px4_autopilot/EKF/estimator_interface.h

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/**
 * @file estimator_interface.h
 * Definition of base class for attitude estimators
 *
 * @author Roman Bast <bapstroman@gmail.com>
 *
 */

#include <stdint.h>
#include <matrix/matrix/math.hpp>
#include "RingBuffer.h"
#include "geo.h"
#include "common.h"
#include "mathlib.h"

using namespace estimator;
class EstimatorInterface
{

public:
	EstimatorInterface();
	~EstimatorInterface();

	virtual bool init(uint64_t timestamp) = 0;
	virtual bool update() = 0;

	// gets the innovations of velocity and position measurements
	// 0-2 vel, 3-5 pos
	virtual void get_vel_pos_innov(float vel_pos_innov[6]) = 0;

	// gets the innovations of the earth magnetic field measurements
	virtual void get_mag_innov(float mag_innov[3]) = 0;

	// gets the innovation of airspeed measurement
 	virtual void get_airspeed_innov(float *airspeed_innov) = 0;

	// gets the innovations of the heading measurement
	virtual void get_heading_innov(float *heading_innov) = 0;

	// gets the innovation variances of velocity and position measurements
	// 0-2 vel, 3-5 pos
	virtual void get_vel_pos_innov_var(float vel_pos_innov_var[6]) = 0;

	// gets the innovation variances of the earth magnetic field measurements
	virtual void get_mag_innov_var(float mag_innov_var[3]) = 0;

	// gets the innovation variance of the airspeed measurement
 	virtual void get_airspeed_innov_var(float *get_airspeed_innov_var) = 0;

	// gets the innovation variance of the heading measurement
	virtual void get_heading_innov_var(float *heading_innov_var) = 0;

	virtual void get_state_delayed(float *state) = 0;

	virtual void get_wind_velocity(float *wind) = 0;

	virtual void get_covariances(float *covariances) = 0;

	// gets the variances for the NED velocity states
	virtual void get_vel_var(Vector3f &vel_var) = 0;

	// gets the variances for the NED position states
	virtual void get_pos_var(Vector3f &pos_var) = 0;

	// gets the innovation variance of the flow measurement
	virtual void get_flow_innov_var(float flow_innov_var[2]) = 0;

	// gets the innovation of the flow measurement
	virtual void get_flow_innov(float flow_innov[2]) = 0;

	// gets the innovation variance of the HAGL measurement
	virtual void get_hagl_innov_var(float *flow_innov_var) = 0;

	// gets the innovation of the HAGL measurement
	virtual void get_hagl_innov(float *flow_innov_var) = 0;

	// return an array containing the output predictor angular, velocity and position tracking
	// error magnitudes (rad), (m/s), (m)
	virtual void get_output_tracking_error(float error[3]) = 0;

	/*
	Returns  following IMU vibration metrics in the following array locations
	0 : Gyro delta angle coning metric = filtered length of (delta_angle x prev_delta_angle)
	1 : Gyro high frequency vibe = filtered length of (delta_angle - prev_delta_angle)
	2 : Accel high frequency vibe = filtered length of (delta_velocity - prev_delta_velocity)
	*/
	virtual void get_imu_vibe_metrics(float vibe[3]) = 0;

	// get the ekf WGS-84 origin positoin and height and the system time it was last set
	virtual void get_ekf_origin(uint64_t *origin_time, map_projection_reference_s *origin_pos, float *origin_alt) = 0;

	// get the 1-sigma horizontal and vertical position uncertainty of the ekf WGS-84 position
	virtual void get_ekf_accuracy(float *ekf_eph, float *ekf_epv, bool *dead_reckoning) = 0;

	// ask estimator for sensor data collection decision and do any preprocessing if required, returns true if not defined
	virtual bool collect_gps(uint64_t time_usec, struct gps_message *gps) { return true; }

	// accumulate and downsample IMU data to the EKF prediction rate
	virtual bool collect_imu(imuSample &imu) { return true; }

	// set delta angle imu data
	void setIMUData(uint64_t time_usec, uint64_t delta_ang_dt, uint64_t delta_vel_dt, float *delta_ang, float *delta_vel);

	// set magnetometer data
	void setMagData(uint64_t time_usec, float *data);
	//void setMagData(uint64_t time_usec, struct magSample *mag);

	// set gps data
	void setGpsData(uint64_t time_usec, struct gps_message *gps);

	// set baro data
	void setBaroData(uint64_t time_usec, float *data);

	// set airspeed data
	void setAirspeedData(uint64_t time_usec, float *true_airspeed, float *eas2tas);

	// set range data
	void setRangeData(uint64_t time_usec, float *data);

