1

I then tried changing the Altitude PID from 125 to 70, thinking that maybe the value was just to aggressive, but it didn't have any noticeable effect: laser2

If I had to guess, I would think that a sign is reversed somewhere.

MatzElectronics commented 7 years ago

This appears to be solved by removing the filtering on the SF-11C, which is turned on by default. @RoboTechie has drafted instructions