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Oct 05, 2012, 05:00 AM
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Quad becomes aware

So after some more banging, the Syma finally took off, hovered, & landed all on autopilot. It was extremely stable, but needed nearly 100% pitch trim. The shadow of the 1st personal drone which could follow you around a building started to appear.

It finally proved the stereo vision concept. Haven't seen any other case of a stereo camera flying something, anywhere. Previously, they all used multiple cameras throughout the room or a single camera & multiple markers. The stereo camera is how a human flies, biologically inspired.

Vision needed a very precise servo PWM conversion to degrees. The ultimate vision system would give the exact camera direction from an IMU, for each frame. The PID limits had to be reduced to get horizontal position to stabilize.

So far, have learned the Syma has a calibration stage in which it needs to be very still to calibrate the gyros. This is the #1 reason it's sometimes unstable & probably why it needed so much pitch trim.

The agenda has a few more steps before any time can go into photographing it. The motors also have a very finite life.

It turned out the Syma has no accelerometer. There's absolutely no feedback if it's tilted in your hand.

It's actually mechanically stabilized, which is probably more effective than an accelerometer. An accelerometer searching for its perceived level point would never hit the exact equilibrium attitude the way the Syma is.

The mechanical stabilization also eliminates drift in the ITG3205. Yaw still drifts, since that axis doesn't naturally return to a neutral point to bias the ITG3205 from.

It can only be some gyroscopic effect of using massive propellers, like how a monocopter stabilizes position by rotating its entire mass. It's enough to overcome the unbalancing of the LED.

After a few good runs with the network, it failed again. Gave up on multiple stations & returned to just the ground station responding to beacons. That cleared everything up. There was no interference from the 2.4Ghz DSSS. Making the aircraft send video over wifi would require having the ground cameras on USB. There might be a better way with bluetooth.

Finally, the Syma computer surprisingly doesn't run directly off the 4.2V battery. It has a boost converter boost it to 6.4V, then a linear regulator reduce it to 3.3V. It must have required extremely stable, low ripple voltage for the ITG3205.
Last edited by Jack Crossfire; Oct 05, 2012 at 05:07 AM.
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