摘要
提高玉米播深合格率和一致性,并保持适宜的压实度,可以确保种子和土壤的良好接触,从而促进玉米苗期生长,有利于提高产量。本文对播深和压实度控制过程进行了分析,通过实时调节施加在四连杆仿形机构上的液压力调节下压力,实现播深的间接控制,通过实时调节镇压机构处的弹簧伸长量调节镇压力,从而间接控制压实度。从播深和压实度综合控制角度出发,设计了播深和压实度电液控制系统,主要包括测控系统、液压系统和机械部分等。控制系统的阶跃响应测试结果表明:下压力控制系统的调节时间均值为2.69 s,稳态误差均值为91.5 N,超调量均值为22.95%;镇压力控制系统的调节时间均值为1.44 s,稳态误差均值为30 N,超调量均值为1.83%。田间试验表明,当设定播深为50 mm、目标下压力为3000 N、目标镇压力传感器测量值为400 N、播种机作业速度为6~10 km/h时,电液主动调节方式下的播深合格率均值为91.33%,播深变异系数均值为8.98%,机械调节方式下的播深合格率均值为82.67%,播深变异系数均值为16.73%。基于电液主动调节方式的播种机的试验指标优于基于机械调节方式的指标。
Keeping appropriate and consistent seeding depth and compaction pressure is beneficial to rapid and consistent seed germination,and finally increases yield.Seeding depth and compaction pressure varies with terrain floating and different field conditions.In order to make the planter adapt to varying field conditions and keep the seeding depth and compaction pressure in the set range,an electro-hydraulic precise control system for seeding depth and compaction pressure was designed,including hydraulic system,controller,downforce sensor,compaction pressure sensor,oil pressure sensor,and A/D signal acquisition modules.The downforce sensor and compaction pressure sensor were used to sense the real-time downforce and compaction pressure.Control signals were sent to hydraulic valves after calculating the differences between set value and actual measured value by controller,then the action direction and pressure of the hydraulic cylinder connected to the planter unit frame were adjusted,therefore the downforce and compaction pressure applied to the planter unit were adjusted.Through bench test,the control process of the system was calibrated.The step response test results of control system showed that the average adjustment time of the downforce control system was 2.69 s,the average steady state error was 91.5 N,and the average overshoot was 22.95%.The adjustment time of the compaction pressure control system was 1.44 s,the stable state error was 30 N and the overshoot was 1.83%.The mechanical spring-regulated seeding unit and electro-hydraulic-regulated seeding unit were installed on a same planter and their performances were obtained and compared though field tests.As for electro-hydraulic-regulated seeding unit,the seeding depth was set to 50 mm,the target value of downforce was set to 3000 N,and the target value of compaction pressure sensor was set to 400 N.The planter operated at 6~10 km/h.For the unit under electro-hydraulic active adjustment mode,the seed depth qualification rate was 91.33%,the coefficient of variation(CV)was 8.98%.For the unit under the mechanical adjustment mode,the seed depth qualification rate was 82.67%,and the CV was 16.73%.The test index of the unit based on the electro-hydraulic active adjustment method was better than the index of the unit based on the mechanical spring adjustment method.The research result provided a kind of electro-hydraulic method and system to adjust downforce and compaction pressure actively and accurately,which can finally realize consistent seeding depth and compaction pressure.
作者
白慧娟
方宪法
王德成
苑严伟
周利明
牛康
BAI Huijuan;FANG Xianfa;WANG Decheng;YUAN Yanwei;ZHOU Liming;NIU Kang(College of Engineering,China Agricultural University,Beijing 100083,China;The State Key Laboratory of Soil Plant Machine System Technology,Chinese Academy of Agricultural Mechanization Sciences,Beijing 100083,China)
出处
《农业机械学报》
EI
CAS
CSCD
北大核心
2020年第9期61-72,共12页
Transactions of the Chinese Society for Agricultural Machinery
基金
国家重点研发计划项目(2016YFD0700103、2016YFD0200607)。
关键词
玉米播种机
播深
下压力
镇压力
控制系统
corn planter
seeding depth
downforce
compaction pressure
control system
