File content as of revision 6:cc0a54642cdb:

/*CODED by Qiyong Mu on 21/06/2014
kylongmu@msn.com
*/
#include "mbed.h"
#include "MPU9250.h"
#define Kp 0.5f         // proportional gain governs rate of convergence to accelerometer/magnetometer
#define Ki 0.0f//0.005f       // integral gain governs rate of convergence of gyroscope biases
 Timer LoopTimer;
 Timer SensorTimer;
float Times[10] = {0,0,0,0,0,0,0,0,0,0};
float control_frequency = 800;//PPM_FREQU;         // frequency for the main loop in Hz
int counter = 0;
int divider = 20;
float dt;                       // time for entire loop
float dt_sensors;               // time only to read sensors
float q0 = 1, q1 = 0, q2 = 0, q3 = 0;
float q0_A = 1, q1_A = 0, q2_A = 0, q3_A = 0;
float exInt = 0, eyInt = 0, ezInt = 0;
float OX = 0, OY = 0, OZ = 0;
float Mag_x_pre,Mag_y_pre,Mag_z_pre;
float Mag_x_pre_L,Mag_y_pre_L,Mag_z_pre_L;
float Mag_x_pre_LL,Mag_y_pre_LL,Mag_z_pre_LL;
float Mag_x_pre_LLL,Mag_y_pre_LLL,Mag_z_pre_LLL;
float Mag_x_ave,Mag_y_ave,Mag_x_total,Mag_y_total;
float Cal_Mag_x_pre_LL,Cal_Mag_x_pre_L,Cal_Mag_x_pre,Cal_Mag_x;
float GYRO_z_pre,GYRO_z_pre_L,GYRO_z_pre_LL,GYRO_z_pre_LLL;
float GYRO_z_total,GYRO_z_offset,Global_GYRO_z;
float Global_mag_vector_angle,Yaw_pre;
float Global_mag_x_vector_angle,Mag_x_vector_angle;
float Global_mag_y_vector_angle,Mag_y_vector_angle;
int Count_mag_check=0;
float angle[3];
float Roll,Pitch,Yaw;
float calibrated_values[3],magCalibrationp[3];
float v_index[3];
float dest1,dest2;
int f=0;
int j=0;
int k=0;
int g=0;
int count1=0,count2=0,count3=0,count4=0,count5=0,count6=0,count7=0,count8=0,count9=0,count11=0,count12=0,count14=0;
int Rot_index;
float mRes = 10.*4912./32760.0;
DigitalOut myled(LED1);
Serial pc(SERIAL_TX, SERIAL_RX);
SPI spi(SPI_MOSI, SPI_MISO, SPI_SCK);
mpu9250_spi imu(spi,SPI_CS);   //define the mpu9250 object

void Filter_IMUupdate(float halfT, float gx, float gy, float gz, float ax, float ay, float az) {
    float norm;
    float vx, vy, vz;
    float ex, ey, ez;         
    
    // normalise the measurements
    norm = sqrt(ax*ax + ay*ay + az*az);
    if(norm == 0.0f) return;   
    ax /= norm;
    ay /= norm;
    az /= norm;      
    
    // estimated direction of gravity
    vx = 2*(q1*q3 - q0*q2);
    vy = 2*(q0*q1 + q2*q3);
    vz = q0*q0 - q1*q1 - q2*q2 + q3*q3;
    
    // error is sum of cross product between reference direction of field and direction measured by sensor
    ex = (ay*vz - az*vy);
    ey = (az*vx - ax*vz);
    ez = (ax*vy - ay*vx);
    
    // integral error scaled integral gain
    exInt += ex*Ki;
    eyInt += ey*Ki;
    ezInt += ez*Ki;
    
    // adjusted gyroscope measurements
    gx += Kp*ex + exInt;
    gy += Kp*ey + eyInt;
    gz += Kp*ez + ezInt;
    
    // integrate quaternion rate and normalise
    float q0o = q0; // he did the MATLAB to C error by not thinking of the beginning vector elements already being changed for the calculation of the rest!
    float q1o = q1;
    float q2o = q2;
    float q3o = q3;
    q0 += (-q1o*gx - q2o*gy - q3o*gz)*halfT;
    q1 += (q0o*gx + q2o*gz - q3o*gy)*halfT;
    q2 += (q0o*gy - q1o*gz + q3o*gx)*halfT;
    q3 += (q0o*gz + q1o*gy - q2o*gx)*halfT;  
    
