The Design And Experimental Research On Working Depth Control System Of Soybean Intra-row Mechanical Weeding

China is an agricultural country and soybean is one of the main food crops.In the Northeast,the planting pattern of soybean crop is two-row on ridge,and 32~38 million seedlings per hectare should be kept generally.However,farmland weed is one of the main disasters in the early growth stage of Northeast soybean.Therefore,it is an important measure for keeping the seedlings,increasing production and improving the quality of soybean to loose intra-row topsoil and remove young weeds after the emergence of soybean seedlings.It takes advantage of the features that crop seedlings have better developed root system and the distribution of broad and deep than young weeds during intra-row mechanical weeding in farmland.According to above characteristics,young weeds between seedlings can be removed by mechanical components that loosen or move the intra-row topsoil.So,the claw-tooth loosening depth has great influence on mechanical weeding performance.However,existing intra-row mechanical weeders still have problems with high rate of seedling injury and poor weeding effect due to its component loosening depth controlled by the depth wheel walking between the crop rows.It is impossible for weeding component to be kept stable loosening depth during intra-row mechanical weeding,which can lead to working depth variations.So the unreliable loosening depth control is one of the main reasons leading to the above problems during intra-row mechanical weeding.Thus,in order to improve the loosening depth control precision of working component of soybean intra-row mechanical weeding device,as well as to reduce the rate of injured seedlings and burial seedlings,a loosening depth automatic control method of intra-row mechanical weeding component based on ultrasonic distance measurement was proposed in this paper.On the basis of research and development of intra-row weeding mechanism,an automatic control system for loosening depth of weeding component was designed.And the loosening depth measurement and control test of the component was carried out on the built indoor intra-row weeding experimental platform.The main research contents and main results are as follows.(1)Designed a loosening depth control system of weeding component used on intra-row mechanical weeding mechanism and analyzed its working principle.Also,in order to avoid the effect of seedlings,weeds and so on to ultrasonic distance measurement,an independent sled profiling platform was designed.(2)Designed the hardware of automatic control system,and the selection of modules in hardware system was illustrated.Developed and designed system software,work flow of modules in software was introduced.Also,designed hydraulic pressure system and the type of component was selected.The correspondence between cylinder piston displacement and loosening depth variation was also analyzed used the graphical method.(3)Designed and simulated the circuit of automatic control system by electronic design and simulation software Proteus 8.6.The simulation results showed that the program file of automatic control system was without written error,there was no electrical error in connections between components,and the system could achieve its anticipated function and effect well.So the automatic control system was of good properties and could meet practical operation requirements.(4)Experimental study on component loosening depth automatic control system of intra-row mechanical weeding was conducted using static and dynamic test.Experimental results showed that it was not feasible to measure the distance of intra-row surface directly by ultrasonic module.In dynamic experiment,there were some defects in distance measuring on the surface with seedlings or without seedlings directly by ultrasonic sensor,and it was unaffected by seedlings,grass and soil properties on surface to use sled profiling platform.At the working speed of 0.278 m/s,0.556 m/s and 0.833 m/s,the average contrast errors of measured values were 4.95 mm,5.36 mm and 5.90 mm respectively,which were obtained by measuring with HC-SR04 ultrasonic module and manual measurement for the location of each sample point,and the maximum contrast errors were 6.6 mm,7.4 mm and 8.3 mm respectively.(5)Comprehensive performance test on weeding component loosening depth automatic control system was carried out.The experimental results showed that the control system could realize stable control in loosening depth of intra-row mechanical weeding component,and the depth range increased with the increasing of speed.At the traveling speed of 0.278 m/s,the loosening depth variation of component could be controlled in the range of ±10 mm at the zero point was 270 mm,which could meet the deep adjustment requirement of mechanical weeding.The research in this paper provided new thought to solve the problem for accurate control in loosening depth of intra-row weeding parts,and provided theory and method reference for the research and development of soybean intra-row weeder with automatic control in loosening depth.