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Fixed Wing Auto TakeOff
« on: October 13, 2017, 02:21:13 pm »
Hi guys!!!
I'm writhing here because i would like to know something about the AutoTake off mode to be used on a Flying Wing... I read the wiki about it and it says that after take off the model remain stationary maintaining the height and so i assume that this mode is adopted especially on drones... the question is: can it be selected also with fixed wings?
There is another topic about that, where in one of the replies is mentioned a path with the users settings but i cannot find it...
Can you help me?
Thank you very much!!!

Re: Fixed Wing Auto TakeOff
« Reply #1 on: October 13, 2017, 05:30:40 pm »
I don't know of anyone who has used fixed wing auto takeoff or landing in 16.09.  It looks like this can be set up as part of a waypoint flight in addition to being FMS flight modes.

It is very handy to have telemetry set up.  You use it for settings changes, waypoint upload each flight, logging flights to look at values later...

I have done some waypoint flights with fixed wing.  The procedure I used requires that you can fly fixed wing manually.
Run setup wizard or transmitter wizard with transmitter trims in the center.  The point here is not to run it again, but that the trims need to always be where they were when you ran the setup wizard.
Get your GPS and mag configured and calibrated.  Enable INS13 in Attitude->Settings.
Fly manually and trim it out.  After landing adjust the linkages so you can put transmitter trims back in the center.  Repeat till it flies well with the transmitter trims in the center.
Set up FMS to have Manual and Rate.  Fly Rate mode and adjust PIDs to get that working well.
Understand what Attitude mode is and how the sticks are different.
Set up FMS to have Rate and Attitude.  Take off in Rate and switch to Attitude to test it.  Adjust PIDs to get Attitude mode working well.
Use GPS ground speed to estimate airspeed by setting AirspeedSettings AirspeedSensorType to GroundSpeedBasedWindEstimation
Log a flight.  Fly at a nice average speed.  Play the log back and look at the graph (Scopes) of the GPS speed to determine a good airspeed.  Mine was 12 m/s.

Oh yea, I also set FWPFS.ThrustLimits min,neutral,max to something like 0.1, 0.55, 0.65 to keep it from going full throttle.  It tended to change from low to full and back.

At this point I started setting up and testing waypoint flights, but it would be better to test flight with a GPS flight mode like AutoCruise or VelocityRoam.  I had to adjust fixedwingpathfollower PIDs, and set HorizontalVelMax and HorizontalVelMin to the same number (I used 12 m/s) to try to force it to maintain a constant speed.  This (min = 12 m/s) won't work for landing though. I had to set the waypoint ErrorDestinations to -1 to ignore all the airspeed warnings, etc.  Yes, this is a bit hackish, you should really set reasonable min and max, but for these to be obeyed without excursions, needs additional tuning.

To generate a waypoint flight plan and upload it, you click on the GCS map and press Ctrl-A a few times to make a flight plan.  You must edit it to at least set airspeed and altitude for each waypoint before uploading it.  Save it to disk too.  Each new battery you must load it off the disk using the waypoint editor and upload it to the FC.

This needs a good write up.  I have to leave though.

A couple years ago @CorvusCorax did some fancy stuff with to make it land automatically, including flying the landing pattern and aborting if the speed and height was not acceptable.  I haven't seen him here in the forum in a long time though.
« Last Edit: October 13, 2017, 07:12:51 pm by TheOtherCliff »


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Re: Fixed Wing Auto TakeOff
« Reply #2 on: October 14, 2017, 01:34:17 am »
First of all thank you very much for the answer!!! Probably i had to mention it in the first post, but i'm using a CC3D board without any gps or other sensors... I'm really sorry... If i had said it before maybe you couldn't have spent such a long time in writing the answer!!!
When i found the Auto TakeOff mode in libre pilot i hoped it could be something like the same Mode on iNav where you can trow the plane and, feeling the acceleration, the board starts the motor and maintain a preset climbing rate...
But reading your explanation i think i cannot set up it for my fixed wing...
However, thank you very much again for you help!!!