    // normalise quaternion
    norm = sqrt(q0*q0 + q1*q1 + q2*q2 + q3*q3);
    q0 = q0 / norm;
    q1 = q1 / norm;
    q2 = q2 / norm;
    q3 = q3 / norm;
}
void IMU_AHRSupdate(float halfT, float gx, float gy, float gz, float ax, float ay, float az, float mx, float my, float mz) {
    float norm;
    float hx, hy, hz, bx, bz;
    float vx, vy, vz, wx, wy, wz;
    float ex, ey, ez;

    // auxiliary variables to reduce number of repeated operations
    float q0q0 = q0*q0;
    float q0q1 = q0*q1;
    float q0q2 = q0*q2;
    float q0q3 = q0*q3;
    float q1q1 = q1*q1;
    float q1q2 = q1*q2;
    float q1q3 = q1*q3;
    float q2q2 = q2*q2;   
    float q2q3 = q2*q3;
    float q3q3 = q3*q3;          
    
    // normalise the measurements
    norm = sqrt(ax*ax + ay*ay + az*az);
    if(norm == 0.0f) return;
    ax = ax / norm;
    ay = ay / norm;
    az = az / norm;
    norm = sqrt(mx*mx + my*my + mz*mz);
  
    if(norm == 0.0f) return;
    mx = mx / norm;
    my = my / norm;
    mz = mz / norm;         
    /*OX=mx;
    OY=my;
    OZ=mz;*/
    // compute reference direction of flux
    hx = 2*mx*(0.5 - q2q2 - q3q3) + 2*my*(q1q2 - q0q3) + 2*mz*(q1q3 + q0q2);
    hy = 2*mx*(q1q2 + q0q3) + 2*my*(0.5 - q1q1 - q3q3) + 2*mz*(q2q3 - q0q1);
    hz = 2*mx*(q1q3 - q0q2) + 2*my*(q2q3 + q0q1) + 2*mz*(0.5 - q1q1 - q2q2);         
    bx = sqrt((hx*hx) + (hy*hy));
    bz = hz;        
    // estimated direction of gravity and flux (v and w)
    vx = 2*(q1q3 - q0q2);
    vy = 2*(q0q1 + q2q3);
    vz = q0q0 - q1q1 - q2q2 + q3q3;
    wx = 2*bx*(0.5 - q2q2 - q3q3) + 2*bz*(q1q3 - q0q2);
    wy = 2*bx*(q1q2 - q0q3) + 2*bz*(q0q1 + q2q3);
    wz = 2*bx*(q0q2 + q1q3) + 2*bz*(0.5 - q1q1 - q2q2);  
    
    // error is sum of cross product between reference direction of fields and direction measured by sensors
    ex = (ay*vz - az*vy) + (my*wz - mz*wy);
    ey = (az*vx - ax*vz) + (mz*wx - mx*wz);
    ez = (ax*vy - ay*vx) + (mx*wy - my*wx);
    

    // integral error scaled integral gain
    exInt = exInt + ex*Ki;
    eyInt = eyInt + ey*Ki;
    ezInt = ezInt + ez*Ki;
  
    // adjusted gyroscope measurements
    gx = gx + Kp*ex + exInt;
    gy = gy + Kp*ey + eyInt;
    gz = gz + Kp*ez + ezInt;
    
    // integrate quaternion rate and normalise
    q0_A = q0_A + (-q1*gx - q2*gy - q3*gz)*halfT;
    q1_A = q1_A + (q0*gx + q2*gz - q3*gy)*halfT;
    q2_A = q2_A + (q0*gy - q1*gz + q3*gx)*halfT;
    q3_A = q3_A + (q0*gz + q1*gy - q2*gx)*halfT;  
    
    // normalise quaternion
    norm = sqrt(q0*q0 + q1*q1 + q2*q2 + q3*q3);
    q0_A = q0_A / norm;
    q1_A = q1_A / norm;
    q2_A = q2_A / norm;
    q3_A = q3_A / norm;
}

    
    

void Filter_compute(float dt, const float * Gyro_data, const float * Acc_data, const float * Comp_data)
{
    // IMU/AHRS

    float d_Gyro_angle[3];
    void get_Acc_angle(const float * Acc_data);
     // IMU/AHRS (from http://www.x-io.co.uk/open-source-imu-and-ahrs-algorithms/)   
    float radGyro[3],Gyro_cal_data; // Gyro in radians per second
    
    for(int i=0; i<3; i++)
        radGyro[i] = Gyro_data[i] * 3.14159/ 180;
        
