玉米免耕播种自动调偏系统设计与试验

Design and Test of Automatic Deviation Adjustment System for No-tillage Sowing of Maize

为适应新疆滴灌区宽窄行免耕种植模式,解决传统大型玉米免耕播种机播种过程中触碰根茬、无法精确约束路径、玉米粒距合格率低等问题,结合免耕播种农艺要求,在采用导航定位技术获取播种机当前位置与目标路径间偏差的基础上,设计一种玉米免耕播种自动调偏系统。该系统主要包括避茬装置、液压执行系统和控制系统,通过建立整机力学模型,对避茬装置和液压执行系统进行运动和受力分析,确定避茬装置和液压执行系统关键结构参数,获取避茬装置最佳挂接长度和液压执行系统最大驱动力。进一步优化控制系统,实现避茬装置自动调偏及接收反馈信息功能。对免耕播种避茬装置自动调偏系统进行性能试验,试验结果表明,神经网络PID的期望调偏角最大稳态误差为0.932°,超调量全部小于1%,平均响应稳态误差小于0.9°,满足预期。田间试验结果表明,当拖拉机作业速度不大于1.0 m/s、行间秸秆覆盖量不大于1.0 kg/m^(2)时,避茬率不小于85%,纵向调整距离不大于8.6 m,玉米粒距变异系数不大于21.63%。此时播种机调偏避茬效果最佳,满足玉米免耕播种机农艺指标要求。

To meet the no-till sowing pattern of wide and narrow rows in the drip irrigation area of Xinjiang,the sowing of traditional large maize no-till planter has problems of touching stubble,failing to constrain path accurately and having a low qualified rate of maize kernel spacing.Combining the agronomic requirements of no-tillage seeding,the navigation and positioning technology was utilized to obtain information about the deviation between the current position of the seeder and the target path.The deviation automatic adjustment system was designed based on the no-tillage seeding stubble avoidance device.The system included a stubble avoidance device,a hydraulic actuating system,and a hydraulic steering control system.Through establishing the mechanical model of machine,stubble avoidance device and hydraulic actuating system were analyzed in terms of movement and force.The key structural parameters of stubble avoidance and hydraulic steering were determined.Meanwhile,the optimal hook-up length of stubble avoidance device and the maximum driving force of hydraulic actuating system were obtained.Moreover,the hydraulic steering control system was optimized to realize function of automatic adjustment for stubble avoidance devices and acceptance of feedback information.The results showed that the maximum steady state error of desired adjustment angle was 0.932°for neural network PID,the overshooting amount was less than 1%,and the average response steady state error was less than 0.9°,which met expectations.When the tractor operating speed was no more than 1.0m/s and amount of straw covered between rows was no more than 1.0kg/m^(2),the field test showed that the stubble avoidance rate was no less than 85%,vertical adjustment distance was no more than 8.6m,and coefficient of variation for qualifying grain spacing in maize was no more than 21.63%.Seeder had the best effect of offsetting and stubble avoidance and met the agronomic index requirements of maize no-tillage planter.