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This thread is privately moderated by Jack Crossfire, who may elect to delete unwanted replies.
Aug 22, 2007, 01:34 PM
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Jack Crossfire's Avatar
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While you're waiting for GPS to calibrate

So every day, it takes around 30 minutes to boot up GPS indoors after being powered down for 22 hours. After its internal capacitor is recharged and it's recalibrated, power cycling is very fast.

Tried the following algorithms:

specific limits for proportion, integration, and derivative feedback.

Less horizontal feedback when throttle feedback is higher.

Feedback based on a predicted future position. So far just adding current velocity to position. It's the same effect as adding derivative feedback.

None of them seemed 2 have any effect. Tried pure attitude hold again and she actually held position better than with position hold. Tried holding position the way the computer would, by slowly trimming the tabs, and couldn't do it.

Looks like the inertial navigation is just not fast enough to achieve position hold. The Kalman might be faster, but it would have to run at 200Hz to defeat aliasing. The 600Mhz Gumstix is unlikely to achieve more than 90Hz because it still has no floating point.

Only the old PC104 single board computers have enough flops to do the job. That what Neural Robotics uses. They weigh 8oz and cost $340. Imagine having to go back in time to get a better product. That's U. Know. Where.
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Aug 27, 2007, 05:18 AM
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Mark Harris's Avatar
Not sure what gps you're using, but that sounds like an awful long time. The new EB-85's take at most around 1.5 minutes to get all its locks - plus it supports a backup battery (just a cr2032).

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