	// set optical flow data
	void setOpticalFlowData(uint64_t time_usec, flow_message *flow);

	// set external vision position and attitude data
	void setExtVisionData(uint64_t time_usec, ext_vision_message *evdata);

	// return a address to the parameters struct
	// in order to give access to the application
	parameters *getParamHandle() {return &_params;}

	// set vehicle landed status data
	void set_in_air_status(bool in_air) {_control_status.flags.in_air = in_air;}

	// return true if the global position estimate is valid
	virtual bool global_position_is_valid() = 0;

	// return true if the estimate is valid
	// return the estimated terrain vertical position relative to the NED origin
	virtual bool get_terrain_vert_pos(float *ret) = 0;

	// return true if the local position estimate is valid
	bool local_position_is_valid();


	void copy_quaternion(float *quat)
	{
		for (unsigned i = 0; i < 4; i++) {
			quat[i] = _output_new.quat_nominal(i);
		}
	}
	// get the velocity of the body frame origin in local NED earth frame
	void get_velocity(float *vel)
	{
		// calculate the average angular rate across the last IMU update
		Vector3f ang_rate = _imu_sample_new.delta_ang * (1.0f/_imu_sample_new.delta_ang_dt);
		// calculate the velocity of the relative to the body origin
		// Note % operator has been overloaded to performa cross product
		Vector3f vel_imu_rel_body = cross_product(ang_rate , _params.imu_pos_body);
		// rotate the relative velocty into earth frame and subtract from the EKF velocity
		// (which is at the IMU) to get velocity of the body origin
		Vector3f vel_earth = _output_new.vel - _R_to_earth_now * vel_imu_rel_body;
		// copy to output
		for (unsigned i = 0; i < 3; i++) {
			vel[i] = vel_earth(i);
		}
	}
	// get the position of the body frame origin in local NED earth frame
	void get_position(float *pos)
	{
		// rotate the position of the IMU relative to the boy origin into earth frame
		Vector3f pos_offset_earth = _R_to_earth_now * _params.imu_pos_body;
		// subtract from the EKF position (which is at the IMU) to get position at the body origin
		for (unsigned i = 0; i < 3; i++) {
			pos[i] = _output_new.pos(i) - pos_offset_earth(i);
		}
	}
	void copy_timestamp(uint64_t *time_us)
	{
		*time_us = _time_last_imu;
	}

	// Copy the magnetic declination that we wish to save to the EKF2_MAG_DECL parameter for the next startup
	void copy_mag_decl_deg(float *val)
	{
		*val = _mag_declination_to_save_deg;
	}

	virtual void get_accel_bias(float bias[3]) = 0;
	virtual void get_gyro_bias(float bias[3]) = 0;

	// get EKF mode status
	void get_control_mode(uint16_t *val)
	{
		*val = _control_status.value;
	}

	// get EKF internal fault status
	void get_filter_fault_status(uint16_t *val)
	{
		*val = _fault_status.value;
	}

	// get GPS check status
	virtual void get_gps_check_status(uint16_t *val) = 0;

	// return the amount the local vertical position changed in the last reset and the number of reset events
	virtual void get_posD_reset(float *delta, uint8_t *counter) = 0;

	// return the amount the local vertical velocity changed in the last reset and the number of reset events
	virtual void get_velD_reset(float *delta, uint8_t *counter) = 0;

	// return the amount the local horizontal position changed in the last reset and the number of reset events
	virtual void get_posNE_reset(float delta[2], uint8_t *counter) = 0;

	// return the amount the local horizontal velocity changed in the last reset and the number of reset events
	virtual void get_velNE_reset(float delta[2], uint8_t *counter) = 0;

	// return the amount the quaternion has changed in the last reset and the number of reset events
	virtual void get_quat_reset(float delta_quat[4], uint8_t *counter) = 0;

	// get EKF innovation consistency check status information comprising of:
	// status - a bitmask integer containing the pass/fail status for each EKF measurement innovation consistency check
	// Innovation Test Ratios - these are the ratio of the innovation to the acceptance threshold.
	// A value > 1 indicates that the sensor measurement has exceeded the maximum acceptable level and has been rejected by the EKF
	// Where a measurement type is a vector quantity, eg magnetoemter, GPS position, etc, the maximum value is returned.
	virtual void get_innovation_test_status(uint16_t *status, float *mag, float *vel, float *pos, float *hgt, float *tas, float *hagl) = 0;

