//欧拉角转四元数

void cjx_from_euler(float roll, float pitch, float yaw)

{

    float cr2 = cosf(roll*0.5f);

    float cp2 = cosf(pitch*0.5f);

    float cy2 = cosf(yaw*0.5f);

    float sr2 = sinf(roll*0.5f);

    float sp2 = sinf(pitch*0.5f);

    float sy2 = sinf(yaw*0.5f);

    q1 = cr2*cp2*cy2 + sr2*sp2*sy2;

    q2 = sr2*cp2*cy2 - cr2*sp2*sy2;

    q3 = cr2*sp2*cy2 + sr2*cp2*sy2;

    q4 = cr2*cp2*sy2 - sr2*sp2*cy2;

}

#define RAD_TO_DEG 57.29577951f

//弧度转角度

float degrees(float rad) 

{

return rad * RAD_TO_DEG;

}

//四元数转欧拉角

void cjx_to_euler(float *roll, float *pitch, float *yaw)

{

    if (roll) {

        *roll = degrees(atan2f(2.0f*(q1*q2 + q3*q4),1 - 2.0f*(q2*q2 + q3*q3)));

    }

    if (pitch) {

        // 使用safe_asin()来处理pitch接近90/-90时的奇点

        *pitch = degrees(safe_asin(2.0f*(q1*q3 - q2*q4)));

    }

    if (yaw) {

        *yaw = degrees(atan2f(2.0f*(q2*q3 - q1*q4), 2.0f*(q1*q1 + q2*q2) - 1));

    }

}

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飞控姿态解算中，欧拉角与四元数之间的转换