mc_pos_control: use weathervane library to make vehicle turn into relative wind

Signed-off-by: Roman <bapstroman@gmail.com>

src/lib/FlightTasks/FlightTasks.hpp

@@ -44,6 +44,7 @@
 #include "FlightTask.hpp"
 #include "SubscriptionArray.hpp"
 #include "FlightTasks_generated.hpp"
+#include <lib/WeatherVane/WeatherVane.hpp>
 
 #include <new>
 
@@ -125,6 +126,11 @@ public:
 	 */
 	const char *errorToString(const int error);
 
+	/**
+	 * Sets an external yaw handler. The active flight task can use the yaw handler to implement a different yaw control strategy.
+	 */
+	void set_yaw_handler(WeatherVane *ext_yaw_handler) {_current_task.task->set_yaw_handler(ext_yaw_handler);}
+
 private:
 
 	/**

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

@@ -62,6 +62,12 @@ bool FlightTaskAutoMapper::update()
 		_reset();
 	}
 
+	// check if an external yaw handler is active and if yes, let it compute the yaw setpoints
+	if (_ext_yaw_handler != nullptr && _ext_yaw_handler->is_active()) {
+		_yaw_setpoint = _yaw;
+		_yawspeed_setpoint = _ext_yaw_handler->get_weathervane_yawrate();
+	}
+
 	// The only time a thrust set-point is sent out is during
 	// idle. Hence, reset thrust set-point to NAN in case the
 	// vehicle exits idle.

src/lib/FlightTasks/tasks/AutoMapper/FlightTaskAutoMapper.hpp

@@ -50,6 +50,11 @@ public:
 	bool activate() override;
 	bool update() override;
 
+	/**
+	 * Sets an external yaw handler which can be used to implement a different yaw control strategy.
+	 */
+	void set_yaw_handler(WeatherVane *ext_yaw_handler) override {_ext_yaw_handler = ext_yaw_handler;}
+
 protected:
 
 	float _alt_above_ground{0.0f}; /**< If home provided, then it is altitude above home, otherwise it is altitude above local position reference. */
@@ -73,6 +78,9 @@ protected:
 	void updateParams() override; /**< See ModuleParam class */
 
 private:
+	WeatherVane *_ext_yaw_handler =
+		nullptr;	/**< external weathervane library, used to implement a yaw control law that turns the vehicle nose into the wind */
+
 	void _reset(); /**< Resets member variables to current vehicle state */
 	WaypointType _type_previous{WaypointType::idle}; /**< Previous type of current target triplet. */
 	bool _highEnoughForLandingGear(); /**< Checks if gears can be lowered. */

src/lib/FlightTasks/tasks/FlightTask/FlightTask.hpp

@@ -51,6 +51,7 @@
 #include <uORB/topics/vehicle_constraints.h>
 #include <uORB/topics/vehicle_attitude.h>
 #include <uORB/topics/vehicle_trajectory_waypoint.h>
+#include <lib/WeatherVane/WeatherVane.hpp>
 #include "SubscriptionArray.hpp"
 
 class FlightTask : public ModuleParams
@@ -140,6 +141,12 @@ public:
 		updateParams();
 	}
 
+	/**
+	 * Sets an external yaw handler which can be used by any flight task to implement a different yaw control strategy.
+	 * This method does nothing, each flighttask which wants to use the yaw handler needs to override this method.
+	 */
+	virtual void set_yaw_handler(WeatherVane *ext_yaw_handler) {};
+
 protected:
 
 	uORB::Subscription<vehicle_local_position_s> *_sub_vehicle_local_position{nullptr};

src/lib/FlightTasks/tasks/ManualStabilized/FlightTaskManualStabilized.cpp

@@ -88,6 +88,12 @@ void FlightTaskManualStabilized::_updateHeadingSetpoints()
 			}
 		}
 	}
+
+	// check if an external yaw handler is active and if yes, let it compute the yaw setpoints
+	if (_ext_yaw_handler != nullptr && _ext_yaw_handler->is_active()) {
+		_yaw_setpoint = NAN;
+		_yawspeed_setpoint += _ext_yaw_handler->get_weathervane_yawrate();
+	}
 }
 
 void FlightTaskManualStabilized::_updateThrustSetpoints()

src/lib/FlightTasks/tasks/ManualStabilized/FlightTaskManualStabilized.hpp

@@ -52,6 +52,11 @@ public:
 	bool updateInitialize() override;
 	bool update() override;
 
