Quad won't disarm in poshold mode?

Hey there.I’m tuning a 30" 12s quad. For some reason it doesn’t want to disarm in poshold mode. No problems in stabilize. Any ideas?

You mean you cannot disarm with RC in poshold mode right? Have you tried on althld?
If that is also the case, and I assume your copter is on the ground and have no rangefinder. I think you have a problem with vibration.
Condition for land check are

  1. No or very low acceleration (including vibration)
  2. No or low vertical velocities
  3. Motor throttle are near minimum
  4. (if available) rangefinder reads lower than the configured minimum land altitude (in parameter)

Landing condition are check in all mode in order to disarm except STAB and ACRO.

Try to see your log if you have a vibration problem or post your flight log.

add lidar to the configuration - a small tf mini or similar - and make lidar source of altitude for ekf while in range - EK2_RNG_M_NSE=0.2 ,
that will significantly improve accuracy of landing and will make it to disarm properly on its own after landing. check also you have foam on baro as when on land air from props boosts up pressure.

and of course keep EK2_ALT_SOURCE=0

My understanding is that it is almost never a good idea to set the the Alt Source for the EKF to Lidar. Our terrain following wiki page is here and you’ll see no reference of changing this EKF parameter. Please help me get the word out that people should not be changing the EK2_ALT_SOURCE parameter to Lidar. The only rare case the EK2_ALT_SOURCE should be set to Lidar is when the vehicle is being flown indoors where there are no obstructions below and there is a lot of barometer interference.

Sorry to be a bit strong in my response on this but I see people changing this parameter especially when they’re trying to achieve terrain following (which is different from this user’s issue) and then running into troubles. I have not tried using it to improve landings…


A log will better show why the landing detector isn’t registering the landing (this is why it won’t allow disarming from the RC) but to explain how we detect landings, the land_detector code is here and it uses the following checks:

  • checks the motor outputs are at their lower limits. This check is normally the one that fails and this can happen in Land, Loiter, PosHold etc when the position controller increases the motors to try and reduce some position error (i.e. a difference between where the vehicle wants to be horizontally vs where it actually is). This can come from a GPS glitch or if vehicle was moving horizontally while descending.
  • accelerometers must show less than 1m/s/s of acceleration. This where high vibration may be a problem as @tecnic08 suggests.
  • vehicle is not climbing or descending faster than 1m/s. Barometer interference can cause this to fail, try enabling the ground effect compensation.
  • range finder (if attached) shows < 2m (it’s a hardcoded number, not actually related to any parameter)
  • all the above must continue for 1 second

Hope this helps.

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yes, and, with parameters as i specified model is capable to fly indoors in alt hold with no issues, as lidar is followed correctly.