Design And Experiment Of Seedling Avoidable Weeding Control Device For Intertillage Maize

As one of the most important crops in the world,maize has an important economic position.Under the background of the changing global economy and trade,the contradiction between the decreasing area of maize cultivated land and the increasing demand for maize yield has become increasingly prominent in China,and the effective reduction of weeds in the field is one of the important ways to improve maize yield.With the de velopment of modern agricultural weeding technology,on the basis of traditional artificial weeding,chemical weeding,mechanical weeding,physical weeding and biological weeding are gradually emerging.Although the chemical weeding method is efficient and convenient,it is contrary to the development requirements of modern organic agriculture because it is easy to cause environmental pollution and human hazards.Physical and biological weeding methods have not been promoted for the time being due to the limitation of activity cost and use conditions.Mechanical weeding methods have become a hot research topic because of its clean and efficient characteristics.Aiming at the problem that the existing seedling-avoiding and weeding devices in Dryland mostly depend on intelligent navigation platform,and the mechanical seedling-avoiding and weeding de vices can not determine the position of seedlings,this paper makes a comparative analysis of the root physical characteristics of maize and weeds,the height characteristics of maize and weeds and their ability to resist external appearance,and takes this as the starting point of the study,explores the operation mechanism of mechanical sensing components.According to the structure and characteristics of root-soil complex of maize weeds,the executive components of weeding were designed and selected to complete the research and design of weeding mechanism of seedling-avoiding and weeding device.Based on the idea of intermittent rotating motion of weeding executive parts,a seedling-avoiding and weeding de vice was designed for maize field during middle tillage period.The device consists of driving de vice,connecting rod assembly and weeding component.The soft axis is used as the signal input of the mechanical sensor,and the control system controls the rotation of the executing parts at a fixed angle.Under the combined movement of the horizontal movement of the forward direction of the tool and the rotation of the output axis,the work of weeding and seedling avoidance can be completed by rotating 120 degrees.The device replaces the visual recognition method with low-cost mechanical sensor,and gets rid of the dependence on the intelligent navigation platform.Compared with the pure mechanical seedling avoidance and weeding device,the device can identify the specific position of the corn plant.The rationality and feasibility of the theoretical design are verified by theoretical analysis and DMU motion simulation.The orthogonal experiment of three factors and four levels was carried out in the soil trough Laboratory of Jilin University.The results showed that when the seedling spacing was 26 cm,the comb penetration depth was 20 mm and the forward speed was 5 km/h,the seedling injury rate of the device was 13.43%,the average weeding rate was 91.25%.The variance analysis showed that the maize seedling spacing had the most si gnificant effect on the seedling injury rate(P < 0.05).Soil penetration depth had significant effects on seedling injury rate and weeding rate(P < 0.05),but operation speed had no significant effect on seedling injury rate and weeding rate(P > 0.05).According to the problems appearing in the validation test of soil trough,the frame,suspension device and executing mechanism of weeding device were optimized,improved weeding de vice was designed,and field performance validation test was carried out.Field experiments showed that under the same experimental conditions,the average weeding rate of the improved weeding de vice was 4.6% higher and the average seedling injury rate was 3.7% lower than that of the improved weeding de vice.The experimental inde xes of the improved weeding device have been optimized.The device can meet the requirement of maize seedling avoidance and weeding operation in the field.The research results can provide reference for the optimization and design of mechanical weeding in the field.It provides a new method and way to solve the problems of traditional mid-tillage weeder that can not identify seedling belt,weeding components have low weeding rate,high seedling injury rate,large labor force,chemical residues harming human body and polluting environment,so as to meet the needs of mechanical weeding between maize plants in mid-tillage period.