File content as of revision 12:5638ddcd8477:

/**
 * Masahiro FURUKAWA - m.furukawa@ist.osaka-u.ac.jp
 *
 * June 17, 2016
 *
 * MPU9250 9DoF Sensor (Extended to Ch1 ~ Ch2)
 *
 **/

#include "mbed.h"
#include "MPU9250.h"
#include "KalmanFilter.h"


/* MPU9250 Library
 *
 *  https://developer.mbed.org/users/kylongmu/code/MPU9250_SPI_Test/file/5839d1b118bc/main.cpp

    MOSI (Master Out Slave In)  p5
    MISO (Master In Slave Out   p6
    SCK  (Serial Clock)         p7
    ~CS  (Chip Select)          p8
 */

/* Reference
 *
 * AHRS algorithm is one of hte sensor fusion algorism.
 * http://www.x-io.co.uk/open-source-imu-and-ahrs-algorithms/AHRS algorithm is one of hte sensor fusion algorism.
 * http://www.x-io.co.uk/open-source-imu-and-ahrs-algorithms/
 */
 
//---------------------------------------------------------------------------------------------------
// Definitions

#define sampleFreq  500.0f      // sample frequency in Hz
#define betaDef     1.0f        // 2 * proportional gain
#define PI          3.14159265358979f
#define DEGREE2RAD  PI/180.0f
class MadgwickAHRS
{
//---------------------------------------------------------------------------------------------------
// Variable definitions

private:
    volatile float beta;         // 2 * proportional gain (Kp)
    
//---------------------------------------------------------------------------------------------------
// Function declarations
public:
    volatile float q0,q1,q2,q3;  // quaternion of sensor frame relative to auxiliary frame

    MadgwickAHRS();
    void update(float gx, float gy, float gz, float ax, float ay, float az, float mx, float my, float mz);
    void updateIMU(float gx, float gy, float gz, float ax, float ay, float az);
    float invSqrt(float x);
};
//====================================================================================================
// Functions

//---------------------------------------------------------------------------------------------------
// AHRS algorithm update
MadgwickAHRS::MadgwickAHRS()
{
    beta = betaDef;     // 2 * proportional gain (Kp)
    q0 = 1.0f;
    q1 = 0.0f;
    q2 = 0.0f;
    q3 = 0.0f;          // quaternion of sensor frame relative to auxiliary frame
}
void MadgwickAHRS::update(float gx, float gy, float gz, float ax, float ay, float az, float mx, float my, float mz)
{
    float recipNorm;
    float s0, s1, s2, s3;
    float qDot1, qDot2, qDot3, qDot4;
    float hx, hy;
    float _2q0mx, _2q0my, _2q0mz, _2q1mx, _2bx, _2bz, _4bx, _4bz, _2q0, _2q1, _2q2, _2q3, _2q0q2, _2q2q3, q0q0, q0q1, q0q2, q0q3, q1q1, q1q2, q1q3, q2q2, q2q3, q3q3;

    // Use IMU algorithm if magnetometer measurement invalid (avoids NaN in magnetometer normalisation)
    if((mx == 0.0f) && (my == 0.0f) && (mz == 0.0f)) {
        updateIMU(gx, gy, gz, ax, ay, az);
        return;
    }

    // Rate of change of quaternion from gyroscope
    qDot1 = 0.5f * (-q1 * gx - q2 * gy - q3 * gz);
    qDot2 = 0.5f * (q0 * gx + q2 * gz - q3 * gy);
    qDot3 = 0.5f * (q0 * gy - q1 * gz + q3 * gx);
    qDot4 = 0.5f * (q0 * gz + q1 * gy - q2 * gx);

    // Compute feedback only if accelerometer measurement valid (avoids NaN in accelerometer normalisation)
    if(!((ax == 0.0f) && (ay == 0.0f) && (az == 0.0f))) {

        // Normalise accelerometer measurement
        recipNorm = invSqrt(ax * ax + ay * ay + az * az);
        ax *= recipNorm;
        ay *= recipNorm;
        az *= recipNorm;

        // Normalise magnetometer measurement
        recipNorm = invSqrt(mx * mx + my * my + mz * mz);
        mx *= recipNorm;
        my *= recipNorm;
        mz *= recipNorm;

