PX4 Parameters

Full documentation on PX4 parameters: https://docs.px4.io/master/en/advanced_config/parameter_reference.html.

For changing PX4 parameters, use QGroundControl software, connect to Clover over Wi-Fi or USB. Go to Vehicle Setup panel (click on the QGroundControl logo in the top-left corner) and choose Parameters menu.

Common parameters

Parameter Value Comment
SENS_FLOW_ROT 0 (No rotation) If using PX4Flow hardware, keep the default value
SENS_FLOW_MINHGT 0.0 For VL53L1X rangefinder
SENS_FLOW_MAXHGT 4.0 For VL53L1X rangefinder
SENS_FLOW_MAXR 10.0
SYS_HAS_MAG 0 If impossible to run the magnetometer (No mags found error)

Estimator subsystem parameters

In case of using LPE (COEX patched firmware):

Parameter Value Comment
LPE_FUSION 86 Checkboxes: flow + vis + land detector + gyro comp. If flying over horizontal floor pub agl as lpos down checkbox is allowed.
Details: Optical Flow, ArUco markers, GPS.
LPE_VIS_DELAY 0.0
LPE_VIS_Z 0.1
LPE_FLW_SCALE 1.0
LPE_FLW_R 0.2
LPE_FLW_RR 0.0
LPE_FLW_QMIN 10
ATT_W_EXT_HDG 0.5 Enabling usage of external yaw angle (when navigating using markers map)
ATT_EXT_HDG_M 1 (Vision)
ATT_W_MAG 0 Disabling usage of the magnetometer (when navigating indoor)

In case of using EKF2 (official firmware):

Parameter Value Comment
EKF2_AID_MASK 26 Checkboxes: flow + vision position + vision yaw.
Details: Optical Flow, ArUco markers, GPS.
EKF2_OF_DELAY 0
EKF2_OF_QMIN 10
EKF2_OF_N_MIN 0.05
EKF2_OF_N_MAX 0.2
EKF2_HGT_MODE 2 (Range sensor) If the rangefinder is present and flying over horizontal floor
EKF2_EVA_NOISE 0.1
EKF2_EVP_NOISE 0.1
EKF2_EV_DELAY 0
EKF2_MAG_TYPE 5 (None) Disabling usage of the magnetometer (when navigating indoor)

See also: list of default parameters of the Clover simulator: https://github.com/CopterExpress/clover/blob/master/clover_simulation/airframes/4500_clover.

Additional information

The SYS_MC_EST_GROUP parameter defines the estimator subsystem to use.

Estimator subsystem is a group of modules that calculates the current state of the copter using readings from the sensors. The copter state includes:

  • Angle rate of the copter – pitch_rate, roll_rate, yaw_rate;
  • Copter orientation (in the local coordinate system) – pitch, roll, yaw (one of presentations);
  • Copter position (in the local coordinate system) – x, y, z;
  • Copter speed (in the local coordinate system) – vx, vy, vz;
  • Global coordinates of the copter – latitude, longitude, altitude;
  • Altitude above the surface;
  • Other parameters (the drift of gyroscopes, wind speed, etc.).

SYS_AUTOCONFIG — resets all parameters (sets to 1).

EKF2

EKF2_AID_MASK — selects sensors that are used by EKF2 to calculate the copter state.

EKF2_HGT_MODE is the main source of height data (z in the local coordinate system):

  • 0 – pressure reading on the barometer.
  • 1 – GPS.
  • 2 – distance meter (for example, vl53l1x).
  • 3 – data from VPE.

Variant 2 is the most accurate; however, it is correct to use it only if the surface the copter flies over is flat. Otherwise, the Z axis origin will move up and down with the altitude of the surface.

Multicopter Position Control

These parameters adjust the flight of the copter by position (POSCTL, OFFBOARD, AUTO modes).

MPC_THR_HOVER — hovering throttle. This option is to set to the approximate percentage of throttle needed to make the copter maintain its altitude. If copter has a tendency to gain or lose altitude during the hovering mode, reduce or increase this value.

MPC_XY_P – position factor P of the ESC. This parameter affects how sharply the copter will react to the position commands. A too high value may cause overshoots.

MPC_XY_VEL_P – speed factor P of the ESC. This parameter also affects the accuracy and sharpness of copter execution of the given position. A too high value may cause overshoots.

MPC_XY_VEL_MAX — the maximum horizontal speed in POSCTL, OFFBOARD, AUTO modes.

MPC_Z_P, MPC_Z_VEL_P – vertical position and speed factors P of the ESCs they determine the copter's ability to maintain the desired altitude.

MPC_LAND_SPEED is the vertical velocity of landing in the LAND mode.

LPE + Q attitude estimator

These parameters configure the behavior of the lpe and q modules, which compute the state (orientation, position) of the copter. These parameters apply only if the SYS_MC_EST_GROUP parameter is set to 1 (local_position_estimator, attitude_estimator_q).

Commander

Prearm checks, switching the modes and states of the copter.

Sensors

Enabling, disabling and configuring various sensors.

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