Add gyroscopic torque cancellation loop for single-rotor drones

src/lib/control_allocation/actuator_effectiveness/ActuatorEffectiveness.hpp

@@ -200,6 +200,8 @@ class ActuatorEffectiveness
 				    int matrix_index, ActuatorVector &actuator_sp, const matrix::Vector<float, NUM_ACTUATORS> &actuator_min,
 				    const matrix::Vector<float, NUM_ACTUATORS> &actuator_max) {}
 
+	const ActuatorVector &getActuatorEffectivenessScale() { return _actuator_effectiveness_scale; }
+
 	/**
 	 * Get a bitmask of motors to be stopped
 	 */
@@ -222,4 +224,6 @@ class ActuatorEffectiveness
 protected:
 	FlightPhase _flight_phase{FlightPhase::HOVER_FLIGHT};
 	uint32_t _stopped_motors_mask{0};
+
+	ActuatorVector _actuator_effectiveness_scale;
 };

src/lib/control_allocation/control_allocation/ControlAllocation.hpp

@@ -143,7 +143,7 @@ class ControlAllocation
 	 * @return Control vector
 	 */
 	matrix::Vector<float, NUM_AXES> getAllocatedControl() const
-	{ return (_effectiveness * (_actuator_sp - _actuator_trim)).emult(_control_allocation_scale); }
+	{ return (_effectiveness * (_actuator_sp - _actuator_trim).emult(_actuator_effectiveness_scale)).emult(_control_allocation_scale); }
 
 	/**
 	 * Get the control effectiveness matrix
@@ -233,12 +233,15 @@ class ControlAllocation
 
 	matrix::Matrix<float, NUM_AXES, NUM_ACTUATORS> _effectiveness;  ///< Effectiveness matrix
 	matrix::Vector<float, NUM_AXES> _control_allocation_scale;  	///< Scaling applied during allocation
+	matrix::Vector<float, NUM_AXES> _actuator_sp_scale;  	///< Scaling durectly applied to the actuator setpoint
 	matrix::Vector<float, NUM_ACTUATORS> _actuator_trim; 	///< Neutral actuator values
 	matrix::Vector<float, NUM_ACTUATORS> _actuator_min; 	///< Minimum actuator values
 	matrix::Vector<float, NUM_ACTUATORS> _actuator_max; 	///< Maximum actuator values
 	matrix::Vector<float, NUM_ACTUATORS> _actuator_slew_rate_limit; 	///< Slew rate limit
 	matrix::Vector<float, NUM_ACTUATORS> _prev_actuator_sp;  	///< Previous actuator setpoint
 	matrix::Vector<float, NUM_ACTUATORS> _actuator_sp;  	///< Actuator setpoint
+	matrix::Vector<float, NUM_ACTUATORS> _actuator_effectiveness_scale; ///< Scaling applied after inilial
+	///allocation (e.g.: when effectiveness changes due to airspeed or thrust)
 	matrix::Vector<float, NUM_AXES> _control_sp;   		///< Control setpoint
 	matrix::Vector<float, NUM_AXES> _control_trim; 		///< Control at trim actuator values
 	int _num_actuators{0};

src/lib/rate_control/rate_control.cpp

@@ -74,8 +74,12 @@ Vector3f RateControl::update(const Vector3f &rate, const Vector3f &rate_sp, cons
 	// angular rates error
 	Vector3f rate_error = rate_sp - rate;
 
+	// assume the rotor angular momentum is aligned with the Z axis
+	const Vector3f gyroscopic_torque = rate.cross(Vector3f(0.f, 0.f, _rotor_angular_momentum));
+
 	// PID control with feed forward
-	const Vector3f torque = _gain_p.emult(rate_error) + _rate_int - _gain_d.emult(angular_accel) + _gain_ff.emult(rate_sp);
+	const Vector3f torque = _gain_p.emult(rate_error) + _rate_int - _gain_d.emult(angular_accel) + _gain_ff.emult(
+					rate_sp) - gyroscopic_torque;
 
 	// update integral only if we are not landed
 	if (!landed) {

src/lib/rate_control/rate_control.hpp

@@ -71,6 +71,12 @@ class RateControl
 	 */
 	void setFeedForwardGain(const matrix::Vector3f &FF) { _gain_ff = FF; };
 
+	/**
+	 * Set the total angular momentum produced by the rotors
+	 * @param norm of angular momentum along the Z body axis
+	 */
+	void setRotorAngularMomentum(float momentum) { _rotor_angular_momentum = momentum; };
+
 	/**
 	 * Set saturation status
 	 * @param control saturation vector from control allocator
@@ -129,6 +135,7 @@ class RateControl
 	matrix::Vector3f _gain_d; ///< rate control derivative gain
 	matrix::Vector3f _lim_int; ///< integrator term maximum absolute value
 	matrix::Vector3f _gain_ff; ///< direct rate to torque feed forward gain only useful for helicopters
+	float _rotor_angular_momentum{0.f}; ///< used to cancel out the gyroscopic torque generated by the rotors
 
