基于BDS的果园施药机自动导航控制系统

Navigation Control System for Orchard Spraying Machine Based on Beidou Navigation Satellite System

根据果园施药机自动导航喷药作业需求,设计了一种基于北斗卫星导航系统(BDS)的施药机自动导航控制系统。该系统主要包括RTK-BDS接收机、导航控制器、转向控制器、电控气动转向系统和三轴电子罗盘。其中转向控制器、电控气动转向系统和三轴电子罗盘构成转向角闭环控制回路,该回路可根据导航控制器发送的施药机期望转向角实现转向角的随动控制。将施药机的运动学模型和纯追踪模型相结合,设计了施药机直线跟踪导航控制器,输入为位置坐标和方位角,输出为期望转向角。针对果园地形特点对施药机进行了导航路径规划,并在果园进行现场试验。试验结果表明:所设计的导航控制系统,在施药机行进速度为2 km/h时,直线跟踪最大误差不大于0.13 m,平均跟踪误差不大于0.03 m,能满足果园自动导航作业精度要求。

According to the demand of automatic navigation of orchard spraying machine,a navigation control system for spraying robot based on Beidou navigation satellite system（ BDS） was designed. The system included RTK-BDS receiver,navigation controller,steering controller,electro pneumatic steering system,three dimensional electronic compass. The closed control loop of steering angle was composed of steering controller,electro pneumatic steering system,three dimensional electronic compass. The closed loop could realize the servo control of steering angle according to control command from navigation controller. The kinematics and dynamics models of spraying machine were analyzed and a look-ahead dynamic path search model was established. The input of the look-ahead dynamic path search model was lateral tracking error and the output was steering angle from navigation controller. Navigation path planning on the spraying machine was designed according to the characteristics of the orchard,and field tests were carried out in the orchard. The tests were done at different traveling speeds,which showed the offset error became bigger with the increase of traveling speed and the traveling speed of 2 km / h was the optimal speed for quick steering speed and small offset error. The field tests showed that the maximum offset error was no more than 0. 13 m and the average offset error was no more than 0. 03 m for straight tracking at the traveling speed of 2 km / h. The field tests indicated that the navigation control method was appropriated to orchard spraying machine.