text: /****************************************************************************
   *
   *   Copyright (c) 2020-2021 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 <px4_platform_common/px4_config.h>
  #include <px4_platform_common/log.h>
  #include <px4_platform_common/module.h>
  #include <px4_platform_common/module_params.h>
  #include <px4_platform_common/time.h>
  #include <lib/mathlib/mathlib.h>
  #include <px4_platform_common/px4_work_queue/ScheduledWorkItem.hpp>
  #include <uORB/Subscription.hpp>
  #include <uORB/SubscriptionCallback.hpp>
  #include <uORB/Publication.hpp>
  #include <uORB/topics/estimator_selector_status.h>
  #include <uORB/topics/estimator_status.h>
  #include <uORB/topics/parameter_update.h>
  #include <uORB/topics/sensor_selection.h>
  #include <uORB/topics/sensors_status_imu.h>
  #include <uORB/topics/vehicle_attitude.h>
  #include <uORB/topics/vehicle_local_position.h>
  #include <uORB/topics/vehicle_global_position.h>
  #include <uORB/topics/vehicle_odometry.h>
  #include <uORB/topics/wind.h>
  
  #if CONSTRAINED_MEMORY
  # define EKF2_MAX_INSTANCES 2
  #else
  # define EKF2_MAX_INSTANCES 9
  #endif
  
  using namespace time_literals;
  
  class EKF2Selector : public ModuleParams, public px4::ScheduledWorkItem
  {
  public:
  	EKF2Selector();
  	~EKF2Selector() override;
  
  	bool Start();
  	void Stop();
  
  	void PrintStatus();
  
  private:
  	static constexpr uint8_t INVALID_INSTANCE{UINT8_MAX};
  	static constexpr uint64_t FILTER_UPDATE_PERIOD{10_ms};
  
  	void Run() override;
  	void PublishVehicleAttitude();
  	void PublishVehicleLocalPosition();
  	void PublishVehicleGlobalPosition();
  	void PublishVehicleOdometry();
  	void PublishWindEstimate();
  	bool SelectInstance(uint8_t instance);
  
  	// Update the error scores for all available instances
  	bool UpdateErrorScores();
  
  	// Subscriptions (per estimator instance)
  	struct EstimatorInstance {
  
  		EstimatorInstance(EKF2Selector *selector, uint8_t i) :
  			estimator_attitude_sub{selector, ORB_ID(estimator_attitude), i},
  			estimator_status_sub{selector, ORB_ID(estimator_status), i},
  			estimator_local_position_sub{ORB_ID(estimator_local_position), i},
  			estimator_global_position_sub{ORB_ID(estimator_global_position), i},
  			estimator_odometry_sub{ORB_ID(estimator_odometry), i},
  			estimator_wind_sub{ORB_ID(estimator_wind), i},
  			instance(i)
  		{}
  
  		uORB::SubscriptionCallbackWorkItem estimator_attitude_sub;
  		uORB::SubscriptionCallbackWorkItem estimator_status_sub;
  
  		uORB::Subscription estimator_local_position_sub;
  		uORB::Subscription estimator_global_position_sub;
  		uORB::Subscription estimator_odometry_sub;
  		uORB::Subscription estimator_wind_sub;
  
  		uint64_t timestamp_sample_last{0};
  
  		uint32_t accel_device_id{0};
  		uint32_t gyro_device_id{0};
  		uint32_t baro_device_id{0};
  		uint32_t mag_device_id{0};
  
  		hrt_abstime time_last_selected{0};
  
  		float combined_test_ratio{NAN};
  		float relative_test_ratio{NAN};
  
  		bool healthy{false};
  		bool filter_fault{false};
  		bool timeout{false};
  
  		const uint8_t instance;
  	};
  
  	static constexpr float _rel_err_score_lim{1.0f}; // +- limit applied to the relative error score
  	static constexpr float _rel_err_thresh{0.5f};    // the relative score difference needs to be greater than this to switch from an otherwise healthy instance
  
  	EstimatorInstance _instance[EKF2_MAX_INSTANCES] {
  		{this, 0},
  		{this, 1},
  #if EKF2_MAX_INSTANCES > 2
  		{this, 2},
  		{this, 3},
  #if EKF2_MAX_INSTANCES > 4
  		{this, 4},
  		{this, 5},
  		{this, 6},
  		{this, 7},
  		{this, 8},
  #endif
  #endif
  	};
  
