基于北斗的农业机械立体视觉辅助导航系统设计

为提高农机在果园复杂环境下作业精度，降低驾驶员劳动强度，设计了精准辅助导航系统。通过北斗差分定位设备获取农业机械的经纬度、航向角度以及行驶速度等数据，根据农田信息规划出全局行驶路径，实时计算农业机械行驶过程中的航向偏角、行驶距离和耕作面积并绘制行驶轨迹，根据观察航向偏角和行驶轨迹，驾驶员来修正作业机械使农机按规划路径行驶。系统采用基于红外散斑的深度立体视觉相机，降低自然光线限制，以此获取农业机械前方深度图像，根据视觉算法对图像中的作物或障碍加以检测，并计算其到农业机械和路径中心线距离，判断是否需要避障并提示驾驶员应调整方向，当调整方向进行避障后返回到已规划路径继续行驶。试验结果表明，辅助导航系统在直线行驶试验时横向行驶最大偏差小于5 cm，能够辅助驾驶员按规划路径精准行驶；基于立体视觉的障碍检测测距误差范围在4%以内，且处理每帧图像耗时最大为40 ms，实时性很高，能高效辅助驾驶员进行精确避障。 

Design of Agricultural Machinery Aided Navigation System Based on BDS and 3D Vision

In order to achieve accurate mechanical work in the farmland，and improve intelligent level of agricultural machinery，an accurate aided navigation system was designed.This system was composed of two subsystems:BDS（BeiDou Navigation Satellite System）navigation subsystem and 3D vision obstacle detection subsystem.The method of BDS navigation subsystem:the RTK-BDS was used for obtaining accurate location data of agricultural machinery，the data typically included latitude and longitude，speed and heading angle.Based on farmland information，BDS navigation subsystem schedule global path of farmland，calculate drift angle，driving distance，area of cultivated of agricultural machinery during driving in the real time and draw the trail.Driver could modify direction of agricultural machinery according to planning path.The 3D vision obstacle detection subsystem:the 3D camera used for obtaining depth data.It was based on principle of infrared speckle，and not affected by natural light.Visual detection method was used to detect obstacle，calculate distance from obstacles to agricultural machinery，obstacles to center line of path，and to judge whether need to adjust direction and give driver tips.Experimental results showed that BDS navigation subsystem achieved high precision，maximum error was not more than 5 cm，and precision of obstacles detection met requirements of obstacle avoidance，its maximum error was not more than 4%.So this showed that accurate auxiliary navigation system could be used to achieve precision mechanical work.