attitude_error_estimator.h

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/*******************************************************************************
 * \file attitude_error_estimator.h
 * 
 * \author MAV'RIC Team
 * \author Julien Lecoeur
 *   
 * \brief A quaternion-based attitude-error estimator, takes a reference 
 * quaternion as input and provides angular errors for roll, pitch and yaw in 
 * the local frame.
 * 
 * \details  WARNING: For optimisation purpose, the computed errors are not in 
 * radians:
 * With \f$ e_{roll} , e_{pitch}, e_{yaw} \f$ the true errors in radians around 
 * the local roll, pitch and yaw axes,
 * this estimator returns 
 * \f$ 2.sin( e_{roll} / 2 ), 2.sin( e_{pitch} / 2 ), 2.sin( e_{yaw} / 2 ) \f$
 * 
 * For small angular errors, this approximation is sensible.
 *
 ******************************************************************************/


#ifndef ATTITUDE_ERROR_ESTIMATOR_H_
#define ATTITUDE_ERROR_ESTIMATOR_H_

#ifdef __cplusplus
extern "C" {
#endif

#include "quaternions.h"
#include "coord_conventions.h"
#include "ahrs.h"

typedef struct 
{
    quat_t quat_ref;            
    float rpy_errors[3];        
    const ahrs_t* ahrs;         
} attitude_error_estimator_t;


void attitude_error_estimator_init(attitude_error_estimator_t* estimator, const ahrs_t* ahrs);


void attitude_error_estimator_set_quat_ref(attitude_error_estimator_t* estimator, const quat_t quat_ref);


void attitude_error_estimator_set_quat_ref_from_aero(attitude_error_estimator_t* estimator, const aero_attitude_t aero);


void attitude_error_estimator_set_quat_ref_from_rpy(attitude_error_estimator_t* estimator, const float rpy[3]);


void attitude_error_estimator_update(attitude_error_estimator_t* estimator);


#ifdef __cplusplus
}
#endif

#endif /* ATTITUDE_ERROR_ESTIMATOR_H_ */