摘要
微型无人飞行器(Mini Unmanned Aerial Vehicle,简称MUAV)由于其独特的优势,在地型勘测、交通疏导、军事侦察等领域中已经有了广泛的应用。作为微型UAV研究领域的热点和重要组成部分,基于计算机视觉的自主降落一直受到世界各国高校及研究机构的高度关注。本文设计了一个可以辅助微型UAV自主降落的视觉系统,为确保飞机安全、精确的降落提供了保障。
论文从硬件构建和软件设计两个方面,围绕如何构建一个可靠的微型UAV视觉辅助降落系统展开讨论。系统的硬件平台使用TMS320DM642 DSP芯片作为核心处理器,辅以双目摄像机、采集模块、对外通讯模块以及电源模块等外围电路。系统的软件部分采用GIO/FVID视频驱动模型,运行的图像处理算法包括均值滤波、二值化、基于不变矩检测的停机坪识别、基于均值漂移的实时跟踪、SUSAN角点检测和双目视差测距等。整个系统能够实现对特定图标的识别、跟踪和相对高度测量。
相对于传统的GPS、声纳、陀螺仪等传感器,本文所设计的机载式DSP平台微型UAV视觉辅助降落系统有效补充了降落中所必须的位置、姿态及高度等信息,使飞机可以执行定点降落任务。同时,在增重负载和增加功耗有限的前提下,摆脱了模拟链路的传输精度限制,具有更高的性价比和灵活性,并易于与飞行控制系统相结合,为以后视觉系统功能的扩展打下了基础。
Mini Unmanned Aerial Vehicle (UAV), which possesses special features, has broad applications in various fields such as geography mapping, traffic management, military reconnaissance, etc. As an indispensable part of Mini UAV, vision system has been paid great attention by colleges and research organizations in the world. Especially, vision-based landing system plays an important role in UAV autonomous landing process. In this paper, we focus on landing vision system design which can assist UAV land automatically.
The design of landing vision system is discussed from both hardware and software aspects. Our system chooses TMS320DM642 DSP as the core processing chip, and is augmented by the capture module, communication module, power supply module, etc. The visual driver is based on TI GIO/FVID model. A series of algorithms including average filter, binarization, Hu invariant moments detection, mean shift following, SUSAN corner detection, etc. are embedded on the hardware platform. The vision system could recognize and track landing-pad, tracking and measure the relative distance based on binocular parallax.
Compare to the traditional sensors such as GPS, sonar and gyroscope, our vision landing system is able to offer positional and height information, as a result, it can assist UAV to land on a certain place. Besides, the DSP vision system designed in this paper which gets rid of the restriction of link's precision for analog transmission is more flexible and is advanced for higher Cost-Performance Ratio. The vision system is also easy to incorporate new capabilities in the future research.
引文
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