Pixhawk 2.1 land problems

Hi, i’ve a problem with my Hexa and no one i know can help me. i’ve replaced the naza v2 of f550 with pixhawk 2.1 and gps here motors are dji 2212 920kv and tarot short landing gear (by me blamed of the problem) sometimes with the wind when landing even with the throttle to the minimum some motors start (asymmetrically) and tips (does not turn off and knock the propellers) does not do it or does it less less in alt hold. Is there a full params option to lower engine disarming time when landing? I did the tests and it does not depend on me … in RTL I did do it to the ground with bad results …
Someone says it is the fault of the original pixhawk 2.1 proficnc that has barometer problems … others tell me it is the fault of esc and dji motors … i accept tips … thanks!
P.S. in Loiter mode the hexa behavior is worse than alt hold mode
P.P.S. PILOT_THR_BHV: Throttle stick behavior can help me?( i’ve not change it value yet, to avoid further problems)
P.P.P.S. i’ve lowered the value of landing final speed to 30 cm/s (the min possible)

thank you in advance

If you have a low landing gear, you can try turning on ground effect compensation: http://ardupilot.org/copter/docs/ground-effect-compensation.html

thank you Francisco! i’ll try that option, but my landing gear aren’t so short … the frame( and the Flight controller so) are 30 cm from the ground… more or less… anyway i’ll try. probably if i remove that landing gear the problem will be solved .
but my target is to find(and solve) the problem and then mount a gimbal with a camera ( about 400gr ).
it’s difficult to explain, but the UAV seem that when touch the ground want to continue to fly, as if don’t understand that it’s landed.