Aiming at situation that small unmanned helicopter( SUH) changes its attitude during landing stage, and non-differential GPS lacks of precision, a monocular vision-based SUH height measurement method is researched to enhance the quality of autonomous landing. Under the condition of obtaining the body attitude angles previously, recognizes and extracts the parallel feature straight lines according to on-board camera projection model,real-time calculate height during landing. The feasibility of this method is testified on the measuring system, and experimental results indicate that the method performs a relative high feature recognizing rate and real-time and accuracy of output result can entirely meet requirements of landing when tilt angle exists between airframe plane and landing plane%针对小型无人直升机自主降落过程中姿态发生变化和非差分GPS高程精度不高的情况,研究了一种基于单目视觉的小型无人直升机离地高度测量方法,用于提高自主降落的品质.在机体姿态角已知的情况下,识别提取降落图标中相互平行的特征直线段,并根据机载摄像头投影模型,实时求解机体降落过程中的离地高度.在测量系统上进行了实体实验,验证了所提出的方法,实验结果表明:该方法特征识别率高,在机体平面与地面存在倾角时,输出结果的实时性与准确性亦均能满足小型无人直升机自主降落要求.
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