摘要
针对农机无人化作业需求,该研究基于DF2204无级变速拖拉机和机器人操作系统(Robot Operating System,ROS),研发了一种适于田间作业的农机无人驾驶自主作业系统。系统由控制、规划、安全和总线通信等模块组成。对DF2204无级变速拖拉机进行硬件改造与集成,设计满足农机无人驾驶要求的控制器局域网(Controller Area Network,CAN)总线协议和ROS与CAN总线通信的消息结构,包括5类控制帧和2类状态帧;设计了基于比例-积分-微分(Proportion Integration Differentiation,PID)控制器的横向跟踪与纵向速度控制算法。在北京密云试验田开展田间小麦播种实际作业试验。试验结果表明,消息结构满足50 Hz通信负载,横向跟踪平均绝对误差为2.96 cm,纵向速度平均绝对误差0.68 m/s。研究结果可为无级变速拖拉机的无人化升级改造提供参考,提高农机智能化水平和作业效率。
Autonomous agricultural vehicle(AAV)is believed to play a significant role in smart agriculture.In future periods,AAV will still be dominated by fuel engines,and the transmission technology will be upgraded from manual shifting to power shifting or CVT(Continuously Variable Transmission)simultaneously for which to improve the power and economy.In response to the demand of AAV,this study devotes to developing an autonomous driving and operation system based on ROS(Robot Operating System)and CVT tractor.The proposed system includes safety,planning,control and CAN bus communication modules.To do that,we integrated and deployed hardware on CVT tractor,designed a CAN bus protocol and implemented data structure for communication between ROS and CAN bus.A close-range anti-collision capability of the tractor is realized based on radar,and a lateral controller based on PID algorithm is adopted.To further validation,a corn sowing experiment was carried out in Miyun District,Beijing,with a total operating area of 2.4 hectares.This research takes DF2204 CVT tractor as the test platform according to the working requirements of autonomous tractors.We also designed the hardware platform of AAV,which was divided into computing layer,sensing layer and actuation layer.Based on the idea of modularization and hierarchy,a software architecture that meets the job requirements was developed with ROS as the middleware,which includes localization,planning,control,CAN communication,and safety modules.And a CAN bus protocol to meet the needs of vehicle control was developed.According to the control characteristics and operation requirements of the CVT tractor,a lateral control module and a longitudinal velocity control module were designed.We counted 22 straight working paths with a total working time of 5943 s(excluding supplemental seeds and fertilizers),of which the total working time of the straight working stage was 4037 s and the time of the U-turn stage was 1906 s,approximately 32%of the total working time.The efficiency of our system was 1.33 hm2/h,and the experimental result shows that the communication node could meet the communication requirements of 50 Hz.The target speed was set to 3 km/h when the tractor turns around,while the harrow was stopped and the seeder was lifted.The engine load was lower when the tractor makes a U-turn,and the torque percentage fluctuates between 10%-30%.After several seconds the engine load continued to increase,and the torque output percentage remained above 80%,with a maximum value of 94%.The engine and transmission will perform a torque reserve in order to meet the instantaneous torque demand(such as increased resistance,climbing,etc.).When the engine revs is higher than the revs corresponding to the torque peak,the increased load will cause the engine to overload,thereby reducing the revs and ego velocity,so as to output more torque.The average lateral error is 2.96 cm and the navigation error was 11.69 cm.The velocity RMSE is 0.98 km/h and MAE was 0.68 km/h.The steering angle RMSE was 1.91°,and MAE was 1.47°.This research shows that the tractor based on wire control technology and CVT tractor can fit the needs of autonomous agricultural vehicles,and the control and planning modules can meet sowing operations.This research could provide a reference for the unmanned upgrading of CVT tractors,and improve the intelligent level and operation efficiency of agricultural machinery.
作者
陈智博
文龙
杨卫中
杨丽丽
赵欣
吴才聪
Chen Zhibo;Wen Long;Yang Weizhong;Yang Lili;Zhao Xin;Wu Caicong(College of Information and Electrical Engineering,China Agricultural University,Beijing 100083,China;Key Laboratory of Agricultural Machinery Monitoring and Big Data Applications,Ministry of Agriculture and Rural Affairs,Beijing 100083,China)
出处
《农业工程学报》
EI
CAS
CSCD
北大核心
2022年第19期1-9,共9页
Transactions of the Chinese Society of Agricultural Engineering
基金
北京市科技计划项目(Z201100008020008)。
关键词
拖拉机
无级变速
无人驾驶
自主作业
线控底盘
tractor
continuously variable transmission
autonomous driving
autonomous operation
wire control chassis
