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Dec 21, 2007, 04:19 AM
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Rotomotion PID controller + uBlox


Well, had enough pullback in the rain to resume test flights. Time to run the Rotomotion PID controller + uBlox scenario. This controller applies position error, integrated position error, and absolute velocity directly to attitude. As with the EM406, it was not even close to the Vicacopter PID controller. Suspect it could be tuned, but the Vicacopter PID controller would always be more stable.

The Vicacopter controller applies position error to target velocity. Then it applies velocity error to attitude.

This time the climb rate was out of control in the same spot it seemed stable on 12/16. It looks like altitude is the first to go back to 1Hz. Whether or not accuracy is to blame, there's a simple matter of throttle not being fast enough to keep up with GPS updates without causing yaw. Sudden yaw throws off horizontal control. That leaves only $133 of the uBlox's $200 tag intact.

The uBlox seems to be an EB85 of another kind. More and more it seems anything above 1Hz is going to require DGPS to give reasonable accuracy. The pros all use >1Hz GPS but they also use DGPS.

Stepped up the XBee telemetry rate yet again by reducing accuracy. The test video is still from the lousy pencam. Obviously the pencam is a bit tilted and we have a few radio dropouts.

Video overlay HUD #2 (1 min 15 sec)
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