        Filter_IMUupdate(dt/2, radGyro[0], radGyro[1], radGyro[2], Acc_data[0], Acc_data[1], Acc_data[2]);
        IMU_AHRSupdate(dt/2, radGyro[0], radGyro[1], radGyro[2], Acc_data[0], Acc_data[1], Acc_data[2], Comp_data[0], Comp_data[1], Comp_data[2]);
        
        float rangle[3]; // calculate angles in radians from quternion output, formula from Wiki (http://en.wikipedia.org/wiki/Conversion_between_quaternions_and_Euler_angles)
        
        rangle[0] = atan2(2*q0*q1 + 2*q2*q3, 1 - 2*(q1*q1 + q2*q2));
        rangle[1] = asin (2*q0*q2 - 2*q3*q1);
        rangle[2] = atan2(2*q0_A*q3_A + 2*q1_A*q2_A, 1 - 2*(q2_A*q2_A + q3_A*q3_A));            // Z-axis
        
        
        for(int i=0; i<2; i++){  // angle in degree
            angle[i] = rangle[i] * 180 / 3.14159;
        }
        Roll=angle[0];
        Pitch=angle[1];
//**************************************************Gyro_data[2]  filter      start
        float GYRO_z=0;

        GYRO_z=Gyro_data[2]*0.15 + GYRO_z_pre*0.20 + GYRO_z_pre_L*0.20 + GYRO_z_pre_LL*0.25 + GYRO_z_pre_LLL*0.20;
        if( count4==1 ){
            GYRO_z_pre_L=GYRO_z_pre;
            
            count4=0;
        }
        if( count5==2 ){
            GYRO_z_pre_LL=GYRO_z_pre_L;
            
            count5=0;
        }
        if( count6==3 ){
            GYRO_z_pre_LLL=GYRO_z_pre_LL;
            
            count6=0;
        }
        
       
        
        count4++;
        count5++;
        count6++;
        GYRO_z_pre=Gyro_data[2];
        Global_GYRO_z=GYRO_z;
       /*pc.printf("     GYRO_z:%10.3f     ,count8:%10d   ", 
            GYRO_z,
            count8
            );*/
        if((count8>5)&&(count8<=805)){
            GYRO_z_total+=GYRO_z;
        }
        if( count8==805 ){
            GYRO_z_offset=GYRO_z_total/800;
            /*pc.printf("     GYRO_z_offset:%10.5f     ", 
            GYRO_z_offset
            );*/
            GYRO_z_total=0;
            count8=0;
        }

        count8++;
//**************************************************Gyro_data[2]'s average  filter   :     answer=GYRO_Z is roughly = 1.05447

//************************************************** calculate Yaw
    if( (count11==35) ){
        if( abs(Yaw_pre-Yaw)<1 ){
            Yaw_pre=Yaw_pre;
        }else{
            Yaw_pre=Yaw;
        }
        count11=0;
    }
    count11++;
        
    if( count12>=20 ){
        Yaw += (Gyro_data[2]-1.05447) *dt; 
    }
    count12++;
    pc.printf("     Yaw:%10.5f     ", 
            Yaw
    );
}
void Mag_Complentary_Filter(float dt, const float * Comp_data)
{
        float Mag_x=0,Mag_y=0,Mag_z=0;
        Mag_x=Comp_data[0]*0.15 + Mag_x_pre*0.20 + Mag_x_pre_L*0.20 + Mag_x_pre_LL*0.25 + Mag_x_pre_LLL*0.20;
        Mag_y=Comp_data[1]*0.15 + Mag_y_pre*0.20 + Mag_y_pre_L*0.20 + Mag_y_pre_LL*0.25 + Mag_y_pre_LLL*0.20;
        Mag_z=Comp_data[2]*0.15 + Mag_z_pre*0.20 + Mag_z_pre_L*0.20 + Mag_z_pre_LL*0.25 + Mag_z_pre_LLL*0.20;
        
        
        if( count1==1 ){
            Mag_x_pre_L=Mag_x_pre;
            Mag_y_pre_L=Mag_y_pre;
            Mag_z_pre_L=Mag_z_pre;
            Cal_Mag_x_pre=Cal_Mag_x;
            
            count1=0;
        }
        if( count2==2 ){
            Mag_x_pre_LL=Mag_x_pre_L;
            Mag_y_pre_LL=Mag_y_pre_L;
            Mag_z_pre_LL=Mag_z_pre_L;
            Cal_Mag_x_pre_L=Cal_Mag_x_pre;
            