  	static constexpr uint8_t IMU_STATUS_SIZE = (sizeof(sensors_status_imu_s::gyro_inconsistency_rad_s) / sizeof(
  				sensors_status_imu_s::gyro_inconsistency_rad_s[0]));
  	static_assert(IMU_STATUS_SIZE == sizeof(estimator_selector_status_s::accumulated_gyro_error) / sizeof(
  			      estimator_selector_status_s::accumulated_gyro_error[0]),
  		      "increase estimator_selector_status_s::accumulated_gyro_error size");
  	static_assert(IMU_STATUS_SIZE == sizeof(estimator_selector_status_s::accumulated_accel_error) / sizeof(
  			      estimator_selector_status_s::accumulated_accel_error[0]),
  		      "increase estimator_selector_status_s::accumulated_accel_error size");
  	static_assert(EKF2_MAX_INSTANCES <= sizeof(estimator_selector_status_s::combined_test_ratio) / sizeof(
  			      estimator_selector_status_s::combined_test_ratio[0]),
  		      "increase estimator_selector_status_s::combined_test_ratio size");
  
  	float _accumulated_gyro_error[IMU_STATUS_SIZE] {};
  	float _accumulated_accel_error[IMU_STATUS_SIZE] {};
  	hrt_abstime _last_update_us{0};
  	bool _gyro_fault_detected{false};
  	bool _accel_fault_detected{false};
  
  	uint8_t _available_instances{0};
  	uint8_t _selected_instance{INVALID_INSTANCE};
  
  	uint32_t _instance_changed_count{0};
  	hrt_abstime _last_instance_change{0};
  
  	hrt_abstime _last_status_publish{0};
  	bool _selector_status_publish{false};
  
  	// vehicle_attitude: reset counters
  	vehicle_attitude_s _attitude_last{};
  	matrix::Quatf _delta_q_reset{};
  	uint8_t _quat_reset_counter{0};
  
  	// vehicle_local_position: reset counters
  	vehicle_local_position_s _local_position_last{};
  	matrix::Vector2f _delta_xy_reset{};
  	float _delta_z_reset{0.f};
  	matrix::Vector2f _delta_vxy_reset{};
  	float _delta_vz_reset{0.f};
  	float _delta_heading_reset{0};
  	uint8_t _xy_reset_counter{0};
  	uint8_t _z_reset_counter{0};
  	uint8_t _vxy_reset_counter{0};
  	uint8_t _vz_reset_counter{0};
  	uint8_t _heading_reset_counter{0};
  
  	// vehicle_odometry
  	vehicle_odometry_s _odometry_last{};
  
  	// vehicle_global_position: reset counters
  	vehicle_global_position_s _global_position_last{};
  	double _delta_lat_reset{0};
  	double _delta_lon_reset{0};
  	float _delta_alt_reset{0.f};
  	uint8_t _lat_lon_reset_counter{0};
  	uint8_t _alt_reset_counter{0};
  
  	// wind estimate
  	wind_s _wind_last{};
  
  	uint8_t _attitude_instance_prev{INVALID_INSTANCE};
  	uint8_t _local_position_instance_prev{INVALID_INSTANCE};
  	uint8_t _global_position_instance_prev{INVALID_INSTANCE};
  
  	uORB::SubscriptionInterval _parameter_update_sub{ORB_ID(parameter_update), 1_s};
  	uORB::Subscription _sensors_status_imu{ORB_ID(sensors_status_imu)};
  
  	// Publications
  	uORB::Publication<estimator_selector_status_s> _estimator_selector_status_pub{ORB_ID(estimator_selector_status)};
  	uORB::Publication<sensor_selection_s>          _sensor_selection_pub{ORB_ID(sensor_selection)};
  	uORB::Publication<vehicle_attitude_s>          _vehicle_attitude_pub{ORB_ID(vehicle_attitude)};
  	uORB::Publication<vehicle_global_position_s>   _vehicle_global_position_pub{ORB_ID(vehicle_global_position)};
  	uORB::Publication<vehicle_local_position_s>    _vehicle_local_position_pub{ORB_ID(vehicle_local_position)};
  	uORB::Publication<vehicle_odometry_s>          _vehicle_odometry_pub{ORB_ID(vehicle_odometry)};
  	uORB::Publication<wind_s>             _wind_pub{ORB_ID(wind)};
  
  	DEFINE_PARAMETERS(
  		(ParamFloat<px4::params::EKF2_SEL_ERR_RED>) _param_ekf2_sel_err_red,
  		(ParamFloat<px4::params::EKF2_SEL_IMU_RAT>) _param_ekf2_sel_imu_angle_rate,
  		(ParamFloat<px4::params::EKF2_SEL_IMU_ANG>) _param_ekf2_sel_imu_angle,
  		(ParamFloat<px4::params::EKF2_SEL_IMU_ACC>) _param_ekf2_sel_imu_accel,
  		(ParamFloat<px4::params::EKF2_SEL_IMU_VEL>) _param_ekf2_sel_imu_velocity
  	)
  };
  