 	// States
 	matrix::Vector3f _rate_int; ///< integral term of the rate controller

src/modules/control_allocator/ControlAllocator.cpp

@@ -270,6 +270,10 @@ ControlAllocator::update_effectiveness_source()
 			tmp = new ActuatorEffectivenessHelicopterCoaxial(this);
 			break;
 
+		case EffectivenessSource::THRUST_VECTORING:
+			tmp = new ActuatorEffectivenessThrustVectoring(this);
+			break;
+
 		default:
 			PX4_ERR("Unknown airframe");
 			break;
@@ -438,6 +442,7 @@ ControlAllocator::Run()
 			_actuator_effectiveness->allocateAuxilaryControls(dt, i, _control_allocation[i]->_actuator_sp); //flaps and spoilers
 			_actuator_effectiveness->updateSetpoint(c[i], i, _control_allocation[i]->_actuator_sp,
 								_control_allocation[i]->getActuatorMin(), _control_allocation[i]->getActuatorMax());
+			_control_allocation[i]->_actuator_effectiveness_scale = _actuator_effectiveness->getActuatorEffectivenessScale();
 
 			if (_has_slew_rate) {
 				_control_allocation[i]->applySlewRateLimit(dt);

src/modules/control_allocator/ControlAllocator.hpp

@@ -44,6 +44,7 @@
 #include <ActuatorEffectiveness.hpp>
 #include <ActuatorEffectivenessMultirotor.hpp>
 #include <ActuatorEffectivenessStandardVTOL.hpp>
+#include <ActuatorEffectivenessThrustVectoring.hpp>
 #include <ActuatorEffectivenessTiltrotorVTOL.hpp>
 #include <ActuatorEffectivenessTailsitterVTOL.hpp>
 #include <ActuatorEffectivenessRoverAckermann.hpp>
@@ -158,6 +159,7 @@ class ControlAllocator : public ModuleBase<ControlAllocator>, public ModuleParam
 		HELICOPTER_TAIL_ESC = 10,
 		HELICOPTER_TAIL_SERVO = 11,
 		HELICOPTER_COAXIAL = 12,
+		THRUST_VECTORING = 14,
 	};
 
 	enum class FailureMode {

src/modules/control_allocator/VehicleActuatorEffectiveness/ActuatorEffectivenessControlSurfaces.cpp

@@ -186,3 +186,18 @@ void ActuatorEffectivenessControlSurfaces::applySpoilers(float spoilers_control,
 		actuator_sp(i + first_actuator_idx) += _spoilers_setpoint_with_slewrate.getState() * _params[i].scale_spoiler;
 	}
 }
+
+void ActuatorEffectivenessControlSurfaces::applyEffectivenessScale(float effectiveness_scale, int first_actuator_idx,
+		ActuatorVector &actuator_sp, ActuatorVector &applied_effectiveness_scale) const
+{
+	if (!PX4_ISFINITE(effectiveness_scale)) {
+		effectiveness_scale = 1.f;
+	}
+
+	const float actuator_scale = 1.f / fmaxf(effectiveness_scale, FLT_EPSILON);
+
+	for (int i = 0; i < _count; ++i) {
+		actuator_sp(i + first_actuator_idx) *= actuator_scale;
+		applied_effectiveness_scale(i + first_actuator_idx) = effectiveness_scale;
+	}
+}

src/modules/control_allocator/VehicleActuatorEffectiveness/ActuatorEffectivenessControlSurfaces.hpp

@@ -91,6 +91,7 @@ class ActuatorEffectivenessControlSurfaces : public ModuleParams, public Actuato
 
 	void applyFlaps(float flaps_control, int first_actuator_idx, float dt, ActuatorVector &actuator_sp);
 	void applySpoilers(float spoilers_control, int first_actuator_idx, float dt, ActuatorVector &actuator_sp);
+	void applyEffectivenessScale(float scale, int first_actuator_idx, ActuatorVector &actuator_sp, ActuatorVector &applied_effectiveness_scale) const;
 
 private:
 	void updateParams() override;

src/modules/control_allocator/VehicleActuatorEffectiveness/ActuatorEffectivenessThrustVectoring.cpp

