Copter-3.4: throttle feedback changes

[Randy Mackay]

This throttle feedback change from Leonard and I has just gone into master.

 

This resolves the cause of a number of crashes on powerful copters that had their THR_MID value set too high.  The cause of the problems was that we had an assumption that a copter could never get off the ground when it’s output throttle was below THR_MID/2 (i.e. 25%).  Because of this assumption the land-complete was true while the vehicle was flying but the vehicle would instantly crash if the user then switched to LAND mode (which would think, “oh, we’re not flying, let’s disarm”).

 

I'd appreciate any/all feedback on how the throttle responds especially before takeoff.

 

To give a more detailed explanation of how it’s changed:

 

Copter-3.3:

-          When landed the motors spin between spin-when-armed (i.e. 7%) and THR_MID/2 (i.e. 25%).  The motor speed climbs linearly as the pilot raises his/her throttle from 0 to top of the deadband.

 

Copter-3.4:

-          When landed the motors spin at either spin-when-armed (7%) and mot-spin-min (i.e. 13%).  The motors speed is spin-when-armed whenever the pilot’s throttle is below the deadzone.  It’s mot-spin-min (i.e. 13%) when the pilot’s throttle is in the deadzone.