precisionAccelerometer.h

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/*! \file precisionAccelerometer.h
    \brief Implements accelerometer calibration routines
*/

#ifndef PRECISIONACCELEROMETER_H
#define PRECISIONACCELEROMETER_H

/// calibration constants
#define ACCEL_CAL_AVERAGING_SECS    2       ///< calibration measurement averaging period (s)
#define MAX_ACCEL_CAL_ORIENTATIONS  12      ///< number of stored precision accelerometer measurements

/// accelerometer measurement buffer
typedef struct AccelBuffer
{
    float fGsStored[MAX_ACCEL_CAL_ORIENTATIONS][3]; ///< uncalibrated accelerometer measurements (g)
    float fSumGs[3];                ///< averaging sum for current storage location
    int16_t iStoreCounter;              ///< number of remaining iterations at FUSION_HZ to average measurement
    int16_t iStoreLocation;             ///< -1 for none, 0 to 11 for the 12 storage locations
    int16_t iStoreFlags;                ///< denotes which measurements are present
} AccelBuffer;

/// precision accelerometer calibration structure
typedef struct AccelCalibration
{
    // start of elements stored in flash memory
    float fV[3];                    ///< offset vector (g)
    float finvW[3][3];              ///< inverse gain matrix
    float fR0[3][3];                ///< forward rotation matrix for measurement 0
    // end of elements stored in flash memory
    float fmatA[10][10];                    ///< scratch 10x10 matrix used by calibration algorithms
    float fmatB[10][10];                    ///< scratch 10x10 matrix used by calibration algorithms
    float fvecA[10];                ///< scratch 10x1 vector used by calibration algorithms
    float fvecB[4];                 ///< scratch 4x1 vector used by calibration algorithms
    float fA[3][3];                 ///< ellipsoid matrix A
    float finvA[3][3];              ///< inverse of the ellipsoid matrix A
} AccelCalibration;

struct AccelSensor;  // actual typedef is located in sensor_fusion_types.h

// function prototypes for functions in precisionAcclerometer.c
/// Initialize the accelerometer calibration functions
void fInitializeAccelCalibration(
    struct AccelCalibration *pthisAccelCal,             ///< Accelerometer calibration parameter structure
    struct AccelBuffer *pthisAccelBuffer,               ///< Buffer of measurements used as input to the accel calibration functions
    volatile int8_t *AccelCalPacketOn                   ///< Used to coordinate calibration sample storage and communications
);
/// Update the buffer used to store samples used for accelerometer calibration.
void fUpdateAccelBuffer(
    struct AccelCalibration *pthisAccelCal,             ///< Accelerometer calibration parameter structure
    struct AccelBuffer *pthisAccelBuffer,               ///< Buffer of measurements used as input to the accel calibration functions
    struct AccelSensor* pthisAccel,                     ///< Pointer to the accelerometer input/state structure
    volatile int8_t *AccelCalPacketOn                   ///< Used to coordinate calibration sample storage and communications
);
/// function maps the accelerometer data fGs (g) onto precision calibrated and de-rotated data fGc (g), iGc (counts)
void fInvertAccelCal(
    struct AccelSensor *pthisAccel,                     ///< Pointer to the accelerometer input/state structure
    struct AccelCalibration *pthisAccelCal              ///< Accelerometer calibration parameter structure
);
/// function runs the precision accelerometer calibration
void fRunAccelCalibration(
    struct AccelCalibration *pthisAccelCal,             ///< Accelerometer calibration parameter structure
    struct AccelBuffer *pthisAccelBuffer,               ///< Buffer of measurements used as input to the accel calibration functions
    struct AccelSensor* pthisAccel                      ///< Pointer to the accelerometer input/state structure
);
/// calculate the 4 element calibration from the available measurements
void fComputeAccelCalibration4(
    struct AccelBuffer *pthisAccelBuffer,               ///< Buffer of measurements used as input to the accel calibration functions
    struct AccelCalibration *pthisAccelCal,             ///< Accelerometer calibration parameter structure
    struct AccelSensor* pthisAccel                      ///< Pointer to the accelerometer input/state structure
);
/// calculate the 7 element calibration from the available measurements
void fComputeAccelCalibration7(
    struct AccelBuffer *pthisAccelBuffer,               ///< Buffer of measurements used as input to the accel calibration functions
    struct AccelCalibration *pthisAccelCal,             ///< Accelerometer calibration parameter structure
    struct AccelSensor* pthisAccel                      ///< Pointer to the accelerometer input/state structure
);
/// calculate the 10 element calibration from the available measurements
void fComputeAccelCalibration10(
    struct AccelBuffer *pthisAccelBuffer,               ///< Buffer of measurements used as input to the accel calibration functions
    struct AccelCalibration *pthisAccelCal,             ///< Accelerometer calibration parameter structure
    struct AccelSensor* pthisAccel                      ///< Pointer to the accelerometer input/state structure
);

#endif // PRECISIONACCELEROMETER_H