        // Auxiliary variables to avoid repeated arithmetic
        _2q0mx = 2.0f * q0 * mx;
        _2q0my = 2.0f * q0 * my;
        _2q0mz = 2.0f * q0 * mz;
        _2q1mx = 2.0f * q1 * mx;
        _2q0 = 2.0f * q0;
        _2q1 = 2.0f * q1;
        _2q2 = 2.0f * q2;
        _2q3 = 2.0f * q3;
        _2q0q2 = 2.0f * q0 * q2;
        _2q2q3 = 2.0f * q2 * q3;
        q0q0 = q0 * q0;
        q0q1 = q0 * q1;
        q0q2 = q0 * q2;
        q0q3 = q0 * q3;
        q1q1 = q1 * q1;
        q1q2 = q1 * q2;
        q1q3 = q1 * q3;
        q2q2 = q2 * q2;
        q2q3 = q2 * q3;
        q3q3 = q3 * q3;

        // Reference direction of Earth's magnetic field
        hx = mx * q0q0 - _2q0my * q3 + _2q0mz * q2 + mx * q1q1 + _2q1 * my * q2 + _2q1 * mz * q3 - mx * q2q2 - mx * q3q3;
        hy = _2q0mx * q3 + my * q0q0 - _2q0mz * q1 + _2q1mx * q2 - my * q1q1 + my * q2q2 + _2q2 * mz * q3 - my * q3q3;
        _2bx = sqrt(hx * hx + hy * hy);
        _2bz = -_2q0mx * q2 + _2q0my * q1 + mz * q0q0 + _2q1mx * q3 - mz * q1q1 + _2q2 * my * q3 - mz * q2q2 + mz * q3q3;
        _4bx = 2.0f * _2bx;
        _4bz = 2.0f * _2bz;

        // Gradient decent algorithm corrective step
        s0 = -_2q2 * (2.0f * q1q3 - _2q0q2 - ax) + _2q1 * (2.0f * q0q1 + _2q2q3 - ay) - _2bz * q2 * (_2bx * (0.5f - q2q2 - q3q3) + _2bz * (q1q3 - q0q2) - mx) + (-_2bx * q3 + _2bz * q1) * (_2bx * (q1q2 - q0q3) + _2bz * (q0q1 + q2q3) - my) + _2bx * q2 * (_2bx * (q0q2 + q1q3) + _2bz * (0.5f - q1q1 - q2q2) - mz);
        s1 = _2q3 * (2.0f * q1q3 - _2q0q2 - ax) + _2q0 * (2.0f * q0q1 + _2q2q3 - ay) - 4.0f * q1 * (1 - 2.0f * q1q1 - 2.0f * q2q2 - az) + _2bz * q3 * (_2bx * (0.5f - q2q2 - q3q3) + _2bz * (q1q3 - q0q2) - mx) + (_2bx * q2 + _2bz * q0) * (_2bx * (q1q2 - q0q3) + _2bz * (q0q1 + q2q3) - my) + (_2bx * q3 - _4bz * q1) * (_2bx * (q0q2 + q1q3) + _2bz * (0.5f - q1q1 - q2q2) - mz);
        s2 = -_2q0 * (2.0f * q1q3 - _2q0q2 - ax) + _2q3 * (2.0f * q0q1 + _2q2q3 - ay) - 4.0f * q2 * (1 - 2.0f * q1q1 - 2.0f * q2q2 - az) + (-_4bx * q2 - _2bz * q0) * (_2bx * (0.5f - q2q2 - q3q3) + _2bz * (q1q3 - q0q2) - mx) + (_2bx * q1 + _2bz * q3) * (_2bx * (q1q2 - q0q3) + _2bz * (q0q1 + q2q3) - my) + (_2bx * q0 - _4bz * q2) * (_2bx * (q0q2 + q1q3) + _2bz * (0.5f - q1q1 - q2q2) - mz);
        s3 = _2q1 * (2.0f * q1q3 - _2q0q2 - ax) + _2q2 * (2.0f * q0q1 + _2q2q3 - ay) + (-_4bx * q3 + _2bz * q1) * (_2bx * (0.5f - q2q2 - q3q3) + _2bz * (q1q3 - q0q2) - mx) + (-_2bx * q0 + _2bz * q2) * (_2bx * (q1q2 - q0q3) + _2bz * (q0q1 + q2q3) - my) + _2bx * q1 * (_2bx * (q0q2 + q1q3) + _2bz * (0.5f - q1q1 - q2q2) - mz);
        recipNorm = invSqrt(s0 * s0 + s1 * s1 + s2 * s2 + s3 * s3); // normalise step magnitude
        s0 *= recipNorm;
        s1 *= recipNorm;
        s2 *= recipNorm;
        s3 *= recipNorm;

        // Apply feedback step
        qDot1 -= beta * s0;
        qDot2 -= beta * s1;
        qDot3 -= beta * s2;
        qDot4 -= beta * s3;
    }

