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  • can you clarify  
    is q0 q1 q2 q3 is w x y z of quat or x y z w. 

    my data is like this

    Sample acceleration data is
    -0.92 0.18 10.15
    -2.14 0.83 10.07
    -1.05 0.23 10.14 

    And sample quat data is (Not normalized)
    16363 201 754 -300
    16363 201 754 -273
    16364 201 753 -234

    what do mean by accel_x_scaled? And what should i do in my case



    Baris said:

    basicly convert your imu readings to quaternion  then

    gx, gy, gz represents gravity in x, y and z axis respectively

    gx = 2 * (q1 * q3 - q0 * q2);
    gy = 2 * (q0 * q1 + q2 * q3);
    gz = q0 * q0 - q1 * q1 - q2 * q2 + q3 * q3;

    the result of gx gy and gz will be unit vector

    then conver all your accelerometer results to g ex: assume your accelerometer reads z = 256 x = 0 y = 0  when its leveled so accel_z_scaled = 256/256 = 1g,  accel_x_scaled = 0/256 = 0g, accel_y_scaled= 0/256 = 0g  

    acc_x_wog = (accel_x_scaled - gx) * 9.8;

    acc_y_wog = (accel_y_scaled - gy) * 9.8;
    acc_z_wog = (accel_z_scaled - gz) * 9.8;

    will give you linear acceleration in each axis even in any attitude

    note: wog means: w/o gravity

    and sorry this is not in cosine matrix, I only know in quaternion

  • @Baris can you clarify  
    is q0 q1 q2 q3 is w x y z of quat or x y z w. 

    my data is like this

    Sample acceleration data is
    -0.92 0.18 10.15
    -2.14 0.83 10.07
    -1.05 0.23 10.14 

    And sample quat data is (Not normalized)
    16363 201 754 -300
    16363 201 754 -273
    16364 201 753 -234

    what do mean by accel_x_scaled? And what should i do in my case

  • basicly convert your imu readings to quaternion  then

    gx, gy, gz represents gravity in x, y and z axis respectively

    gx = 2 * (q1 * q3 - q0 * q2);
    gy = 2 * (q0 * q1 + q2 * q3);
    gz = q0 * q0 - q1 * q1 - q2 * q2 + q3 * q3;

    the result of gx gy and gz will be unit vector

    then conver all your accelerometer results to g ex: assume your accelerometer reads z = 256 x = 0 y = 0  when its leveled so accel_z_scaled = 256/256 = 1g,  accel_x_scaled = 0/256 = 0g, accel_y_scaled= 0/256 = 0g  

    acc_x_wog = (accel_x_scaled - gx) * 9.8;

    acc_y_wog = (accel_y_scaled - gy) * 9.8;
    acc_z_wog = (accel_z_scaled - gz) * 9.8;

    will give you linear acceleration in each axis even in any attitude

    note: wog means: w/o gravity

    and sorry this is not in cosine matrix, I only know in quaternion

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