Comment by iangl on July 9, 2011 at 8:33am

First errata corrige: in paragraph 2, talking about the yaw rotation, "when its rotation axis is displaced perpendicularly to the yaw axis" there should be "parallel"

Comment by Adrian Eves on July 9, 2011 at 8:58am

Why?

Moderator Comment by Gary Mortimer on July 9, 2011 at 9:02am

Because

Comment by iangl on July 9, 2011 at 9:25am

because you can't rotate about a certain axis if you're on another axis! goodbye

Comment by Coptaire on July 9, 2011 at 9:55am

MO, center of mass is easily lowered by design, and using a low LiPo cage. So, center of mass is not calling for such a thing.

 

The underlaying problematic is about the hovering thrust/vector and the displacement thrust/vector.

Mainstream designs found features a thrust system that combine them, modulating propellers speed.

Another design could have separate thrust vector for hovering and displacement.

 

Instead of this pulley system, very sensible to acceleration, uncontrollable I think, you can have propellers dedicated to hovering, and one rotating propeller for the displacement, with one rotating arm for yaw (found in tricopter).

Compared to your study, it is more reliable, but add unuseful complexitiy.

(If you like complexity, you could use 4 linear actuators instead of pulley, rigid and more weight!)

 

I can't find the least seducing aspect contained in your pendular/pulley design.

Moderator Comment by Gary Mortimer on July 9, 2011 at 11:59am

I can always find seduction in pendular, oh no hang on that's another thing.

Comment by ionut on July 10, 2011 at 1:19am

Why don't you attach a balloon full of helium instead?

Comment by Mike on July 10, 2011 at 3:31am

Not sure if it is the same issue but professional photographers and videographers tend to keep the payload as close to the plane of the rotor as possible on helicopters. Whilst there is some inherent stability in lowering the payload it also introduces greater inertial forces to be overcome in maintaining stabilised flight. So you will see many camera mounts on the front of helis, just under the rotor, rather than underslung albeit not entirely for stability reasons. There are videos of a tricopter lifting heavy loads (I think one load is a TRex450) and you can get an idea from there of how they behave - not agile!

 

When you move the aircraft horizontally there will a delay whilst the payload catches up and when you stop the payload will keep going! There will also be pendulum/rotation effects.

 

However, I might be talking a load of old s@#$e as your paper is not exactly clear, to me anyway, exactly what you want to achieve......but good luck all the same!

Comment by Yuan Gao on July 10, 2011 at 6:29am

In terms of practicality, isn't one of the main benefits of a quadrotor the mechanical simplicity with no moving parts other than rotors?  If I had to put two or four actuators onto the quad and increase cost and complexity, I'd rather have them doing something that I can't do already like vectoring thrust or adjusting blade pitch rather than steering.

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