px4-firmware/airdata/WindEstimator.hpp

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/**
 * @file WindEstimator.hpp
 * A wind and airspeed scale estimator.
 */

#pragma once

#include <mathlib/mathlib.h>
#include <matrix/math.hpp>

class WindEstimator
{
public:
	WindEstimator() = default;
	~WindEstimator() = default;

	// no copy, assignment, move, move assignment
	WindEstimator(const WindEstimator &) = delete;
	WindEstimator &operator=(const WindEstimator &) = delete;
	WindEstimator(WindEstimator &&) = delete;
	WindEstimator &operator=(WindEstimator &&) = delete;

	void update(uint64_t time_now);

	void fuse_airspeed(uint64_t time_now, float true_airspeed, const matrix::Vector3f &velI,
			   const matrix::Vector2f &velIvar);
	void fuse_beta(uint64_t time_now, const matrix::Vector3f &velI, const matrix::Quatf &q_att);

	void get_wind(float wind[2])
	{
		wind[0] = _state(w_n);
		wind[1] = _state(w_e);
	}

	bool is_estimate_valid() { return _initialised; }

	bool check_if_meas_is_rejected(uint64_t time_now, float innov, float innov_var, uint8_t gate_size, uint64_t &time_meas_rejected,
				       bool &reinit_filter);

	float get_tas_scale() { return _state(tas); }
	float get_tas_innov() { return _tas_innov; }
	float get_tas_innov_var() { return _tas_innov_var; }
	float get_beta_innov() { return _beta_innov; }
	float get_beta_innov_var() { return _beta_innov_var; }
	void get_wind_var(float wind_var[2])
	{
		wind_var[0] = _P(0, 0);
		wind_var[1] = _P(1, 1);
	}

	void set_wind_p_noise(float wind_sigma) { _wind_p_var = wind_sigma * wind_sigma; }
	void set_tas_scale_p_noise(float tas_scale_sigma) { _tas_scale_p_var = tas_scale_sigma * tas_scale_sigma; }
	void set_tas_noise(float tas_sigma) { _tas_var = tas_sigma * tas_sigma; }
	void set_beta_noise(float beta_var) { _beta_var = beta_var * beta_var; }
	void set_tas_gate(uint8_t gate_size) {_tas_gate = gate_size; }
	void set_beta_gate(uint8_t gate_size) {_beta_gate = gate_size; }

private:
	enum {
		w_n = 0,
		w_e,
		tas
	};	///< enum which can be used to access state.

	matrix::Vector3f _state;		///< state vector
	matrix::Matrix3f _P;		///< state covariance matrix

	float _tas_innov{0.0f};	///< true airspeed innovation
	float _tas_innov_var{0.0f};	///< true airspeed innovation variance

	float _beta_innov{0.0f};	///< sideslip innovation
	float _beta_innov_var{0.0f};	///< sideslip innovation variance

	bool _initialised{false};	///< True: filter has been initialised

	float _wind_p_var{0.1f};	///< wind process noise variance
	float _tas_scale_p_var{0.0001f};	///< true airspeed scale process noise variance
	float _tas_var{1.4f};		///< true airspeed measurement noise variance
	float _beta_var{0.5f};	///< sideslip measurement noise variance
	uint8_t _tas_gate{3};	///< airspeed fusion gate size
	uint8_t _beta_gate{1};	///< sideslip fusion gate size

	uint64_t _time_last_airspeed_fuse = 0;	///< timestamp of last airspeed fusion
	uint64_t _time_last_beta_fuse = 0;		///< timestamp of last sideslip fusion
	uint64_t _time_last_update = 0;			///< timestamp of last covariance prediction
	uint64_t _time_rejected_beta = 0;		///< timestamp of when sideslip measurements have consistently started to be rejected
	uint64_t _time_rejected_tas =
		0;		///<timestamp of when true airspeed measurements have consistently started to be rejected

	// initialise state and state covariance matrix
	bool initialise(const matrix::Vector3f &velI, const matrix::Vector2f &velIvar, const float tas_meas);

	void run_sanity_checks();
};