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This continues to move forward.  Decided attitude sensing is required for what we need.

After some complicated math problems, finally derived an empirical method for determining attitude from video.  It most definitely isn't accurate enough for our needs.  There's going to be a lot of horizontal drift.  The tilt of the camera has a big effect on it.

The takeoff is still problematic.  Attitude really needs to be level before it lifts off.  It's most definitely not passively stable.

PID tuning for attitude control with the altitude control nailed down.  It's most definitely not passively stable.

The great problem with Marcy 1 is devising a stabilized takeoff.  It needs to start tracking position at some point before it can actually track position.


The 1st algorithm was to apply fixed throttle that was known to go fast enough to control attitude but not take off.  Once the RPM was certain to be fast enough to return a valid position & attitude, apply cyclic to level the attitude without increasing throttle.  

This has been killing us, since attitude oscillates at low throttle.  For now, it just ramps up at the point in the oscillation when it's level enough & hopes there's enough control to keep it level. 


The moment it starts ramping up, it starts tracking position.  Since it can't move, the integrals build up.


Making it ignore position until reaching a minimum altitude has been tried.  The takeoff attitude is never level because the camera is never level, so it would fly away without active control.


 Resetting the integrals before reaching a minimum altitude, but having proportional feedback is yet to be tried.  Trying to stabilize the oscillation at low RPM, with derivatives is yet to be tried.


Loosening the steel wire to give it some horizontal range has shown whether or not feedback was going in the right direction.  Another idea is using fishing line instead of steel & tightening it if it gets out of control.

Marcy 1 does 4 autonomous flights without the tether. It's pretty bad. Throttle is a lot more unstable. Position tracking is erratic. The last crash might have been an unknown air current. Put a lot of work into making the takeoffs exactly level. Honestly thought that would never happen, but we got level takeoffs. Now, the XY camera movement seems to confuse it.

  Began by running the takeoff sequence up to the stabilized attitude stage to show machine vision could keep it level. Then switched to manual mode with cyclic at neutral to show how it doesn't naturally stay level. Then ran down the battery with the stabilized attitude on, to show the algorithm could keep it level for all battery voltages.

Perfectly level attitude is required for takeoff. Deglitching the video & getting such a slowly rotating blade level was a buster.

Reasonably pleased with new progress in leveling the aircraft on the test stand.  Maintaining a perfectly level aircraft during the takeoff is key to everything else.

Key to leveling the aircraft was using much higher gains than we used before.  A manual test showed the D gain was capable of an amazing job stabilizing the aircraft.

Also, application of the deglitching algorithm formerly used in sonar to the vision system greatly improved matters without causing a delay.  Finally, the trig had some more corner case tests.

Currently, the next flight test is programmed to feed position directly to cyclic, because vision isn't seen as accurate enough to give useful attitude information on a moving object.  All these changes still may get it to work with attitude hold.

Need to find more propellers 1st.  All suppliers are moving to China.  It takes several months to get anything from China. We've actually haven't gotten anything from the last 2 hobbyking orders.

More stable takeoff algorithm, deglitching, & direct position to cyclic feedback, but still no luck.  It's taking 1 propeller for every 4 test flights. 


We got the takeoffs very reliable.  It doesn't fly off the stand in a random direction unless the propeller breaks.  The only algorithm left is going back to the attitude feedback.