Re: [Paparazzi-devel] Re: AUTO2 throttle management

[Dirk-Willem van Gulik]

On 14 jun 2008, at 20:32, Christophe De Wagter wrote:

> Living in the windy Netherlands we encountered this problem quite  
> often. I would even add the following to your observations. When the  
> ground speed (temporarily) becomes negative the navigation turns the  
> wrong way as it uses the estimator_hspeed_dir which is defined as  
> atan2 of the GPS speeds. So we added a line to use the heading  
> instead of the ground track for any turn over 60 degrees. (This is a  
> big recommendation as things get increasingly nasty if the plane  
> turns the wrong way in high winds)

Could this always be done - or should one really augment the code to  
'detect' windspeed and direction more robustly and 'switch' to this  
mode automagically ?
> Concerning forward speed, adding quite some of "pitch_of_vz" helps a  
> lot (similar to the PITCH_LOOP but keeping the THROTTLE_LOOP  
> active). Furthermore the loiter-cruise-dash trims are very useful to  
> overcome the wind. By adding a pitch down trim, a sufficient auto  
> throttle i_gain will automatically find a higher throttle setting to  
> maintain altitude and the result will be a faster forward speed...  
> finally getting you somewhere. But there is also a ground speed loop  
> if you are interested: #define NAV_GROUND_SPEED_PGAIN. If you use  
> this one in high winds, make sure your throttle_cruise_min is high  
> enough to maintain altitude when flying downwind. Last month we flew  
> at >11m/s wind speeds and our 390 gram 50cm MAV handled the weather  
> very well, while manual flight had became close to impossible as  
> combination of the gusts and visibility issues.

Dw