    // Integrate rate of change of quaternion to yield quaternion
    q0 += qDot1 * (1.0f / sampleFreq);
    q1 += qDot2 * (1.0f / sampleFreq);
    q2 += qDot3 * (1.0f / sampleFreq);
    q3 += qDot4 * (1.0f / sampleFreq);

    // Normalise quaternion
    recipNorm = invSqrt(q0 * q0 + q1 * q1 + q2 * q2 + q3 * q3);
    q0 *= recipNorm;
    q1 *= recipNorm;
    q2 *= recipNorm;
    q3 *= recipNorm;
}

//---------------------------------------------------------------------------------------------------
// IMU algorithm update

void MadgwickAHRS::updateIMU(float gx, float gy, float gz, float ax, float ay, float az)
{
    float recipNorm;
    float s0, s1, s2, s3;
    float qDot1, qDot2, qDot3, qDot4;
    float _2q0, _2q1, _2q2, _2q3, _4q0, _4q1, _4q2 ,_8q1, _8q2, q0q0, q1q1, q2q2, q3q3;

    // Rate of change of quaternion from gyroscope
    qDot1 = 0.5f * (-q1 * gx - q2 * gy - q3 * gz);
    qDot2 = 0.5f * (q0 * gx + q2 * gz - q3 * gy);
    qDot3 = 0.5f * (q0 * gy - q1 * gz + q3 * gx);
    qDot4 = 0.5f * (q0 * gz + q1 * gy - q2 * gx);

    // Compute feedback only if accelerometer measurement valid (avoids NaN in accelerometer normalisation)
    if(!((ax == 0.0f) && (ay == 0.0f) && (az == 0.0f))) {

        // Normalise accelerometer measurement
        recipNorm = invSqrt(ax * ax + ay * ay + az * az);
        ax *= recipNorm;
        ay *= recipNorm;
        az *= recipNorm;

        // Auxiliary variables to avoid repeated arithmetic
        _2q0 = 2.0f * q0;
        _2q1 = 2.0f * q1;
        _2q2 = 2.0f * q2;
        _2q3 = 2.0f * q3;
        _4q0 = 4.0f * q0;
        _4q1 = 4.0f * q1;
        _4q2 = 4.0f * q2;
        _8q1 = 8.0f * q1;
        _8q2 = 8.0f * q2;
        q0q0 = q0 * q0;
        q1q1 = q1 * q1;
        q2q2 = q2 * q2;
        q3q3 = q3 * q3;

        // Gradient decent algorithm corrective step
        s0 = _4q0 * q2q2 + _2q2 * ax + _4q0 * q1q1 - _2q1 * ay;
        s1 = _4q1 * q3q3 - _2q3 * ax + 4.0f * q0q0 * q1 - _2q0 * ay - _4q1 + _8q1 * q1q1 + _8q1 * q2q2 + _4q1 * az;
        s2 = 4.0f * q0q0 * q2 + _2q0 * ax + _4q2 * q3q3 - _2q3 * ay - _4q2 + _8q2 * q1q1 + _8q2 * q2q2 + _4q2 * az;
        s3 = 4.0f * q1q1 * q3 - _2q1 * ax + 4.0f * q2q2 * q3 - _2q2 * ay;
        recipNorm = invSqrt(s0 * s0 + s1 * s1 + s2 * s2 + s3 * s3); // normalise step magnitude
        s0 *= recipNorm;
        s1 *= recipNorm;
        s2 *= recipNorm;
        s3 *= recipNorm;

        // Apply feedback step
        qDot1 -= beta * s0;
        qDot2 -= beta * s1;
        qDot3 -= beta * s2;
        qDot4 -= beta * s3;
    }

    // Integrate rate of change of quaternion to yield quaternion
    q0 += qDot1 * (1.0f / sampleFreq);
    q1 += qDot2 * (1.0f / sampleFreq);
    q2 += qDot3 * (1.0f / sampleFreq);
    q3 += qDot4 * (1.0f / sampleFreq);

    // Normalise quaternion
    recipNorm = invSqrt(q0 * q0 + q1 * q1 + q2 * q2 + q3 * q3);
    q0 *= recipNorm;
    q1 *= recipNorm;
    q2 *= recipNorm;
    q3 *= recipNorm;
}

//---------------------------------------------------------------------------------------------------
// Fast inverse square-root
// See: http://en.wikipedia.org/wiki/Fast_inverse_square_root

float MadgwickAHRS::invSqrt(float x)
{
    float halfx = 0.5f * x;
    float y = x;
    long i = *(long*)&y;
    i = 0x5f3759df - (i>>1);
    y = *(float*)&i;
    y = y * (1.5f - (halfx * y * y));
    return y;
}



