基于稻田除草部件横向偏距视觉感知的对行控制系统设计与试验

目的 为使水稻机械除草部件作业时能避开秧苗、降低伤苗率，设计了一种基于机器视觉与比例积分微分(Proportion integration differentiation，PID)控制的避苗控制系统。方法 利用改进超绿算法对秧苗进行灰度化，运用图像投影法对感兴趣区域(Region of interest，ROI)内的秧苗进行特征提取及图像坐标定位，采用稳健回归算法拟合秧苗，得到苗带中心线，通过小孔成像模型转换，获得秧苗的地面坐标位置及除草部件中心与苗带中心线的距离。基于PID控制算法对液压纠偏系统进行控制，并应用Matlab/Simulink对系统进行仿真研究。结果 系统可实现避苗作业，模型的稳态响应时间为0.34 s。系统性能对比试验的结果表明：避苗控制系统明显减少了除草部件的伤苗情况，平均伤苗率为3.75%；而没有避苗控制系统的情况下，平均伤苗率为24.88%。结论 本文设计的对行控制系统满足除草部件作业路径实时校正要求，可有效降低稻田机械除草的伤苗率。研究结果为水稻及其他作物的机械除草对行控制提供参考。

Design and test of row-follow control system based on visual perception of lateral-offset of weeding component in paddy field

Objective In order to avoid seedling and reduce seedling damage rate during the operation of mechanical weeding, a control system of avoiding seedling based on machine vision and proportion integration differentiation (PID) control technology was designed. Method The improved extra-green algorithm was used to gray rice seedlings. The image projection method was used to extract the characteristics of rice seedlings within the region of interest (ROI) to obtain the corresponding image coordinates. The robust regression algorithm was used to fit rice seedlings to obtain the center line of seedling belt. The ground coordinate position of seedling, and the distance between the center of weeding unit and the center line of seedling belt were obtained by transforming the model of aperture imaging. The hydraulic rectifying system was controlled based on PID control algorithm, and the Simulink in Matlab software was used for the simulation analysis of the system. Result The seedling avoidance was realized, and the steady-state response time of the system model was 0.34 s. The performance comparison tests of the control system with and without the control system of avoiding seedlings showed that the control system of avoiding seedlings could obviously reduce the seedling damage of weeding components, with the average seedling injury rate of 3.75%, and the rate without the control system of avoiding seedlings was 24.88%. Conclusion The row-follow control system for mechanical weeding designed in this study can correct the working path of the weeding components in real time, which effectively reduces the seedling injury rate of mechanical weeding. The results of this study can provide some reference for mechanical weeding row-follow control of rice and other crops.