| Sowing section control technology is a precision agricultural technology,which aims at minimizing the repeated operation area in the field and controls the start and stop of seed metering device differently.It can not only improve the crop yield in the field,but also greatly reduce the waste of improved seeds.The research on section control in China is relatively backward,which can not realize intelligent control,and the repeated operation in the field caused by uneven sowing lines cannot be improved.However,the section control system in foreign has some problems such as high price and technical blockade,which is not conducive to the development of agriculture in China.In view of the above problems,a method for precision sowing section control of electric drive is proposed,and a control system for precision sowing section of corn by electric drive with independent and automatic control of drill units is integrated and created.Specific research contents are as follows:(1)The electric drive precision seeding technology was studied.An electric-driven seed metering device was constructed and an electric-driven seeding method based on RTK speed measurement and DC brush motor drive was proposed,the mathematical model of motor speed,operating speed and grain spacing was established,and the scheme is based on the 20 cm target grain distance.At 4,6,8,and 10km/h operating speeds,the grain distance qualification indices are 99.60%,98.81%,98.81%,and 96.14%,respectively,and the coefficients of variation are11.70%,12.34%,17.02% and 19.04%,which meet the quality requirements of precision seeding operations,and have high seeding control accuracy and stability.(2)A Section control method based on electric drive seeding was proposed.The boundary acquisition method based on vehicle RTK and the area division method based on equidistant offset are constructed;the relative positional relationship between the receiver antenna and drill units in the process of straight-line seeding is analyzed,and a single positioning antenna multiunit positioning model is established to realize arbitrary positioning.In the working direction,the position of any drill unit is obtained based on the position of a single antenna;based on the ray method,an algorithm for discriminating the relative positional relationship between the drill units and field is established to determine the seeding state of the drill units at any time.(3)An electric drive seeding section control system based on STM32 controller was built.Based on electric drive seeding technology and section control method,programs such as data acquisition and extraction of receiver,status judgment of seeding unit and motor PID speed regulation are designed,and man-machine interface of vehicle terminal based on RS232 communication is designed to realize positioning model,configuration of seeding parameters and dynamic display of the drill unit position.(4)Bench and field tests were carried out.The bench test verifies the validity of the drill units positioning model and the state judgment of the drill units,in which the time-consuming algorithm for the state judgment of the drill units does not exceed 0.6ms.Field trials of sowing section control were carried out based on speed(4,5,6,7,8km/h),frequency of positioning data transmission(1,5,10Hz),angle of entry and exit(45,67.5 and 90 degrees).The test results show that the system has good control performance,with sowing lag between 0.56 m and 2.63 m and boundary fitting coefficient between 0.05 and 1.05. |
