Design And Research Of The Planting Depth Control System Of The Hanging-cup Transplanter

Aiming at the problem of inconsistent planting depth due to uneven ground formed after soil preparation and filming when the hanging cup transplanter is in the field,this thesis uses PID and fuzzy PID control algorithms to design a planting depth control system to achieve the purpose of real-time adjustment of planting depth.A transplanting experiment was carried out in a soil trough,and the control effects of the two algorithms were compared through the maximum deviation error,response time and stability indicators.The planting depth control system of the hanging-cup transplanter is mainly composed of hardware and software.The hardware part includes the improvement of the planting depth control mechanism and the design of the hydraulic system and control system.The software part includes the creation of the human-machine interface(HMI),the programming of PID and fuzzy PID control algorithms.According to the principle of planting depth control and PLC as the controller,the sensor collects the surface unevenness information of the transplanter during operation,and drives the hydraulic actuator through PID or fuzzy PID control algorithm to realize the real-time control of the planting depth of the hanging-cup transplanter.Staggered convex-concave platforms of different heights are arranged in the soil trough,and the control system is tested for static response and dynamic response through PID control and fuzzy PID control algorithm.The static test results show that: the PID parameters of the adjustment system are Kp=4.0,Ki=750ms,Kd=5ms,and the heights are 50 mm,40mm,30 mm,20mm,10 mm in turn.The Maximum deviation error of PID is reduced from 4.21 cm to 0.14 cm,and the adjustment time is reduced from 13.5s to 5.5s;the Maximum deviation error of fuzzy PID is reduced from 4.15 cm to 0.14 cm,and the adjustment time is reduced from 13.0s to 4.5s.After placing 50 mm,40mm,30 mm,20mm,and 10 mm recesses in sequence,the PID Maximum deviation error is reduced from 5.57 cm to 0.35 cm,and the adjustment time is reduced from 14.0s to 6.5s;The Maximum deviation error of fuzzy PID is reduced from 5.26 cm to 0.20 cm,and the adjustment time is reduced from 13.0s to 4.5s.The dynamic test results show that the transplanting machine is on a convex and concave platform with a height of 50 mm,and the dynamic response test is carried out at three speeds of 1.0km/h,1.25km/h and 1.5km/h.It can be seen that when the forward speed is 1.0km/h,the qualified rate of planting depth is the highest;When the transplanter is at a speed of1.0km/h and the height of the convex and concave platform is 50 mm,40mm,30 mm,20mm,10 mm,the qualified rate of the planting depth increases as the height of the convex and concave platform decreases;When the transplanter is operated at 1.0km/h and the height of the convex and concave platforms is less than 20 mm,the planting depth qualification rate is greater than 80%,which can basically meet the requirements of consistent planting depth in field operations.Through static response test and dynamic response test results,it is found that the control effect of fuzzy PID is better than PID.Therefore,the fuzzy PID algorithm is selected as the control strategy of the planting depth control system of the hanging cup transplanter.