Drone hops/accelerates upwards on landing

PX4 v1.8.0

My problem: I trigger AUTO.LAND mode while in OFFBOARD mode. The mode transition works fine and the drone begins its descent toward the ground. Sometimes, when the drone makes contact with the ground, it hops upwards. In worse cases, it begins to slowly rise without stopping or attempting to “re-land”. In several of these cases, PX4 seems to have already detected landing, and these anomalies occur in the time between “land detected” and when COM_DISARM_LAND triggers disarm.

A smattering a logs where the problem occurred. You can see that the local position measurements blow up (and in some cases correct themselves). Similarly, the roll, pitch, and yaw estimates become extremely erroneous when the drone (presumably) hits the ground.

Which PX4 parameters should I adjust to alleviate this issue? What other helpful data can I provide to you?


I have noticed the same issue while landing in Position or Alt Hold mode. The drone touches the ground and bounce at least 3 times (sometime giving some yaw) before it stops the motors and disarm. It does the same while using the RTL function. We have 6 F450 at our drone school and they all do the same. They all have original pixracer FC and they all run PX4 1.8.0 (1.9.0 caused some of the unit to have motor not turning upon arming so I reverted them all to the working 1.8.0).

Usually it is caused by the pressure created by the props close to the ground to the barometer. It should happen in modes where automatic position control is enabled (position, alt hold, …).
What happen is that the pressure tricks the barometer to think the quad is lower than actual altitude, so the controller tries to compensate and pushes upward.
Please check the logs to see if the barometer has this behavior.
To avoid this behavior you can put longer legs to the quad, or switch in manual mode in the last meter.


The thing that is weird is that I don’t remember this behavior some time ago, the drone would simply land and hardly bounced once, now it’s all the time when using position and halt old or rtl. The thing is that I have been absent from the school’s field for some time so I don’T know when it started. Is there a parameter to change where it can detect the student deceleration when touching the ground?

My VTOL delta has same problem. After it touches ground, it starts to jump and only way how to calm him is to use safety switch. I use 1.11.0 version of PX4 firmware.