@@ -0,0 +1,101 @@
+/****************************************************************************
+ *
+ *   Copyright (c) 2023 PX4 Development Team. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name PX4 nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+#include "ActuatorEffectivenessThrustVectoring.hpp"
+
+using namespace matrix;
+
+ActuatorEffectivenessThrustVectoring::ActuatorEffectivenessThrustVectoring(ModuleParams *parent)
+	: ModuleParams(parent),
+	  _rotors(this, ActuatorEffectivenessRotors::AxisConfiguration::FixedUpwards),
+	  _control_surfaces(this)
+{
+}
+
+bool
+ActuatorEffectivenessThrustVectoring::getEffectivenessMatrix(Configuration &configuration,
+		EffectivenessUpdateReason external_update)
+{
+	if (external_update == EffectivenessUpdateReason::NO_EXTERNAL_UPDATE) {
+		return false;
+	}
+
+	// Motors
+	_rotors.enablePropellerTorque(false);
+	const bool rotors_added_successfully = _rotors.addActuators(configuration);
+
+	// Control Surfaces
+	_first_control_surface_idx = configuration.num_actuators_matrix[0];
+	const bool surfaces_added_successfully = _control_surfaces.addActuators(configuration);
+
+	return (rotors_added_successfully && surfaces_added_successfully);
+}
+
+void ActuatorEffectivenessThrustVectoring::updateSetpoint(const matrix::Vector<float, NUM_AXES> &control_sp,
+		int matrix_index, ActuatorVector &actuator_sp, const matrix::Vector<float, NUM_ACTUATORS> &actuator_min,
+		const matrix::Vector<float, NUM_ACTUATORS> &actuator_max)
+{
+	esc_status_s esc_status;
+	hrt_abstime now = hrt_absolute_time();
+	float rpm = 0.f;
+
+	if (_esc_status_sub.copy(&esc_status) && (now < esc_status.timestamp + 1_s)) {
+
+		for (size_t esc = 0; esc < math::min(esc_status.esc_count, (uint8_t)MAX_NUM_ESCS); esc++) {
+			const esc_report_s &esc_report = esc_status.esc[esc];
+
+			const bool esc_connected = (esc_status.esc_online_flags & (1 << esc)) || (esc_report.esc_rpm != 0);
+
+			if (esc_connected && (now < esc_report.timestamp + 1_s)) {
+				rpm = esc_report.esc_rpm;
+				break;
+			}
+		}
+	}
+
+	const  float rpm_scaled = rpm / 20000.f; // scale down the thrust to keep values in a reasonable range
+	float thrust = rpm_scaled * rpm_scaled;
+
+	// Use thrust setpoint if there is no ESC telemetry available
+	if (thrust < FLT_EPSILON) {
+		vehicle_thrust_setpoint_s vehicle_thrust_setpoint;
+
+		if (_vehicle_thrust_setpoint_sub.copy(&vehicle_thrust_setpoint)) {
+			thrust = vehicle_thrust_setpoint.xyz[2];
+		}
+	}
+
+	const float effectiveness_scale = fmaxf(thrust, 0.2f);
+	_control_surfaces.applyEffectivenessScale(effectiveness_scale, _first_control_surface_idx, actuator_sp,
+			_actuator_effectiveness_scale);
+}

src/modules/control_allocator/VehicleActuatorEffectiveness/ActuatorEffectivenessThrustVectoring.hpp

@@ -0,0 +1,67 @@
+/****************************************************************************
+ *
+ *   Copyright (c) 2023 PX4 Development Team. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name PX4 nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+#pragma once
+
+#include "ActuatorEffectiveness.hpp"
+#include "ActuatorEffectivenessRotors.hpp"
+#include "ActuatorEffectivenessControlSurfaces.hpp"
+
+#include <uORB/topics/esc_status.h>
+#include <uORB/topics/vehicle_thrust_setpoint.h>
+
+class ActuatorEffectivenessThrustVectoring : public ModuleParams, public ActuatorEffectiveness
+{
+public:
+	ActuatorEffectivenessThrustVectoring(ModuleParams *parent);
+	virtual ~ActuatorEffectivenessThrustVectoring() = default;
+
+	bool getEffectivenessMatrix(Configuration &configuration, EffectivenessUpdateReason external_update) override;
+
+	const char *name() const override { return "Thrust Vectoring"; }
+
+	void updateSetpoint(const matrix::Vector<float, NUM_AXES> &control_sp, int matrix_index,
+			    ActuatorVector &actuator_sp, const matrix::Vector<float, NUM_ACTUATORS> &actuator_min,
+			    const matrix::Vector<float, NUM_ACTUATORS> &actuator_max) override;
+
+private:
+	static constexpr int MAX_NUM_ESCS = sizeof(esc_status_s::esc) / sizeof(esc_status_s::esc[0]);
+
+	ActuatorEffectivenessRotors _rotors;
+	ActuatorEffectivenessControlSurfaces _control_surfaces;
+
+	uORB::Subscription _vehicle_thrust_setpoint_sub{ORB_ID(vehicle_thrust_setpoint)};
+	uORB::Subscription _esc_status_sub {ORB_ID(esc_status)};
+
+	int _first_control_surface_idx{0};
+};

