Re: [Paparazzi-devel] question about nav_circle_XY()

[Gautier Hattenberger]

Hi,

In NAV_MODE_COURSE, the carrot is placed on a line tangent to the circle 
in front of the plane. That's why you can see it outside of the circle 
on the GCS. The actual commanded bank angle is then:
- a pre-command that correspond to the theoretical bank angle for a 
coordinated turn at a given speed and radius (see nav.c:136)
- a correction based on the carrot (your speed vector should aim at the 
carrot)

As a side note, the other mode (NAV_MODE_ROLL) places the carrot 
directly on the circle and directly compute the bank angle. The result 
is almost the same in the end.

Gautier


Le 26/08/2014 15:53, wertrrte a écrit :
> Hi,
>
> I'm learning the nav_circle_XY() code,and I think I have understood the main
> part about it.But for the  following sentence,I really cannot  understand
> why.
>
> *  if (nav_mode == NAV_MODE_COURSE) {
>      radius_carrot += (abs_radius / cos(carrot_angle) - abs_radius);
>    }*
>
> This 'if block' says,if nav_mode equals NAV_MODE_COURSE,the 'radius_carrot'
> becomes radius_carrot/cos(carrot_angle).So radius_carrot becomes bigger.Why
> this?If so,the plane will fly in a bigger circle other than the
> desired?!!Looking forward to your enlightment.
>
> wertrrte
>
>
>
>
>
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