对靶喷雾机器人视觉伺服控制系统研究

发布时间：2018-03-01 00:31

本文关键词： 对靶喷雾视觉伺服轨迹规划机器人手眼系统　出处：《中国农业大学》2017年博士论文　论文类型：学位论文

【摘要】：对靶喷雾技术对减少农药使用量、降低作物农药残留、保护环境和劳动者具有重要意义。本文针对温室作物对靶喷雾作业,提出了一种基于视觉伺服的喷雾机器人方案并构建了试验系统,研究了基于该方案的视觉伺服对靶控制算法。主要研究内容如下:(1)对靶喷雾机器人方案设计与试验系统构建。提出了一种基于单目场景/单目手眼混合视觉结构的对靶喷雾机器人方案;根据该方案选定了喷雾机械臂的结构形式,对喷雾机械臂进行了运动学位置正逆解、正逆向微分动力学及工作空间分析,并根据所需工作空间对其主要结构参数进行了优化,根据优化结果确定了机械臂型号;设计了喷雾机械臂在笛卡尔空间和关节空间的轨迹插值方法;构建了对靶喷雾机器人试验系统,完成了试验系统的软硬件设计。(2)作物图像背景分割与靶标信息提取方法研究。以定植初期的葫芦幼苗为研究对象,通过对比各颜色空间常用算子对样本图像的背景分割效果,发现RGB空间的CIVE与2G-R-B算子的分割效果最好;以样本图像灰度直方图的重叠区域占比、均值间距、标准偏差及算法耗时等为衡量指标,采用遗传算法在RGB空间内搜索,获得了性能更优的分割算子;鉴于该算子对作物占比较小的图像分割效果不理想,提出了一种该算子+ Ostu分割法与a分量固定阈值分割法相结合的组合分割策略;针对选取的作物形心、包围圆等对靶特征,设计了作物连通区域提取方法和包围圆特征提取算法。(3)喷雾机器人视觉伺服控制研究。针对喷雾机器人选用的速度控制器,设计了一组基于作物冠层包围圆特征计算的喷头位置偏差和一组期望值不随作业目标更换而变化的矩特征等两种反馈特征,室内试验证明,选用两种反馈特征的控制器均具有较好的对靶及跟踪控制性能。此外,针对喷雾机器人的连续运动作业模式,提出了一种基于改进势场法的喷雾机械臂运动规划对靶实时控制算法,该算法在传统势场法基础上引入了速度势场、视场约束和关节极限位置约束,可规划出更优的喷雾机械臂运动轨迹,有效提高喷雾机器人对靶控制的鲁棒性。针对喷雾机器人的间歇运动作业模式,在确定各目标作物喷雾点及各喷雾点两两间可行路径的基础上,采用枚举法与改进近邻法相结合的组合策略进行喷雾路径规划,并控制喷雾机械臂对靶,试验验证了该算法的可行性。
[Abstract]:Target spray technology to reduce the use of pesticides, crops reduce pesticide residues, has important significance to protect the environment and workers. According to the operation of greenhouse crops target spray, based on spraying robot visual servo scheme and the construction of the test system based on the scheme of visual servo control algorithm. The main research target the contents are as follows: (1) the construction of system design and test target spraying robot. This paper proposes a scheme based on monocular scene / single hand eye vision mixed structure on target spray robot scheme; according to the program selected the structure of mechanical arm to spray, spray manipulator kinematic position of forward and inverse solution analysis, reverse differential dynamics and the work space, and according to the required working space to optimize the main structure parameters, according to the optimization results of manipulator models were determined; the design of spray Trajectory interpolation method of fog manipulator in Cartesian space and joint space; construct the target spraying robot test system, designs the hardware and software of the test system. (2) crop image background segmentation and target information extraction method. In the early colonization of pumpkin seedlings as the research object, through the comparison of the commonly used color space operator based on the sample image segmentation effect, found that the best CIVE RGB space and 2G-R-B operator segmentation; gray histogram with overlapping sample image ratio, mean spacing, standard deviation and time-consuming algorithm as the measure, the genetic algorithm is used to search in the RGB space, the segmentation operator has better performances in view; the operator of the crops accounted for relatively small image segmentation effect is not ideal, put forward a kind of the operator + Ostu segmentation method and a component fixed threshold segmentation method combining the segmentation strategy; For the selected crops on the target centroid, surrounded by circular features, design method of connected region extraction and surrounded by the crop circle feature extraction algorithm. (3) study of visual servo control for speed controller. The robot spraying robot selection, a set of nozzle position deviation of crop canopy surrounded by circular features and a set of calculation based on the expected value do not change with changing job target moment features two kinds of feedback feature design, experiment show that the selection of two kinds of feedback characteristics of the controller have better targeting and tracking control performance. In addition, according to the operation mode of continuous motion of robot, proposes an improved potential field method of spray manipulator motion planning the target real-time control algorithm based on the algorithm in the method based on the introduction of the traditional potential field velocity potential field, field constraint and joint limit position constraint, can plan out the sprayer better Mechanical arm motion trajectory, effectively improve the robustness of the spraying robot target control. For intermittent operation mode of spraying robot, based on determining the target point and the crop spray spray point 22 feasible paths, combination strategies and improved nearest neighbor method combining the enumeration method of path planning and control of spray, spray the mechanical arm of the target, test and verify the feasibility of the algorithm.

【学位授予单位】：中国农业大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TP391.41;TP242

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