Design And Research Of Drag-reduction Subsoiler And The Device Of Tillage Depth Detecting Based On Soil Dynamics

There is a solid hardpan under tillage layer because of the wider use of tillage equipment such as moldboard plough and rotary cultivator.It is difficult for the root of crop to grow and reach the deep soil and absorb the nutrients and water in deep soil,the causing the decrease of yield due to the existence of hardpan.Meanwhile,the hardpan impact the infiltration of water seriously which cause the runoff in soil surface easily in rainfall.Thus,it is of great significance to break the hardpan to increase crop yield and keep the soil and water in farmland.Subsoiling is a very effective method to break the hardpan.However,the subsoiler which as the key part in subsoiling has a high energy consumption because of the resistance from soil and hardpan.Besides,it is also difficult to obtain the information of tillage depth and keep the work quality when subsoiling.All of these reasons restrict the extension of subsoiling work severely.In order to resolve the issues of the high resistance and energy consumption as well as the information of tillage depth,this paper designs a curved and sweep subsoiler with lower resistance and a device to detect the tillage depth accurately,and the major research results are as following:(1)A layered soil model was established via element discrete method(EDM)and the interaction between subsoilers and soil was simulated to analyze the working resistance and soil disturbance.The parameters of EDM were calibrated after sample and test the soil in farmland.Then the working process of five subsoilers: straight shank with a chisel tine,straight shank with a sweep tine,curved shank with a chisel tine,curved shank with a sweep tine,and bent leg shank with a chisel tine were simulated.The results shows the software of EDM can simulate the working process of subsoiler effectively,and the results of simulation are constant with the results from field experiments.The shank of subsoiler has more influence on draught force and the draught force of subsoiler with straight shank is bigger than that of subsoiler with curved shank.The soil disturbance was affected by tine mainly,and the sweep tine has a strong influence on soil disturbance.The subsoiler with curved shank and sweep tine was selected as the research object of drag-reduction subsoiler.(2)The tillage mechanical model of subsoiler with curved shank and chisel tine was established.The working state and the type of soil disturbance were analyzed.The resistance of subsoiler with curved shank and chisel tine subsoiler were divided into soil cutting force,friction force and inertial force considering the subsoiler with curved shank and chisel tine will cut and uplift a wedge soil to a certain extent.Then the tillage mechanical model of subsoiler with curved shank and chisel tine was established based on the classical mechanics.Three drag-reduction subsoilers with curved shank and chisel tine were designed according to the genetic algorithm based the tillage mechanical model in order to minimize the specific resistance.Three drag-reduction subsoilers with curved shank and chisel tine were S-30,S-40 and S-50 which adapting to the 30 cm,40 cm and 50 cm tillage depth.(3)The tillage mechanical model was verified and the three drag-reduction subsoilers with curved shank and sweep were tested in field.The field experiment results showed that the tillage mechanical model can calculated the draft force and specific resistance accurately.In 30 cm,40 cm and 50 cm tillage depth,the correlation coefficient between the calculated draft force and measured draft force were 0.9912?0.9978 and 0.9885;the correlation coefficient between the calculated specific resistance and measured specific resistance were 0.9911?0.9987 and0.9903.Thus,relationship between the results from tillage mechanical model and results from field experiment was significant.The results of field experiment shows the draught force of S-30,S-40 and S-50 in the adapting depth were smaller 14.2%,11.7% and 6.6% than that of conventional subsoiler.The specific resistance of S-30,S-40 and S-50 in the design depth were also smaller 14.1%,15.6% and 17.5% than that of conventional subsoiler.These three subsoilers have good performance in drag-reduction and subsoiling efficiency.(4)A tillage depth detecting device based on Kalman filer and fusion algorithm was designed.An ultrasonic sensor and an infrared sensor were used to detect the tillage depth by time of flight and triangulation measurement in order to improve the accuracy and stability.The detecting data from two sensors were filtered and fused by Kalman filer and fusion algorithm.The results of field experiment shows the filtered and fused data has a good result in both even ground and straw mulching ground.In the tillage depth of 30 cm and 40 cm,the average of Kalman filtered and fused data were 30.06 cm and 39.95 cm,the coefficients f variation of tillage depth were 1.07% and 1.00%.The data after filtered and fused was close to the tillage depth manually.The tillage depth variation calculated from filtered and fused data can response the changing trend of actual tillage depth.