How does the H know it has landed

[Dustoff]

stupid question but curious as to how the H knows it is on the ground .

If I would guess it senses that it’s rate of descent is zero while still having command to desend

 

[PatR]

That’s as good a guess as any as the H without Real Sense does not have any ground proximity sensors, nor does it “remember” the take off altitude. Those are two reasons to minimize using the self landing feature incorporated with the RTH function as it will make contact with the ground at the programmed RTH descent speed, which is quite fast, and bounce.

 

[h-elsner]

My theory is the pointed to the accelerator sensor. If it do register no more movement then the SW detect this as landed and reduces the speed of the rotors (the Typhoon H Plus cuts the motors in that case). During flight, there are always movements visible for the 6-axis accelerator chip.

For example, I cannot start my Q500 when I hold it in my hands. OK, maybe I'm too old, but also works for younger people. On the ground it can be armed.

br HE

 

[PatR]

Good theory.

 

[JulesTEO]

I also believe it has to do mostly with the accelerometer values

On this matter, I did notice a difference on way the H revved down before going to idle with the latest update, which does states it has "Improved Landing Protection".

The H used to go into idle much faster on earlier firmwares. (which I believe was changed in order to prevent premature idling?)

I actually have proof of this heheh:

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Logic could be something like:

IF throttle is held at -100% AND accelerometer values are zero in all axes (since I believe it COULD be possible to get zero "descent" mid-air while holding the throttle down because of updrafts or something like that) THEN start reducing motor speed. IF nothing changes for 2 seconds THEN idle.

Since the H also "Emergency kills" the motors when it is flipped over; status lamp starts flashing red and a slow beeping, I would say its all about the accelerometer and the calculations that programmers have considered for different scenarios. (The logic for this last scenario would be much simpler: "IF position = upside down = crash = emergency shutdown" lol )


Greetings!

 

[h-elsner]

The status "Emergency kills" will be detected either by motor current and/or rate of rotation of the motors. I have tested Motor status bit this way by stopping the motor by hand (without propellers of course). If motor status <> 255 then FlightMode = 12 "Emergency kills".

br HE