TradHeli needs improved Auto-Landing

[R-Lefebvre]

Currently, when Auto-landing, the code will naturally shut down the motors on a multi-rotor when it bumps the ground. This is because the controller moves the throttle setpoint towards zero. However on a heli, all that happens is that the throttle moves down, creating negative pitch, pushing the heli into the ground. This is harsh. And the motor continues to run indefinitely.

The controller must be modified for helis to limit negative collective to some reasonable setpoint. Further, we need some sort of system to signal the ESC to stop when we have confirmed we are on the ground.

[clovett]

Yeah, I want to improve the landing for quadrocopters too, the current landing code seems very basic. I want something that drops quickly and ramps down the descent as it gets closer to the ground. I've looked at the code and I don't think it is doing that today, instead you set a min and max descent speed, which seems silly to me. I want the speed computed in order to minimize landing time, but maximize smoothness of landing. I think we could detect the "bump" from hitting the ground using the accelerometer and power down the rotors at that point. Clearly on the heli it needs to know where zero power is, and not go negative. But if negative is possible a bit of it could be handy to stop it from bouncing, then ramp to back to zero from there. Please send me a comment if you want to help work on this - especially if you know how the existing code works. I want something like this:

Then figuring out how to land in a cross wind, or deal with surprising little updrafts without slamming into the ground would also be fun...

[rmackay9]

AC3.1 includes a new parameter H_LAND_COL_MIN which allows the user to set the minimum collective that is used in during landing. This should stop the swash from going too low during landing.

I'm closing this issue because I don't think it reflects the current code and issues (if any) with auto landing.