Describe the bug
We are using a custom flight controller based on the PX4_V4 hardware, equipped with GPS and a laser rangefinder. The height reference (HGT_REF) is set to GPS, and we are not using the rangefinder data for altitude control. After takeoff, the vehicle can maintain its position in the XY plane relatively well. However, the altitude fluctuates significantly around the setpoint (Z_SETPOINT). Adjusting the MPC_Z_P parameter has little effect on stabilizing the altitude. The issue persists even with the latest 1.16.0 firmware.
To Reproduce
Take off.
Manually control the vehicle to a certain altitude.
Center the remote control sticks.
The altitude continues to fluctuate.
Expected behavior
The relative altitude should be accurate, and the vehicle should maintain a stable hover without significant altitude fluctuations.
Screenshot / Media
None.
Flight Log
https://logs.px4.io/plot_app?log=6fdf707b-1d74-4710-964b-6594fed8969c
Software Version
Release 1.13.0 stable
One test with 1.16.0 alpha
Flight controller
Type: PX4_V4
Vehicle type
Multicopter
How are the different components wired up (including port information)
Not provided.
Additional context
When the vehicle reaches its lowest point and begins to ascend, there is a slight vibration.
When using ekf2_rng_ctrl enabled and Terrain Hold mode, the vehicle can maintain a stable altitude within the rangefinder’s 8-meter range.