Originally Posted by happul3
Autoland is state reached when duration of transmitter signal loss exceeds hard-coded value. In that state, arduino send land command to the drone. Land mode, as implemented by drone pilot program, ignores all further communication from external agents such as idev or mod/arduino, except perhaps emergency command. From this explanation it should be clear that steering while executing standard land command can never be implemented in the mod.
I thought it was probably something like that. Handing it off to the firmware makes sense if you don't want
to recover control. But presumably, Landing isn't all that involved for the firmware either. Does it do more than ignore AILE and ELEV, apply gentle TS_DN until the Ultrasound signals the Drone has landed and turn off the motors?
The Sketch could do much the same and not hand over control to the drone until a few metres above the ground - when you don't need steering any more - and let it kill the motors etc. Until then, it could allow some
steering - in the case of 'Land by switch' - and in the case of 'Land by loss of Tx signal', allow TS_UP to regain control when back in range. 'Land by Emergency low battery': unless you can stop the firmware elbowing in and taking over, can't be changed. But if the Sketch can
tell the firmware not to worry until the battery is at 1%, but does the Low battery landing itself at 10% (or whatever the point the firmware takes over currently), then it could handle that too.
Not saying it's trivial - although the main loop with extra flags to flash LEDs, reduce steering angles to 'avoid trees only' levels to avoid people trying to continue doing tricks etc. and delay handing over to the firmware until 2 meters above the ground, would just about cover it - but it would be useful.
If nothing else, it could also help complement GPS RTH, when you see it's following a nice straight line into a tree - unless waypoints are going to be implemented soon.