Blogs

This video was the 1st time we saw a camera on a monocopter getting useful images.  Indeed, it was the 1st video anyone ever made from a high speed camera.  Now we knew the shutter speed in daylight was fast enough & the image could be stabilized. 

If a flash is timed with the rotation, the camera could work in the dark.  The monocopter could be the pocketable flying camera that automatically takes self portraits everyone dreams of.

  So a common, analog, wireless camera with an LED flash to time the exposures is a start towards aircraft imaging.  That would work in the dark.  Analog cameras that small are expensive.  There isn't a standalone module which outputs composite video for under $50.

 The ideal system would use 802.11 for all radio communication.  We could play with the input clock signal to make it shoot at exactly the right moment. 

Went through some rearrangements of the POV attachment.

To shift the mass outward & add stability.  What happened was increased RPM, reduced coning angle, & less stability.  The RPM definitely needs to be lower for motor pulsing to work.  It's the same weight, but it's spinning faster.  That was unexpected.

The LED orientation definitely affected drag.  There may be a limit to the amount of weight on the outside.  Too much & the center of wing rotation moves too far out, less of the wing generates lift, & it spins faster.  Some other mechanism may reduce the angle of attack when the coning angle is reduced.

You want the lowest RPM, so that dictates mass as close to the center as possible.

With the weight shifted back to the middle & the LEDs in the more streamlined angle, the takeoff started jumping up while the control authority was regained, but we still saw the motor overheating & the greatly reduced flight times of the outer LED weight.  It was almost like the motor was damaged.

  For some guys, it's smoking.  For some guys, it's alcohol.   Just when you think it can't happen again, it's a 3600kv, 12x30mm motor.  It was the lowest kv ever & we hooked it up to a full 3030 propeller.

This configuration leaped into the air at only -0.3 throttle & after 6 minutes, it stayed a reasonable temperature, even in a pusher configuration. At least we now know the optimum power system for a micro tri rotor.  No-one has ever made a micro tri-rotor.

 The LEDs on the other hand are constantly burning out.  They're stepped down to 2.9V & still burning out.

The flash overwhelmed the LEDs in this shot, revealing differences in LED brightness.  The LED which was ground off in 2010 & which was still working was brighter, so we figured on grinding them all off.

1st the same way the 1st one was ground off.

But then we realized they could be ground diagonally, to deflect the light & be more aerodynamic.

The default lens made them project into the room instead of light up the aircraft.  Grinding them may also be useful for machine vision.

Well, it didn't even out the brightness in the properly exposed shot.

It did subjectively improve the clarity & brightness in the visually accurate shot.

In other object detection adventures, even replacing an object detected with SURF is pretty bad.  All these object detection technologies are good enough for toys, but not for video production.

To be sure, we used a sheet of paper, which can't be perfectly matched to the object, instead of a rigid plane. 

The key to daylight machine vision is a large lit surface with low intensity, so the image sensor doesn't overload, yet can still distinguish from background color.  Vicon markers are 1" balls, but the guys who use them are 10 years younger than us.