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Dependencies:   mbed

Fusion/FusionAhrs.h@1:57502185804c, 2021-10-30 (annotated)

Committer:
natvich
Date:
Sat Oct 30 17:17:07 2021 +0000
Revision:
1:57502185804c
Projet ATTITUDE IMU

Who changed what in which revision?

UserRevisionLine numberNew contents of line
natvich 1:57502185804c 1 /**
natvich 1:57502185804c 2 * @file FusionAhrs.h
natvich 1:57502185804c 3 * @author Seb Madgwick
natvich 1:57502185804c 4 * @brief The AHRS sensor fusion algorithm to combines gyroscope, accelerometer,
natvich 1:57502185804c 5 * and magnetometer measurements into a single measurement of orientation
natvich 1:57502185804c 6 * relative to the Earth (NWU convention).
natvich 1:57502185804c 7 *
natvich 1:57502185804c 8 * The algorithm behaviour is governed by a gain. A low gain will decrease the
natvich 1:57502185804c 9 * influence of the accelerometer and magnetometer so that the algorithm will
natvich 1:57502185804c 10 * better reject disturbances causes by translational motion and temporary
natvich 1:57502185804c 11 * magnetic distortions. However, a low gain will also increase the risk of
natvich 1:57502185804c 12 * drift due to gyroscope calibration errors. A typical gain value suitable for
natvich 1:57502185804c 13 * most applications is 0.5.
natvich 1:57502185804c 14 *
natvich 1:57502185804c 15 * The algorithm allows the application to define a minimum and maximum valid
natvich 1:57502185804c 16 * magnetic field magnitude. The algorithm will ignore magnetic measurements
natvich 1:57502185804c 17 * that fall outside of this range. This allows the algorithm to reject
natvich 1:57502185804c 18 * magnetic measurements that do not represent the direction of magnetic North.
natvich 1:57502185804c 19 * The typical magnitude of the Earth's magnetic field is between 20 uT and
natvich 1:57502185804c 20 * 70 uT.
natvich 1:57502185804c 21 *
natvich 1:57502185804c 22 * The algorithm can be used without a magnetometer. Measurements of
natvich 1:57502185804c 23 * orientation obtained using only gyroscope and accelerometer measurements
natvich 1:57502185804c 24 * can be expected to drift in the yaw component of orientation only. The
natvich 1:57502185804c 25 * application can reset the drift in yaw by setting the yaw to a specified
natvich 1:57502185804c 26 * angle at any time.
natvich 1:57502185804c 27 *
natvich 1:57502185804c 28 * The algorithm provides the measurement of orientation as a quaternion. The
natvich 1:57502185804c 29 * library includes functions for converting this quaternion to a rotation
natvich 1:57502185804c 30 * matrix and Euler angles.
natvich 1:57502185804c 31 *
natvich 1:57502185804c 32 * The algorithm also provides a measurement of linear acceleration and Earth
natvich 1:57502185804c 33 * acceleration. Linear acceleration is equal to the accelerometer measurement
natvich 1:57502185804c 34 * with the 1 g of gravity removed. Earth acceleration is a measurement of
natvich 1:57502185804c 35 * linear acceleration in the Earth coordinate frame.
natvich 1:57502185804c 36 */
natvich 1:57502185804c 37
natvich 1:57502185804c 38 #ifndef FUSION_AHRS_H
natvich 1:57502185804c 39 #define FUSION_AHRS_H
natvich 1:57502185804c 40
natvich 1:57502185804c 41 //------------------------------------------------------------------------------
natvich 1:57502185804c 42 // Includes
natvich 1:57502185804c 43
natvich 1:57502185804c 44 #include "FusionTypes.h"
natvich 1:57502185804c 45 #include <stdbool.h>
natvich 1:57502185804c 46
natvich 1:57502185804c 47 //------------------------------------------------------------------------------
natvich 1:57502185804c 48 // Definitions
natvich 1:57502185804c 49
natvich 1:57502185804c 50 /**
natvich 1:57502185804c 51 * @brief AHRS algorithm structure. Structure members are used internally and
natvich 1:57502185804c 52 * should not be used by the user application.
natvich 1:57502185804c 53 */
natvich 1:57502185804c 54 typedef struct {
natvich 1:57502185804c 55 float gain;
natvich 1:57502185804c 56 float minimumMagneticFieldSquared;
natvich 1:57502185804c 57 float maximumMagneticFieldSquared;
natvich 1:57502185804c 58 FusionQuaternion quaternion; // describes the Earth relative to the sensor
natvich 1:57502185804c 59 FusionVector3 linearAcceleration;
natvich 1:57502185804c 60 float rampedGain;
natvich 1:57502185804c 61 bool zeroYawPending;
natvich 1:57502185804c 62 } FusionAhrs;
natvich 1:57502185804c 63
natvich 1:57502185804c 64 //------------------------------------------------------------------------------
natvich 1:57502185804c 65 // Function prototypes
natvich 1:57502185804c 66
natvich 1:57502185804c 67 void FusionAhrsInitialise(FusionAhrs * const fusionAhrs, const float gain);
natvich 1:57502185804c 68 void FusionAhrsSetGain(FusionAhrs * const fusionAhrs, const float gain);
natvich 1:57502185804c 69 void FusionAhrsSetMagneticField(FusionAhrs * const fusionAhrs, const float minimumMagneticField, const float maximumMagneticField);
natvich 1:57502185804c 70 void FusionAhrsUpdate(FusionAhrs * const fusionAhrs, const FusionVector3 gyroscope, const FusionVector3 accelerometer, const FusionVector3 magnetometer, const float samplePeriod);
natvich 1:57502185804c 71 void FusionAhrsUpdateWithoutMagnetometer(FusionAhrs * const fusionAhrs, const FusionVector3 gyroscope, const FusionVector3 accelerometer, const float samplePeriod);
natvich 1:57502185804c 72 FusionQuaternion FusionAhrsGetQuaternion(const FusionAhrs * const fusionAhrs);
natvich 1:57502185804c 73 FusionVector3 FusionAhrsGetLinearAcceleration(const FusionAhrs * const fusionAhrs);
natvich 1:57502185804c 74 FusionVector3 FusionAhrsGetEarthAcceleration(const FusionAhrs * const fusionAhrs);
natvich 1:57502185804c 75 void FusionAhrsReinitialise(FusionAhrs * const fusionAhrs);
natvich 1:57502185804c 76 bool FusionAhrsIsInitialising(const FusionAhrs * const fusionAhrs);
natvich 1:57502185804c 77 void FusionAhrsSetYaw(FusionAhrs * const fusionAhrs, const float yaw);
natvich 1:57502185804c 78
natvich 1:57502185804c 79 #endif
natvich 1:57502185804c 80
natvich 1:57502185804c 81 //------------------------------------------------------------------------------
natvich 1:57502185804c 82 // End of file