IM _Stab_Col and Alt Hold Help Please

ArduCopter Traditional Helicopter
1

Thanks in advance for any help
Alt hold advise Arducopter 3.4.6 FBL 450 helicopter, trouble with altitude dropping when Alt Hold switch is applied ( I do not know how far heli would drop as I always turn off Alt Hold before getting tooo close to ground)
Chris O was kind enough to inform me that I could adjust the IM_STAB_COL values to get the helicopter to hover at mid-stick in Stabilize, so that when you switch to Alt Hold the helicopter doesn’t suddenly go up or down.
Can someone please explain the steps for this process?
Thanks

2

Let me ask you this, when you switch to altitude hold mode, where is your collective/throttle stick on your transmitter? If you can, glance down quickly during stabilize (in a hover) and see how close it is to center. If your collective/throttle stick is lower than center, then what you describe sounds correct and Chris Olson’s solution will fix it.

3

Actually throttle stick is pretty close to center position, so I am thinking I need to adjust Im_stab_col parameters, but I am not sure what direction to go to correct this altitude drop problem?
Thanks

4

William,
You will have to make IM_STAB_COL2 and IM_STAB_COL3 lower so as to capture your collective for hover at mid stick. you could probably figure this out from the log file by seeing what RCIN3 is in a hover.

Regards,
Bill