	// return a bitmask integer that describes which state estimates can be used for flight control
	virtual void get_ekf_soln_status(uint16_t *status) = 0;

protected:

	parameters _params;		// filter parameters

	static const uint8_t OBS_BUFFER_LENGTH = 10;	// defines how many measurement samples we can buffer
	static const uint8_t IMU_BUFFER_LENGTH = 30;	// defines how many imu samples we can buffer
	static const unsigned FILTER_UPDATE_PERIOD_MS = 10;	// ekf prediction period in milliseconds

	unsigned _min_obs_interval_us; // minimum time interval between observations that will guarantee data is not lost (usec)

	float _dt_imu_avg;	// average imu update period in s

	imuSample _imu_sample_delayed;	// captures the imu sample on the delayed time horizon

	// measurement samples capturing measurements on the delayed time horizon
	magSample _mag_sample_delayed;
	baroSample _baro_sample_delayed;
	gpsSample _gps_sample_delayed;
	rangeSample _range_sample_delayed;
	airspeedSample _airspeed_sample_delayed;
	flowSample _flow_sample_delayed;
	extVisionSample _ev_sample_delayed;

	outputSample _output_sample_delayed;	// filter output on the delayed time horizon
	outputSample _output_new;	// filter output on the non-delayed time horizon
	imuSample _imu_sample_new;	// imu sample capturing the newest imu data
	Matrix3f _R_to_earth_now; // rotation matrix from body to earth frame at current time

	uint64_t _imu_ticks;	// counter for imu updates

	bool _imu_updated;      // true if the ekf should update (completed downsampling process)
	bool _initialised;      // true if the ekf interface instance (data buffering) is initialized

	bool _NED_origin_initialised;
	bool _gps_speed_valid;
	float _gps_origin_eph; // horizontal position uncertainty of the GPS origin
	float _gps_origin_epv; // vertical position uncertainty of the GPS origin
	struct map_projection_reference_s _pos_ref;    // Contains WGS-84 position latitude and longitude (radians)

	// innovation consistency check monitoring ratios
	float _yaw_test_ratio;          // yaw innovation consistency check ratio
	float _mag_test_ratio[3];       // magnetometer XYZ innovation consistency check ratios
	float _vel_pos_test_ratio[6];   // velocity and position innovation consistency check ratios
	float _tas_test_ratio;		// tas innovation consistency check ratio
	float _terr_test_ratio;		// height above terrain measurement innovation consistency check ratio
	innovation_fault_status_u _innov_check_fail_status;

	// IMU vibration monitoring
	Vector3f _delta_ang_prev;	// delta angle from the previous IMU measurement
	Vector3f _delta_vel_prev;	// delta velocity from the previous IMU measurement
	float _vibe_metrics[3];		// IMU vibration metrics
					// [0] Level of coning vibration in the IMU delta angles (rad^2)
					// [1] high frequency vibraton level in the IMU delta angle data (rad)
					// [2] high frequency vibration level in the IMU delta velocity data (m/s)

	// data buffer instances
	RingBuffer<imuSample> _imu_buffer;
	RingBuffer<gpsSample> _gps_buffer;
	RingBuffer<magSample> _mag_buffer;
	RingBuffer<baroSample> _baro_buffer;
	RingBuffer<rangeSample> _range_buffer;
	RingBuffer<airspeedSample> _airspeed_buffer;
	RingBuffer<flowSample> 	_flow_buffer;
	RingBuffer<extVisionSample> _ext_vision_buffer;
	RingBuffer<outputSample> _output_buffer;

	uint64_t _time_last_imu;	// timestamp of last imu sample in microseconds
	uint64_t _time_last_gps;	// timestamp of last gps measurement in microseconds
	uint64_t _time_last_mag;	// timestamp of last magnetometer measurement in microseconds
	uint64_t _time_last_baro;	// timestamp of last barometer measurement in microseconds
	uint64_t _time_last_range;	// timestamp of last range measurement in microseconds
	uint64_t _time_last_airspeed;	// timestamp of last airspeed measurement in microseconds
	uint64_t _time_last_ext_vision; // timestamp of last external vision measurement in microseconds
	uint64_t _time_last_optflow;

	fault_status_u _fault_status;

	// allocate data buffers and intialise interface variables
	bool initialise_interface(uint64_t timestamp);

	// free buffer memory
	void unallocate_buffers();

	float _mag_declination_gps;         // magnetic declination returned by the geo library using the last valid GPS position (rad)
	float _mag_declination_to_save_deg; // magnetic declination to save to EKF2_MAG_DECL (deg)

	// this is the current status of the filter control modes
	filter_control_status_u _control_status;

	// this is the previous status of the filter control modes - used to detect mode transitions
	filter_control_status_u _control_status_prev;

	// perform a vector cross product
	Vector3f cross_product(const Vector3f &vecIn1, const Vector3f &vecIn2);

	// calculate the inverse rotation matrix from a quaternion rotation
	Matrix3f quat_to_invrotmat(const Quaternion quat);

};