A few questions about Velocity setpoint

Hi all!

Here are my params:
Airframe: Generic Quadcopter Quadrotor x (4001)
Hardware: PX4_FMU_V5X (V5X02)
Software Version: v1.13.1 (dc7f29e2)
OS Version: NuttX, v10.2.0
Estimator: EKF2

And I have a couple of questions about setting velocity.

First, I noticed that with the Land command, the minimum landing speed = 0.6 m/s. This is a very high speed! Landing is more like falling. And after a couple of such landings, I have to repair my MPC.

I don’t understand why not able to set it to a lower speed…
But I thought: “This is not a problem I’ll do everything wright”:

I am working with MAVSDK and sending the real position of the MPC at 50 Hz;

...
_mocap->set_vision_position_estimate(_currentVisionPositionEstimate);
...

It’s ok.

Then I use set_velocity_ned :

...
mavsdk::Offboard::VelocityNedYaw velocityNedYaw ={0,0,0,0};
velocityNedYaw.down_m_s = 0.20;
auto result = _offboard->set_velocity_ned(velocityNedYaw);
...

And this is what happened on average:

Here’s what happens when velocityNedYaw.down_m_s = 0.15

or even so

And another experiment with set_position_ned:

...
_currentPositionNedYaw.down_m += 0.15;
_offboard->set_position_ned(_currentPositionNedYaw.down_m);
...

Here the PX4 successfully sets the Z setpoint to approximately 0.2 m/s and sticks to it.

Why doesn’t PX4 execute the _offboard->set_velocity_ned command if it can set itself such a speed?

P.S. The PX4 only receives or sets new Setpoints at 10 Hz. This is a very small frequency, is it possible to somehow increase it? I want to fly through difficult trajectories at high speed!

Interested to hear any opinion!