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Jun 28, 2009, 08:22 PM
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1/2 Ground Based Autopilot Takes Flight

Heading hold mode takes flight (1 min 22 sec)

So this was heading hold mode on the airframe & full quaternion feedback on the ground in 105F weather. The ground computer commands cyclic at 50Hz to achieve a target attitude & the airborne computer commands cyclic again at 200Hz to achieve the desired change in attitude.

Unfortunately, there was too much lag between position feedback & attitude. The heading hold software isn't tuned for the optimum response. Any time U command changes in attitude instead of absolute attitude, you're heading for serious lag, but heading hold gyros can do snap turns so U still have a few more blog posts 2 go.

Vika 1 heading hold implementation (1 min 43 sec)

On the test stand, heading hold actually didn't look any better than rate damping alone.

Unfortunately, Vika 2 died on the first autopilot switchon in an old fashioned software bug. Switched to Vika 1 & smashed her when the position oscillations got too big.

For the moment, heading hold seems to be a waste of time. When you've got full attitude control at 50Hz, the 200Hz layer only seems to benefit rate damping.
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