            count2=0;
        }
        if( count7==3 ){
            Mag_x_pre_LLL=Mag_x_pre_LL;
            Mag_y_pre_LLL=Mag_y_pre_LL;
            Mag_z_pre_LLL=Mag_z_pre_LL;
            Cal_Mag_x_pre_LL=Cal_Mag_x_pre_L;
        
            count7=0;
        }

        
        count1++;
        count2++;
        count7++;
        Mag_x_pre=Comp_data[0];
        Mag_y_pre=Comp_data[1];
        Mag_z_pre=Comp_data[2];
        if( count14>4 ){ 
            Cal_Mag_x=Mag_x;             
        }
        count14++;
        
        
//*************************************Mag_ave calculate
        if(count3<=20){
            Mag_x_total+=Mag_x;
            Mag_y_total+=Mag_y;
        }
        if( count3==20){
            Mag_x_ave=Mag_x_total/21;
            Mag_y_ave=Mag_y_total/21;
            /*pc.printf("     Mag_x_ave:%10.5f    ,Mag_y_ave:%10.5f     ", 
            Mag_x_ave,
            Mag_y_ave
            );*/
            Mag_x_total=0;
            Mag_y_total=0;
            count3=0;
            
            
        }
        count3++;
        
//********************************ROT_check  start

        float v_length,v_length_ave,MagVector_angle;
        v_length=sqrt( Mag_x*Mag_x + Mag_y*Mag_y );
        v_length_ave=sqrt( Mag_x_ave*Mag_x_ave + Mag_y_ave*Mag_y_ave );
        
        MagVector_angle=acos(( Mag_x*Mag_x_ave + Mag_y*Mag_y_ave )/(v_length*v_length_ave))*57.3;
        
        if( count9==3 ){
            Global_mag_vector_angle=MagVector_angle;
            count9=0;
        }
        count9++;
        
        
        if( (abs(Global_mag_vector_angle-MagVector_angle)<5) && (abs(Global_GYRO_z)<5) ){
            Count_mag_check++;
            
        }else{ Count_mag_check=0; }
        
        if( Count_mag_check==30 ){
            Yaw=Yaw_pre;
            Count_mag_check=0;
        }
        float ABS_CHECK=abs(Global_mag_vector_angle-MagVector_angle);
//********************************Theta_check  end
        /*pc.printf("ABS_CHECK:%10.3f,Cal_Mag_x_pre_LL:%10.3f,Mag_x:%10.3f,Count_mag_check:%10d ,Yaw_pre:%10.3f,Yaw_filter:%10.3f    ", 
            ABS_CHECK,
            Cal_Mag_x_pre_LL,
            Mag_x,
            Count_mag_check,
            Yaw_pre,
            Yaw
            );*/

}
int main(){
    pc.baud(115200);
    if(imu.init(1,BITS_DLPF_CFG_188HZ)){  //INIT the mpu9250
        pc.printf("\nCouldn't initialize MPU9250 via SPI!");
    }    
    pc.printf("\nWHOAMI=0x%2x\n",imu.whoami()); //output the I2C address to know if SPI is working, it should be 104
    wait(1);    
    pc.printf("Gyro_scale=%u\n",imu.set_gyro_scale(BITS_FS_2000DPS));    //Set full scale range for gyros
    wait(1);  
    pc.printf("Acc_scale=%u\n",imu.set_acc_scale(BITS_FS_16G));          //Set full scale range for accs
    wait(1);
    pc.printf("AK8963 WHIAM=0x%2x\n",imu.AK8963_whoami());
    wait(0.1);  
    imu.AK8963_calib_Magnetometer();
    while(1) {

        LoopTimer.start();
        wait(0.1);
        
        SensorTimer.start();
        Times[1] = LoopTimer.read(); // 197us
        SensorTimer.stop(); // stop time for measuring sensors
        dt_sensors = SensorTimer.read();
        SensorTimer.reset();
        // meassure dt since last measurement for the filter
        dt = LoopTimer.read(); // time in s since last loop
        LoopTimer.reset();
        
        
        imu.read_all();
        
        Mag_Complentary_Filter(dt,imu.Magnetometer);
        Filter_compute(dt, imu.gyroscope_data, imu.accelerometer_data, imu.Magnetometer);
        
        pc.printf("Roll:%10.3f,Pitch:%10.3f,Yaw:%10.3f   \n", 
            Roll,
            Pitch,
            Yaw
            );
        
    }
}