//define the mpu9250 object
mpu9250_spi     *imu[2];
MadgwickAHRS    *ahrs[2];
Serial          pc(USBTX, USBRX);
SPI             spi(p5, p6, p7);
KalmanFilter    *kf[12];
Ticker          ticker;

float x,y,z,gxOfs,gyOfs,gzOfs;
// Calibration wait

void resetOffset(void)
{

    gxOfs = 0.0f;
    gyOfs = 0.0f;
    gzOfs = 0.0f;

    imu[0]->deselect();
    imu[1]->deselect();

    imu[0]->select();

    for(int i=0; i<1000; i++) {

        imu[0]->read_all();

        gxOfs += imu[0]->gyroscope_data[0];
        gyOfs += imu[0]->gyroscope_data[1];
        gzOfs += imu[0]->gyroscope_data[2];

        wait_us(1000000.0f/sampleFreq);
    }

    gxOfs /= 1000.0f;
    gyOfs /= 1000.0f;
    gzOfs /= 1000.0f;

    ahrs[0]->q0 = 1.0f;
    ahrs[0]->q1 = 0.0f;
    ahrs[0]->q2 = 0.0f;
    ahrs[0]->q3 = 0.0f;
}

void init(void)
{

    pc.baud(921600);

    imu[0] = new mpu9250_spi(spi, p8);
    imu[1] = new mpu9250_spi(spi, p9);

    ahrs[0] = new MadgwickAHRS();
    ahrs[1] = new MadgwickAHRS();

    for(int i=0; i<2; i++) {

        imu[0]->deselect();
        imu[1]->deselect();
        imu[i]->select();

        if(imu[i]->init(1,BITS_DLPF_CFG_188HZ)) { //INIT the mpu9250
            printf("\nCH %d\n\nCouldn't initialize MPU9250 via SPI!", i);
            wait(90);
        }
        printf("\nCH %d\nWHOAMI=0x%2x\n",i, imu[i]->whoami()); //output the I2C address to know if SPI is working, it should be 104
        printf("Gyro_scale=%u\n",imu[i]->set_gyro_scale(BITS_FS_1000DPS));    //Set full scale range for gyros
        printf("Acc_scale=%u\n",imu[i]->set_acc_scale(BITS_FS_16G));          //Set full scale range for accs
        printf("AK8963 WHIAM=0x%2x\n",imu[i]->AK8963_whoami());
        imu[i]->AK8963_calib_Magnetometer();
        wait(0.1);
    }
    resetOffset();
}

void eventFunc(void)
{
    for(int i=0; i<2; i++) {

        imu[0]->deselect();
        imu[1]->deselect();

        imu[i]->select();
        imu[i]->read_all();
    }
    for(int i=0; i<2; i++) {
        ahrs[i]->update(
            (imu[i]->gyroscope_data[0]-gxOfs)*DEGREE2RAD,
            (imu[i]->gyroscope_data[1]-gyOfs)*DEGREE2RAD,
            (imu[i]->gyroscope_data[2]-gzOfs)*DEGREE2RAD,
            imu[i]->accelerometer_data[0],
            imu[i]->accelerometer_data[1],
            imu[i]->accelerometer_data[2],
            imu[i]->Magnetometer[0],
            imu[i]->Magnetometer[1],
            imu[i]->Magnetometer[2]
        );

        printf("%+0.3f,%+0.3f,%+0.3f,%+0.3f,",
               ahrs[i]->q0,ahrs[i]->q1,ahrs[i]->q2,ahrs[i]->q3);
    }
    printf("\n");
}

int main()
{
    init();

    ticker.attach_us(eventFunc, 1000000.0f/sampleFreq);

    while(1) {

        if(pc.readable())
            if(pc.getc() == 'r') {
                ticker.detach();
                resetOffset();
                ticker.attach_us(eventFunc, 1000000.0f/sampleFreq);
            }
        /*
        imu[i]->read_all();
        printf("%10.3f,%10.3f,%10.3f,%10.3f,%10.3f,%10.3f,%10.3f,%10.3f,%10.3f,%10.3f ",
               imu[i]->Temperature,
               imu[i]->gyroscope_data[0],
               imu[i]->gyroscope_data[1],
               imu[i]->gyroscope_data[2],
               imu[i]->accelerometer_data[0],
               imu[i]->accelerometer_data[1],
               imu[i]->accelerometer_data[2],
               imu[i]->Magnetometer[0],
               imu[i]->Magnetometer[1],
               imu[i]->Magnetometer[2]
              );*/
        //myled = 0;
        //wait(0.5);
    }
}