缺株玉米行中心线提取算法研究

无人驾驶农机自主进行行驶路径检测和识别系统需要具备环境感知能力。作物行的中心线识别是环境感知的一个重要方面，已有的作物行中心线识别算法在缺株作物行中心线提取中存在检测精度低的问题。该研究提出了一种能够在缺株情况下提取玉米作物行中心线的算法。首先采用限定HSV颜色空间中颜色分量范围的方法将作物与背景分割，通过形态学处理对图像进行去噪并填补作物行空洞；然后分别在图像底部和中部的横向位置设置条状感兴趣区（Region of Interest，ROI），提取ROI内的作物行轮廓重心作为定位点。在图像顶端间隔固定步长设置上端点，利用定位点和上端点组成的扫描线扫描图像，通过作物行区域最多的扫描线即为对应目标作物行的最优线；将获取的最优线与作物行区域进行融合填充作物行中的缺株部位；最后设置动态ROI，作物行区域内面积最大轮廓拟合的直线即为目标作物行中心线。试验结果表明，对于不同缺株情况下的玉米图像，该算法的平均准确率达到84.2%，每帧图像的平均检测时间为0.092 s。该研究算法可提高缺株情况下的作物行中心线识别率，具有鲁棒性强、准确度高的特点，可为无人驾驶农机在作物行缺株的农田环境下进行作业提供理论依据。

Extraction algorithm of the center line of maize row in case of plants lacking

Abstract: Banana straw is usually broken into pieces to degrade naturally in the farmland. However, severe entanglement of knife roller easily causes the wear of blades, leading to a short service life and low crushing efficiency in the conventional banana straw-crushing and returning machine. A great challenge has also been posed on the effective coordination of fixed knives during operation, especially in the case of high toughness after the aging of banana straw. Therefore, this study aims to improve the smashing rate of banana straw up to the standard requirement, thereby avoiding the winding of banana straw in pulverizers. An anti-wrapping device with a fixed flailing knife was also designed to reduce the entanglement for the banana straw-crushing and returning machine. Specifically, the movable and fixed knife was effectively coordinated in the machine. Three-point support was also formed using the crushing fixed knife and the Y-shaped flailing knife in high-speed crushing operation for the banana straw. As such, the highly efficient straw-crushing was realized to avoid straw entanglement. Among them, the Y-shaped flailing knife was composed of two L-shaped blades combined with a Y-shaped flailing knife and a flail. A systematic investigation was made on the optimization of structural parameters for the key components of crushing, the arrangement and combination of fixed knives, as well as the force analysis of banana straw during crushing. Correspondingly, the main test factors were determined as the forward speed of the returning machine, the speed of the crushing knife roller, and the bending angle of the Y-shaped flailing knife. A three-level three-factor orthogonal field test was then carried out, where the evaluation indicators were set as the crushing qualification rate of banana straw, and the unevenness of throwing. An optimal parameter combination was achieved, where the forward speed was 1.85 m /s, the knife roller speed was 1500 r/min, and the bending angle of the Y-shaped flailing knife was 140°. In this case, the crushing qualification rate of banana straw was 95.1%, and the unevenness of throwing was 14.6%, indicating suitable for the actual situation of banana straw crushing. A comparison test was also conducted to verify the performance of the improved pulverizer. It was found that the qualified rate of straw smashing increased by 1.7 percentage points in the fixed-blade anti-wrapping banana straw crushing and returning machine, where the anti-wrapping device performed better. Consequently, the anti-wrapped banana straw crushing and returning machine with a fixed flailing knife can be expected to realize the sliding cooperation of the flailing and fixed knife for a better crushing effect, thereby reducing the entanglement of crushing knife roller. As such, the higher squeezing force of the cutter on the straw greatly contributed to effectively improving the crushing performance under the optimal operation requirements in the southern banana areas. The finding can provide strong technical support to the straw crushing and returning to the field in the banana areas.