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Archive for April, 2008 - Page 2
Posted by Jack Crossfire | Apr 04, 2008 @ 05:25 AM | 3,453 Views
Found another bug in the inertial navigation. To get the quaternion integration to work, had to use negative pitch for nose up. That bought her first pirouettes without complete loss of control & it may have improved stability. Turning is still risky business because the GPS is slow.

Can finally say the global equilibrium tilt is working. The IMU is not perfectly square so yaw does talk to pitch. To get good pirouettes on 1Hz GPS, it takes real sharp alignment of all the bits. Neural network swashplate mixing seems to be working. Sttill seems 2 B less coupling of cyclic inputs with it.
Posted by Jack Crossfire | Apr 03, 2008 @ 03:22 AM | 3,565 Views
The XCite batteries arrived after 2 weeks completely unbalanced. The actual weight was much more than the quoted weight 2 weeks ago. At 319g, they're the heaviest we've flown. Will need another BEC to power the camera.

Tweeked the image stabilization settings some more & got some really smooth results on footage once deemed unusable.

Autonomous helicopter photographs pilot (0 min 20 sec)

Posted by Jack Crossfire | Apr 02, 2008 @ 03:21 AM | 3,926 Views
Was surprised to learn the first stabilization algorithm we wrote 8 years ago is quite effective on timelapse copter footage. It only compares the current frame to the previous frame & accumulates offset. It emulated cheap camcorder stabilization & was too slow for past computers to do it very well.

Now, it's back & fortified with frame stacking & a few Opterons. It's overall, quite an improvement over hand stabilization. Stabilization can be even smoother by increasing frame rate & waiting a few days.

Windy hover with software stabilization (1 min 58 sec)

The download is in 1920x1440 if U want 2 feel like you're really flying.

Decided the RCE-BL35X is pegging up to full throttle when the battery is dead instead of giving throttle warning pulses. What a piece of trash.

In terms of modern photo support, rcgroups sux. We now have full resolution photos from CopterCam on Ning. U can see just how sharp a flybarless 450 on autopilot can be & how useful that might be for spying. It also lets U set your own GooTube resolution in HTML.

Posted by Jack Crossfire | Apr 01, 2008 @ 04:01 AM | 3,829 Views
Wrote a cheat sheet for the swashplate. Tweeked the video recognition. Have the cyclic alignment down to just feeding in a phase & the computer figures out the blade pitches for the disc.

Well, the phase ended up being 15' instead of 30' like it was before & still is on the rate damping.

Neural network mixing works & is a lot neater than the algebraic method so it's staying. Have hardly flown the T-Rex in manual mode at all since its birth but a backwards figure 8 definitely felt easier with neural network mixing & the phase tweek.

Stepped up the cyclic gain to where it oscillates & got more turn stability. Oscillation is caused by the neural network velocity predictions. Stepped collective P gain back to 0.01 & got the usual less stable altitude but no vortex ring states.

Did an endurance test & our oldest 3.3Ah battery hovered 10 minutes in ground effect. It's previous flight ended after 7 min with the camera payload. This one is mainly used for test stand operations.

Well, like millions of others, got charged $4 by The Portland Chap & the credit card had to be disabled. All it takes is 1 insecure website. Charge $4 on a million credit card numbers. No-one cares about a $4 charge, but U just made $4 million.

No camera replacement this week. The total amount of fraud between Blockbuster accounting errors & credit card charges is $30 this year. Over 30 years, that could end up $900 just in fraud.

2 weeks after ordering, xcitebattery.com said they shipped the next round of batteries.