Development and performance evaluation of an electro-hydraulic downforce control system for planter row unit
2020
Jing, Huirong | Zhang, Dongxing | Wang, Yunxia | Yang, Li | Fan, Chenlong | Zhao, Huihui | Wu, Hailiang | Zhang, Yaohui | Pei, Jingchun | Cui, Tao
To avoid the issues of uneven germination and undesired soil compaction associated with the changing soil conditions, this paper presented the design of an electro-hydraulic downforce control system for planter row units. The control system deployed a PID (Proportional-Integral-Derivative) closed-loop algorithm to control planting downforce exerted on the gauge wheel in response to varying soil conditions, and the results of the test bench showed that the detecting accuracy of the control system was within tolerance ±1.02% and the control algorithm can meet the design requirement with smallest rise time of 0.045 s. Moreover, field experiments were conducted using a four-row corn pneumatic planter at the driving speed of 8 km/h in the tilled field (TF) and untilled field (UTF) respectively. The predetermined seeding depths for corn seeds were 35, 50 and 80 mm, and four levels of downforce range were selected as Light (18–50 kg), Medium (50–90 kg), Heavy (90–120 kg) and Spring (conventional adjustment). The results demonstrated that compared with spring adjustment, the control system had better performance in adjusting downforce and enhanced consistency of seeding depth with an improvement of 1.05–2.23%. The results also implied that the control system with appropriate downforce input improved the qualified index than spring did, increasing by 3.12–34.38%. Thus it can be seen that corresponding to different soil conditions and sowing depths, a proper downforce from the planter unit with the developed control system could obtain better working quality than the results with traditional springs.
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