Study On Key Technology Of Row Control Of Weeding Components In Paddy Field

In the rice ecosystem,weeds compete with rice for growth space,fertilizer nutrients,light,heat and other resources,which is one of the important reasons for the decline of rice yield and quality.Effective control of weed growth is an important part of rice growth.The application of chemical herbicides is a widely used way of weed control.Long-term,large-scale and high-frequency application of herbicides will cause negative problems such as weed resistance,drug damage and environmental pollution.Therefore,to develop mechanical weeding is the key to ensure the sustainable development of agriculture.However,in the actual operation,the change of the curvature of the seedling belt causes the seedling injury of the executive parts of weeding,which seriously restricts the development of mechanical weeding technology.Therefore,it is an urgent problem for mechanical weeding to realize the automatic control of weeding components and avoid the mechanical damage of rice seedlings.According to the differences of physiological structure and mechanics between rice and weeds in weeding period,the tactile sensing method is proposed to realize the recognition and location of rice plant,and the decision data of row regulation is obtained through calculation.On this basis,the hydraulic control system of traverse row is constructed to complete the design of row regulation system.The system of perception,control and decision is integrated to realize the mechanical weeding.The feasibility of the control system is verified by the soil tank test.The main research contents and conclusions are as follows:(1)According to the physiological structure and mechanical difference of rice grass in weeding period,a rice plant identification and positioning device based on the fusion of diffuse reflector and piezoelectric film sensor was designed.On this basis,a quantitative model of row regulation amount offset was established,tested,optimized parameters and completed the design of row sensing link.(2)According to the principle of paddy field mechanical weeding and the actual requirements of production,the design of the hydraulic control system of the opposite row is constructed,which is composed of the actuator,hydraulic system and control system.The opposite row actuator is of internal and external sliding beam type.The opposite row hydraulic system includes hsg40-50-25-100 type hydraulic cylinder,D633 series proportional directional valve;the contralateral control system includes ktrc-125 lmm type pull rod linear displacement sensor,LADRC controller designed by stm32f407 chip,1which completes the contralateral execution link design.(3)The design and Simulation of linear auto disturbance rejection controller(LADRC)is aimed at the complicated paddy field environment and the large disturbance of the system.The traditional PID is used to deal with the problems of the small plant spacing crop,such as the poor regulation effect,the easy occurrence of delay and overshoot.The linear Auto disturbance rejection controller is designed,including the basic structure of the controller,the stability proof and the parameter adjustment.Through the simulation analysis,compared with the traditional PID control,the linear auto disturbance rejection control has a certain immunity,good stability,and completes the design of the decision-making link.(4)Performance test of line control system: according to the composition of the line control system,test the measurement accuracy and stability of the sensing device,test the control accuracy and responsiveness of the hydraulic execution system,and test and verify the actual tracking effect of the line control system.The experiment of the sensing link shows that the sensing device can control the error of the lateral offset of the adjacent rice plants within ± 2.5cm at different contact heights;the error of the lateral offset of the adjacent rice plants can be controlled within ± 2.3cm at different number of rice holes.The experiment results verify that the accuracy and stability of the sensing device can meet the system requirements.The implementation effect test shows that: in the fine tuning of 0.5cm,1 of the regulation,and 7.2 of the high regulation and control 7.2 of the input signals,the LADRC meets the requirements of row operation in steady state error and response time,and the dynamic performance is obviously superior to the traditional PID control.The results showed that the safe distance between weeding parts and rice plant was always kept under the normal speed,and the maximum lateral deviation was less than 3cm,which met the actual production requirements.