| At present,the rice precision acupoint direct seeding machine mainly relies on the ground wheel as the power driven seeding device for sowing,and the ground wheel slippage causes problems such as uneven seeding of the planter,missed sowing and low precision of plant spacing adjustment.In this paper,2BDH-10 rice precision acupoint direct seeding machine is taken as the research object,and an electric drive control system is designed to replace the traditional ground wheel drive seeding to realize automatic control and adjustment of seeding.This paper focuses on tractor speed measurement and stepping.The motor drive section was designed and rigged and field tested separately.The main research contents and conclusions are as follows:(1)Overall design of the electric drive seeding system.Through the research on the structure,sowing method,technical parameters and plant spacing control principle of 2BDH-10 rice precision acupoint direct seeding machine,the overall scheme design of automatic control system based on motor instead of ground wheel drive was determined.Including tractor speed measuring part,single-chip host controller,human-computer interaction,stepper motor drive and job speed limit alarm prompts.Among them,the speed limit alarm device is designed according to the principle of plant spacing control and the characteristics of the seed meter,which can avoid the problem of poor seeding effect caused by excessive working speed.(2)Design of tractor speed measuring device.Through the analysis of various speed sensors,it is determined that the GPS and Hall sensors are used for the tractor speed test.The GPS module speed measurement error range is 0.093～0.331km/h(0.026m/s～0.092m/s).The Hall sensor is compared with the theoretical speed measurement data by the actual test data.The deviation range is 0.01～0.67r/min,and the speed measurement error is ±0.108km/h.The Kalman filter-based filtering algorithm is designed to combine the GPS and Hall sensor speed signals to eliminate the system deviation of the Hall sensor,so that the speed value is more accurate and reliable.As the input of the electric drive signal,it is the next step.Drive control provides the foundation.(3)Design of the seed meter drive device.Through the comparison of the motor drive mode,the mode of driving the single seed meter by the small torque stepping motor was selected,and the corresponding driving device was selected to improve the original transmission structure of the seeding machine,and the small torque motor was designed and installed.The reliability of open-loop control of stepping motor is analyzed.The sowing test under various speed measuring methods with plant spacing as the evaluation index is proposed.The program flow chart of plant spacing parameter setting,seeding sowing and alarm is designed.(4)Field test of speed measurement system.The GPS,Hall sensor and Kalman filter were used to measure the three speed values.The maximum deviation and average deviation of the three different speed measurement modes at the average speed of 3.394km/h,4.2 km/h and 5km/h were analyzed.The test results show that the deviation after filtering is smaller than that of GPS and Hall sensor,the maximum deviation is 0.128 km/h,the minimum deviation is 0.004 km/h,the minimum standard deviation is 0.021km/h,and the maximum standard deviation is 0.052km/h,which indicates that it is processed by Kalman filter.The resulting optimal estimated speed value is more reliable.(5)Electric drive seeding system bench and field test.The bench test results showed that the average distance of the test plants was within the allowable range,and the variation coefficient of the plant spacing was less than 12%.In the field test,the speed signal processed by the Kalman filter was used to drive the seeding.When the working speed was 3.05km/h and 5.12km/h,the pass rate of the plant spacing was 12～24cm,which was above 88%,which could satisfy the filming.The quality of the drilling machine operation is standard,and the coefficient of variation is less than 11%.When the plant spacing is 20 cm,the rate of plant spacing is 85.13% and the coefficient of variation is 8.2% in the shifting operation of 3km/h 5.5km/h.In addition,comparing the GPS and Hall sensors to measure the speed and drive the seeding,and the speed is processed by the Kalman filter and then driven,the three-way method of uniform speed operation in different speed segments of 3～6km/h.The test results show that the seeding rate of the seedlings processed by the Kalman filter is higher than that of the GPS and Hall sensors,with a maximum of 96.47% and a coefficient of variation of 5.31%.The speed limit alarm is designed to respond when the motor speed exceeds 60r/min.The electric drive seeding system can meet the requirements of direct seeding of rice abundance. |
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