FlightTasks: do not adjust tilt limit of the position control

Adjusting the tilt limit can lead to diverging position control
and should only be used by setting a sanity limit for the controller
and not to adjust during the descent phase of a Land or RTL.
Otherwise it leads to flyaways in important failsafe modes when
there's stronger disturbance e.g. wind.

src/lib/flight_tasks/tasks/AutoMapper/FlightTaskAutoMapper.cpp

@@ -127,14 +127,10 @@ void FlightTaskAutoMapper::_prepareIdleSetpoints()
 
 void FlightTaskAutoMapper::_prepareLandSetpoints()
 {
-	float land_speed = _getLandSpeed();
-
 	// Keep xy-position and go down with landspeed
+	float land_speed = _getLandSpeed();
 	_position_setpoint = Vector3f(_target(0), _target(1), NAN);
 	_velocity_setpoint = Vector3f(Vector3f(NAN, NAN, land_speed));
-
-	// set constraints
-	_constraints.tilt = math::radians(_param_mpc_tiltmax_lnd.get());
 	_gear.landing_gear = landing_gear_s::GEAR_DOWN;
 }
 

src/lib/flight_tasks/tasks/FlightTask/FlightTask.cpp

@@ -181,7 +181,7 @@ void FlightTask::_setDefaultConstraints()
 	_constraints.speed_xy = _param_mpc_xy_vel_max.get();
 	_constraints.speed_up = _param_mpc_z_vel_max_up.get();
 	_constraints.speed_down = _param_mpc_z_vel_max_dn.get();
-	_constraints.tilt = math::radians(_param_mpc_tiltmax_air.get());
+	_constraints.tilt = NAN;
 	_constraints.min_distance_to_ground = NAN;
 	_constraints.max_distance_to_ground = NAN;
 	_constraints.want_takeoff = false;

src/lib/flight_tasks/tasks/FlightTask/FlightTask.hpp

@@ -260,7 +260,6 @@ class FlightTask : public ModuleParams
 	DEFINE_PARAMETERS_CUSTOM_PARENT(ModuleParams,
 					(ParamFloat<px4::params::MPC_XY_VEL_MAX>) _param_mpc_xy_vel_max,
 					(ParamFloat<px4::params::MPC_Z_VEL_MAX_DN>) _param_mpc_z_vel_max_dn,
-					(ParamFloat<px4::params::MPC_Z_VEL_MAX_UP>) _param_mpc_z_vel_max_up,
-					(ParamFloat<px4::params::MPC_TILTMAX_AIR>) _param_mpc_tiltmax_air
+					(ParamFloat<px4::params::MPC_Z_VEL_MAX_UP>) _param_mpc_z_vel_max_up
 				       )
 };

src/lib/flight_tasks/tasks/ManualAltitude/FlightTaskManualAltitude.cpp

@@ -60,8 +60,6 @@ bool FlightTaskManualAltitude::activate(vehicle_local_position_setpoint_s last_s
 	_velocity_setpoint(2) = 0.f;
 	_setDefaultConstraints();
 
-	_constraints.tilt = math::radians(_param_mpc_man_tilt_max.get());
-
 	_updateConstraintsFromEstimator();
 
 	_max_speed_up = _constraints.speed_up;

src/lib/flight_tasks/tasks/ManualPosition/FlightTaskManualPosition.cpp

@@ -61,8 +61,6 @@ bool FlightTaskManualPosition::activate(vehicle_local_position_setpoint_s last_s
 	// all requirements from altitude-mode still have to hold
 	bool ret = FlightTaskManualAltitude::activate(last_setpoint);
 
-	_constraints.tilt = math::radians(_param_mpc_tiltmax_air.get());
-
 	// set task specific constraint
 	if (_constraints.speed_xy >= _param_mpc_vel_manual.get()) {
 		_constraints.speed_xy = _param_mpc_vel_manual.get();

src/modules/mc_pos_control/PositionControl/PositionControl.hpp

@@ -109,7 +109,7 @@ class PositionControl
 
 	/**
 	 * Set the maximum tilt angle in radians the output attitude is allowed to have
-	 * @param tilt angle from level orientation in radians
+	 * @param tilt angle in radians from level orientation
 	 */
 	void setTiltLimit(const float tilt) { _lim_tilt = tilt; }