Elevons for wing controller

[ArduCrow]

Hi Tim! I love this idea. I have a couple of RC flying wings I would like to try this out on. Do you have any idea off the top of your head how you would convert this to work on a wing with elevons?

My thoughts are removing the elevator PID instance, to only have the aileron PID instance remaining. There would surely have to be some integration though.

[timmarkhuff]

I think this could definitely be adapted for elevons.

You would still need two PID controllers to manage roll and pitch, however the outputs of each would be shared by each elevon. The result might look something like the pseudocode below.

# run PID controllers
ail_output = roll_pid(roll)
ele_output = pitch_pid(pitch)

# actuate elevons
left_elevon_servo.value = ail_output  + ele_output 
right_elevon_servo.value = -ail_output  + ele_output 

Simply adding the values together should work, but perhaps there is a more nuanced approach that I haven't considered.

The function that actuates the servos only takes values between -1 and 1, so you have to make sure you are never providing values outside that range. One way to do that would be to set a limit for each controller that is equal to or less than .5. I recommend a low value like .2. You don't need a lot of deflection when running autopilot.

roll_pid.output_limits = -.2, .2
pitch_pid.output_limits = -.2, .2