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Re: [Paparazzi-devel] heli autopilot


From: Christophe De Wagter
Subject: Re: [Paparazzi-devel] heli autopilot
Date: Wed, 2 Mar 2011 21:07:53 +0100

Worked on autonomous heli's quite a bit from 2001 to 2005. 

Comparison Quad versus Conventional Helicopter:

Similarities:

-thrust vectoring principle
-identical control loops can be used
-lisa/booz can control even a flybarless heli (do not save on servo's here though -> 400Hz servos)

Differences:

-Fragile Mechanical Complexity versus Rugged Simplicity
-The main difference from a control point of view with quadrotors is that conventional helicopters have much more control couplings. The main and most obvious is the main rotor torque on the yaw (tail rotor), followed by the lateral force of the tail rotor yielding lateral acceleration compensated with a right/left bank angle of a few degrees, followed by the need to pull and roll on right turns and push and roll on slow left turns to compensate for the change in roll trim plane, followed by an extra need of thrust for every cyclic motion, followed by many aerodynamic effects also found in quadrotors like pitch moment due to forward speed, the ... 

However, if neglecting those effects that are just too hard to tune decently anyway both are the same. (Unless you follow the adaptive-control approach: all these hard to tune feed-forward gains are the reason why especially conventional helicopters benefit a lot from adaptive control.)

-Christophe 



On Tue, Mar 1, 2011 at 5:59 PM, Felix Ruess <address@hidden> wrote:
Hi Ana,

there is of course no reason why Booz and Lisa could not be used for
(also flybarless) Helis. I know that Eric has started some work with
variable pitch quadcopters and eventually helis. But I think there was
just not much time lately with all the cleanup, Mac OSX port and new
toolchain...

Don't know if anyone else has done some work in that direction?

Cheers, Felix

P.S. I was wondering if you could share your experiences (and airframe
file/ imu parameters) for the razzor IMU used with the analog_imu
subsystem. I guess that all worked out since we haven't heard anything
in that regard lately?

On Mon, Feb 28, 2011 at 10:11 AM, GARCIA ALVAREZ, ANA
<address@hidden> wrote:
> Hi,
>
> I have been reading about Booz and Lisa. I have seen they are used with
> quadrotors and multiple rotors, but don’t know if they can be(and are) used
> with helis(main rotor and tail rotor). I suppose there is a lot of theory
> and software implementation around it. Any related info?
>
> Thanks
>
> _______________________________________________
> Paparazzi-devel mailing list
> address@hidden
> http://lists.nongnu.org/mailman/listinfo/paparazzi-devel
>
>

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