基于三目视觉的自主导航拖拉机行驶轨迹预测方法及试验  

Traveling trajectory prediction method and experiment of autonomous navigation tractor based on trinocular vision

作　　者：田光兆[1] 顾宝兴[1] Irshad Ali Mari 周俊[1] 王海青[1] Tian Guangzhao;Gu Baoxing;Irshad Ali Mari;Zhou Jun;Wang Haiqing(College of Engineering,Nanjing Agricultural University,Nanjing 210031,China;Khairpur College of Engineering and Technology,Sindh Agriculture University,Khairpur 66020,Pakistan)

机构地区：[1]南京农业大学工学院,南京210031 [2]巴基斯坦信德农业大学凯尔布尔工程技术学院,凯尔布尔66020

出　　处：《农业工程学报》2018年第19期40-45,共6页Transactions of the Chinese Society of Agricultural Engineering

基　　金：中央高校基本业务费资助项目(KYGX201701);国家自然科学基金资助项目(31401291);江苏省自然科学基金资助项目(BK20140729)

摘　　要：为了实现自主导航拖拉机离开卫星定位系统时能够持续可靠工作,该文提出了基于三目视觉的拖拉机行驶轨迹预测方法。该方法将三目相机分解为长短基线2套双目视觉系统分时独立工作。通过检测相邻时刻农业环境中同一特征点的坐标变化反推拖拉机在水平方向上的运动矢量,并通过灰色模型预测未来时刻的运动矢量变化,最终建立不同速度下的前进方向误差模型。试验结果表明:拖拉机行驶速度为0.2 m/s时,46.5 s后前进方向误差超过0.1 m,对应行驶距离为9.3 m。行驶速度上升到0.5 m/s时,该时间和行驶距离分别降低到17.2 s和8.6 m。当行驶速度上升到0.8 m/s时,该时间和距离分别快速降低至8.5 s和6.8 m。行驶速度越高,前进方向误差增速越高。该方法可用于短时预测拖拉机的行驶轨迹,为自主导航控制提供依据。In order to make the autonomous navigation tractors work steadily and continuously without the satellite positioning system,a traveling trajectory prediction system and method based on trinocular vision were designed in this paper.The system was composed of a trinocular vision camera,an IEEE 1394 acquisition card and an embedded industrial personal computer(IPC).The right and left sub cameras constituted a binocular vision system with a long base line.The right and middle sub cameras constituted another binocular vision system with a narrow base line.To obtain more precise measurement results,the two binocular vision systems worked independently and in time-sharing.Then the motion vectors of tractor,which were in presentation of horizontal direction data,were calculated by the feature point coordinate changing in the working environment of the tractor.Finally,the error models which were in the direction of heading were established at different velocities,and the motion vectors of tractor were predicted by the models based on grey method.The contrast experiments were completed with a modified tractor of Dongfanghong SG250 at the speed of 0.2,0.5 and 0.8m/s.During the experiments,the IPC was used to collect RTK-GPS data and predict movement tracks.The RTK-GPS used in the experiments was a kind of high-precision measuring device,and the measuring precision can reach 1-2 cm.Therefore,the location data of RTK-GPS were supposed as the standard which was used to compare with the data from trinocular vision system.The experimental results showed that the method mentioned above could accurately predict the trajectory of the tractor on the plane with an inevitable error which was mainly caused by the visual measurement error of the forward direction(z direction).When the tractor travelled at the speed of 0.2 m/s,the time and the distance that the error in forward direction exceeded 0.1 m equaled 46.5 s and 9.3 m,respectively.When the speed increased to 0.5 m/s,the time and the distance decreased to 17.2 s and 8.6 m,respect

关 键 词：拖拉机 自主导航 机器视觉 轨迹预测 灰色模型 

分 类 号：S219.1[农业科学—农业机械化工程]