+	/**
+	 * Sets an external yaw handler which can be used to implement a different yaw control strategy.
+	 */
+	void set_yaw_handler(WeatherVane *ext_yaw_handler) override {_ext_yaw_handler = ext_yaw_handler;}
+
 protected:
 	virtual void _updateSetpoints(); /**< updates all setpoints*/
 	virtual void _scaleSticks(); /**< scales sticks to yaw and thrust */
@@ -64,6 +69,9 @@ private:
 
 	float _throttle{}; /** mapped from stick z */
 
+	WeatherVane *_ext_yaw_handler =
+		nullptr;	/**< external weathervane library, used to implement a yaw control law that turns the vehicle nose into the wind */
+
 	DEFINE_PARAMETERS_CUSTOM_PARENT(FlightTaskManual,
 					(ParamFloat<px4::params::MPC_MAN_Y_MAX>) _yaw_rate_scaling, /**< scaling factor from stick to yaw rate */
 					(ParamFloat<px4::params::MPC_MAN_TILT_MAX>) _tilt_max_man, /**< maximum tilt allowed for manual flight */

src/lib/WeatherVane/CMakeLists.txt

@@ -31,4 +31,4 @@
 #
 ############################################################################
 
-px4_add_library(WeatherVane WeatherVane.cpp)
+px4_add_library(WeatherVane WeatherVane.cpp)

src/lib/WeatherVane/WeatherVane.cpp

@@ -79,4 +79,4 @@ float WeatherVane::get_weathervane_yawrate()
 
 	return math::constrain(roll_exceeding_treshold * _wv_gain, -_wv_yawrate_max_rad,
 			       _wv_yawrate_max_rad);
-}
+}

src/lib/WeatherVane/WeatherVane.hpp

@@ -77,4 +77,4 @@ private:
 	float _wv_min_roll_rad = 0.01f;		// minimum roll angle setpoint for the controller to output a non-zero yawrate setpoint
 	float _wv_yawrate_max_rad = 1.0f;	// maximum yaw-rate the controller will output
 
-};
+};

src/modules/mc_pos_control/CMakeLists.txt

@@ -44,4 +44,5 @@ px4_add_module(
 		FlightTasks
 		git_ecl
 		ecl_geo
-	)
+		WeatherVane
+	)

src/modules/mc_pos_control/mc_pos_control_main.cpp

@@ -67,6 +67,7 @@
 #include <controllib/blocks.hpp>
 
 #include <lib/FlightTasks/FlightTasks.hpp>
+#include <lib/WeatherVane/WeatherVane.hpp>
 #include "PositionControl.hpp"
 #include "Utility/ControlMath.hpp"
 
@@ -141,7 +142,12 @@ private:
 		(ParamInt<px4::params::MPC_POS_MODE>) MPC_POS_MODE,
 		(ParamInt<px4::params::MPC_ALT_MODE>) MPC_ALT_MODE,
 		(ParamFloat<px4::params::MPC_IDLE_TKO>) MPC_IDLE_TKO, /**< time constant for smooth takeoff ramp */
-		(ParamInt<px4::params::MPC_OBS_AVOID>) MPC_OBS_AVOID /**< enable obstacle avoidance */
+		(ParamInt<px4::params::MPC_OBS_AVOID>) MPC_OBS_AVOID, /**< enable obstacle avoidance */
+		(ParamBool<px4::params::MPC_WV_MAN_EN>) _wv_manual_enabled,
+		(ParamBool<px4::params::MPC_WV_AUTO_EN>) _wv_auto_enabled,
+		(ParamFloat<px4::params::MPC_WV_ROLL_MIN>) _wv_min_roll,
+		(ParamFloat<px4::params::MPC_WV_GAIN>) _wv_gain,
+		(ParamFloat<px4::params::MPC_WV_YRATE_MAX>) _wv_max_yaw_rate
 	);
 
 	control::BlockDerivative _vel_x_deriv; /**< velocity derivative in x */
@@ -172,6 +178,8 @@ private:
 
 	systemlib::Hysteresis _failsafe_land_hysteresis{false}; /**< becomes true if task did not update correctly for LOITER_TIME_BEFORE_DESCEND */
 
