Design Of Visual System Based On Real-time Linux

Vision sensors are good choices for their advanced theory and their own superiorities. So a real-time, efficient visual system is essential to improve robots' perceptual ability. However, for basing mainly on general operation system, visual system lacks optimized visual sensor driver, and for their image-processing software highly redundant and lack of unified programming interface, the system is of low efficiency and bad portable ability.This thesis focuses on the following three aspects during the design of visual system:1. Real-time transformation of general Linux. Low-Latency Patch and Preemptible kernel patch had been accepted by standard Linux 2.6 kernel now, which had greatly reduced the latency in the kernel. This thesis makes a deep research on the two realizations, and introduce a fully preemptible kernel patch to enhance the preemptability of the Linux kernel, making the kernel almost preemtible everywhere to reduce latency more efficiently.2. Design a high precise timer. In order to improve real-time capacity of Linux system, it is crucial to improve the resolution of kernel timer. Since the original timers only have MS resolution, this thesis designs aμS resolution timer based on GTOD, which is organised by red-black-tree and adopts nanosecond as its timing unit.3. Design a USB camera driver based on V4L2. For the time being, as for USB camera drivers, GSPCA, based on V4L1, is the most popular one among Linux open source community and surppots the widest scope of cameras. To promote the gathering efficiency of videos and make a full use of V4L2, it is essential to redesign V4L2-based camera driver.4. Design a color segmentation library. To meet robots' visual processing demands, this paper designs a color image segmentation library by adopting real-time segmenting algorithm. The segmentation library, with real-time process and abundant target message interfaces, can greatly simplify high-level image processing program, so developers can concentrate more on high-level process and ignore low-level details.It is proved that, the visual system designed in this paper have the characteristics of low response latency, fast image-gathering speed, comparatively strong image-processing ability and color segmentation library which can provide low-level interfaces for different image-processing research. In one word, this design of visual system is a success.