基于玉米播深控制的农田地形模拟系统设计与试验

Design and Test of Farmland-terrain Simulation System for Corn Sowing Depth Control

开展了玉米播种单体试验台用仿形机构研究,设计了一种可适用于地形上下起伏和地形倾斜的农田地形模拟系统。系统由地形模拟机构、液压系统、电控系统等组成。重点对地形模拟机构进行数学建模,得出了被仿形地形倾斜角与液压缸伸缩的几何关系,并计算确定了地形模拟机构机械尺寸参数。对液压缸进行受力分析,在此基础上对仿形机构的液压系统参数进行了理论计算,确定了液压系统参数,集成电控系统形成了农田地形模拟系统。对农田模拟系统进行了地形模拟试验,在2.0 m/s作业速度下高程模拟误差平均值为1.61 mm,坡度模拟误差平均值为0.56°。试验结果表明,农田地形模拟系统对地形高程和坡度模拟的快速性和准确性能满足农田地形模拟的要求,为播种播深控制系统试验提供了试验平台。

The laboratory simulation of the sowing depth consistency control system is mostly testing parallel four-bar linkage or up-and-down movement due to surface fluctuation,while the actual farmland surface morphology varies irregularly in both elevation and slope.In view of this,a farmland-terrain simulation system suitable for rugged topography is designed to study the irregularities of farmland surface morphology led by both topographic fluctuation and terrain tilt.The system consists of terrain simulation mechanism,hydraulic system,control system,etc.The terrain simulation mechanism is connected to the rack through hydraulic cylinder to simulate farmland surface fluctuation.The hydraulic system controls the hydraulic cylinder to drive the terrain simulation mechanism through the electro-hydraulic proportional directional valve.The control system controls hydraulic system and drives the terrain simulation mechanism according to the topographic data.The physical parameters of the terrain simulation mechanism are achieved by mathematic modeling of the profiling mechanism and building the geometrical relationship between the telescopic gradient angle and the expansion or contraction of the hydraulic cylinders.Based on the force analysis of hydraulic cylinder,the parameters of the hydraulic system are determined by theoretical calculation.In the simulation at 2.0 m/s operating speed,the average elevation error is 1.61 mm and the average slope error is 0.56°.The experimental results indicate that the system showed rapid and accurate performance on terrain elevation and slope simulation,and it can meet the requirements of farmland terrain simulation.