+	WeatherVane _wv_controller;
+
 	/**
 	 * Update our local parameter cache.
 	 * Parameter update can be forced when argument is true.
@@ -371,6 +379,10 @@ MulticopterPositionControl::parameters_update(bool force)
 
 		// set trigger time for arm hysteresis
 		_arm_hysteresis.set_hysteresis_time_from(false, (int)(MPC_IDLE_TKO.get() * 1000000.0f));
+
+		_wv_controller.set_weathervane_gain(_wv_gain.get());
+		_wv_controller.set_min_roll_rad(math::radians(_wv_min_roll.get()));
+		_wv_controller.set_yawrate_max_rad(math::radians(_wv_max_yaw_rate.get()));
 	}
 
 	return OK;
@@ -587,6 +599,19 @@ MulticopterPositionControl::task_main()
 		// set dt for control blocks
 		setDt(dt);
 
+		// activate the weathervane controller if required. If activated a flighttask can use it to implement a yaw-rate control strategy
+		// that turns the nose of the vehicle into the wind
+		if (_control_mode.flag_control_manual_enabled && _control_mode.flag_control_attitude_enabled
+		    && _wv_manual_enabled.get()) {
+			_wv_controller.activate();
+
+		} else if (_control_mode.flag_control_auto_enabled && _wv_auto_enabled.get()) {
+			_wv_controller.activate();
+
+		} else {
+			_wv_controller.deactivate();
+		}
+
 		if (_control_mode.flag_armed) {
 			// as soon vehicle is armed check for flighttask
 			start_flight_task();
@@ -607,6 +632,8 @@ MulticopterPositionControl::task_main()
 			// setpoints from flighttask
 			vehicle_local_position_setpoint_s setpoint;
 
+			_flight_tasks.set_yaw_handler(&_wv_controller);
+
 			// update task
 			if (!_flight_tasks.update()) {
 				// FAILSAFE
@@ -721,6 +748,8 @@ MulticopterPositionControl::task_main()
 			_att_sp.disable_mc_yaw_control = false;
 			_att_sp.apply_flaps = false;
 
+			_wv_controller.update(matrix::Quatf(&_att_sp.q_d[0]), _local_pos.yaw);
+
 			if (!constraints.landing_gear) {
 				if (constraints.landing_gear == vehicle_constraints_s::GEAR_UP) {
 					_att_sp.landing_gear = vehicle_attitude_setpoint_s::LANDING_GEAR_UP;

src/modules/mc_pos_control/mc_pos_control_params.c

@@ -672,3 +672,52 @@ PARAM_DEFINE_INT32(MPC_OBS_AVOID, 0);
  * @group Mission
  */
 PARAM_DEFINE_INT32(MPC_YAW_MODE, 0);
+
+/**
+ * Enable weathervane for manual.
+ *
+ * @value 0 Disabled
+ * @value 1 Enabled
+ * @group Multicopter Position Control
+ */
+PARAM_DEFINE_INT32(MPC_WV_MAN_EN, 0);
+
+/**
+ * Enable weathervane for auto.
+ *
+ * @value 0 Disabled
+ * @value 1 Enabled
+ * @group Multicopter Position Control
+ */
+PARAM_DEFINE_INT32(MPC_WV_AUTO_EN, 0);
+
+/**
+ * Weather-vane yaw rate from roll gain.
+ *
+ * The desired gain to convert roll sp into yaw rate sp.
+ *
+ * @min 0.0
+ * @max 3.0
+ * @increment 0.01
+ * @decimal 3
+ * @group VTOL Attitude Control
+ */
+PARAM_DEFINE_FLOAT(MPC_WV_GAIN, 1.0f);
+
+/**
+ * Minimum roll angle setpoint for weathervane controller to demand a yaw-rate.
+ *
+ * @min 0
+ * @max 5
+ * @group Multicopter Position Control
+ */
+PARAM_DEFINE_FLOAT(MPC_WV_ROLL_MIN, 1.0f);
+
+/**
+ * Maximum yawrate the weathervane controller is able to demand.
+ *
+ * @min 0
+ * @max 120
+ * @group Multicopter Position Control
+ */
+PARAM_DEFINE_FLOAT(MPC_WV_YRATE_MAX, 90.0f);