Additionally, a state-space observer was designed to estimate the sideslip angle, which was difficult to measure directly. 由于质心侧偏角信号难以直接测量，设计了状态观测器对该信号进行估计。
The direction of the emergent ray is then known, and the angle of deviation may be found. 这样就得知出射光线的方向，从而可求得偏向角。