src/modules/control_allocator/VehicleActuatorEffectiveness/CMakeLists.txt

@@ -15,6 +15,8 @@ px4_add_library(VehicleActuatorEffectiveness
 	ActuatorEffectivenessMCTilt.hpp
 	ActuatorEffectivenessMultirotor.cpp
 	ActuatorEffectivenessMultirotor.hpp
+	ActuatorEffectivenessThrustVectoring.cpp
+	ActuatorEffectivenessThrustVectoring.hpp
 	ActuatorEffectivenessTilts.cpp
 	ActuatorEffectivenessTilts.hpp
 	ActuatorEffectivenessRotors.cpp

src/modules/control_allocator/module.yaml

@@ -31,6 +31,7 @@ parameters:
                 11: Helicopter (tail Servo)
                 12: Helicopter (Coaxial)
                 13: Rover (Mecanum)
+                14: Thrust Vectoring
             default: 0
 
         CA_METHOD:

src/modules/mc_rate_control/MulticopterRateControl.cpp

@@ -185,6 +185,28 @@ MulticopterRateControl::Run()
 			}
 		}
 
+		if (_esc_status_sub.updated()) {
+			esc_status_s esc_status;
+
+			if (_esc_status_sub.copy(&esc_status) && (now < esc_status.timestamp + 1_s)) {
+				float rpm_sum = 0.f;
+
+				for (size_t esc = 0; esc < math::min(esc_status.esc_count, (uint8_t)MAX_NUM_ESCS); esc++) {
+					const esc_report_s &esc_report = esc_status.esc[esc];
+
+					const bool esc_connected = (esc_status.esc_online_flags & (1 << esc)) || (esc_report.esc_rpm != 0);
+
+					// assuming all the rotors are in the same plane, the gyroscopic torque is proportional to the
+					// difference between the CW and CCW rotation speed
+					if (esc_connected && (now < esc_report.timestamp + 1_s)) {
+						rpm_sum += esc_report.esc_rpm;
+					}
+				}
+
+				_rate_control.setRotorAngularMomentum(rpm_sum * _param_mc_precess_gain.get());
+			}
+		}
+
 		// run the rate controller
 		if (_vehicle_control_mode.flag_control_rates_enabled) {
 

src/modules/mc_rate_control/MulticopterRateControl.hpp

@@ -50,6 +50,7 @@
 #include <uORB/topics/actuator_controls_status.h>
 #include <uORB/topics/battery_status.h>
 #include <uORB/topics/control_allocator_status.h>
+#include <uORB/topics/esc_status.h>
 #include <uORB/topics/manual_control_setpoint.h>
 #include <uORB/topics/parameter_update.h>
 #include <uORB/topics/rate_ctrl_status.h>
@@ -94,6 +95,7 @@ class MulticopterRateControl : public ModuleBase<MulticopterRateControl>, public
 
 	uORB::Subscription _battery_status_sub{ORB_ID(battery_status)};
 	uORB::Subscription _control_allocator_status_sub{ORB_ID(control_allocator_status)};
+	uORB::Subscription _esc_status_sub {ORB_ID(esc_status)};
 	uORB::Subscription _manual_control_setpoint_sub{ORB_ID(manual_control_setpoint)};
 	uORB::Subscription _vehicle_control_mode_sub{ORB_ID(vehicle_control_mode)};
 	uORB::Subscription _vehicle_land_detected_sub{ORB_ID(vehicle_land_detected)};
@@ -110,6 +112,8 @@ class MulticopterRateControl : public ModuleBase<MulticopterRateControl>, public
 	uORB::Publication<vehicle_torque_setpoint_s>	_vehicle_torque_setpoint_pub;
 	uORB::Publication<vehicle_thrust_setpoint_s>	_vehicle_thrust_setpoint_pub;
 
+	static constexpr int MAX_NUM_ESCS = sizeof(esc_status_s::esc) / sizeof(esc_status_s::esc[0]);
+
 	vehicle_control_mode_s	_vehicle_control_mode{};
 	vehicle_status_s	_vehicle_status{};
 
@@ -155,6 +159,8 @@ class MulticopterRateControl : public ModuleBase<MulticopterRateControl>, public
 		(ParamFloat<px4::params::MC_YAWRATE_K>) _param_mc_yawrate_k,
 		(ParamFloat<px4::params::MC_YAW_TQ_CUTOFF>) _param_mc_yaw_tq_cutoff,
 
+		(ParamFloat<px4::params::MC_PRECESS_GAIN>) _param_mc_precess_gain,
+
 		(ParamFloat<px4::params::MC_ACRO_R_MAX>) _param_mc_acro_r_max,
 		(ParamFloat<px4::params::MC_ACRO_P_MAX>) _param_mc_acro_p_max,
 		(ParamFloat<px4::params::MC_ACRO_Y_MAX>) _param_mc_acro_y_max,