Research On Digging Depth Control System Of Digging-pulling Cassava Harvester

Cassava which also known as manioc cassava is one of the world's three largest potato crops.In our country,cassava is mainly planted in the tropics.Cassava is an important economic crop that is planted widely in the HanNan,GuangXi and FuJian province and its cultivated area is increasing year by year.The main harvesting method is manpower,which is very labor-intensive,time-consuming and inefficiency.Cassava mechanized harvesting is also a weak link in cassava industry.At present,no adaptable cassava harvester has been introduced to replace artificial harvest.In this paper,the digging and pulling cassava harvester is pulled by tractors during the harvest process,the digging shovel with a certain angle of inclination will have the trend towards the direction of deeper direction.For this problem,a test bed for digging depth control system is studied.The test bed can satisfy the rational control of digging depth of digging shovel.While ensuring it do not damage cassava,the power consumption of machines can also be reduced.The main research contents and conclusions are as follows:(1)By referring to the relevant data of agricultural machinery at home and abroad,methods for automatic control of contact soil part are used.Field research on the agronomic and biological characteristics of cassava cultivation.By studying on soil properties of cassava growing environment and parameters affecting traction resistance of digging shovel,this paper established mechanical model of digging shovel and soil-potato function and obtained the best dip angle conducive to excavating the ability of shoveling into soil and crushed soil.The overall control scheme of the designed excavation shovel control depth system and the best installation scheme on the complete machine are determined.(2)The mechanical structure of the digging depth control system of the digging and pulling cassava harvester includes the hydraulic shovel actuator and the surface profiling mechanism.By analyzing and comparing of the advantages and disadvantages of the angle adjustment methods of the cassava digging shovel,a depth adjustment mechanism suitable for the cassava digging device is designed.The three-dimensional model is established through SoildWorks and its size of each mechanism is determined.By analyzing the movement characteristics of the mechanism through adams,the results show that the hydraulic shovel actuator meets the action requirements.A reasonable surface profiling mechanism is designed and the distance from the ground is adjustable.The adjustment range is completely suitable for the use of the digging and pulling cassava harvester.By analyzing the profiling mechanism,the mathematical relationship between the profiling amount and the sensor detection angle is determined.(3)According to the profiling mechanism,a high precision Holzer angle sensor is selected and the surface profiling micro controller based on the STM32 minimum system is designed.The overall control scheme was determined and the test controller is conformed to the control requirements.(4)The hydraulic control system is designed.According to the working conditions of the hydraulic shovel actuator,the hydraulic components suitable for the whole system are selected.The hydraulic actuators are designed to meet the requirements through theoretical research and calculation.On the Amesim platform,the hydraulic control system is simulated and analyzed and the results show that the response time of the piston rod of the hydraulic cylinder and the angle adjusting cylinder is 0.5s and 1s respectively,which meet the demand for the response time of the digging depth control test.(5)Experimenting with performance of the surface profiling mechanism,the response of control system and performance of the digging depth control system.It turned out that Profiling amount is 10?120mm,the profiling accuracy of surface profiling mechanism was as high as 96.5%,the response time of control system is 1.7s,and the digging depth control system can automatically adjust the travel as the angle changes.