Remove horizontal slow down close to ground

Because based on the numerous complaints it was disabled by default
(only velocities above 10m/s were limited)
and since then no one intentionally used it anymore. But
there were some minor investigations of drones not reaching
their maximum speed which always showed 10m/s.

src/modules/flight_mode_manager/tasks/ManualPosition/FlightTaskManualPosition.cpp

@@ -102,8 +102,6 @@ void FlightTaskManualPosition::_scaleSticks()
 		_velocity_scale = _constraints.speed_xy;
 	}
 
-	_velocity_scale = fminf(_computeVelXYGroundDist(), _velocity_scale);
-
 	// scale velocity to its maximum limits
 	Vector2f vel_sp_xy = stick_xy * _velocity_scale;
 
@@ -118,20 +116,6 @@ void FlightTaskManualPosition::_scaleSticks()
 	_velocity_setpoint.xy() = vel_sp_xy;
 }
 
-float FlightTaskManualPosition::_computeVelXYGroundDist()
-{
-	float max_vel_xy = _constraints.speed_xy;
-
-	// limit speed gradually within the altitudes MPC_LAND_ALT1 and MPC_LAND_ALT2
-	if (PX4_ISFINITE(_dist_to_ground)) {
-		max_vel_xy = math::gradual(_dist_to_ground,
-					   _param_mpc_land_alt2.get(), _param_mpc_land_alt1.get(),
-					   _param_mpc_land_vel_xy.get(), _constraints.speed_xy);
-	}
-
-	return max_vel_xy;
-}
-
 void FlightTaskManualPosition::_updateXYlock()
 {
 	/* If position lock is not active, position setpoint is set to NAN.*/

src/modules/flight_mode_manager/tasks/ManualPosition/FlightTaskManualPosition.hpp

@@ -65,12 +65,10 @@ protected:
 
 	DEFINE_PARAMETERS_CUSTOM_PARENT(FlightTaskManualAltitude,
 					(ParamFloat<px4::params::MPC_VEL_MANUAL>) _param_mpc_vel_manual,
-					(ParamFloat<px4::params::MPC_LAND_VEL_XY>) _param_mpc_land_vel_xy,
 					(ParamFloat<px4::params::MPC_ACC_HOR_MAX>) _param_mpc_acc_hor_max,
 					(ParamFloat<px4::params::MPC_HOLD_MAX_XY>) _param_mpc_hold_max_xy
 				       )
 private:
-	float _computeVelXYGroundDist();
 	float _velocity_scale{0.0f}; //scales the stick input to velocity
 	uint8_t _reset_counter{0}; /**< counter for estimator resets in xy-direction */
 

src/modules/mc_pos_control/MulticopterPositionControl.cpp

@@ -121,7 +121,6 @@ int MulticopterPositionControl::parameters_update(bool force)
 			num_changed += _param_mpc_vel_manual.commit_no_notification(xy_vel);
 			num_changed += _param_mpc_xy_cruise.commit_no_notification(xy_vel);
 			num_changed += _param_mpc_xy_vel_max.commit_no_notification(xy_vel);
-			num_changed += _param_mpc_land_vel_xy.commit_no_notification(xy_vel * 0.75f);
 		}
 
 		if (_param_mpc_z_vel_all.get() >= 0.f) {

src/modules/mc_pos_control/MulticopterPositionControl.hpp

@@ -172,8 +172,7 @@ private:
 		(ParamFloat<px4::params::MPC_MAN_Y_TAU>) _param_mpc_man_y_tau,
 
 		(ParamFloat<px4::params::MPC_XY_VEL_ALL>) _param_mpc_xy_vel_all,
-		(ParamFloat<px4::params::MPC_Z_VEL_ALL>) _param_mpc_z_vel_all,
+		(ParamFloat<px4::params::MPC_Z_VEL_ALL>) _param_mpc_z_vel_all
-		(ParamFloat<px4::params::MPC_LAND_VEL_XY>) _param_mpc_land_vel_xy
 	);
 
 	control::BlockDerivative _vel_x_deriv; /**< velocity derivative in x */

src/modules/mc_pos_control/mc_pos_control_params.c

@@ -363,18 +363,6 @@ PARAM_DEFINE_FLOAT(MPC_TILTMAX_LND, 12.0f);
  */
 PARAM_DEFINE_FLOAT(MPC_LAND_SPEED, 0.7f);
 
-/**
- * Maximum horizontal position mode velocity when close to ground/home altitude
- *
- * Set the value higher than the otherwise expected maximum to disable any slowdown.
- *
- * @unit m/s
- * @min 0
- * @decimal 1
- * @group Multicopter Position Control
- */
-PARAM_DEFINE_FLOAT(MPC_LAND_VEL_XY, 10.0f);
-
 /**
  * Enable user assisted descent speed for autonomous land routine.
  *
@@ -659,12 +647,8 @@ PARAM_DEFINE_FLOAT(MPC_YAWRAUTO_MAX, 45.0f);
 /**
  * Altitude for 1. step of slow landing (descend)
  *
- * Below this altitude:
+ * Below this altitude descending velocity gets limited to a value
- * - descending velocity gets limited to a value
  * between "MPC_Z_VEL_MAX_DN" and "MPC_LAND_SPEED"
- * - horizontal velocity gets limited to a value
- * between "MPC_VEL_MANUAL" and "MPC_LAND_VEL_XY"
- * for a smooth descent and landing experience.
  * Value needs to be higher than "MPC_LAND_ALT2"
  *
  * @unit m
@@ -678,8 +662,8 @@ PARAM_DEFINE_FLOAT(MPC_LAND_ALT1, 10.0f);
 /**
  * Altitude for 2. step of slow landing (landing)
  *
- * Below this altitude descending and horizontal velocities get
+ * Below this altitude descending velocity gets
- * limited to "MPC_LAND_SPEED" and "MPC_LAND_VEL_XY", respectively.
+ * limited to "MPC_LAND_SPEED".
  * Value needs to be lower than "MPC_LAND_ALT1"
  *
  * @unit m