四阶龙格-库塔，姿态角四元数更新算法，坐标系转换去除重力分量-Runge- Kutta attitude angle quaternion algorithm update

由于加速度计采到的数据，会受到重力轴的影响，本代码主要是去除重力。(As the accelerometer picks up the data, it will be affected by the gravitational axis. This code basically removes gravity.)