Re: [Paparazzi-devel] Limiting Speed in Fixed Wing UAVs

[Hector Garcia de Marina]

Hi Alexander,

You cannot control it obviously, but you can "fix it" somehow with the nominal throttle and pitch signals.

Also, you can figure out the average airspeed if you fly in circles (wind estimation).

If you fly a day without wind, then your GPS speed will be very close to the airspeed.

Best,

On Mon, Jan 18, 2021 at 8:34 PM Alexander Strong <alex.j.strong@gmail.com> wrote:

Hi again,

So on aircrafts that don't have an airspeed sensor, is there no feasible way to limit the airspeed?

Thanks,

Alex

On Sun, Jan 17, 2021 at 3:47 PM Gautier Hattenberger <gautier.hattenberger@gmail.com> wrote:

Hello,

The control of speed is significantly more complex on a fixed wing aircraft than on a rotorcraft where you can easily and safely control the ground speed from GPS.

First, you need to control airspeed and not ground speed to prevent stalling which means that you need an airspeed sensor with a fairly good calibration. Then the longitudinal control presents a coupling between pitch and throttle commands, which is a bit harder to tune.

Paparazzi has several control loops using airspeed when available and enabled, usually with the USE_AIRSPEED flag. It is the case for the legacy basic controller, as well as "adaptive" and "new" variations. The "energy" controller requires airspeed sensor to be used.

http://docs.paparazziuav.org/latest/onboard_modules.html#modules_category_control

https://wiki.paparazziuav.org/wiki/Control_Loops#Control_loops_using_Airspeed_Sensor

https://wiki.paparazziuav.org/wiki/Control_Loops#Energy_Control_loops_using_Airspeed_Sensor

Gautier

Le 15/01/2021 à 22:38, Alexander Strong a écrit :

Hi all,

As far as I can tell, the paparazzi language has support for limiting the speed of rotorcrafts but not of fixed wing UAVs. Is this feature currently being developed? Are there significant roadblocks preventing it from being developed?

Thanks,

Alex

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Héctor García de Marina

Personal website: https://sites.google.com/view/hgdemarina

Team member in the open-source UAV hardware and software project Paparazzi: https://wiki.paparazziuav.org