【作者】 张林焕；

【导师】 张书慧；

【作者基本信息】 吉林大学 ， 农业机械化工程， 2009， 硕士

【摘要】 本文结合国家科技部“十一五”科技支撑计划“多功能农业装备与设施研制”之子项目“仿生智能作业机械研究与开发”(2006BAD11A08)开展了PLC和液压技术在变量施肥中的应用研究工作。变量施肥技术对我国农业发展有着非常积极的意义,实施按需变量施肥,可以大大提高肥料利用率,减少肥料的浪费以及多余肥料对环境的不良影响,其经济、社会和生态效益显著。调速控制系统作为变肥施肥技术中的重要组成部分,其性能的优劣直接影响着变量施肥作业的效果。因此,本文采用PLC和电液比例液压传动技术设计了变量施肥机液压无级调速系统,并对该系统进行试验验证。试验表明,变量施肥机液压无级调速系统工作稳定、性能可靠,功率质量比高,且具有操作方便、系统价格便宜等特点,为下一步开发大型自动变量施肥机提供了理论和技术参考。更多还原

【Abstract】 The core of study and development of the technology of Precision Agriculture (PA) is precision positioning and variable rate application which is supported by GPS, GIS and RS, etc. The fertilizer is main elements of agricultural high yield and increase production, and the cost of fertilizer takes greater parts among total cost. The input and the utilization ratio of fertilizer effects agricultural output, peasant’s income and environmental quality directly. Variable Rate Fertilization (VRF) is suitable for different needs for areas, crops, soils and crops growth environment. With balance applying fertilizer, VRF can improve the fertilizer utilization ratio, and has obvious economic and environmental benefits.Inputting fertilizer has some problems in our country, such as unreasonable structure, low average utilization ratio of fertilizer, failing to give full play of fertilizer in increasing production benefit. In researching of VRF, it is main work to introduce foreign advanced equipments to track, digest and absorb. So, it is necessary to study and to develop the technology of VRF according to our national conditions, which has important theoretical meaning and practical value to realize agricultural sustainable developments.The paper is supported by the subject of“Biomimetic smart operating machinery research and development”founded by National science and technology support plant of“Multi-functional development of the agricultural equipment and facilities”supported by National Ministry of Science and Technology office. Designed automatic variable rate fertilizing machine control and drive system etc. The main work and results are as followed:(1)Control project and model of automatic VRF are established. To the existing Development characteristics of China’s agricultural machinery, working condition of countryside in China, and fully considering the reliability that agricultural machinery needs, manual, Non-GPS positioning and automatic methods of control are adopted in the automatic control systems of VRF. On the base of analyzing the main elements that effect fertilizer and the rule of control fertilization, the control model of Hydraulic Motor rotary speed in automatic VRF is confirmed. It sets up theoretical foundation for automatic controls of VRF.(2)The hydraulic stepless speed regulation system is designed and debugged. Electro-hydraulic proportional control system test rig is established through the reasonable selection of components, and the Proportional velocity regulating valve and the hydraulic Motor Speed control system is studied. Selecte and designe the components of the hydraulic drive system such as: hydraulic motor, proportional velocity regulating valve, amplifiers, filter, joints, Tubing and Chain drive system. After experiment, find the hydraulic drive system can achieve the goal of stepless speed regulation, and meet the requirements of VRF. (3)PLC control system is developed as controller of automatic VRF executive body. According to the requests of control system, the input and output of system and the communication are analyzed, the EM235 module is deployed and calibrated, and the structure of control system is designed. The hardware electric circuit of PLC control system is confirmed, which includes receiving DGPS signals, receiving sensor signal of tractor velocity, keyboard inputting, pulse output of step motor, displaying screen and warning etc. Verified by the experiment, the control system is relatively steady, reliable, and meets the request of using.(4)Design program of control system. The program is written by using Ladder Diagram Language tool that used in Step 7-Micro/WIN Programming software. It can realize VRF by means of manual、Non-GPS and automatic control. In automatic method of control, program has finished the work of receiving positional and velocity information from GPS receiver working in mode of DGPS. It can identify the grid block correctly and accurately find out the needs of fertilizer, and then outputs the corresponding voltage to drive motor and completes VRF. In Non-GPS method of control, the grid block identify, fertilizer needs search and voltage output is based on the pick and deal with of the pulse signal outputted by near switching speed sensor. In manual method of control, program can receive and deal with sensor pulse signal and keyboard characters. Then it outputs the corresponding voltage to drive motor and completes VRF. These three operations can be selected according to needs and conditions.(5)The speed-demarcate experiments of the hydraulic motor is finished. The speed-demarcate experiments is did under different engine speeds and calendared the speed of hydraulic motor when the PLC output one voltage and then next. Then fits the experimental data and obtains the curve about voltage and the speed of hydraulic motor(6)Demarcate experiments are done of four line variable rate fertilizer applicator. Through analyzing liner correlation can be conclude between rotation speed of fertilization sprayer and quality of fertilization. The uniform and stability among all sprays can meet the demand. I select linear function to control VRF. At last, considering synthetically the influence that velocity of tractor and rotation speed of fertilization sprayer to quality of fertilization per hectare, I obtain the mathematical function of these variable parameters. The automatic control system of VRF is based on map in this paper. The control system can receive DGPS signal automatically and get the positioning and velocity information of the tractor by GPS receiver, then it can complete automatic VRF according to the decision value of the quality of fertilization. Through manual and automatic method of control, quality of fertilization per hectare can adjust within range from 80 to 500 kg/ha, the rotary speed of hydraulic motor is 20~150rpm. System has many characters such as simple structure, convenient to operating, the quality of fertilization range heavy to change, controller relatively steady and reliable, ideal control accuracy etc. In addition, this system is exploited by ourselves and the control system’s cost is relatively low, and the hydraulic system can output magnitude power.更多还原